build(deps): bump grpc from 1.73.0 to 1.74.0

Bumps `grpc` from 1.73.0 to 1.74.0.

Updates `io.grpc:grpc-core` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-netty` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-protobuf` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-stub` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-grpclb` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-inprocess` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

Updates `io.grpc:grpc-util` from 1.73.0 to 1.74.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](https://github.com/grpc/grpc-java/compare/v1.73.0...v1.74.0)

---
updated-dependencies:
- dependency-name: io.grpc:grpc-core
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-netty
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-protobuf
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-stub
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-grpclb
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-inprocess
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.grpc:grpc-util
  dependency-version: 1.74.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,25 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+**Versions**
+- etcd: _add the etcd version here_
+- jetcd: _add the jetcd version here_
+- java: _add the java version here_
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps or reproducer to reproduce the behavior in a form of a unit test.
+This section *must* be provided, if not, the issue may not get attention since the maintainers have very limited capacity.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/dependabot.yml

@@ -0,0 +1,18 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: daily
+      time: "19:30"
+      timezone: Europe/Paris
+  - package-ecosystem: "gradle"
+    directory: "/"
+    schedule:
+      interval: daily
+      time: "19:30"
+      timezone: Europe/Paris
+    labels:
+      - area/dependencies
+    ignore:
+      - dependency-name: com.google.protobuf:protoc

.github/workflows/build-main.yml

@@ -0,0 +1,76 @@
+#
+# Copyright 2016-2023 The jetcd authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+name: Build and Publish (Snapshot)
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.sha }}
+  cancel-in-progress: true
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+  schedule:
+  - cron: "0 0 * * *"
+
+jobs:
+  checks:
+    uses: ./.github/workflows/checks.yml
+
+  build:
+    needs:
+      - checks
+    strategy:
+      matrix:
+        java-version:
+          - 11
+          - 17
+          - 21
+        etcd:
+          - quay.io/coreos/etcd:v3.5.21
+          - quay.io/coreos/etcd:v3.6.0
+    uses: ./.github/workflows/build.yml
+    with:
+      javaVersion: "${{ matrix.java-version }}"
+      etcdImage: "${{ matrix.etcd }}"
+
+  publish:
+    runs-on: ubuntu-latest
+    needs:
+      - build
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: 'Set Up Java'
+        uses: actions/setup-java@v4
+        with:
+          java-version: 11
+          distribution: 'temurin'
+          cache: 'gradle'
+      - name: 'Collect Info'
+        run: |
+          ./gradlew currentVersion
+      - name: 'Publish Snapshot'
+        if: github.event_name != 'schedule'
+        env:
+          NEXUS_USERNAME: ${{ secrets.OSSRH_USERNAME }}
+          NEXUS_PASSWORD: ${{ secrets.OSSRH_PASSWORD }}
+        run: |
+          ./gradlew publishToSonatype -Prelease.forceSnapshot

.github/workflows/build-master.yml

@@ -1,41 +0,0 @@
-#
-# Copyright 2016-2020 The jetcd authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-name: master
-
-on:
-  push:
-    branches:
-      - master
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-            fetch-depth: 0
-      - name: Set Up Java
-        uses: actions/setup-java@v1
-        with:
-          java-version: 1.8
-      - name: Build Project
-        env:
-          OSSRH_USERNAME: ${{ secrets. OSSRH_USERNAME }}
-          OSSRH_PASSWORD: ${{ secrets. OSSRH_PASSWORD }}
-        run: |
-          ./mvnw -V -ntp clean deploy -DskipTests -Pcheck-format --settings etc/mvn-deploy-settings.xml

.github/workflows/build-pr.yml

@@ -1,5 +1,5 @@
 #
-# Copyright 2016-2020 The jetcd authors
+# Copyright 2016-2023 The jetcd authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -16,24 +16,36 @@
 
 name: Build PR
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
 on:
   pull_request:
     branches:
-      - master
+      - main
+  workflow_dispatch:
 
 jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-            fetch-depth: 0
-      - name: Set Up Java
-        uses: actions/setup-java@v1
-        with:
-          java-version: 1.8
-      - name: Build Project
-        run: |
-          ./mvnw -V -ntp -Pcheck-format clean install
+  checks:
+    uses: ./.github/workflows/checks.yml
 
+  build:
+    needs:
+      - checks
+    strategy:
+      matrix:
+        java-version:
+          - 11
+          - 17
+          - 21
+        etcd:
+          - quay.io/coreos/etcd:v3.5.21
+          - quay.io/coreos/etcd:v3.6.0
+    uses: ./.github/workflows/build.yml
+    with:
+      javaVersion: "${{ matrix.java-version }}"
+      etcdImage: "${{ matrix.etcd }}"

.github/workflows/build.yml

@@ -0,0 +1,33 @@
+name: Build
+
+on:
+  workflow_call:
+    inputs:
+      javaVersion:
+        required: true
+        type: string
+      etcdImage:
+        required: true
+        type: string
+
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@v4
+      - name: 'Set Up Java'
+        uses: actions/setup-java@v4
+        with:
+          java-version: ${{ inputs.javaVersion }}
+          distribution: 'temurin'
+          cache: 'gradle'
+      - name: 'Build Project'
+        env:
+          ETCD_IMAGE: ${{ inputs.etcdImage }}
+        run: |
+          export TC_USER="$(id -u):$(id -g)"
+          echo "tc user -> $TC_USER"
+
+          ./gradlew test --info

.github/workflows/checks.yml

@@ -0,0 +1,37 @@
+name: Checks
+
+on:
+  workflow_call:
+
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: 'Set Up Java'
+        uses: actions/setup-java@v4
+        with:
+          java-version: 11
+          distribution: 'temurin'
+          cache: 'gradle'
+      - name: 'Run check task'
+        run: |
+          ./gradlew check -x test
+      - name: 'Run check script'
+        run: |
+          bash ./.github/workflows/scripts/precheck.sh
+        shell: bash
+
+  deps:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+    steps:
+      - name: 'Checkout'
+        uses: actions/checkout@v4
+      - name: 'Dependency Review'
+        uses: actions/dependency-review-action@v4

.github/workflows/scripts/precheck.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+failed=0
+
+# Check trailing whitespace
+files=$(find . -type f \
+    -not -path "./.git/*" \
+    -not -path "*/.gradle/*" \
+    -not -path "*/.idea/*" \
+    -not -path "*/.vscode/*" \
+    -not -path "*/build/*" \
+    -not -path "*/out/*" \
+    -not -path "*/bin/*" \
+    -not -name "*.jar" \
+    -not -name "*.java" \
+    -exec grep -E -l " +$" {} \;)
+
+count=0
+
+for file in $files; do
+    ((count++))
+    echo "$file"
+done
+
+if [ $count -ne 0 ]; then
+    failed=1
+    echo "Error: trailing whitespace(s) in the above $count file(s)"
+fi
+
+# Check newline
+files=$(find . -type f -size +0c \
+    -not -path "./.git/*" \
+    -not -path "*/.gradle/*" \
+    -not -path "*/.idea/*" \
+    -not -path "*/.vscode/*" \
+    -not -path "*/build/*" \
+    -not -path "*/out/*" \
+    -not -path "*/bin/*" \
+    -not -name "*.jar" \
+    -not -name "*.java" \
+    -exec bash -c 'if [[ $(tail -c1 "$0" | wc -l) -eq 0 ]]; then echo "$0"; fi' {} \;)
+
+count=0
+
+for file in $files; do
+    ((count++))
+    echo "$file"
+done
+
+if [ $count -ne 0 ]; then
+    failed=1
+    echo "Error: no newline in the above $count file(s)"
+fi
+
+exit $failed

.github/workflows/stale.yml

@@ -1,5 +1,5 @@
 #
-# Copyright 2016-2020 The jetcd authors
+# Copyright 2016-2023 The jetcd authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -24,15 +24,16 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/stale@v1
+    - uses: actions/stale@v9
       with:
         repo-token: ${{ secrets.GITHUB_TOKEN }}
         days-before-stale: 60
         days-before-close: 7
+        only-labels: 'waiting-for-feedbacks'
         stale-issue-label: stale
-        exempt-issue-label: never-stale
+        exempt-issue-labels: never-stale
         stale-pr-label: stale
-        exempt-pr-label: never-stale
+        exempt-pr-labels: never-stale
         stale-issue-message: |
           This issue is stale because it has been open 60 days with no activity.
           Remove stale label or comment or this will be closed in 7 days.

.gitignore

@@ -1,7 +1,7 @@
 .*
 !.github
 !.gitignore
-!.travis.yml
+!gradle/wrapper/gradle-wrapper.jar
 target/
 target-ide/
 *.iml
@@ -13,8 +13,6 @@ logs/
 .project
 .env
 .sdkmanrc
-
-# Created by './scripts/run_etcd.sh'
-/external/
+build/
 bin/
-/jetcd-all/dependency-reduced-pom.xml
+out/

.mvn/wrapper/MavenWrapperDownloader.java

@@ -1,107 +0,0 @@
-/*
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
-*/
-
-import java.util.Properties;
-
-public class MavenWrapperDownloader {
-
-    /**
-     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
-     */
-    private static final String DEFAULT_DOWNLOAD_URL =
-            "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.4.0/maven-wrapper-0.4.0.jar";
-
-    /**
-     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to
-     * use instead of the default one.
-     */
-    private static final String MAVEN_WRAPPER_PROPERTIES_PATH =
-            ".mvn/wrapper/maven-wrapper.properties";
-
-    /**
-     * Path where the maven-wrapper.jar will be saved to.
-     */
-    private static final String MAVEN_WRAPPER_JAR_PATH =
-            ".mvn/wrapper/maven-wrapper.jar";
-
-    /**
-     * Name of the property which should be used to override the default download url for the wrapper.
-     */
-    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";
-
-    public static void main(String args[]) {
-        System.out.println("- Downloader started");
-        File baseDirectory = new File(args[0]);
-        System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath());
-
-        // If the maven-wrapper.properties exists, read it and check if it contains a custom
-        // wrapperUrl parameter.
-        File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH);
-        String url = DEFAULT_DOWNLOAD_URL;
-        if(mavenWrapperPropertyFile.exists()) {
-            FileInputStream mavenWrapperPropertyFileInputStream = null;
-            try {
-                mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile);
-                Properties mavenWrapperProperties = new Properties();
-                mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream);
-                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url);
-            } catch (IOException e) {
-                System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
-            } finally {
-                try {
-                    if(mavenWrapperPropertyFileInputStream != null) {
-                        mavenWrapperPropertyFileInputStream.close();
-                    }
-                } catch (IOException e) {
-                    // Ignore ...
-                }
-            }
-        }
-        System.out.println("- Downloading from: : " + url);
-
-        File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH);
-        if(!outputFile.getParentFile().exists()) {
-            if(!outputFile.getParentFile().mkdirs()) {
-                System.out.println(
-                        "- ERROR creating output direcrory '" + outputFile.getParentFile().getAbsolutePath() + "'");
-            }
-        }
-        System.out.println("- Downloading to: " + outputFile.getAbsolutePath());
-        try {
-            downloadFileFromURL(url, outputFile);
-            System.out.println("Done");
-            System.exit(0);
-        } catch (Throwable e) {
-            System.out.println("- Error downloading");
-            e.printStackTrace();
-            System.exit(1);
-        }
-    }
-
-    private static void downloadFileFromURL(String urlString, File destination) throws Exception {
-        URL website = new URL(urlString);
-        ReadableByteChannel rbc;
-        rbc = Channels.newChannel(website.openStream());
-        FileOutputStream fos = new FileOutputStream(destination);
-        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
-        fos.close();
-        rbc.close();
-    }
-
-}

.mvn/wrapper/maven-wrapper.properties

@@ -1 +0,0 @@
-distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip

CONTRIBUTING.md

@@ -4,7 +4,7 @@ jetcd is Apache 2.0 licensed and accepts contributions via GitHub pull requests.
 
 # Email and chat
 
-- Email: [etcd-dev](https://groups.google.com/forum/?hl=en#!forum/etcd-dev)
+- Email: [etcd-dev](https://groups.google.com/g/etcd-dev)
 - IRC: #[etcd](irc://irc.freenode.org:6667/#etcd) IRC channel on freenode.org
 
 ## Getting started
@@ -25,7 +25,7 @@ This is a rough outline of what a contributor's workflow looks like:
 - Make sure commit messages are in the proper format (see below).
 - Push changes in a topic branch to a personal fork of the repository.
 - Submit a pull request to etcd-io/jetcd.
-- The PR must receive a LGTM from at least one maintainer found in the [MAINTAINERS](https://github.com/etcd-io/etcd/blob/master/MAINTAINERS) file.
+- The PR must receive a LGTM from at least one maintainer found in the [OWNERS](https://github.com/etcd-io/jetcd/blob/main/OWNERS) file.
 
 Thanks for contributing!
 
@@ -40,7 +40,7 @@ Please follow this style to make jetcd easy to review, maintain, and develop.
 To make sure CI checks would pass please run
 
 ```bash
-./mvnw license:format
+./gradlew spotlessApply
 ```
 
 and including any changes in PR before opening it.

MAINTAINERS

@@ -1,5 +0,0 @@
-Fanmin Shi <fanmin.shi@coreos.com> (@fanminshi) pkg:*
-Luca Burgazzoli <lburgazzoli@gmail.com> (@lburgazzoli) pkg:*
-Xiang Li <xiang.li@coreos.com> (@xiang90) pkg:*
-Anthony Romano <anthony.romano@coreos.com> (@heyitsanthony) pkg:*
-

OWNERS

@@ -0,0 +1,6 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+  - fanminshi       # Fanmin Shi <fanmin.shi@coreos.com>
+  - lburgazzoli     # Luca Burgazzoli <lburgazzoli@gmail.com>
+  - vorburger       # Michael Vorburger <mike@vorburger.ch>

README.md

@@ -1,8 +1,7 @@
 # jetcd - A Java Client for etcd
-[![Build Status](https://github.com/etcd-io/jetcd/workflows/master/badge.svg)](https://github.com/etcd-io/jetcd/actions)
+[![Build Status](https://github.com/etcd-io/jetcd/actions/workflows/build-main.yml/badge.svg)](https://github.com/etcd-io/jetcd/actions)
 [![License](https://img.shields.io/badge/Licence-Apache%202.0-blue.svg?style=flat-square)](http://www.apache.org/licenses/LICENSE-2.0.html)
 [![Maven Central](https://img.shields.io/maven-central/v/io.etcd/jetcd-core.svg?style=flat-square)](https://search.maven.org/#search%7Cga%7C1%7Cio.etcd)
-[![GitHub release](https://img.shields.io/github/release/etcd-io/jetcd.svg?style=flat-square)](https://github.com/etcd-io/jetcd/releases)
 [![Javadocs](http://www.javadoc.io/badge/io/etcd/jetcd-core.svg)](https://javadoc.io/doc/io.etcd/jetcd-core)
 
 jetcd is the official java client for [etcd](https://github.com/etcd-io/etcd) v3.
@@ -11,7 +10,7 @@ jetcd is the official java client for [etcd](https://github.com/etcd-io/etcd) v3
 
 ## Java Versions
 
-Java 8 or above is required.
+Java 11 or above is required.
 
 ## Download
 
@@ -24,23 +23,31 @@ Java 8 or above is required.
 </dependency>
 ```
 
-Development snapshots are available in [Sonatypes's snapshot repository](https://oss.sonatype.org/content/repositories/snapshots/io/etcd).
+Development snapshots are available in [Sonatypes's snapshot repository](https://oss.sonatype.org/content/repositories/snapshots/io/etcd/).
 
 ### Gradle
 
 ```
 dependencies {
-    compile "io.etcd:jetcd-core:$jetcd-version"
+    implementation "io.etcd:jetcd-core:$jetcd-version"
 }
 ```
 
 ### Usage
 
 ```java
-// create client
-Client client = Client.builder().endpoints("http://localhost:2379").build();
-KV kvClient = client.getKVClient();
+// create client using endpoints
+Client client = Client.builder().endpoints("http://etcd0:2379", "http://etcd1:2379", "http://etcd2:2379").build();
+```
 
+```java
+// create client using target which enable using any name resolution mechanism provided
+// by grpc-java (i.e. dns:///foo.bar.com:2379)
+Client client = Client.builder().target("ip:///etcd0:2379,etcd1:2379,etcd2:2379").build();
+```
+
+```java
+KV kvClient = client.getKVClient();
 ByteSequence key = ByteSequence.from("test_key".getBytes());
 ByteSequence value = ByteSequence.from("test_value".getBytes());
 
@@ -56,12 +63,13 @@ GetResponse response = getFuture.get();
 // delete the key
 kvClient.delete(key).get();
 ```
+To build one ssl secured client, refer to [secured client config](docs/SslConfig.md).
 
-For full etcd v3 API, plesase refer to [API_Reference](https://github.com/etcd-io/etcd/blob/master/Documentation/dev-guide/api_reference_v3.md).
+For full etcd v3 API, plesase refer to the [official API documentation](https://etcd.io/docs/current/learning/api/).
 
 ### Examples
 
-The [examples](https://github.com/etcd-io/jetcd/tree/master/jetcd-examples) are standalone projects that show usage of jetcd.
+The [jetcd-ctl](https://github.com/etcd-io/jetcd/tree/master/jetcd-ctl) is a standalone projects that show usage of jetcd.
 
 ## Launcher
 
@@ -69,12 +77,15 @@ The `io.etcd:jetcd-test` offers a convenient utility to programmatically start &
 
 ```java
 import io.etcd.jetcd.Client;
-import io.etcd.jetcd.launcher.EtcdCluster;
 import io.etcd.jetcd.test.EtcdClusterExtension;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
-@RegisterExtension static final EtcdCluster etcd = new EtcdClusterExtension("test-etcd", 1);
-Client client = Client.builder().endpoints(etcd.getClientEndpoints()).build();
+@RegisterExtension
+public static final EtcdClusterExtension cluster = EtcdClusterExtension.builder()
+        .withNodes(1)
+        .build();
+
+Client client = Client.builder().endpoints(cluster.clientEndpoints()).build();
 ```
 
 This launcher uses the Testcontainers framework.
@@ -88,10 +99,10 @@ The current major version is zero (0.y.z). Anything may change at any time. The
 
 ## Build from source
 
-The project can be built with [Apache Maven](https://maven.apache.org/):
+The project can be built with [Gradle](https://gradle.org/):
 
 ```
-mvn clean install -DskipTests
+./gradlew compileJava
 ```
 
 ## Running tests
@@ -99,33 +110,8 @@ mvn clean install -DskipTests
 The project is tested against a three node `etcd` setup started with the Launcher (above) :
 
 ```sh
-$ mvn test
-...
-
-[INFO]  T E S T S
-[INFO] -------------------------------------------------------
-[INFO] Running TestSuite
-[WARNING] Tests run: 104, Failures: 0, Errors: 0, Skipped: 3, Time elapsed: 31.308 s - in TestSuite
-[INFO]
-[INFO] Results:
-[INFO]
-[WARNING] Tests run: 104, Failures: 0, Errors: 0, Skipped: 3
-...
-[INFO] Reactor Summary:
-[INFO]
-[INFO] jetcd .............................................. SUCCESS [  0.010 s]
-[INFO] jetcd-core ......................................... SUCCESS [ 55.480 s]
-[INFO] jetcd-discovery-dns-srv ............................ SUCCESS [  3.225 s]
-[INFO] jetcd-watch-example ................................ SUCCESS [  0.291 s]
-[INFO] jetcd-simple-ctl ................................... SUCCESS [  0.028 s]
-[INFO] jetcd-examples ..................................... SUCCESS [  0.000 s]
-[INFO] ------------------------------------------------------------------------
-[INFO] BUILD SUCCESS
-[INFO] ------------------------------------------------------------------------
-[INFO] Total time: 59.929 s
-[INFO] Finished at: 2018-02-13T12:51:13-08:00
-[INFO] Final Memory: 84M/443M
-````
+$ ./gradlew test
+```
 
 ### Troubleshooting
 
@@ -133,17 +119,14 @@ It recommmonds building the project before running tests so that you have artifa
 
 ## Contact
 
-* Mailing list: [etcd-dev](https://groups.google.com/forum/?hl=en#!forum/etcd-dev)
-* IRC: #[etcd](irc://irc.freenode.org:6667/#etcd) on freenode.org
+* Mailing list: [etcd-dev](https://groups.google.com/g/etcd-dev)
 
 ## Contributing
 
 See [CONTRIBUTING](https://github.com/etcd-io/jetcd/blob/master/CONTRIBUTING.md) for details on submitting patches and the contribution workflow.
 
-## Reporting bugs
-
-See [reporting bugs](https://github.com/etcd-io/etcd/blob/master/Documentation/reporting-bugs.md) for details about reporting any issues.
-
 ## License
 
 jetcd is under the Apache 2.0 license. See the [LICENSE](https://github.com/etcd-io/jetcd/blob/master/LICENSE) file for details.
+
+

build.gradle

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+buildscript {
+    repositories {
+        gradlePluginPortal()
+    }
+    dependencies {
+        classpath "com.github.ben-manes:gradle-versions-plugin:${libs.versions.versionsPlugin.get()}"
+        classpath "com.diffplug.spotless:spotless-plugin-gradle:${libs.versions.spotlessPlugin.get()}"
+        classpath "net.ltgt.gradle:gradle-errorprone-plugin:${libs.versions.errorPronePlugin.get()}"
+        classpath "io.github.gradle-nexus:publish-plugin:${libs.versions.nexusPublishPlugin.get()}"
+        classpath "com.adarshr:gradle-test-logger-plugin:${libs.versions.testLoggerPlugin.get()}"
+        classpath "pl.allegro.tech.build:axion-release-plugin:${libs.versions.axionReleasePlugin.get()}"
+        classpath "org.gradle:test-retry-gradle-plugin:${libs.versions.testRetryPlugin.get()}"
+    }
+}
+
+apply from: "${rootProject.projectDir}/gradle/versions.gradle"
+apply from: "${rootProject.projectDir}/gradle/publish.gradle"
+apply from: "${rootProject.projectDir}/gradle/release.gradle"
+
+group = 'io.etcd'
+
+allprojects {
+    repositories {
+        mavenLocal()
+        mavenCentral()
+    }
+}
+
+subprojects {
+    apply from: "${rootProject.projectDir}/gradle/style.gradle"
+    apply from: "${rootProject.projectDir}/gradle/quality.gradle"
+    apply from: "${rootProject.projectDir}/gradle/publishing-release.gradle"
+    apply from: "${rootProject.projectDir}/gradle/publishing-release-tasks.gradle"
+
+    apply plugin: 'java-library'
+    apply plugin: 'com.adarshr.test-logger'
+    apply plugin: 'org.gradle.test-retry'
+
+    configurations.api {
+        exclude group: 'com.google.code.gson', module: 'gson'
+        exclude group: 'com.google.android', module: 'annotations'
+        exclude group: 'com.google.j2objc', module: 'j2objc-annotations'
+        exclude group: 'org.codehaus.mojo', module: 'animal-sniffer-annotations'
+        exclude group: 'com.google.errorprone', module: 'error_prone_annotations'
+        exclude group: 'com.google.code.findbugs', module: 'jsr305'
+        exclude group: 'org.checkerframework', module: 'checker-compat-qual'
+    }
+
+    compileJava {
+        options.release = 11
+    }
+
+    test {
+        useJUnitPlatform()
+
+        maxParallelForks = Runtime.runtime.availableProcessors() ?: 1
+
+        retry {
+            maxRetries = 1
+            maxFailures = 5
+        }
+    }
+    testing {
+        suites {
+            test {
+                useJUnitJupiter()
+            }
+        }
+    }
+
+    testlogger {
+        theme 'mocha-parallel'
+        showStandardStreams false
+    }
+
+    tasks.register('allDeps', DependencyReportTask)
+
+    tasks.withType(AbstractArchiveTask).configureEach {
+        preserveFileTimestamps = false
+        reproducibleFileOrder = true
+    }
+}
+
+

code-of-conduct.md

@@ -1,61 +1,3 @@
-## CoreOS Community Code of Conduct
+## etcd Community Code of Conduct
 
-### Contributor Code of Conduct
-
-As contributors and maintainers of this project, and in the interest of
-fostering an open and welcoming community, we pledge to respect all people who
-contribute through reporting issues, posting feature requests, updating
-documentation, submitting pull requests or patches, and other activities.
-
-We are committed to making participation in this project a harassment-free
-experience for everyone, regardless of level of experience, gender, gender
-identity and expression, sexual orientation, disability, personal appearance,
-body size, race, ethnicity, age, religion, or nationality.
-
-Examples of unacceptable behavior by participants include:
-
-* The use of sexualized language or imagery
-* Personal attacks
-* Trolling or insulting/derogatory comments
-* Public or private harassment
-* Publishing others' private information, such as physical or electronic addresses, without explicit permission
-* Other unethical or unprofessional conduct.
-
-Project maintainers have the right and responsibility to remove, edit, or
-reject comments, commits, code, wiki edits, issues, and other contributions
-that are not aligned to this Code of Conduct. By adopting this Code of Conduct,
-project maintainers commit themselves to fairly and consistently applying these
-principles to every aspect of managing this project. Project maintainers who do
-not follow or enforce the Code of Conduct may be permanently removed from the
-project team.
-
-This code of conduct applies both within project spaces and in public spaces
-when an individual is representing the project or its community.
-
-Instances of abusive, harassing, or otherwise unacceptable behavior may be
-reported by contacting a project maintainer, Brandon Philips
-<brandon.philips@coreos.com>, and/or Rithu John <rithu.john@coreos.com>.
-
-This Code of Conduct is adapted from the Contributor Covenant
-(http://contributor-covenant.org), version 1.2.0, available at
-http://contributor-covenant.org/version/1/2/0/
-
-### CoreOS Events Code of Conduct
-
-CoreOS events are working conferences intended for professional networking and
-collaboration in the CoreOS community. Attendees are expected to behave
-according to professional standards and in accordance with their employer’s
-policies on appropriate workplace behavior.
-
-While at CoreOS events or related social networking opportunities, attendees
-should not engage in discriminatory or offensive speech or actions including
-but not limited to gender, sexuality, race, age, disability, or religion.
-Speakers should be especially aware of these concerns.
-
-CoreOS does not condone any statements by speakers contrary to these standards.
-CoreOS reserves the right to deny entrance and/or eject from an event (without
-refund) any individual found to be engaging in discriminatory or offensive
-speech or actions.
-
-Please bring any concerns to the immediate attention of designated on-site
-staff, Brandon Philips <brandon.philips@coreos.com>, and/or Rithu John <rithu.john@coreos.com>.
+etcd follows the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md).

docs/KeyVal.adoc

@@ -26,6 +26,3 @@ for (KeyValue kv : response.getKvs()) {
     );
 }
 ----
-
-
-

docs/Lease.md

@@ -46,7 +46,7 @@ The Lease interface provides methods to grant, revoke, and keepalive leases.
 1. This function is called periodically by `keepAliveSchedule`.
 2. The lease may expire as:
      * The etcd respond overtime.
-     * The client faile to send request in time.
+     * The client fails to send request in time.
 3. It will scan the keepAlives map and find the leases that requires keepAlive requests to send based on its nextKeepAliveTime.
 4. Send request to the StreamObserver for these leases.
 

docs/RELEASE.adoc

@@ -0,0 +1,21 @@
+= Release
+
++
+[source,shell]
+----
+$ ./gradlew currentVersion
+Project version: 0.7.5-SNAPSHOT
+
+$ ./gradlew release
+
+$ git tag
+jetcd-0.7.5
+
+$ ./gradlew currentVersion
+Project version: 0.7.5
+
+$ ./gradlew publish
+published jetcd-0.7.5 release version
+
+$ ./gradlew markNextVersion -Prelease.version=0.7.6
+----

docs/SslConfig.md

@@ -0,0 +1,36 @@
+# How to Build Jectd Client for One TLS Secured Etcd Cluster
+
+# prepare certification files
+
+If your etcd cluster is installed using [etcdadm](https://github.com/kubernetes-sigs/etcdadm), you are likely to find
+certification files in the path `/etc/etcd/pki/`: `ca.crt`, `etcdctl-etcd-client.key`, `etcdctl-etcd-client.crt`.
+
+If your etcd cluster is the builtin etcd in one kubernetes cluster(
+using [kubeadm](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/setup-ha-etcd-with-kubeadm/)),
+
+you can find the same files in `/etc/kubernetes/pki/etcd/`: `ca.crt`, `healthcheck-client.crt`, `healthcheck-client.key`.
+
+Because `SslContextBuilder` only support a PKCS#8 private key file in PEM format, convert  `etcdctl-etcd-client.key`
+to `etcdctl-etcd-client.key.pem` according
+to [netty SslContextBuilder doc](https://netty.io/wiki/sslcontextbuilder-and-private-key.html).
+
+# build jetcd client
+
+```
+        File cert = new File("ca.crt");
+        File keyCertChainFile = new File("etcdctl-etcd-client.crt");
+        File keyFile = new File("etcdctl-etcd-client.key.pem");
+        SslContext context = GrpcSslContexts.forClient()
+                .trustManager(cert)
+                .keyManager(keyCertChainFile, keyFile)
+                .build();
+        Client client = Client.builder()
+                .endpoints("https://10.168.168.66:2379")
+                .sslContext(context)
+                .build();
+
+        client.getClusterClient().listMember().get().getMembers().forEach(member -> {
+            logger.info("member: {}", member);
+        });
+
+```

docs/Watch.md

@@ -12,9 +12,11 @@ The Watch provide methods to watch on a key interval and cancel a watcher. If th
 
 4. Cancel watch request, the etcd client should process watch cancellation and filter all the notification after cancellation request.
 
+5. The watch client should be able to make a progress notify request that propagates the latest revision number to all watches.
+
 # Implementation
 
-The etcd client process watch request with [watch function](#watch-function), process notification with [processEvents function](#processevents-function) , process resume with [resume function](#resume-function) and process cancel with [cancelWatch function](#cancelwatch-function).
+The etcd client process watch request with [watch function](#watch-function), process notification with [processEvents function](#processevents-function), process resume with [resume function](#resume-function), process cancel with [cancelWatch function](#cancelwatch-function) and request progress with [requestProgress function](#requestProgress-function).
 
 ## watch function
 
@@ -44,6 +46,13 @@ Cancel the watch task with the watcher, the `onCanceled` will be called after su
 1. The watcher will be removed from [watchers](#watchers-instance) map.
 2. If the [watchers](#watchers-instance) map contain the watcher, it will be moved to [cancelWatchers](#cancelwatchers) and send cancel request to [requestStream](#requeststream-instance).
 
+## requestProgress function
+
+Send the latest revision processed to all active [watchers](#watchers-instance)
+
+1. Send a progress request to [requestStream](#requeststream-instance).
+2. Working watchers will receive a WatchResponse containing the latest revision number. All future revision numbers are guaranteed to be greater than or equal to the received revision number.
+
 ## requestStream instance
 
 StreamObserver instance

etc/eclipse-formatter-config.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright 2016-2020 The jetcd authors
+    Copyright 2016-2023 The jetcd authors
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -88,7 +88,6 @@
         <setting id="org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_cases" value="true"/>
         <setting id="org.eclipse.jdt.core.formatter.indent_switchstatements_compare_to_switch" value="true"/>
         <setting id="org.eclipse.jdt.core.formatter.indentation.size" value="8"/>
-        <setting id="org.eclipse.jdt.core.formatter.insert_new_line_after_annotation" value="insert"/>
         <setting id="org.eclipse.jdt.core.formatter.insert_new_line_after_opening_brace_in_array_initializer" value="do not insert"/>
         <setting id="org.eclipse.jdt.core.formatter.insert_new_line_at_end_of_file_if_missing" value="insert"/>
         <setting id="org.eclipse.jdt.core.formatter.insert_new_line_before_catch_in_try_statement" value="do not insert"/>
@@ -272,4 +271,3 @@
         <setting id="org.eclipse.jdt.core.formatter.enabling_tag" value="CHECKSTYLE:ON"/>
     </profile>
 </profiles>
-

etc/eclipse.importorder

@@ -0,0 +1,7 @@
+0=java
+1=javax
+2=org
+2=io
+4=com
+5=
+6=\#

etc/license-formatting.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright 2016-2020 The jetcd authors
+    Copyright 2016-2021 The jetcd authors
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.

etc/license.txt

@@ -1,4 +1,4 @@
-Copyright ${license.git.copyrightYears} The jetcd authors
+Copyright $YEAR The jetcd authors
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.

etc/mvn-deploy-settings.xml

@@ -1,33 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!--
-
-    Copyright 2016-2020 The jetcd authors
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-        http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
-
--->
-<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
-          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-          xsi:schemaLocation="
-            http://maven.apache.org/SETTINGS/1.0.0
-            http://maven.apache.org/xsd/settings-1.0.0.xsd">
-
-  <servers>
-    <server>
-      <id>ossrh</id>
-      <username>${env.OSSRH_USERNAME}</username>
-      <password>${env.OSSRH_PASSWORD}</password>
-    </server>
-  </servers>
-
-</settings>

etc/pmd-ruleset.xml

@@ -0,0 +1,93 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright 2016-2023 The jetcd authors
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+-->
+<ruleset name="PMD-Rules"
+         xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
+
+    <description>PMD Rules that govern static code analysis for jetcd</description>
+
+    <exclude-pattern>.*/io/etcd/jetcd/api/.*</exclude-pattern>
+
+    <rule ref="category/java/bestpractices.xml/AvoidUsingHardCodedIP"/>
+    <rule ref="category/java/bestpractices.xml/UnusedFormalParameter"/>
+    <rule ref="category/java/bestpractices.xml/UnusedLocalVariable"/>
+    <rule ref="category/java/bestpractices.xml/UnusedPrivateField"/>
+    <rule ref="category/java/bestpractices.xml/UnusedPrivateMethod"/>
+    <rule ref="category/java/bestpractices.xml/OneDeclarationPerLine"/>
+    <rule ref="category/java/bestpractices.xml/UseCollectionIsEmpty"/>
+    <rule ref="category/java/bestpractices.xml/PreserveStackTrace"/>
+    <rule ref="category/java/bestpractices.xml/SimplifiableTestAssertion" />
+
+    <rule ref="category/java/codestyle.xml/ExtendsObject"/>
+    <rule ref="category/java/codestyle.xml/ForLoopShouldBeWhileLoop"/>
+    <rule ref="category/java/codestyle.xml/UnnecessaryFullyQualifiedName"/>
+    <rule ref="category/java/codestyle.xml/UnnecessaryModifier"/>
+    <rule ref="category/java/codestyle.xml/UnnecessaryReturn"/>
+    <rule ref="category/java/codestyle.xml/UselessParentheses"/>
+    <rule ref="category/java/codestyle.xml/UselessQualifiedThis"/>
+    <rule ref="category/java/codestyle.xml/ControlStatementBraces"/>
+    <rule ref="category/java/codestyle.xml/UnnecessaryImport"/>
+    <rule ref="category/java/codestyle.xml/EmptyControlStatement"/>
+
+    <rule ref="category/java/design.xml/FinalFieldCouldBeStatic">
+        <priority>4</priority>
+    </rule>
+    <rule ref="category/java/design.xml/SimplifiedTernary">
+        <priority>4</priority>
+    </rule>
+    <rule ref="category/java/design.xml/CollapsibleIfStatements">
+        <priority>4</priority>
+    </rule>
+    <rule ref="category/java/design.xml/UselessOverridingMethod">
+        <priority>4</priority>
+    </rule>
+
+    <rule ref="category/java/errorprone.xml/AvoidBranchingStatementAsLastInLoop"/>
+    <rule ref="category/java/errorprone.xml/AvoidMultipleUnaryOperators"/>
+    <rule ref="category/java/errorprone.xml/AvoidUsingOctalValues"/>
+    <rule ref="category/java/errorprone.xml/BrokenNullCheck"/>
+    <rule ref="category/java/errorprone.xml/ClassCastExceptionWithToArray"/>
+    <rule ref="category/java/errorprone.xml/DontUseFloatTypeForLoopIndices"/>
+
+    <rule ref="category/java/errorprone.xml/EmptyCatchBlock">
+        <priority>4</priority>
+        <properties>
+            <property name="allowCommentedBlocks" value="true"/>
+            <property name="allowExceptionNameRegex" value="ignored"/>
+        </properties>
+    </rule>
+
+    <rule ref="category/java/errorprone.xml/JumbledIncrementer"/>
+    <rule ref="category/java/errorprone.xml/MisplacedNullCheck"/>
+    <rule ref="category/java/errorprone.xml/OverrideBothEqualsAndHashcode"/>
+    <rule ref="category/java/errorprone.xml/ReturnFromFinallyBlock"/>
+    <rule ref="category/java/errorprone.xml/UnconditionalIfStatement"/>
+    <rule ref="category/java/errorprone.xml/UnnecessaryConversionTemporary"/>
+    <rule ref="category/java/errorprone.xml/UnusedNullCheckInEquals"/>
+    <rule ref="category/java/errorprone.xml/UselessOperationOnImmutable"/>
+    <rule ref="category/java/errorprone.xml/ConstructorCallsOverridableMethod"/>
+    <rule ref="category/java/errorprone.xml/DoNotTerminateVM"/>
+
+    <rule ref="category/java/multithreading.xml/AvoidThreadGroup"/>
+    <rule ref="category/java/multithreading.xml/DontCallThreadRun"/>
+
+    <rule ref="category/java/performance.xml/BigIntegerInstantiation"/>
+    <rule ref="category/java/bestpractices.xml/PrimitiveWrapperInstantiation" />
+</ruleset>

etc/versions-rules.xml

@@ -1,35 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!--
-
-    Copyright 2016-2020 The jetcd authors
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-        http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
-
--->
-<ruleset xmlns="http://mojo.codehaus.org/versions-maven-plugin/rule/2.0.0"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    comparisonMethod="maven"
-    xsi:schemaLocation="http://mojo.codehaus.org/versions-maven-plugin/rule/2.0.0 http://mojo.codehaus.org/versions-maven-plugin/xsd/rule-2.0.0.xsd">
-    <ignoreVersions>
-        <!-- Ignore Alpha's, Beta's, release candidates and milestones -->
-        <ignoreVersion type="regex">(?i).*Alpha(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*a(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*Beta(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*-B(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*RC(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*CR(?:-?\d+)?</ignoreVersion>
-        <ignoreVersion type="regex">(?i).*M(?:-?\d+)?</ignoreVersion>
-    </ignoreVersions>
-    <rules>
-    </rules>
-</ruleset>

gradle.properties

@@ -0,0 +1,10 @@
+#
+# project
+#
+gitProject  = https://github.com/etcd-io/jetcd
+gitURL      = git@github.com/etcd-io/jetcd.git
+
+#
+# gradle
+#
+org.gradle.parallel = true

gradle/libs.versions.toml

@@ -0,0 +1,86 @@
+[versions]
+grpc = "1.74.0"
+log4j = "2.25.1"
+mockito = "5.18.0"
+slf4j = "2.0.17"
+guava = "33.4.8-jre"
+assertj = "3.27.3"
+junit = "5.13.4"
+testcontainers = "1.21.3"
+protoc = "3.25.1"
+failsafe = "3.3.2"
+awaitility = "4.3.0"
+commonsIo = "2.20.0"
+commonCompress = "1.28.0"
+autoService = "1.1.1"
+errorprone = "2.30.0"
+vertx = "5.0.1"
+picocli = "4.7.7"
+restAssured = "5.5.5"
+javaxAnnotation = "1.3.2"
+
+versionsPlugin = "0.52.0"
+errorPronePlugin = "4.0.1"
+spotlessPlugin = "6.25.0"
+shadowPlugin = "8.1.1"
+testLoggerPlugin = "4.0.0"
+protobufPlugin = "0.9.5"
+nexusPublishPlugin = "2.0.0"
+axionReleasePlugin = "1.18.17"
+testRetryPlugin = "1.6.2"
+
+
+[libraries]
+slf4j = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
+guava = { module = "com.google.guava:guava", version.ref = "guava" }
+assertj = { module = "org.assertj:assertj-core", version.ref = "assertj" }
+junit = { module = "org.junit.jupiter:junit-jupiter", version.ref = "junit" }
+testcontainers = { module = "org.testcontainers:testcontainers", version.ref = "testcontainers" }
+protoc = { module = "com.google.protobuf:protoc", version.ref = "protoc" }
+failsafe = { module = "dev.failsafe:failsafe", version.ref = "failsafe" }
+awaitility = { module = "org.awaitility:awaitility", version.ref = "awaitility" }
+picocli  = { module = "info.picocli:picocli", version.ref = "picocli"}
+restAssured = { module = "io.rest-assured:rest-assured", version.ref = "restAssured"}
+
+commonsIo = { module = "commons-io:commons-io", version.ref = "commonsIo" }
+commonsCompress = { module = "org.apache.commons:commons-compress", version.ref = "commonCompress" }
+
+mockitoCore = { module = "org.mockito:mockito-core", version.ref = "mockito" }
+mockitoJunit = { module = "org.mockito:mockito-junit-jupiter", version.ref = "mockito" }
+
+grpcCore = { module = "io.grpc:grpc-core", version.ref = "grpc" }
+grpcNetty = { module = "io.grpc:grpc-netty", version.ref = "grpc" }
+grpcProtobuf = { module = "io.grpc:grpc-protobuf", version.ref = "grpc" }
+grpcStub = { module = "io.grpc:grpc-stub", version.ref = "grpc" }
+grpcGrpclb = { module = "io.grpc:grpc-grpclb", version.ref = "grpc" }
+grpcInprocess = { module = "io.grpc:grpc-inprocess", version.ref = "grpc" }
+grpcUtil = { module = "io.grpc:grpc-util", version.ref = "grpc" }
+
+vertxGrpc = { module = "io.vertx:vertx-grpc", version.ref = "vertx" }
+
+log4jApi = { module = "org.apache.logging.log4j:log4j-api", version.ref = "log4j" }
+log4jCore = { module = "org.apache.logging.log4j:log4j-core", version.ref = "log4j" }
+log4jSlf4j = { module = "org.apache.logging.log4j:log4j-slf4j2-impl", version.ref = "log4j" }
+log4j12 = { module = "org.apache.logging.log4j:log4j-1.2-api", version.ref = "log4j" }
+
+autoServiceAnnotations = { module = "com.google.auto.service:auto-service-annotations", version.ref = "autoService"}
+autoServiceProcessor = { module = "com.google.auto.service:auto-service", version.ref = "autoService"}
+
+javaxAnnotation = { module = "javax.annotation:javax.annotation-api", version.ref = "javaxAnnotation" }
+
+errorprone = { module = "com.google.errorprone:error_prone_core", version.ref = "errorprone" }
+errorproneAnnotations = { module = "com.google.errorprone:error_prone_annotations", version.ref = "errorprone" }
+errorproneJavac = { module = "com.google.errorprone:javac", version = "9+" }
+
+[bundles]
+grpc     = [ "grpcCore", "grpcNetty", "grpcProtobuf", "grpcStub", "grpcGrpclb", "grpcUtil"]
+grpcTest = [ "grpcInprocess"]
+log4j    = [ "log4jApi", "log4jCore", "log4jSlf4j", "log4j12" ]
+mockito  = [ "mockitoCore", "mockitoJunit" ]
+testing  = ["junit", "assertj", "mockitoCore", "mockitoJunit"]
+javax    = [ "javaxAnnotation" ]
+
+
+[plugins]
+shadow = { id = "com.github.johnrengelman.shadow", version.ref = "shadowPlugin" }
+protobuf = { id = "com.google.protobuf", version.ref = "protobufPlugin" }

gradle/publish.gradle

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: "signing"
+apply plugin: "maven-publish"
+apply plugin: "io.github.gradle-nexus.publish-plugin"
+
+ext {
+    if (!project.hasProperty('nexusUsername')) {
+        nexusUsername = "$System.env.NEXUS_USERNAME"
+    }
+    if (!project.hasProperty('nexusPassword')) {
+        nexusPassword = "$System.env.NEXUS_PASSWORD"
+    }
+}
+
+nexusPublishing {
+    repositories {
+        sonatype {
+            username = nexusUsername
+            password = nexusPassword
+        }
+    }
+}
+
+//afterReleaseBuild.dependsOn publishToSonatype

gradle/publishing-release-tasks.gradle

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2016-2023 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'maven-publish'
+
+task pubblications {
+    doLast {
+        project.publishing.publications.each { publication ->
+            println "Publication $publication.name [$publication.groupId/$publication.artifactId/$publication.version]"
+        }
+    }
+}

gradle/publishing-release.gradle

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2016-2023 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'java-library'
+apply plugin: 'maven-publish'
+apply plugin: 'signing'
+
+java {
+    withJavadocJar()
+    withSourcesJar()
+}
+
+publishing {
+    publications {
+        "${project.name}"(MavenPublication) {
+            groupId = rootProject.group
+
+            from components.java
+
+            pom {
+                name = project.name
+                description = project.name
+                url = "${gitProject}"
+
+                scm {
+                    url = "${gitProject}"
+                    connection = "scm:${gitProject}"
+                    developerConnection = "scm:${gitURL}"
+                }
+
+                licenses {
+                    license {
+                        name = 'The Apache Software License, Version 2.0'
+                        url = 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+                        distribution = 'repo'
+                    }
+                }
+
+                developers {
+                    developer {
+                        id = 'lburgazzoli'
+                        name = 'Luca Burgazzoli'
+                        organization = 'Red Hat'
+                        organizationUrl = 'http://redhat.com'
+                    }
+                    developer {
+                        name = 'Fanmin Shi'
+                        organization = 'CoreOS'
+                        organizationUrl = 'http://coreos.com'
+                    }
+                    developer {
+                        name = 'Xiang Li'
+                        organization = 'CoreOS'
+                        organizationUrl = 'http://coreos.com'
+                    }
+                    developer {
+                        name = 'Anthony Romano'
+                        organization = 'CoreOS'
+                        organizationUrl = 'http://coreos.com'
+                    }
+                }
+            }
+        }
+    }
+}
+
+signing {
+    required {
+        !version.endsWith('SNAPSHOT')
+    }
+
+    if (!version.endsWith('SNAPSHOT')) {
+        useGpgCmd()
+    }
+
+    sign publishing.publications."${project.name}"
+}
+
+check.dependsOn javadoc
+
+javadoc {
+    if(JavaVersion.current().isJava9Compatible()) {
+        options.addBooleanOption('html5', true)
+    }
+
+    exclude "**/io/etcd/jetcd/api/**"
+}

gradle/quality.gradle

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: "net.ltgt.errorprone"
+apply plugin: "pmd"
+
+dependencies {
+    errorprone(libs.errorprone)
+    errorprone(libs.errorproneAnnotations)
+    errorproneJavac(libs.errorproneJavac)
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.errorprone {
+        excludedPaths = '.*/generated/.*'
+        disableWarningsInGeneratedCode = true
+    }
+    options.deprecation = true
+}
+
+pmd {
+    consoleOutput = true
+    ruleSets = [ "${project.rootDir}/etc/pmd-ruleset.xml" ]
+}

gradle/release.gradle

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2016-2023 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: "pl.allegro.tech.build.axion-release"
+
+
+scmVersion {
+    tag {
+        prefix = 'jetcd-'
+    }
+}
+
+allprojects {
+    project.version = scmVersion.version
+}

gradle/style.gradle

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: "com.diffplug.spotless"
+
+spotless {
+    java {
+        removeUnusedImports()
+        trimTrailingWhitespace()
+        indentWithSpaces(4)
+        endWithNewline()
+        importOrderFile(rootProject.file('etc/eclipse.importorder'))
+        eclipse().configFile(rootProject.file('etc/eclipse-formatter-config.xml'))
+        targetExclude("build/generated/**/*.java")
+    }
+}

gradle/versions.gradle

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'com.github.ben-manes.versions'
+
+dependencyUpdates.configure {
+
+    def isNonStable = { String version ->
+        return ['alpha', 'beta', 'rc', 'cr', 'm', 'ea'].any { keyword -> version.toUpperCase().contains(keyword.toUpperCase())}
+    }
+
+    rejectVersionIf {
+        isNonStable(it.candidate.version)
+    }
+}
+
+task deps {
+    dependsOn dependencyUpdates
+}

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

@@ -0,0 +1,251 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH="\\\"\\\""
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -0,0 +1,94 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

jetcd-all/pom.xml

@@ -1,135 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!--
-
-    Copyright 2016-2020 The jetcd authors
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-        http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
-
--->
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-
-    <parent>
-        <groupId>io.etcd</groupId>
-        <artifactId>jetcd-parent</artifactId>
-        <version>0.5.4</version>
-    </parent>
-
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>jetcd-all</artifactId>
-    <packaging>jar</packaging>
-
-    <dependencies>
-        <dependency>
-            <groupId>io.etcd</groupId>
-            <artifactId>jetcd-common</artifactId>
-            <exclusions>
-              <exclusion>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>animal-sniffer-annotations</artifactId>
-              </exclusion>
-              <exclusion>
-                <groupId>org.checkerframework</groupId>
-                <artifactId>checker-compat-qual</artifactId>
-              </exclusion>
-              <exclusion>
-                <groupId>com.google.errorprone</groupId>
-                <artifactId>error_prone_annotations</artifactId>
-              </exclusion>
-              <exclusion>
-                <groupId>com.google.j2objc</groupId>
-                <artifactId>j2objc-annotations</artifactId>
-              </exclusion>
-              <exclusion>
-                <groupId>com.google.code.findbugs</groupId>
-                <artifactId>jsr305</artifactId>
-              </exclusion>
-            </exclusions>
-        </dependency>
-        <dependency>
-            <groupId>io.etcd</groupId>
-            <artifactId>jetcd-core</artifactId>
-            <exclusions>
-              <exclusion>
-                <groupId>org.checkerframework</groupId>
-                <artifactId>checker-compat-qual</artifactId>
-              </exclusion>
-            </exclusions>
-        </dependency>
-        <dependency>
-            <groupId>io.etcd</groupId>
-            <artifactId>jetcd-extensions</artifactId>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-shade-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>shade</goal>
-                        </goals>
-                        <configuration>
-                            <createSourcesJar>true</createSourcesJar>
-                            <createDependencyReducedPom>true</createDependencyReducedPom>
-                            <shadedArtifactAttached>false</shadedArtifactAttached>
-                            <minimizeJar>false</minimizeJar>
-                            <artifactSet>
-                                <excludes>
-                                    <exclude>org.slf4j:slf4j-api</exclude>
-                                    <exclude>com.google.errorprone:error_prone_annotations</exclude>
-                                </excludes>
-                            </artifactSet>
-                            <relocations>
-                                <relocation>
-                                    <pattern>com.google</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.com.google</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>io.grpc</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.io.grpc</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>io.netty</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.io.netty</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>javax.annotation</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.javax.annotation</shadedPattern></relocation>
-                                <relocation>
-                                    <pattern>io.opencensus</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.io.opencensus</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>io.opencensus</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.io.opencensus</shadedPattern>
-                                </relocation>
-                                <relocation>
-                                    <pattern>net.jodah</pattern>
-                                    <shadedPattern>io.etcd.jetcd.shaded.net.jodah</shadedPattern>
-                                </relocation>
-                            </relocations>
-                            <transformers>
-                                <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
-                            </transformers>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-        </plugins>
-    </build>
-
-</project>

jetcd-api/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,4 +14,7 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd.all;
+
+dependencies {
+    api libs.slf4j
+}

jetcd-common/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,9 +14,12 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd.extensions;
 
-public final class Extensions {
-    private Extensions() {
-    }
+dependencies {
+    api libs.slf4j
+    api libs.guava
+    api libs.grpcCore
+
+    testImplementation libs.bundles.testing
+    testRuntimeOnly libs.bundles.log4j
 }

jetcd-common/pom.xml

@@ -1,69 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!--
-
-    Copyright 2016-2020 The jetcd authors
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-        http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
-
--->
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-
-    <parent>
-        <groupId>io.etcd</groupId>
-        <artifactId>jetcd-parent</artifactId>
-        <version>0.5.4</version>
-    </parent>
-
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>jetcd-common</artifactId>
-    <packaging>jar</packaging>
-
-    <dependencies>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-core</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>com.google.guava</groupId>
-            <artifactId>guava</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-            </plugin>
-            <plugin>
-                <groupId>org.jacoco</groupId>
-                <artifactId>jacoco-maven-plugin</artifactId>
-                <configuration>
-                    <excludes>
-                        <exclude>io/etcd/jetcd/api/**</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-resources-plugin</artifactId>
-            </plugin>
-        </plugins>
-    </build>
-
-</project>

jetcd-common/src/main/java/io/etcd/jetcd/common/Service.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.etcd.jetcd.common;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public abstract class Service implements AutoCloseable {
+    private final AtomicBoolean running;
+
+    protected Service() {
+        this.running = new AtomicBoolean();
+    }
+
+    public void start() {
+        if (this.running.compareAndSet(false, true)) {
+            doStart();
+        }
+    }
+
+    public void stop() {
+        if (this.running.compareAndSet(true, false)) {
+            doStop();
+        }
+    }
+
+    public void restart() {
+        stop();
+        start();
+    }
+
+    @Override
+    public void close() {
+        stop();
+    }
+
+    public boolean isRunning() {
+        return running.get();
+    }
+
+    protected abstract void doStart();
+
+    protected abstract void doStop();
+}

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/ClosedClientException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/ClosedKeepAliveListenerException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/ClosedSnapshotException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/ClosedWatcherException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/CompactedException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/ErrorCode.java

@@ -31,12 +31,22 @@ import io.grpc.Status;
  */
 public enum ErrorCode {
 
-    CANCELLED(Status.CANCELLED), UNKNOWN(Status.UNKNOWN), INVALID_ARGUMENT(Status.INVALID_ARGUMENT),
-    DEADLINE_EXCEEDED(Status.DEADLINE_EXCEEDED), NOT_FOUND(Status.NOT_FOUND), ALREADY_EXISTS(Status.ALREADY_EXISTS),
-    PERMISSION_DENIED(Status.PERMISSION_DENIED), UNAUTHENTICATED(Status.UNAUTHENTICATED),
-    RESOURCE_EXHAUSTED(Status.RESOURCE_EXHAUSTED), FAILED_PRECONDITION(Status.FAILED_PRECONDITION), ABORTED(Status.ABORTED),
-    OUT_OF_RANGE(Status.OUT_OF_RANGE), UNIMPLEMENTED(Status.UNIMPLEMENTED), INTERNAL(Status.INTERNAL),
-    UNAVAILABLE(Status.UNAVAILABLE), DATA_LOSS(Status.DATA_LOSS),;
+    CANCELLED(Status.CANCELLED),
+    UNKNOWN(Status.UNKNOWN),
+    INVALID_ARGUMENT(Status.INVALID_ARGUMENT),
+    DEADLINE_EXCEEDED(Status.DEADLINE_EXCEEDED),
+    NOT_FOUND(Status.NOT_FOUND),
+    ALREADY_EXISTS(Status.ALREADY_EXISTS),
+    PERMISSION_DENIED(Status.PERMISSION_DENIED),
+    UNAUTHENTICATED(Status.UNAUTHENTICATED),
+    RESOURCE_EXHAUSTED(Status.RESOURCE_EXHAUSTED),
+    FAILED_PRECONDITION(Status.FAILED_PRECONDITION),
+    ABORTED(Status.ABORTED),
+    OUT_OF_RANGE(Status.OUT_OF_RANGE),
+    UNIMPLEMENTED(Status.UNIMPLEMENTED),
+    INTERNAL(Status.INTERNAL),
+    UNAVAILABLE(Status.UNAVAILABLE),
+    DATA_LOSS(Status.DATA_LOSS),;
 
     private static final Map<Integer, ErrorCode> errorByRpcCode;
 

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/EtcdException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,7 @@
 
 package io.etcd.jetcd.common.exception;
 
-import static com.google.common.base.Preconditions.checkNotNull;
+import java.util.Objects;
 
 /**
  * Base exception type for all exceptions produced by the etcd service.
@@ -27,11 +27,13 @@ public class EtcdException extends RuntimeException {
 
     EtcdException(ErrorCode code, String message, Throwable cause) {
         super(message, cause);
-        this.code = checkNotNull(code);
+        this.code = Objects.requireNonNull(code, "Error code must not be null");
     }
 
     /**
      * Returns the error code associated with this exception.
+     *
+     * @return a {@link ErrorCode}
      */
     public ErrorCode getErrorCode() {
         return code;

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/EtcdExceptionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,9 +16,10 @@
 
 package io.etcd.jetcd.common.exception;
 
+import java.util.Objects;
+
 import io.grpc.Status;
 
-import static com.google.common.base.Preconditions.checkNotNull;
 import static io.grpc.Status.fromThrowable;
 
 /**
@@ -65,7 +66,7 @@ public final class EtcdExceptionFactory {
     }
 
     public static EtcdException toEtcdException(Throwable cause) {
-        checkNotNull(cause, "cause can't be null");
+        Objects.requireNonNull(cause, "cause can't be null");
         if (cause instanceof EtcdException) {
             return (EtcdException) cause;
         }
@@ -74,7 +75,7 @@ public final class EtcdExceptionFactory {
     }
 
     public static EtcdException toEtcdException(Status status) {
-        checkNotNull(status, "status can't be null");
+        Objects.requireNonNull(status, "status can't be null");
         return fromStatus(status);
     }
 

jetcd-core/build.gradle

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016-2021 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+dependencies {
+    api project(':jetcd-grpc')
+    api project(':jetcd-api')
+    api project(':jetcd-common')
+
+    api libs.slf4j
+    api libs.guava
+    api libs.failsafe
+
+    //compileOnly libs.javaxAnnotation
+    compileOnly libs.autoServiceAnnotations
+
+    annotationProcessor libs.autoServiceProcessor
+
+    testImplementation project(':jetcd-launcher')
+    testImplementation project(':jetcd-test')
+
+    testImplementation libs.restAssured
+    testImplementation libs.awaitility
+    testImplementation libs.commonsIo
+    testImplementation libs.bundles.testing
+
+    testRuntimeOnly libs.bundles.log4j
+}

jetcd-core/pom.xml

@@ -1,227 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!--
-
-    Copyright 2016-2020 The jetcd authors
-
-    Licensed under the Apache License, Version 2.0 (the "License");
-    you may not use this file except in compliance with the License.
-    You may obtain a copy of the License at
-
-        http://www.apache.org/licenses/LICENSE-2.0
-
-    Unless required by applicable law or agreed to in writing, software
-    distributed under the License is distributed on an "AS IS" BASIS,
-    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-    See the License for the specific language governing permissions and
-    limitations under the License.
-
--->
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-
-    <parent>
-        <groupId>io.etcd</groupId>
-        <artifactId>jetcd-parent</artifactId>
-        <version>0.5.4</version>
-    </parent>
-
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>jetcd-core</artifactId>
-    <packaging>jar</packaging>
-
-    <dependencies>
-        <dependency>
-            <groupId>${project.groupId}</groupId>
-            <artifactId>jetcd-common</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-core</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-netty</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-protobuf</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-stub</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-grpclb</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>net.jodah</groupId>
-            <artifactId>failsafe</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>com.google.auto.service</groupId>
-            <artifactId>auto-service-annotations</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.mockito</groupId>
-            <artifactId>mockito-core</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.logging.log4j</groupId>
-            <artifactId>log4j-api</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.logging.log4j</groupId>
-            <artifactId>log4j-core</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.logging.log4j</groupId>
-            <artifactId>log4j-slf4j-impl</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.logging.log4j</groupId>
-            <artifactId>log4j-1.2-api</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter-migrationsupport</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.mockito</groupId>
-            <artifactId>mockito-junit-jupiter</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.awaitility</groupId>
-            <artifactId>awaitility</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>io.grpc</groupId>
-            <artifactId>grpc-testing</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>io.netty</groupId>
-            <artifactId>netty-tcnative-boringssl-static</artifactId>
-            <version>${netty-tcnative.version}</version>
-            <classifier>${os.detected.classifier}</classifier>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>${project.groupId}</groupId>
-            <artifactId>jetcd-test</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>commons-io</groupId>
-            <artifactId>commons-io</artifactId>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>kr.motd.maven</groupId>
-                <artifactId>os-maven-plugin</artifactId>
-                <version>${os-maven-plugin.version}</version>
-                <extensions>true</extensions>
-                <executions>
-                    <execution>
-                        <phase>validate</phase>
-                        <goals>
-                            <goal>detect</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-
-            <plugin>
-                <groupId>org.xolstice.maven.plugins</groupId>
-                <artifactId>protobuf-maven-plugin</artifactId>
-                <configuration>
-                    <protocArtifact>
-                        com.google.protobuf:protoc:${protobuf.version}:exe:${os.detected.classifier}
-                    </protocArtifact>
-                    <pluginId>grpc-java</pluginId>
-                    <pluginArtifact>
-                        io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}
-                    </pluginArtifact>
-                </configuration>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>compile</goal>
-                            <goal>compile-custom</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>build-helper-maven-plugin</artifactId>
-                <executions>
-                    <execution>
-                        <id>test</id>
-                        <phase>generate-sources</phase>
-                        <goals>
-                            <goal>add-source</goal>
-                        </goals>
-                        <configuration>
-                            <sources>
-                                <source>${basedir}/target/generated-sources/protobuf/grpc-java</source>
-                                <source>${basedir}/target/generated-sources/protobuf/java</source>
-                            </sources>
-                        </configuration>
-                    </execution>
-                </executions>
-            </plugin>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-            </plugin>
-
-            <plugin>
-                <groupId>org.jacoco</groupId>
-                <artifactId>jacoco-maven-plugin</artifactId>
-                <configuration>
-                    <excludes>
-                        <exclude>io/etcd/jetcd/api/**</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-resources-plugin</artifactId>
-            </plugin>
-        </plugins>
-    </build>
-
-</project>

jetcd-core/src/main/java/io/etcd/jetcd/Auth.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-core/src/main/java/io/etcd/jetcd/ByteSequence.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.etcd.jetcd;
 
 import java.nio.charset.Charset;
+import java.util.Objects;
 
 import com.google.protobuf.ByteString;
 
@@ -31,6 +32,7 @@ public final class ByteSequence {
     private final ByteString byteString;
 
     private ByteSequence(ByteString byteString) {
+        Objects.requireNonNull(byteString, "byteString should not be null");
         this.byteString = byteString;
         this.hashVal = byteString.hashCode();
     }
@@ -43,9 +45,10 @@ public final class ByteSequence {
      *                byte sequence represented by this string; <code>false</code> otherwise.
      */
     public boolean startsWith(ByteSequence prefix) {
-        ByteString baseByteString = this.getByteString();
-        ByteString prefixByteString = prefix.getByteString();
-        return baseByteString.startsWith(prefixByteString);
+        if (prefix == null) {
+            return false;
+        }
+        return byteString.startsWith(prefix.byteString);
     }
 
     /**
@@ -55,7 +58,19 @@ public final class ByteSequence {
      * @return       a new {@code ByteSequence} instance
      */
     public ByteSequence concat(ByteSequence other) {
-        return new ByteSequence(this.byteString.concat(other.getByteString()));
+        Objects.requireNonNull(other, "other byteSequence should not be null");
+        return new ByteSequence(this.byteString.concat(other.byteString));
+    }
+
+    /**
+     * Concatenate the given {@code ByteSequence} to this one.
+     *
+     * @param  other string to concatenate
+     * @return       a new {@code ByteSequence} instance
+     */
+    public ByteSequence concat(ByteString other) {
+        Objects.requireNonNull(other, "other byteSequence should not be null");
+        return new ByteSequence(this.byteString.concat(other));
     }
 
     /**
@@ -107,10 +122,6 @@ public final class ByteSequence {
         return hashVal;
     }
 
-    ByteString getByteString() {
-        return this.byteString;
-    }
-
     public String toString(Charset charset) {
         return byteString.toString(charset);
     }
@@ -127,6 +138,11 @@ public final class ByteSequence {
         return byteString.size();
     }
 
+    @Override
+    public String toString() {
+        return byteString.toStringUtf8();
+    }
+
     /**
      * Create new ByteSequence from a String.
      *
@@ -136,16 +152,26 @@ public final class ByteSequence {
      */
     public static ByteSequence from(String source, Charset charset) {
         byte[] bytes = source.getBytes(charset);
-
         return new ByteSequence(ByteString.copyFrom(bytes));
     }
 
+    /**
+     * Create new ByteSequence from a {@link ByteString}.
+     *
+     * @param  source input {@link ByteString}
+     * @return        the ByteSequence
+     */
     public static ByteSequence from(ByteString source) {
         return new ByteSequence(source);
     }
 
+    /**
+     * Create new ByteSequence from raw bytes.
+     *
+     * @param  source input bytes
+     * @return        the ByteSequence
+     */
     public static ByteSequence from(byte[] source) {
         return new ByteSequence(ByteString.copyFrom(source));
     }
-
 }

jetcd-core/src/main/java/io/etcd/jetcd/Client.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,42 +26,58 @@ package io.etcd.jetcd;
 public interface Client extends AutoCloseable {
 
     /**
-     * @return the {@link Auth} client.
+     * Returns the {@link Auth} client.
+     *
+     * @return the client.
      */
     Auth getAuthClient();
 
     /**
-     * @return the {@link KV} client.
+     * Returns the {@link KV} client.
+     *
+     * @return the client.
      */
     KV getKVClient();
 
     /**
-     * @return the {@link Cluster} client.
+     * Returns the {@link Cluster} client.
+     *
+     * @return the client.
      */
     Cluster getClusterClient();
 
     /**
-     * @return the {@link Maintenance} client.
+     * Returns the {@link Maintenance} client.
+     *
+     * @return the client.
      */
     Maintenance getMaintenanceClient();
 
     /**
-     * @return the {@link Lease} client.
+     * Returns the {@link Lease} client.
+     *
+     * @return the client.
      */
     Lease getLeaseClient();
 
     /**
-     * @return the {@link Watch} client.
+     * Returns the {@link Watch} client.
+     *
+     * @return the client.
      */
     Watch getWatchClient();
 
     /**
-     * @return the {@link Lock} client.
+     * Returns the {@link Lock} client.
+     *
+     * @return the client.
      */
     Lock getLockClient();
 
     /**
-     * @return the {@link Election} client.
+     * Returns the {@link Election} client.
+     *
+     * @return the client.
      */
     Election getElectionClient();
 
@@ -69,7 +85,9 @@ public interface Client extends AutoCloseable {
     void close();
 
     /**
-     * @return a new {@link ClientBuilder}.
+     * Returns a new {@link ClientBuilder}.
+     *
+     * @return the builder.
      */
     static ClientBuilder builder() {
         return new ClientBuilder();

jetcd-core/src/main/java/io/etcd/jetcd/ClientBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,39 +17,36 @@
 package io.etcd.jetcd;
 
 import java.net.URI;
+import java.time.Duration;
 import java.time.temporal.ChronoUnit;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.ExecutorService;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
 
 import javax.net.ssl.SSLException;
 
 import io.etcd.jetcd.common.exception.EtcdException;
 import io.etcd.jetcd.common.exception.EtcdExceptionFactory;
+import io.etcd.jetcd.impl.ClientImpl;
+import io.etcd.jetcd.resolver.IPNameResolver;
 import io.grpc.ClientInterceptor;
 import io.grpc.Metadata;
 import io.grpc.netty.GrpcSslContexts;
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslContextBuilder;
+import io.vertx.core.Vertx;
 
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Preconditions.checkNotNull;
-import static com.google.common.base.Preconditions.checkState;
+import com.google.common.base.Strings;
 
 /**
- * ClientBuilder knows how to create an Client instance.
+ * ClientBuilder knows how to create a Client instance.
  */
 public final class ClientBuilder implements Cloneable {
 
-    private final Set<URI> endpoints = new HashSet<>();
+    private String target;
     private ByteSequence user;
     private ByteSequence password;
     private ExecutorService executorService;
@@ -58,66 +55,51 @@ public final class ClientBuilder implements Cloneable {
     private String authority;
     private Integer maxInboundMessageSize;
     private Map<Metadata.Key<?>, Object> headers;
+    private Map<Metadata.Key<?>, Object> authHeaders;
     private List<ClientInterceptor> interceptors;
+    private List<ClientInterceptor> authInterceptors;
     private ByteSequence namespace = ByteSequence.EMPTY;
     private long retryDelay = 500;
     private long retryMaxDelay = 2500;
-    private Long keepaliveTimeMs = 30000L;
-    private Long keepaliveTimeoutMs = 10000L;
-    private Boolean keepaliveWithoutCalls = true;
+    private int retryMaxAttempts = 2;
     private ChronoUnit retryChronoUnit = ChronoUnit.MILLIS;
-    private String retryMaxDuration;
-    private Integer connectTimeoutMs;
-    private boolean discovery;
+    private Duration keepaliveTime = Duration.ofSeconds(30L);
+    private Duration keepaliveTimeout = Duration.ofSeconds(10L);
+    private Boolean keepaliveWithoutCalls = true;
+    private Duration retryMaxDuration;
+    private Duration connectTimeout;
+    private boolean waitForReady = true;
+    private Vertx vertx;
 
     ClientBuilder() {
     }
 
     /**
-     * gets the endpoints for the builder.
+     * Gets the etcd target.
      *
-     * @return the list of endpoints configured for the builder
+     * @return the etcd target.
      */
-    public Collection<URI> endpoints() {
-        return Collections.unmodifiableCollection(this.endpoints);
+    public String target() {
+        return target;
     }
 
     /**
      * configure etcd server endpoints.
      *
-     * @param  endpoints                etcd server endpoints, at least one
+     * @param  target               etcd server target
      * @return                      this builder to train
-     * @throws NullPointerException     if endpoints is null or one of endpoint is null
-     * @throws IllegalArgumentException if some endpoint is invalid
+     * @throws NullPointerException if target is null or one of endpoint is null
      */
-    public ClientBuilder endpoints(Collection<URI> endpoints) {
-        checkNotNull(endpoints, "endpoints can't be null");
+    public ClientBuilder target(String target) {
+        Preconditions.checkArgument(!Strings.isNullOrEmpty(target), "target can't be null or empty");
 
-        for (URI endpoint : endpoints) {
-            checkNotNull(endpoint, "endpoint can't be null");
-            checkArgument(endpoint.toString().trim().length() > 0, "invalid endpoint: endpoint=" + endpoint);
-            this.endpoints.add(endpoint);
-        }
+        this.target = target;
 
         return this;
     }
 
     /**
-     * configure etcd server endpoints.
-     *
-     * @param  endpoints                etcd server endpoints, at least one
-     * @return                          this builder to train
-     * @throws NullPointerException     if endpoints is null or one of endpoint is null
-     * @throws IllegalArgumentException if some endpoint is invalid
-     */
-    public ClientBuilder endpoints(URI... endpoints) {
-        checkNotNull(endpoints, "endpoints can't be null");
-
-        return endpoints(Arrays.asList(endpoints));
-    }
-
-    /**
-     * configure etcd server endpoints.
+     * configure etcd server endpoints using the {@link IPNameResolver}.
      *
      * @param  endpoints                etcd server endpoints, at least one
      * @return                          this builder to train
@@ -125,11 +107,60 @@ public final class ClientBuilder implements Cloneable {
      * @throws IllegalArgumentException if some endpoint is invalid
      */
     public ClientBuilder endpoints(String... endpoints) {
-        return endpoints(Util.toURIs(Arrays.asList(endpoints)));
+        return endpoints(
+            Stream.of(endpoints).map(URI::create).toArray(URI[]::new));
     }
 
     /**
-     * @return the auth user
+     * configure etcd server endpoints using the {@link IPNameResolver}.
+     *
+     * @param  endpoints                etcd server endpoints, at least one
+     * @return                          this builder to train
+     * @throws NullPointerException     if endpoints is null or one of endpoint is null
+     * @throws IllegalArgumentException if some endpoint is invalid
+     */
+    public ClientBuilder endpoints(URI... endpoints) {
+        return endpoints(Arrays.asList(endpoints));
+    }
+
+    /**
+     * configure etcd server endpoints using the {@link IPNameResolver}.
+     *
+     * @param  endpoints                etcd server endpoints, at least one
+     * @return                          this builder to train
+     * @throws NullPointerException     if endpoints is null or one of endpoint is null
+     * @throws IllegalArgumentException if some endpoint is invalid
+     */
+    public ClientBuilder endpoints(Iterable<URI> endpoints) {
+        Objects.requireNonNull(endpoints, "endpoints can't be null");
+
+        endpoints.forEach(e -> {
+            if (e.getHost() == null) {
+                throw new IllegalArgumentException("Unable to compute target from endpoint: '" + e + "'");
+            }
+        });
+
+        final String target = StreamSupport.stream(endpoints.spliterator(), false)
+            .map(e -> e.getHost() + (e.getPort() != -1 ? ":" + e.getPort() : ""))
+            .distinct()
+            .collect(Collectors.joining(","));
+
+        if (Strings.isNullOrEmpty(target)) {
+            throw new IllegalArgumentException("Unable to compute target from endpoints: '" + endpoints + "'");
+        }
+
+        return target(
+            String.format(
+                "%s://%s/%s",
+                IPNameResolver.SCHEME,
+                authority != null ? authority : "",
+                target));
+    }
+
+    /**
+     * Returns the auth user
+     *
+     * @return the user.
      */
     public ByteSequence user() {
         return user;
@@ -143,13 +174,15 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if user is <code>null</code>
      */
     public ClientBuilder user(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        Objects.requireNonNull(user, "user can't be null");
         this.user = user;
         return this;
     }
 
     /**
-     * @return the auth password
+     * Returns the auth password
+     *
+     * @return the password.
      */
     public ByteSequence password() {
         return password;
@@ -163,13 +196,15 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if password is <code>null</code>
      */
     public ClientBuilder password(ByteSequence password) {
-        checkNotNull(password, "password can't be null");
+        Objects.requireNonNull(password, "password can't be null");
         this.password = password;
         return this;
     }
 
     /**
-     * @return the namespace of each key used
+     * Returns the namespace of each key used
+     *
+     * @return the namespace.
      */
     public ByteSequence namespace() {
         return namespace;
@@ -184,13 +219,15 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if namespace is <code>null</code>
      */
     public ClientBuilder namespace(ByteSequence namespace) {
-        checkNotNull(namespace, "namespace can't be null");
+        Objects.requireNonNull(namespace, "namespace can't be null");
         this.namespace = namespace;
         return this;
     }
 
     /**
-     * @return the executor service
+     * Returns the executor service
+     *
+     * @return the executor service.
      */
     public ExecutorService executorService() {
         return executorService;
@@ -204,7 +241,7 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if executorService is <code>null</code>
      */
     public ClientBuilder executorService(ExecutorService executorService) {
-        checkNotNull(executorService, "executorService can't be null");
+        Objects.requireNonNull(executorService, "executorService can't be null");
         this.executorService = executorService;
         return this;
     }
@@ -217,7 +254,7 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if loadBalancerPolicy is <code>null</code>
      */
     public ClientBuilder loadBalancerPolicy(String loadBalancerPolicy) {
-        checkNotNull(loadBalancerPolicy, "loadBalancerPolicy can't be null");
+        Objects.requireNonNull(loadBalancerPolicy, "loadBalancerPolicy can't be null");
         this.loadBalancerPolicy = loadBalancerPolicy;
         return this;
     }
@@ -232,7 +269,9 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the ssl context
+     * Returns the ssl context
+     *
+     * @return the ssl context.
      */
     public SslContext sslContext() {
         return sslContext;
@@ -265,13 +304,17 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return The authority used to authenticate connections to servers.
+     * Returns The authority used to authenticate connections to servers.
+     *
+     * @return the authority.
      */
     public String authority() {
         return authority;
     }
 
     /**
+     * Sets the authority used to authenticate connections to servers.
+     *
      * @param  authority the authority used to authenticate connections to servers.
      * @return           this builder
      */
@@ -281,14 +324,18 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the maximum message size allowed for a single gRPC frame.
+     * Returns the maximum message size allowed for a single gRPC frame.
+     *
+     * @return max inbound message size.
      */
     public Integer maxInboundMessageSize() {
         return maxInboundMessageSize;
     }
 
     /**
-     * @param  maxInboundMessageSize Sets the maximum message size allowed for a single gRPC frame.
+     * Sets the maximum message size allowed for a single gRPC frame.
+     *
+     * @param  maxInboundMessageSize the maximum message size allowed for a single gRPC frame.
      * @return                       this builder
      */
     public ClientBuilder maxInboundMessageSize(Integer maxInboundMessageSize) {
@@ -297,14 +344,18 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the headers to be added to http request headers
+     * Returns the headers to be added to http request headers
+     *
+     * @return headers.
      */
     public Map<Metadata.Key<?>, Object> headers() {
         return headers == null ? Collections.emptyMap() : Collections.unmodifiableMap(headers);
     }
 
     /**
-     * @param  headers Sets headers to be added to http request headers.
+     * Sets headers to be added to http request headers.
+     *
+     * @param  headers headers to be added to http request headers.
      * @return         this builder
      */
     public ClientBuilder headers(Map<Metadata.Key<?>, Object> headers) {
@@ -314,6 +365,8 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
+     * Set headers.
+     *
      * @param  key   Sets an header key to be added to http request headers.
      * @param  value Sets an header value to be added to http request headers.
      * @return       this builder
@@ -329,14 +382,56 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the interceptors
+     * Returns the headers to be added to auth request headers
+     *
+     * @return auth headers.
+     */
+    public Map<Metadata.Key<?>, Object> authHeaders() {
+        return authHeaders == null ? Collections.emptyMap() : Collections.unmodifiableMap(authHeaders);
+    }
+
+    /**
+     * Set the auth headers.
+     *
+     * @param  authHeaders Sets headers to be added to auth request headers.
+     * @return             this builder
+     */
+    public ClientBuilder authHeaders(Map<Metadata.Key<?>, Object> authHeaders) {
+        this.authHeaders = new HashMap<>(authHeaders);
+
+        return this;
+    }
+
+    /**
+     * Add an auth header.
+     *
+     * @param  key   Sets an header key to be added to auth request headers.
+     * @param  value Sets an header value to be added to auth request headers.
+     * @return       this builder
+     */
+    public ClientBuilder authHeader(String key, String value) {
+        if (this.authHeaders == null) {
+            this.authHeaders = new HashMap<>();
+        }
+
+        this.authHeaders.put(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER), value);
+
+        return this;
+    }
+
+    /**
+     * Returns the interceptors
+     *
+     * @return the interceptors.
      */
     public List<ClientInterceptor> interceptors() {
         return interceptors;
     }
 
     /**
-     * @param  interceptors Set the interceptors.
+     * Set the interceptors.
+     *
+     * @param  interceptors the interceptors.
      * @return              this builder
      */
     public ClientBuilder interceptors(List<ClientInterceptor> interceptors) {
@@ -346,6 +441,8 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
+     * Add an interceptor.
+     *
      * @param  interceptor  an interceptors to add
      * @param  interceptors additional interceptors
      * @return              this builder
@@ -362,13 +459,56 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return The delay between retries.
+     * Returns the auth interceptors
+     *
+     * @return the interceptors.
+     */
+    public List<ClientInterceptor> authInterceptors() {
+        return authInterceptors;
+    }
+
+    /**
+     * Set the auth interceptors.
+     *
+     * @param  interceptors Set the interceptors to add to the auth chain
+     * @return              this builder
+     */
+    public ClientBuilder authInterceptors(List<ClientInterceptor> interceptors) {
+        this.authInterceptors = new ArrayList<>(interceptors);
+
+        return this;
+    }
+
+    /**
+     * Add an auth interceptor.
+     *
+     * @param  interceptor  an interceptors to add to the auth chain
+     * @param  interceptors additional interceptors to add to the auth chain
+     * @return              this builder
+     */
+    public ClientBuilder authInterceptors(ClientInterceptor interceptor, ClientInterceptor... interceptors) {
+        if (this.authInterceptors == null) {
+            this.authInterceptors = new ArrayList<>();
+        }
+
+        this.authInterceptors.add(interceptor);
+        this.authInterceptors.addAll(Arrays.asList(interceptors));
+
+        return this;
+    }
+
+    /**
+     * Returns The delay between retries.
+     *
+     * @return the retry delay.
      */
     public long retryDelay() {
         return retryDelay;
     }
 
     /**
+     * The delay between retries.
+     *
      * @param  retryDelay The delay between retries.
      * @return            this builder
      */
@@ -378,13 +518,17 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the max backing off delay between retries
+     * Returns the max backing off delay between retries
+     *
+     * @return max retry delay.
      */
     public long retryMaxDelay() {
         return retryMaxDelay;
     }
 
     /**
+     * Set the max backing off delay between retries.
+     *
      * @param  retryMaxDelay The max backing off delay between retries.
      * @return               this builder
      */
@@ -393,34 +537,66 @@ public final class ClientBuilder implements Cloneable {
         return this;
     }
 
-    public Long keepaliveTimeMs() {
-        return keepaliveTimeMs;
+    /**
+     * Returns the max number of retry attempts
+     *
+     * @return max retry attempts.
+     */
+    public int retryMaxAttempts() {
+        return retryMaxAttempts;
+    }
+
+    /**
+     * Set the max number of retry attempts
+     *
+     * @param  retryMaxAttempts The max retry attempts.
+     * @return                  this builder
+     */
+    public ClientBuilder retryMaxAttempts(int retryMaxAttempts) {
+        this.retryMaxAttempts = retryMaxAttempts;
+        return this;
+    }
+
+    /**
+     * Returns the keep alive time.
+     *
+     * @return keep alive time.
+     */
+    public Duration keepaliveTime() {
+        return keepaliveTime;
     }
 
     /**
      * The interval for gRPC keepalives.
      * The current minimum allowed by gRPC is 10s
      *
-     * @param keepaliveTimeMs time in ms between keepalives
+     * @param  keepaliveTime time between keepalives
+     * @return               this builder
      */
-    public ClientBuilder keepaliveTimeMs(Long keepaliveTimeMs) {
+    public ClientBuilder keepaliveTime(Duration keepaliveTime) {
         // gRPC uses a minimum keepalive time of 10s, if smaller values are given.
         // No check here though, as this gRPC value might change
-        this.keepaliveTimeMs = keepaliveTimeMs;
+        this.keepaliveTime = keepaliveTime;
         return this;
     }
 
-    public Long keepaliveTimeoutMs() {
-        return keepaliveTimeoutMs;
+    /**
+     * Returns the keep alive time out.
+     *
+     * @return keep alive time out.
+     */
+    public Duration keepaliveTimeout() {
+        return keepaliveTimeout;
     }
 
     /**
      * The timeout for gRPC keepalives
      *
-     * @param keepaliveTimeoutMs the gRPC keep alive timeout in milliseconds.
+     * @param  keepaliveTimeout the gRPC keep alive timeout.
+     * @return                  this builder
      */
-    public ClientBuilder keepaliveTimeoutMs(Long keepaliveTimeoutMs) {
-        this.keepaliveTimeoutMs = keepaliveTimeoutMs;
+    public ClientBuilder keepaliveTimeout(Duration keepaliveTimeout) {
+        this.keepaliveTimeout = keepaliveTimeout;
         return this;
     }
 
@@ -432,6 +608,7 @@ public final class ClientBuilder implements Cloneable {
      * Keepalive option for gRPC
      *
      * @param  keepaliveWithoutCalls the gRPC keep alive without calls.
+     * @return                       this builder
      */
     public ClientBuilder keepaliveWithoutCalls(Boolean keepaliveWithoutCalls) {
         this.keepaliveWithoutCalls = keepaliveWithoutCalls;
@@ -439,13 +616,17 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return he retries period unit.
+     * Returns he retries period unit.
+     *
+     * @return the chrono unit.
      */
     public ChronoUnit retryChronoUnit() {
         return retryChronoUnit;
     }
 
     /**
+     * Sets the retries period unit.
+     *
      * @param  retryChronoUnit the retries period unit.
      * @return                 this builder
      */
@@ -455,54 +636,100 @@ public final class ClientBuilder implements Cloneable {
     }
 
     /**
-     * @return the retries max duration.
+     * Returns the retries max duration.
+     *
+     * @return retry max duration.
      */
-    public String retryMaxDuration() {
+    public Duration retryMaxDuration() {
         return retryMaxDuration;
     }
 
     /**
-     * @return the connect timeout in milliseconds.
+     * Returns the connect timeout.
+     *
+     * @return connect timeout.
      */
-    public Integer connectTimeoutMs() {
-        return connectTimeoutMs;
+    public Duration connectTimeout() {
+        return connectTimeout;
     }
 
     /**
+     * Set the retries max duration.
+     *
      * @param  retryMaxDuration the retries max duration.
      * @return                  this builder
      */
-    public ClientBuilder retryMaxDuration(String retryMaxDuration) {
+    public ClientBuilder retryMaxDuration(Duration retryMaxDuration) {
         this.retryMaxDuration = retryMaxDuration;
         return this;
     }
 
     /**
-     * @param  connectTimeoutMs Sets the connection timeout in milliseconds.
-     *                          Clients connecting to fault tolerant etcd clusters (eg, clusters with >= 3 etcd server
+     * Set the connection timeout.
+     *
+     * @param  connectTimeout Sets the connection timeout.
+     *                        Clients connecting to fault tolerant etcd clusters (eg, clusters with more than 2 etcd server
      *                        peers/endpoints)
      *                        should consider a value that will allow switching timely from a crashed/partitioned peer to
      *                        a consensus peer.
      * @return                this builder
      */
-    public ClientBuilder connectTimeoutMs(Integer connectTimeoutMs) {
-        this.connectTimeoutMs = connectTimeoutMs;
+    public ClientBuilder connectTimeout(Duration connectTimeout) {
+        if (connectTimeout != null) {
+            long millis = connectTimeout.toMillis();
+            if ((int) millis != millis) {
+                throw new IllegalArgumentException("connectTimeout outside of its bounds, max value: " +
+                    Integer.MAX_VALUE);
+            }
+        }
+        this.connectTimeout = connectTimeout;
         return this;
     }
 
     /**
-     * @return if the endpoint represent a discovery address using dns+srv.
+     * Enable gRPC's wait for ready semantics.
+     *
+     * @return if this client uses gRPC's wait for ready semantics.
+     * @see    <a href="https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md">gRPC Wait for Ready Semantics</a>
      */
-    public boolean discovery() {
-        return discovery;
+    public boolean waitForReady() {
+        return waitForReady;
     }
 
     /**
-     * @param  discovery if the endpoint represent a discovery address using dns+srv.
-     * @return           this builder
+     * Configure the gRPC's wait for ready semantics.
+     *
+     * @param  waitForReady if this client should use gRPC's wait for ready semantics. Enabled by default.
+     * @return              this builder.
+     * @see                 <a href="https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md">gRPC Wait for Ready
+     *                      Semantics</a>
      */
-    public ClientBuilder discovery(boolean discovery) {
-        this.discovery = discovery;
+    public ClientBuilder waitForReady(boolean waitForReady) {
+        this.waitForReady = waitForReady;
+        return this;
+    }
+
+    /**
+     * Gets the Vertx instance.
+     *
+     * @return the vertx instance.
+     */
+    public Vertx vertx() {
+        return vertx;
+    }
+
+    /**
+     * configure Vertx instance.
+     *
+     * @param  vertx                    Vertx instance to use.
+     * @return                          this builder to train
+     * @throws IllegalArgumentException if vertx is null
+     */
+    public ClientBuilder vertx(Vertx vertx) {
+        Preconditions.checkArgument(vertx != null, "vertx can't be null");
+
+        this.vertx = vertx;
+
         return this;
     }
 
@@ -513,13 +740,15 @@ public final class ClientBuilder implements Cloneable {
      * @throws EtcdException if client experiences build error.
      */
     public Client build() {
-        checkState(!endpoints.isEmpty(), "please configure etcd server endpoints before build.");
+        Preconditions.checkState(target != null, "please configure etcd server endpoints before build.");
 
         return new ClientImpl(this);
     }
 
     /**
-     * @return a copy of this builder
+     * Returns a copy of this builder
+     *
+     * @return a copy of the builder.
      */
     public ClientBuilder copy() {
         try {

jetcd-core/src/main/java/io/etcd/jetcd/ClientConnectionManager.java

@@ -1,401 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.net.URI;
-import java.time.Duration;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.concurrent.Callable;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.concurrent.TimeUnit;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.Iterables;
-import com.google.common.util.concurrent.ListenableFuture;
-import com.google.protobuf.ByteString;
-import io.etcd.jetcd.api.AuthGrpc;
-import io.etcd.jetcd.api.AuthenticateRequest;
-import io.etcd.jetcd.api.AuthenticateResponse;
-import io.etcd.jetcd.common.exception.EtcdExceptionFactory;
-import io.etcd.jetcd.resolver.DnsSrvNameResolver;
-import io.etcd.jetcd.resolver.IPNameResolver;
-import io.grpc.CallOptions;
-import io.grpc.Channel;
-import io.grpc.ClientCall;
-import io.grpc.ClientInterceptor;
-import io.grpc.ForwardingClientCall.SimpleForwardingClientCall;
-import io.grpc.ForwardingClientCallListener.SimpleForwardingClientCallListener;
-import io.grpc.ManagedChannel;
-import io.grpc.ManagedChannelBuilder;
-import io.grpc.Metadata;
-import io.grpc.MethodDescriptor;
-import io.grpc.Status;
-import io.grpc.netty.NegotiationType;
-import io.grpc.netty.NettyChannelBuilder;
-import io.grpc.stub.AbstractStub;
-import io.netty.channel.ChannelOption;
-import net.jodah.failsafe.Failsafe;
-import net.jodah.failsafe.RetryPolicy;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import static com.google.common.base.Preconditions.checkArgument;
-import static io.etcd.jetcd.Util.isInvalidTokenError;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.handleInterrupt;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
-
-final class ClientConnectionManager {
-    private static final Logger LOGGER = LoggerFactory.getLogger(ClientConnectionManager.class);
-    private static final Metadata.Key<String> TOKEN = Metadata.Key.of("token", Metadata.ASCII_STRING_MARSHALLER);
-
-    private final Object lock;
-    private final ClientBuilder builder;
-    private final ExecutorService executorService;
-    private volatile ManagedChannel managedChannel;
-    private volatile String token;
-
-    ClientConnectionManager(ClientBuilder builder) {
-        this(builder, null);
-    }
-
-    ClientConnectionManager(ClientBuilder builder, ManagedChannel managedChannel) {
-        this.lock = new Object();
-        this.builder = builder;
-        this.managedChannel = managedChannel;
-
-        if (builder.executorService() == null) {
-            this.executorService = Executors.newCachedThreadPool();
-        } else {
-            this.executorService = builder.executorService();
-        }
-    }
-
-    /**
-     * get token from etcd with name and password.
-     *
-     * @param  channel  channel to etcd
-     * @param  username auth name
-     * @param  password auth password
-     * @return          authResp
-     */
-    private static ListenableFuture<AuthenticateResponse> authenticate(@Nonnull Channel channel, @Nonnull ByteSequence username,
-        @Nonnull ByteSequence password) {
-
-        final ByteString user = username.getByteString();
-        final ByteString pass = password.getByteString();
-
-        checkArgument(!user.isEmpty(), "username can not be empty.");
-        checkArgument(!pass.isEmpty(), "password can not be empty.");
-
-        return AuthGrpc.newFutureStub(channel)
-            .authenticate(AuthenticateRequest.newBuilder().setNameBytes(user).setPasswordBytes(pass).build());
-    }
-
-    ManagedChannel getChannel() {
-        if (managedChannel == null) {
-            synchronized (lock) {
-                if (managedChannel == null) {
-                    managedChannel = defaultChannelBuilder().build();
-                }
-            }
-        }
-
-        return managedChannel;
-    }
-
-    @Nullable
-    private String getToken(Channel channel) {
-        if (token == null) {
-            synchronized (lock) {
-                if (token == null) {
-                    token = generateToken(channel);
-                }
-            }
-        }
-
-        return token;
-    }
-
-    void forceTokenRefresh() {
-        synchronized (lock) {
-            token = null;
-        }
-    }
-
-    private void refreshToken(Channel channel) {
-        synchronized (lock) {
-            token = generateToken(channel);
-        }
-    }
-
-    ByteSequence getNamespace() {
-        return builder.namespace();
-    }
-
-    ExecutorService getExecutorService() {
-        return executorService;
-    }
-
-    /**
-     * create stub with saved channel.
-     *
-     * @param  supplier the stub supplier
-     * @param  <T>      the type of stub
-     * @return          the attached stub
-     */
-    <T extends AbstractStub<T>> T newStub(Function<ManagedChannel, T> supplier) {
-        return supplier.apply(getChannel());
-    }
-
-    void close() {
-        synchronized (lock) {
-            if (managedChannel != null) {
-                managedChannel.shutdownNow();
-            }
-        }
-
-        executorService.shutdownNow();
-    }
-
-    <T extends AbstractStub<T>, R> CompletableFuture<R> withNewChannel(URI endpoint, Function<ManagedChannel, T> stubCustomizer,
-        Function<T, CompletableFuture<R>> stubConsumer) {
-
-        final ManagedChannel channel = defaultChannelBuilder(Collections.singletonList(endpoint)).build();
-        final T stub = stubCustomizer.apply(channel);
-
-        try {
-            return stubConsumer.apply(stub).whenComplete((r, t) -> channel.shutdown());
-        } catch (Exception e) {
-            channel.shutdown();
-            throw EtcdExceptionFactory.toEtcdException(e);
-        }
-    }
-
-    @VisibleForTesting
-    protected ManagedChannelBuilder<?> defaultChannelBuilder() {
-        return defaultChannelBuilder(builder.endpoints());
-    }
-
-    @VisibleForTesting
-    protected ManagedChannelBuilder<?> defaultChannelBuilder(Collection<URI> endpoints) {
-        if (endpoints.isEmpty()) {
-            throw new IllegalArgumentException("At least one endpoint should be provided");
-        }
-
-        final String target;
-
-        if (builder.discovery()) {
-            if (endpoints.size() != 1) {
-                throw new IllegalArgumentException("When configured for discovery, there should be only a single endpoint");
-            }
-
-            target = String.format(
-                "%s:///%s",
-                DnsSrvNameResolver.SCHEME,
-                Iterables.get(endpoints, 0));
-        } else {
-            target = String.format(
-                "%s://%s/%s",
-                IPNameResolver.SCHEME,
-                builder.authority() != null ? builder.authority() : "",
-                endpoints.stream().map(e -> e.getHost() + ":" + e.getPort()).collect(Collectors.joining(",")));
-        }
-
-        final NettyChannelBuilder channelBuilder = NettyChannelBuilder.forTarget(target);
-
-        if (builder.authority() != null) {
-            channelBuilder.overrideAuthority(builder.authority());
-        }
-        if (builder.maxInboundMessageSize() != null) {
-            channelBuilder.maxInboundMessageSize(builder.maxInboundMessageSize());
-        }
-        if (builder.sslContext() != null) {
-            channelBuilder.negotiationType(NegotiationType.TLS);
-            channelBuilder.sslContext(builder.sslContext());
-        } else {
-            channelBuilder.negotiationType(NegotiationType.PLAINTEXT);
-        }
-
-        if (builder.keepaliveTimeMs() != null) {
-            channelBuilder.keepAliveTime(builder.keepaliveTimeMs(), TimeUnit.MILLISECONDS);
-        }
-        if (builder.keepaliveTimeoutMs() != null) {
-            channelBuilder.keepAliveTimeout(builder.keepaliveTimeoutMs(), TimeUnit.MILLISECONDS);
-        }
-        if (builder.keepaliveWithoutCalls() != null) {
-            channelBuilder.keepAliveWithoutCalls(builder.keepaliveWithoutCalls());
-        }
-        if (builder.connectTimeoutMs() != null) {
-            channelBuilder.withOption(ChannelOption.CONNECT_TIMEOUT_MILLIS, builder.connectTimeoutMs());
-        }
-
-        if (builder.loadBalancerPolicy() != null) {
-            channelBuilder.defaultLoadBalancingPolicy(builder.loadBalancerPolicy());
-        } else {
-            channelBuilder.defaultLoadBalancingPolicy("pick_first");
-        }
-
-        channelBuilder.intercept(new AuthTokenInterceptor());
-
-        if (builder.headers() != null) {
-            channelBuilder.intercept(new ClientInterceptor() {
-                @Override
-                public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method,
-                    CallOptions callOptions, Channel next) {
-                    return new SimpleForwardingClientCall<ReqT, RespT>(next.newCall(method, callOptions)) {
-                        @Override
-                        public void start(Listener<RespT> responseListener, Metadata headers) {
-                            builder.headers().forEach((BiConsumer<Metadata.Key, Object>) headers::put);
-                            super.start(responseListener, headers);
-                        }
-                    };
-                }
-            });
-        }
-
-        if (builder.interceptors() != null) {
-            channelBuilder.intercept(builder.interceptors());
-        }
-
-        return channelBuilder;
-    }
-
-    /**
-     * get token with ClientBuilder.
-     *
-     * @return                                              the auth token
-     * @throws io.etcd.jetcd.common.exception.EtcdException a exception indicates failure reason.
-     */
-    @Nullable
-    private String generateToken(Channel channel) {
-        if (builder.user() != null && builder.password() != null) {
-            try {
-                return authenticate(channel, builder.user(), builder.password()).get().getToken();
-            } catch (InterruptedException ite) {
-                throw handleInterrupt(ite);
-            } catch (ExecutionException exee) {
-                throw toEtcdException(exee);
-            }
-        }
-        return null;
-    }
-
-    /**
-     * execute the task and retry it in case of failure.
-     *
-     * @param  task          a function that returns a new ListenableFuture.
-     * @param  resultConvert a function that converts Type S to Type T.
-     * @param  <S>           Source type
-     * @param  <T>           Converted Type.
-     * @return               a CompletableFuture with type T.
-     */
-    public <S, T> CompletableFuture<T> execute(Callable<ListenableFuture<S>> task, Function<S, T> resultConvert) {
-        return execute(task, resultConvert, Util::isRetryable);
-    }
-
-    /**
-     * execute the task and retry it in case of failure.
-     *
-     * @param  task          a function that returns a new SourceFuture.
-     * @param  resultConvert a function that converts Type S to Type T.
-     * @param  doRetry       a function that determines the retry condition base on SourceFuture error.
-     * @param  <S>           Source type
-     * @param  <T>           Converted Type.
-     * @return               a CompletableFuture with type T.
-     */
-    @SuppressWarnings("FutureReturnValueIgnored")
-    public <S, T> CompletableFuture<T> execute(
-        Callable<ListenableFuture<S>> task,
-        Function<S, T> resultConvert,
-        Predicate<Throwable> doRetry) {
-
-        RetryPolicy<CompletableFuture<S>> retryPolicy = new RetryPolicy<CompletableFuture<S>>().handleIf(doRetry)
-            .onRetriesExceeded(e -> LOGGER.warn("maximum number of auto retries reached"))
-            .withBackoff(builder.retryDelay(), builder.retryMaxDelay(), builder.retryChronoUnit());
-
-        if (builder.retryMaxDuration() != null) {
-            retryPolicy = retryPolicy.withMaxDuration(Duration.parse(builder.retryMaxDuration()));
-        }
-
-        return Failsafe.with(retryPolicy).with(executorService)
-            .getAsyncExecution(execution -> {
-                CompletableFuture<S> wrappedFuture = new CompletableFuture<>();
-                ListenableFuture<S> future = task.call();
-                future.addListener(() -> {
-                    try {
-                        wrappedFuture.complete(future.get());
-                        if (execution.complete(wrappedFuture)) {
-                            // success! but nothing to do here
-                        }
-                    } catch (Exception error) {
-                        if (!execution.retryOn(error)) {
-                            // permanent failure
-                            wrappedFuture.completeExceptionally(error);
-                        }
-                    }
-                }, executorService);
-                // note: the actual result value is supplied via execution.complete(..) above
-                return wrappedFuture;
-            }).thenCompose(f -> f.thenApply(resultConvert));
-    }
-
-    /**
-     * AuthTokenInterceptor fills header with Auth token of any rpc calls and
-     * refreshes token if the rpc results an invalid Auth token error.
-     */
-    private class AuthTokenInterceptor implements ClientInterceptor {
-
-        @Override
-        public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method,
-            CallOptions callOptions, Channel next) {
-            return new SimpleForwardingClientCall<ReqT, RespT>(next.newCall(method, callOptions)) {
-                @Override
-                public void start(Listener<RespT> responseListener, Metadata headers) {
-                    String token = getToken(next);
-                    if (token != null) {
-                        headers.put(TOKEN, token);
-                    }
-                    super.start(new SimpleForwardingClientCallListener<RespT>(responseListener) {
-                        @Override
-                        public void onClose(Status status, Metadata trailers) {
-                            if (isInvalidTokenError(status)) {
-                                try {
-                                    refreshToken(next);
-                                } catch (Exception e) {
-                                    // don't throw any error here.
-                                    // rpc will retry on expired auth token.
-                                }
-                            }
-                            super.onClose(status, trailers);
-                        }
-                    }, headers);
-                }
-            };
-        }
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/Cluster.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,13 +39,22 @@ public interface Cluster extends CloseableClient {
     CompletableFuture<MemberListResponse> listMember();
 
     /**
-     * add a new member into the cluster.
+     * add a non-learner new member into the cluster.
      *
      * @param  peerAddrs the peer addresses of the new member
      * @return           the response
      */
     CompletableFuture<MemberAddResponse> addMember(List<URI> peerAddrs);
 
+    /**
+     * add a new member into the cluster.
+     *
+     * @param  peerAddrs the peer addresses of the new member
+     * @param  isLearner whether the member is raft learner
+     * @return           the response
+     */
+    CompletableFuture<MemberAddResponse> addMember(List<URI> peerAddrs, boolean isLearner);
+
     /**
      * removes an existing member from the cluster.
      *

jetcd-core/src/main/java/io/etcd/jetcd/Constants.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,11 +22,11 @@ import io.grpc.Metadata;
  * Constants of Etcd.
  */
 public class Constants {
-
-    public static final String TOKEN = "token";
     public static final ByteSequence NULL_KEY = ByteSequence.from(new byte[] { '\0' });
 
-    public static final Metadata.Key<String> REQUIRE_LEADER_KEY = Metadata.Key.of("hasleader",
+    public static final Metadata.Key<String> REQUIRE_LEADER_KEY = Metadata.Key.of(
+        "hasleader",
         Metadata.ASCII_STRING_MARSHALLER);
+
     public static final String REQUIRE_LEADER_VALUE = "true";
 }

jetcd-core/src/main/java/io/etcd/jetcd/Election.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@ package io.etcd.jetcd;
 
 import java.util.concurrent.CompletableFuture;
 
-import com.google.common.annotations.Beta;
 import io.etcd.jetcd.election.CampaignResponse;
 import io.etcd.jetcd.election.LeaderKey;
 import io.etcd.jetcd.election.LeaderResponse;
@@ -29,7 +28,6 @@ import io.etcd.jetcd.support.CloseableClient;
 /**
  * Interface of leader election client talking to etcd.
  */
-@Beta
 public interface Election extends CloseableClient {
     /**
      * Campaign waits to acquire leadership in an election, returning a leader key

jetcd-core/src/main/java/io/etcd/jetcd/ElectionImpl.java

@@ -1,185 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.util.concurrent.CompletableFuture;
-import java.util.function.Function;
-
-import io.etcd.jetcd.api.CampaignRequest;
-import io.etcd.jetcd.api.ElectionGrpc;
-import io.etcd.jetcd.api.LeaderRequest;
-import io.etcd.jetcd.api.ProclaimRequest;
-import io.etcd.jetcd.api.ResignRequest;
-import io.etcd.jetcd.common.exception.EtcdExceptionFactory;
-import io.etcd.jetcd.election.CampaignResponse;
-import io.etcd.jetcd.election.LeaderKey;
-import io.etcd.jetcd.election.LeaderResponse;
-import io.etcd.jetcd.election.NoLeaderException;
-import io.etcd.jetcd.election.NotLeaderException;
-import io.etcd.jetcd.election.ProclaimResponse;
-import io.etcd.jetcd.election.ResignResponse;
-import io.grpc.StatusRuntimeException;
-import io.grpc.stub.StreamObserver;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-final class ElectionImpl implements Election {
-    private final ElectionGrpc.ElectionStub stub;
-    private final ByteSequence namespace;
-
-    ElectionImpl(ClientConnectionManager connectionManager) {
-        this.stub = connectionManager.newStub(ElectionGrpc::newStub);
-        this.namespace = connectionManager.getNamespace();
-    }
-
-    @Override
-    public CompletableFuture<CampaignResponse> campaign(ByteSequence electionName, long leaseId, ByteSequence proposal) {
-        checkNotNull(electionName, "election name should not be null");
-        checkNotNull(proposal, "proposal should not be null");
-
-        CampaignRequest request = CampaignRequest.newBuilder()
-            .setName(Util.prefixNamespace(electionName.getByteString(), namespace))
-            .setValue(proposal.getByteString())
-            .setLease(leaseId)
-            .build();
-
-        final StreamObserverDelegate<io.etcd.jetcd.api.CampaignResponse, CampaignResponse> observer = new StreamObserverDelegate<>(
-            CampaignResponse::new);
-        stub.campaign(request, observer);
-
-        return observer.getFuture();
-    }
-
-    @Override
-    public CompletableFuture<ProclaimResponse> proclaim(LeaderKey leaderKey, ByteSequence proposal) {
-        checkNotNull(leaderKey, "leader key should not be null");
-        checkNotNull(proposal, "proposal should not be null");
-
-        io.etcd.jetcd.api.LeaderKey leader = io.etcd.jetcd.api.LeaderKey.newBuilder()
-            .setKey(leaderKey.getKey()).setName(leaderKey.getName())
-            .setLease(leaderKey.getLease()).setRev(leaderKey.getRevision())
-            .build();
-        ProclaimRequest request = ProclaimRequest.newBuilder()
-            .setLeader(leader).setValue(proposal.getByteString())
-            .build();
-
-        final StreamObserverDelegate<io.etcd.jetcd.api.ProclaimResponse, ProclaimResponse> observer = new StreamObserverDelegate<>(
-            ProclaimResponse::new);
-        stub.proclaim(request, observer);
-
-        return observer.getFuture();
-    }
-
-    @Override
-    public CompletableFuture<LeaderResponse> leader(ByteSequence electionName) {
-        checkNotNull(electionName, "election name should not be null");
-
-        LeaderRequest request = LeaderRequest.newBuilder()
-            .setName(Util.prefixNamespace(electionName.getByteString(), namespace))
-            .build();
-
-        final StreamObserverDelegate<io.etcd.jetcd.api.LeaderResponse, LeaderResponse> observer = new StreamObserverDelegate<>(
-            input -> new LeaderResponse(input, namespace));
-        stub.leader(request, observer);
-
-        return observer.getFuture();
-    }
-
-    @Override
-    public void observe(ByteSequence electionName, Listener listener) {
-        checkNotNull(electionName, "election name should not be null");
-        checkNotNull(listener, "listener should not be null");
-
-        LeaderRequest request = LeaderRequest.newBuilder().setName(electionName.getByteString()).build();
-
-        stub.observe(request, new StreamObserver<io.etcd.jetcd.api.LeaderResponse>() {
-            @Override
-            public void onNext(io.etcd.jetcd.api.LeaderResponse value) {
-                listener.onNext(new LeaderResponse(value, namespace));
-            }
-
-            @Override
-            public void onError(Throwable error) {
-                listener.onError(EtcdExceptionFactory.toEtcdException(error));
-            }
-
-            @Override
-            public void onCompleted() {
-                listener.onCompleted();
-            }
-        });
-    }
-
-    @Override
-    public CompletableFuture<ResignResponse> resign(LeaderKey leaderKey) {
-        checkNotNull(leaderKey, "leader key should not be null");
-
-        io.etcd.jetcd.api.LeaderKey leader = io.etcd.jetcd.api.LeaderKey.newBuilder()
-            .setKey(leaderKey.getKey()).setName(leaderKey.getName())
-            .setLease(leaderKey.getLease()).setRev(leaderKey.getRevision())
-            .build();
-        ResignRequest request = ResignRequest.newBuilder().setLeader(leader).build();
-
-        final StreamObserverDelegate<io.etcd.jetcd.api.ResignResponse, ResignResponse> observer = new StreamObserverDelegate<>(
-            ResignResponse::new);
-        stub.resign(request, observer);
-
-        return observer.getFuture();
-    }
-
-    @Override
-    public void close() {
-    }
-
-    private static class StreamObserverDelegate<S, T> implements StreamObserver<S> {
-        private final CompletableFuture<T> future = new CompletableFuture<>();
-        private final Function<S, T> converter;
-
-        public StreamObserverDelegate(Function<S, T> converter) {
-            this.converter = converter;
-        }
-
-        @Override
-        public void onNext(S value) {
-            future.complete(converter.apply(value));
-        }
-
-        @Override
-        public void onError(Throwable error) {
-            if (error instanceof StatusRuntimeException) {
-                StatusRuntimeException exception = (StatusRuntimeException) error;
-                String description = exception.getStatus().getDescription();
-                // different APIs use different messages. we cannot distinguish missing leader error otherwise,
-                // because communicated status is always UNKNOWN
-                if ("election: not leader".equals(description)) {
-                    future.completeExceptionally(NotLeaderException.INSTANCE);
-                } else if ("election: no leader".equals(description)) {
-                    future.completeExceptionally(NoLeaderException.INSTANCE);
-                }
-            }
-            future.completeExceptionally(EtcdExceptionFactory.toEtcdException(error));
-        }
-
-        @Override
-        public void onCompleted() {
-        }
-
-        public CompletableFuture<T> getFuture() {
-            return future;
-        }
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/KV.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@ package io.etcd.jetcd;
 
 import java.util.concurrent.CompletableFuture;
 
-import com.google.common.annotations.Beta;
 import io.etcd.jetcd.kv.CompactResponse;
 import io.etcd.jetcd.kv.DeleteResponse;
 import io.etcd.jetcd.kv.GetResponse;
@@ -27,12 +26,12 @@ import io.etcd.jetcd.options.CompactOption;
 import io.etcd.jetcd.options.DeleteOption;
 import io.etcd.jetcd.options.GetOption;
 import io.etcd.jetcd.options.PutOption;
+import io.etcd.jetcd.options.TxnOption;
 import io.etcd.jetcd.support.CloseableClient;
 
 /**
  * Interface of kv client talking to etcd.
  */
-@Beta
 public interface KV extends CloseableClient {
 
     /**
@@ -117,4 +116,12 @@ public interface KV extends CloseableClient {
      * @return a Txn
      */
     Txn txn();
+
+    /**
+     * creates a transaction.
+     *
+     * @param  option TxnOption
+     * @return        a Txn
+     */
+    Txn txn(TxnOption option);
 }

jetcd-core/src/main/java/io/etcd/jetcd/KVImpl.java

@@ -1,169 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.util.concurrent.CompletableFuture;
-
-import io.etcd.jetcd.api.CompactionRequest;
-import io.etcd.jetcd.api.DeleteRangeRequest;
-import io.etcd.jetcd.api.KVGrpc;
-import io.etcd.jetcd.api.PutRequest;
-import io.etcd.jetcd.api.RangeRequest;
-import io.etcd.jetcd.kv.CompactResponse;
-import io.etcd.jetcd.kv.DeleteResponse;
-import io.etcd.jetcd.kv.GetResponse;
-import io.etcd.jetcd.kv.PutResponse;
-import io.etcd.jetcd.kv.TxnResponse;
-import io.etcd.jetcd.op.TxnImpl;
-import io.etcd.jetcd.options.CompactOption;
-import io.etcd.jetcd.options.DeleteOption;
-import io.etcd.jetcd.options.GetOption;
-import io.etcd.jetcd.options.PutOption;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-import static io.etcd.jetcd.options.OptionsUtil.toRangeRequestSortOrder;
-import static io.etcd.jetcd.options.OptionsUtil.toRangeRequestSortTarget;
-
-/**
- * Implementation of etcd kv client.
- */
-final class KVImpl implements KV {
-
-    private final ClientConnectionManager connectionManager;
-
-    private final KVGrpc.KVFutureStub stub;
-
-    private final ByteSequence namespace;
-
-    KVImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(KVGrpc::newFutureStub);
-        this.namespace = connectionManager.getNamespace();
-    }
-
-    @Override
-    public CompletableFuture<PutResponse> put(ByteSequence key, ByteSequence value) {
-        return this.put(key, value, PutOption.DEFAULT);
-    }
-
-    @Override
-    public CompletableFuture<PutResponse> put(ByteSequence key, ByteSequence value, PutOption option) {
-        checkNotNull(key, "key should not be null");
-        checkNotNull(value, "value should not be null");
-        checkNotNull(option, "option should not be null");
-
-        PutRequest request = PutRequest.newBuilder()
-            .setKey(Util.prefixNamespace(key.getByteString(), namespace))
-            .setValue(value.getByteString())
-            .setLease(option.getLeaseId())
-            .setPrevKv(option.getPrevKV())
-            .build();
-
-        return connectionManager.execute(
-            () -> stub.put(request),
-            response -> new PutResponse(response, namespace),
-            Util::isRetryable);
-    }
-
-    @Override
-    public CompletableFuture<GetResponse> get(ByteSequence key) {
-        return this.get(key, GetOption.DEFAULT);
-    }
-
-    @Override
-    public CompletableFuture<GetResponse> get(ByteSequence key, GetOption option) {
-        checkNotNull(key, "key should not be null");
-        checkNotNull(option, "option should not be null");
-
-        RangeRequest.Builder builder = RangeRequest.newBuilder()
-            .setKey(Util.prefixNamespace(key.getByteString(), namespace))
-            .setCountOnly(option.isCountOnly())
-            .setLimit(option.getLimit())
-            .setRevision(option.getRevision())
-            .setKeysOnly(option.isKeysOnly())
-            .setSerializable(option.isSerializable())
-            .setSortOrder(toRangeRequestSortOrder(option.getSortOrder()))
-            .setSortTarget(toRangeRequestSortTarget(option.getSortField()))
-            .setMinCreateRevision(option.getMinCreateRevision())
-            .setMaxCreateRevision(option.getMaxCreateRevision())
-            .setMinModRevision(option.getMinModRevision())
-            .setMaxModRevision(option.getMaxModRevision());
-
-        option.getEndKey().map(endKey -> Util.prefixNamespaceToRangeEnd(endKey.getByteString(), namespace))
-            .ifPresent(builder::setRangeEnd);
-
-        RangeRequest request = builder.build();
-
-        return connectionManager.execute(
-            () -> stub.range(request),
-            response -> new GetResponse(response, namespace),
-            Util::isRetryable);
-    }
-
-    @Override
-    public CompletableFuture<DeleteResponse> delete(ByteSequence key) {
-        return this.delete(key, DeleteOption.DEFAULT);
-    }
-
-    @Override
-    public CompletableFuture<DeleteResponse> delete(ByteSequence key, DeleteOption option) {
-        checkNotNull(key, "key should not be null");
-        checkNotNull(option, "option should not be null");
-
-        DeleteRangeRequest.Builder builder = DeleteRangeRequest.newBuilder()
-            .setKey(Util.prefixNamespace(key.getByteString(), namespace))
-            .setPrevKv(option.isPrevKV());
-
-        option.getEndKey()
-            .map(endKey -> Util.prefixNamespaceToRangeEnd(endKey.getByteString(), namespace))
-            .ifPresent(builder::setRangeEnd);
-
-        DeleteRangeRequest request = builder.build();
-
-        return connectionManager.execute(
-            () -> stub.deleteRange(request),
-            response -> new DeleteResponse(response, namespace),
-            Util::isRetryable);
-    }
-
-    @Override
-    public CompletableFuture<CompactResponse> compact(long rev) {
-        return this.compact(rev, CompactOption.DEFAULT);
-    }
-
-    @Override
-    public CompletableFuture<CompactResponse> compact(long rev, CompactOption option) {
-        checkNotNull(option, "option should not be null");
-
-        CompactionRequest request = CompactionRequest.newBuilder()
-            .setRevision(rev).setPhysical(option.isPhysical())
-            .build();
-
-        return connectionManager.execute(
-            () -> stub.compact(request),
-            CompactResponse::new,
-            Util::isRetryable);
-    }
-
-    public Txn txn() {
-        return TxnImpl.newTxn(
-            request -> connectionManager.execute(
-                () -> stub.txn(request),
-                response -> new TxnResponse(response, namespace), Util::isRetryable),
-            namespace);
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/KeyValue.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package io.etcd.jetcd;
 
+import io.etcd.jetcd.support.Util;
+
 /**
  * Etcd key value pair.
  */
@@ -27,26 +29,35 @@ public class KeyValue {
 
     public KeyValue(io.etcd.jetcd.api.KeyValue kv, ByteSequence namespace) {
         this.kv = kv;
-        this.unprefixedKey = ByteSequence
-            .from(kv.getKey().isEmpty() ? kv.getKey() : Util.unprefixNamespace(kv.getKey(), namespace));
         this.value = ByteSequence.from(kv.getValue());
+
+        this.unprefixedKey = ByteSequence.from(
+            kv.getKey().isEmpty()
+                ? kv.getKey()
+                : Util.unprefixNamespace(kv.getKey(), namespace));
     }
 
     /**
-     * @return the key
+     * Returns the key
+     *
+     * @return the key.
      */
     public ByteSequence getKey() {
         return unprefixedKey;
     }
 
     /**
-     * @return the value
+     * Returns the value
+     *
+     * @return the value.
      */
     public ByteSequence getValue() {
         return value;
     }
 
     /**
+     * Returns the create revision.
+     *
      * @return the create revision.
      */
     public long getCreateRevision() {
@@ -54,6 +65,8 @@ public class KeyValue {
     }
 
     /**
+     * Returns the mod revision.
+     *
      * @return the mod revision.
      */
     public long getModRevision() {
@@ -61,6 +74,8 @@ public class KeyValue {
     }
 
     /**
+     * Returns the version.
+     *
      * @return the version.
      */
     public long getVersion() {
@@ -68,6 +83,8 @@ public class KeyValue {
     }
 
     /**
+     * Returns the lease.
+     *
      * @return the lease.
      */
     public long getLease() {

jetcd-core/src/main/java/io/etcd/jetcd/Lease.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-core/src/main/java/io/etcd/jetcd/LeaseImpl.java

@@ -1,352 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.TimeUnit;
-
-import com.google.common.util.concurrent.FutureCallback;
-import com.google.common.util.concurrent.Futures;
-import com.google.common.util.concurrent.ListeningScheduledExecutorService;
-import com.google.common.util.concurrent.MoreExecutors;
-import io.etcd.jetcd.api.LeaseGrantRequest;
-import io.etcd.jetcd.api.LeaseGrpc;
-import io.etcd.jetcd.api.LeaseKeepAliveRequest;
-import io.etcd.jetcd.api.LeaseRevokeRequest;
-import io.etcd.jetcd.api.LeaseTimeToLiveRequest;
-import io.etcd.jetcd.common.exception.ErrorCode;
-import io.etcd.jetcd.lease.LeaseGrantResponse;
-import io.etcd.jetcd.lease.LeaseKeepAliveResponse;
-import io.etcd.jetcd.lease.LeaseRevokeResponse;
-import io.etcd.jetcd.lease.LeaseTimeToLiveResponse;
-import io.etcd.jetcd.options.LeaseOption;
-import io.etcd.jetcd.support.CloseableClient;
-import io.etcd.jetcd.support.Observers;
-import io.grpc.stub.StreamObserver;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.newClosedLeaseClientException;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.newEtcdException;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
-
-/**
- * Implementation of lease client.
- */
-final class LeaseImpl implements Lease {
-
-    private static final Logger LOG = LoggerFactory.getLogger(LeaseImpl.class);
-
-    /**
-     * FIRST_KEEPALIVE_TIMEOUT_MS is the timeout for the first keepalive request
-     * before the actual TTL is known to the lease client.
-     */
-    private static final int FIRST_KEEPALIVE_TIMEOUT_MS = 5000;
-
-    private final ClientConnectionManager connectionManager;
-    private final LeaseGrpc.LeaseFutureStub stub;
-    private final LeaseGrpc.LeaseStub leaseStub;
-    private final Map<Long, KeepAlive> keepAlives;
-    /**
-     * Timer schedule to send keep alive request.
-     */
-    private final ListeningScheduledExecutorService scheduledExecutorService;
-    private ScheduledFuture<?> keepAliveFuture;
-    private ScheduledFuture<?> deadlineFuture;
-    /**
-     * KeepAlive Request Stream, put request into this stream to keep the lease alive.
-     */
-    private StreamObserver<LeaseKeepAliveRequest> keepAliveRequestObserver;
-
-    /**
-     * KeepAlive Response Streamer, receive keep alive response from this stream and update the
-     * nextKeepAliveTime and deadline of the leases.
-     */
-    private StreamObserver<io.etcd.jetcd.api.LeaseKeepAliveResponse> keepAliveResponseObserver;
-
-    /**
-     * hasKeepAliveServiceStarted indicates whether the background keep alive service has started.
-     */
-    private volatile boolean hasKeepAliveServiceStarted;
-    private volatile boolean closed;
-
-    LeaseImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(LeaseGrpc::newFutureStub);
-        this.leaseStub = Util.applyRequireLeader(true, connectionManager.newStub(LeaseGrpc::newStub));
-        this.keepAlives = new ConcurrentHashMap<>();
-        this.scheduledExecutorService = MoreExecutors.listeningDecorator(Executors.newScheduledThreadPool(2));
-    }
-
-    @Override
-    public CompletableFuture<LeaseGrantResponse> grant(long ttl) {
-        return connectionManager.execute(() -> this.stub.leaseGrant(LeaseGrantRequest.newBuilder().setTTL(ttl).build()),
-            LeaseGrantResponse::new);
-    }
-
-    @Override
-    public CompletableFuture<LeaseGrantResponse> grant(long ttl, long timeout, TimeUnit unit) {
-        return connectionManager.execute(
-            () -> this.stub.withDeadlineAfter(timeout, unit).leaseGrant(LeaseGrantRequest.newBuilder().setTTL(ttl).build()),
-            LeaseGrantResponse::new);
-    }
-
-    @Override
-    public CompletableFuture<LeaseRevokeResponse> revoke(long leaseId) {
-        return connectionManager.execute(() -> this.stub.leaseRevoke(LeaseRevokeRequest.newBuilder().setID(leaseId).build()),
-            LeaseRevokeResponse::new);
-    }
-
-    @Override
-    public synchronized CloseableClient keepAlive(long leaseId, StreamObserver<LeaseKeepAliveResponse> observer) {
-        if (this.closed) {
-            throw newClosedLeaseClientException();
-        }
-
-        KeepAlive keepAlive = this.keepAlives.computeIfAbsent(leaseId, (key) -> new KeepAlive(leaseId));
-        keepAlive.addObserver(observer);
-
-        if (!this.hasKeepAliveServiceStarted) {
-            this.hasKeepAliveServiceStarted = true;
-            this.start();
-        }
-
-        return new CloseableClient() {
-            @Override
-            public void close() {
-                keepAlive.removeObserver(observer);
-            }
-        };
-    }
-
-    @Override
-    public synchronized void close() {
-        if (this.closed) {
-            return;
-        }
-        this.closed = true;
-
-        if (!this.hasKeepAliveServiceStarted) { // hasKeepAliveServiceStarted hasn't started.
-            return;
-        }
-
-        this.keepAliveFuture.cancel(true);
-        this.deadlineFuture.cancel(true);
-        this.keepAliveRequestObserver.onCompleted();
-        this.keepAliveResponseObserver.onCompleted();
-        this.scheduledExecutorService.shutdownNow();
-
-        final Throwable errResp = newClosedLeaseClientException();
-
-        this.keepAlives.forEach((k, v) -> v.onError(errResp));
-        this.keepAlives.clear();
-    }
-
-    private synchronized void removeKeepAlive(long leaseId) {
-        this.keepAlives.remove(leaseId);
-    }
-
-    private void start() {
-        this.sendKeepAliveExecutor();
-        this.deadLineExecutor();
-    }
-
-    private void reset() {
-        this.keepAliveFuture.cancel(true);
-        this.keepAliveRequestObserver.onCompleted();
-        this.keepAliveResponseObserver.onCompleted();
-        this.sendKeepAliveExecutor();
-    }
-
-    private void sendKeepAliveExecutor() {
-        this.keepAliveResponseObserver = Observers.observer(this::processKeepAliveResponse, error -> processOnError());
-        this.keepAliveRequestObserver = this.leaseStub.leaseKeepAlive(this.keepAliveResponseObserver);
-        this.keepAliveFuture = scheduledExecutorService.scheduleAtFixedRate(() -> {
-            // send keep alive req to the leases whose next keep alive is before now.
-            this.keepAlives.entrySet().stream()
-                .filter(entry -> entry.getValue().getNextKeepAlive() < System.currentTimeMillis()).map(Entry::getKey)
-                .map(leaseId -> LeaseKeepAliveRequest.newBuilder().setID(leaseId).build())
-                .forEach(keepAliveRequestObserver::onNext);
-
-        }, 0, 500, TimeUnit.MILLISECONDS);
-    }
-
-    private synchronized void processOnError() {
-        if (this.closed) {
-            return;
-        }
-
-        Futures.addCallback(this.scheduledExecutorService.schedule(this::reset, 500, TimeUnit.MILLISECONDS),
-            new FutureCallback<Object>() {
-                @Override
-                public void onFailure(Throwable throwable) {
-                    LOG.error("scheduled reset failed", throwable);
-                }
-
-                @Override
-                public void onSuccess(Object result) {
-                }
-            }, this.scheduledExecutorService);
-    }
-
-    private synchronized void processKeepAliveResponse(io.etcd.jetcd.api.LeaseKeepAliveResponse leaseKeepAliveResponse) {
-        if (this.closed) {
-            return;
-        }
-
-        final long leaseID = leaseKeepAliveResponse.getID();
-        final long ttl = leaseKeepAliveResponse.getTTL();
-        final KeepAlive ka = this.keepAlives.get(leaseID);
-
-        if (ka == null) {
-            // return if the corresponding keep alive has closed.
-            return;
-        }
-
-        if (ttl > 0) {
-            long nextKeepAlive = System.currentTimeMillis() + ttl * 1000 / 3;
-            ka.setNextKeepAlive(nextKeepAlive);
-            ka.setDeadLine(System.currentTimeMillis() + ttl * 1000);
-            ka.onNext(leaseKeepAliveResponse);
-        } else {
-            // lease expired; close all keep alive
-            this.removeKeepAlive(leaseID);
-            ka.onError(newEtcdException(ErrorCode.NOT_FOUND, "etcdserver: requested lease not found"));
-        }
-    }
-
-    private void deadLineExecutor() {
-        this.deadlineFuture = scheduledExecutorService.scheduleAtFixedRate(() -> {
-            long now = System.currentTimeMillis();
-
-            this.keepAlives.values().removeIf(ka -> {
-                if (ka.getDeadLine() < now) {
-                    ka.onCompleted();
-                    return true;
-                }
-                return false;
-            });
-        }, 0, 1000, TimeUnit.MILLISECONDS);
-    }
-
-    @Override
-    public CompletableFuture<LeaseKeepAliveResponse> keepAliveOnce(long leaseId) {
-        CompletableFuture<LeaseKeepAliveResponse> future = new CompletableFuture<>();
-
-        StreamObserver<LeaseKeepAliveRequest> requestObserver = Observers.observe(
-            this.leaseStub::leaseKeepAlive,
-            response -> future.complete(new LeaseKeepAliveResponse(response)),
-            throwable -> future.completeExceptionally(toEtcdException(throwable)));
-
-        // cancel grpc stream when leaseKeepAliveResponseCompletableFuture completes.
-        CompletableFuture<LeaseKeepAliveResponse> answer = future
-            .whenCompleteAsync((val, throwable) -> requestObserver.onCompleted(), connectionManager.getExecutorService());
-
-        requestObserver.onNext(LeaseKeepAliveRequest.newBuilder().setID(leaseId).build());
-
-        return answer;
-    }
-
-    @Override
-    public CompletableFuture<LeaseTimeToLiveResponse> timeToLive(long leaseId, LeaseOption option) {
-        checkNotNull(option, "LeaseOption should not be null");
-
-        LeaseTimeToLiveRequest leaseTimeToLiveRequest = LeaseTimeToLiveRequest.newBuilder()
-            .setID(leaseId)
-            .setKeys(option.isAttachedKeys())
-            .build();
-
-        return connectionManager.execute(
-            () -> this.stub.leaseTimeToLive(leaseTimeToLiveRequest),
-            LeaseTimeToLiveResponse::new);
-    }
-
-    /**
-     * The KeepAlive hold the keepAlive information for lease.
-     */
-    private final class KeepAlive implements StreamObserver<io.etcd.jetcd.api.LeaseKeepAliveResponse> {
-        private final List<StreamObserver<LeaseKeepAliveResponse>> observers;
-        private final long leaseId;
-
-        private long deadLine;
-        private long nextKeepAlive;
-
-        public KeepAlive(long leaseId) {
-            this.nextKeepAlive = System.currentTimeMillis();
-            this.deadLine = nextKeepAlive + FIRST_KEEPALIVE_TIMEOUT_MS;
-
-            this.observers = new CopyOnWriteArrayList<>();
-            this.leaseId = leaseId;
-        }
-
-        public long getDeadLine() {
-            return deadLine;
-        }
-
-        public void setDeadLine(long deadLine) {
-            this.deadLine = deadLine;
-        }
-
-        public void addObserver(StreamObserver<LeaseKeepAliveResponse> observer) {
-            this.observers.add(observer);
-        }
-
-        //removeObserver only would be called synchronously by close in KeepAliveListener, no need to get lock here
-        public void removeObserver(StreamObserver<LeaseKeepAliveResponse> listener) {
-            this.observers.remove(listener);
-            if (this.observers.isEmpty()) {
-                removeKeepAlive(leaseId);
-            }
-        }
-
-        public long getNextKeepAlive() {
-            return nextKeepAlive;
-        }
-
-        public void setNextKeepAlive(long nextKeepAlive) {
-            this.nextKeepAlive = nextKeepAlive;
-        }
-
-        @Override
-        public void onNext(io.etcd.jetcd.api.LeaseKeepAliveResponse response) {
-            for (StreamObserver<LeaseKeepAliveResponse> observer : observers) {
-                observer.onNext(new LeaseKeepAliveResponse(response));
-            }
-        }
-
-        @Override
-        public void onError(Throwable throwable) {
-            for (StreamObserver<LeaseKeepAliveResponse> observer : observers) {
-                observer.onError(toEtcdException(throwable));
-            }
-        }
-
-        @Override
-        public void onCompleted() {
-            this.observers.forEach(StreamObserver::onCompleted);
-            this.observers.clear();
-        }
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/Lock.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

jetcd-core/src/main/java/io/etcd/jetcd/LockImpl.java

@@ -1,71 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.util.concurrent.CompletableFuture;
-
-import io.etcd.jetcd.api.lock.LockGrpc;
-import io.etcd.jetcd.api.lock.LockRequest;
-import io.etcd.jetcd.api.lock.UnlockRequest;
-import io.etcd.jetcd.lock.LockResponse;
-import io.etcd.jetcd.lock.UnlockResponse;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-final class LockImpl implements Lock {
-
-    private final ClientConnectionManager connectionManager;
-
-    private final LockGrpc.LockFutureStub stub;
-
-    private final ByteSequence namespace;
-
-    LockImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(LockGrpc::newFutureStub);
-        this.namespace = connectionManager.getNamespace();
-    }
-
-    @Override
-    public CompletableFuture<LockResponse> lock(ByteSequence name, long leaseId) {
-        checkNotNull(name);
-
-        LockRequest request = LockRequest.newBuilder()
-            .setName(Util.prefixNamespace(name.getByteString(), namespace))
-            .setLease(leaseId)
-            .build();
-
-        return connectionManager.execute(
-            () -> stub.lock(request),
-            response -> new LockResponse(response, namespace),
-            Util::isRetryable);
-    }
-
-    @Override
-    public CompletableFuture<UnlockResponse> unlock(ByteSequence lockKey) {
-        checkNotNull(lockKey);
-
-        UnlockRequest request = UnlockRequest.newBuilder()
-            .setKey(Util.prefixNamespace(lockKey.getByteString(), namespace))
-            .build();
-
-        return connectionManager.execute(
-            () -> stub.unlock(request),
-            UnlockResponse::new,
-            Util::isRetryable);
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/Maintenance.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,16 +17,9 @@
 package io.etcd.jetcd;
 
 import java.io.OutputStream;
-import java.net.URI;
 import java.util.concurrent.CompletableFuture;
 
-import io.etcd.jetcd.maintenance.AlarmMember;
-import io.etcd.jetcd.maintenance.AlarmResponse;
-import io.etcd.jetcd.maintenance.DefragmentResponse;
-import io.etcd.jetcd.maintenance.HashKVResponse;
-import io.etcd.jetcd.maintenance.MoveLeaderResponse;
-import io.etcd.jetcd.maintenance.SnapshotResponse;
-import io.etcd.jetcd.maintenance.StatusResponse;
+import io.etcd.jetcd.maintenance.*;
 import io.etcd.jetcd.support.CloseableClient;
 import io.grpc.stub.StreamObserver;
 
@@ -69,7 +62,7 @@ public interface Maintenance extends CloseableClient {
     CompletableFuture<AlarmResponse> alarmDisarm(AlarmMember member);
 
     /**
-     * defragment one member of the cluster by its endpoint.
+     * Defragment one member of the cluster by its endpoint.
      *
      * <p>
      * After compacting the keyspace, the backend database may exhibit internal
@@ -85,29 +78,29 @@ public interface Maintenance extends CloseableClient {
      * To defragment multiple members in the cluster, user need to call defragment
      * multiple times with different endpoints.
      *
-     * @param  endpoint the etcd server endpoint.
+     * @param  target the etcd server endpoint.
      * @return        the response result
      */
-    CompletableFuture<DefragmentResponse> defragmentMember(URI endpoint);
+    CompletableFuture<DefragmentResponse> defragmentMember(String target);
 
     /**
      * get the status of a member by its endpoint.
      *
-     * @param  endpoint the etcd server endpoint.
+     * @param  target the etcd server endpoint.
      * @return        the response result
      */
-    CompletableFuture<StatusResponse> statusMember(URI endpoint);
+    CompletableFuture<StatusResponse> statusMember(String target);
 
     /**
      * returns a hash of the KV state at the time of the RPC.
      * If revision is zero, the hash is computed on all keys. If the revision
      * is non-zero, the hash is computed on all keys at or below the given revision.
      *
-     * @param  endpoint the etcd server endpoint.
+     * @param  target the etcd server endpoint.
      * @param  rev    the revision
      * @return        the response result
      */
-    CompletableFuture<HashKVResponse> hashKV(URI endpoint, long rev);
+    CompletableFuture<HashKVResponse> hashKV(String target, long rev);
 
     /**
      * retrieves backend snapshot.

jetcd-core/src/main/java/io/etcd/jetcd/MaintenanceImpl.java

@@ -1,208 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.io.IOException;
-import java.io.OutputStream;
-import java.net.URI;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.atomic.AtomicLong;
-
-import io.etcd.jetcd.api.AlarmRequest;
-import io.etcd.jetcd.api.AlarmType;
-import io.etcd.jetcd.api.DefragmentRequest;
-import io.etcd.jetcd.api.HashKVRequest;
-import io.etcd.jetcd.api.MaintenanceGrpc;
-import io.etcd.jetcd.api.MoveLeaderRequest;
-import io.etcd.jetcd.api.SnapshotRequest;
-import io.etcd.jetcd.api.SnapshotResponse;
-import io.etcd.jetcd.api.StatusRequest;
-import io.etcd.jetcd.maintenance.AlarmResponse;
-import io.etcd.jetcd.maintenance.DefragmentResponse;
-import io.etcd.jetcd.maintenance.HashKVResponse;
-import io.etcd.jetcd.maintenance.MoveLeaderResponse;
-import io.etcd.jetcd.maintenance.StatusResponse;
-import io.grpc.stub.StreamObserver;
-
-import static com.google.common.base.Preconditions.checkArgument;
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
-
-/**
- * Implementation of maintenance client.
- */
-final class MaintenanceImpl implements Maintenance {
-
-    private final ClientConnectionManager connectionManager;
-    private final MaintenanceGrpc.MaintenanceFutureStub stub;
-    private final MaintenanceGrpc.MaintenanceStub streamStub;
-
-    MaintenanceImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(MaintenanceGrpc::newFutureStub);
-        this.streamStub = connectionManager.newStub(MaintenanceGrpc::newStub);
-    }
-
-    /**
-     * get all active keyspace alarm.
-     *
-     * @return alarm list
-     */
-    @Override
-    public CompletableFuture<AlarmResponse> listAlarms() {
-        AlarmRequest alarmRequest = AlarmRequest.newBuilder()
-            .setAlarm(AlarmType.NONE)
-            .setAction(AlarmRequest.AlarmAction.GET)
-            .setMemberID(0)
-            .build();
-
-        return Util.toCompletableFuture(this.stub.alarm(alarmRequest), AlarmResponse::new,
-            this.connectionManager.getExecutorService());
-    }
-
-    /**
-     * disarms a given alarm.
-     *
-     * @param  member the alarm
-     * @return        the response result
-     */
-    @Override
-    public CompletableFuture<AlarmResponse> alarmDisarm(io.etcd.jetcd.maintenance.AlarmMember member) {
-        checkArgument(member.getMemberId() != 0, "the member id can not be 0");
-        checkArgument(member.getAlarmType() != io.etcd.jetcd.maintenance.AlarmType.NONE, "alarm type can not be NONE");
-
-        AlarmRequest alarmRequest = AlarmRequest.newBuilder()
-            .setAlarm(AlarmType.NOSPACE)
-            .setAction(AlarmRequest.AlarmAction.DEACTIVATE)
-            .setMemberID(member.getMemberId())
-            .build();
-
-        return Util.toCompletableFuture(this.stub.alarm(alarmRequest), AlarmResponse::new,
-            this.connectionManager.getExecutorService());
-    }
-
-    /**
-     * defragment one member of the cluster.
-     *
-     * <p>
-     * After compacting the keyspace, the backend database may exhibit internal
-     * fragmentation. Any internal fragmentation is space that is free to use
-     * by the backend but still consumes storage space. The process of
-     * defragmentation releases this storage space back to the file system.
-     * Defragmentation is issued on a per-member so that cluster-wide latency
-     * spikes may be avoided.
-     *
-     * <p>
-     * Defragment is an expensive operation. User should avoid defragmenting
-     * multiple members at the same time.
-     * To defragment multiple members in the cluster, user need to call defragment
-     * multiple times with different endpoints.
-     */
-    @Override
-    public CompletableFuture<DefragmentResponse> defragmentMember(URI endpoint) {
-        return this.connectionManager.withNewChannel(
-            endpoint,
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.defragment(DefragmentRequest.getDefaultInstance()),
-                DefragmentResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    /**
-     * get the status of one member.
-     */
-    @Override
-    public CompletableFuture<StatusResponse> statusMember(URI endpoint) {
-        return this.connectionManager.withNewChannel(
-            endpoint,
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.status(StatusRequest.getDefaultInstance()),
-                StatusResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<MoveLeaderResponse> moveLeader(long transfereeID) {
-        return Util.toCompletableFuture(
-            this.stub.moveLeader(MoveLeaderRequest.newBuilder().setTargetID(transfereeID).build()),
-            MoveLeaderResponse::new,
-            this.connectionManager.getExecutorService());
-    }
-
-    @Override
-    public CompletableFuture<HashKVResponse> hashKV(URI endpoint, long rev) {
-        return this.connectionManager.withNewChannel(
-            endpoint,
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.hashKV(HashKVRequest.newBuilder().setRevision(rev).build()),
-                HashKVResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<Long> snapshot(OutputStream outputStream) {
-        final CompletableFuture<Long> answer = new CompletableFuture<>();
-        final AtomicLong bytes = new AtomicLong(0);
-
-        this.streamStub.snapshot(SnapshotRequest.getDefaultInstance(), new StreamObserver<SnapshotResponse>() {
-            @Override
-            public void onNext(SnapshotResponse snapshotResponse) {
-                try {
-                    snapshotResponse.getBlob().writeTo(outputStream);
-
-                    bytes.addAndGet(snapshotResponse.getBlob().size());
-                } catch (IOException e) {
-                    answer.completeExceptionally(toEtcdException(e));
-                }
-            }
-
-            @Override
-            public void onError(Throwable throwable) {
-                answer.completeExceptionally(toEtcdException(throwable));
-            }
-
-            @Override
-            public void onCompleted() {
-                answer.complete(bytes.get());
-            }
-        });
-
-        return answer;
-    }
-
-    @Override
-    public void snapshot(StreamObserver<io.etcd.jetcd.maintenance.SnapshotResponse> observer) {
-        this.streamStub.snapshot(SnapshotRequest.getDefaultInstance(), new StreamObserver<SnapshotResponse>() {
-            @Override
-            public void onNext(SnapshotResponse snapshotResponse) {
-                observer.onNext(new io.etcd.jetcd.maintenance.SnapshotResponse(snapshotResponse));
-            }
-
-            @Override
-            public void onError(Throwable throwable) {
-                observer.onError(toEtcdException(throwable));
-            }
-
-            @Override
-            public void onCompleted() {
-                observer.onCompleted();
-            }
-        });
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/Preconditions.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2016-2023 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.etcd.jetcd;
+
+public class Preconditions {
+
+    public static void checkArgument(boolean expression, String errorMessage) {
+        if (!expression) {
+            throw new IllegalArgumentException(errorMessage);
+        }
+    }
+
+    public static void checkState(boolean expression, String errorMessage) {
+        if (!expression) {
+            throw new IllegalStateException(errorMessage);
+        }
+    }
+}

jetcd-core/src/main/java/io/etcd/jetcd/Response.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,29 +22,39 @@ package io.etcd.jetcd;
 public interface Response {
 
     /**
-     * @return the response header
+     * Returns the response header
+     *
+     * @return the header.
      */
     Header getHeader();
 
     interface Header {
 
         /**
-         * @return the cluster id
+         * Returns the cluster id
+         *
+         * @return the cluster id.
          */
         long getClusterId();
 
         /**
-         * @return the member id
+         * Returns the member id
+         *
+         * @return the member id.
          */
         long getMemberId();
 
         /**
-         * @return the revision id
+         * Returns the revision id
+         *
+         * @return the revision.
          */
         long getRevision();
 
         /**
-         * @return the raft term
+         * Returns the raft term
+         *
+         * @return theraft term.
          */
         long getRaftTerm();
     }

jetcd-core/src/main/java/io/etcd/jetcd/Txn.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2023 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,20 +25,19 @@ import io.etcd.jetcd.op.Op;
 /**
  * Txn is the interface that wraps mini-transactions.
  *
- * <h3>Usage examples</h3>
+ * <h2>Usage examples</h2>
  *
  * <pre>
  * {@code
  * txn.If(
  *     new Cmp(KEY, Cmp.Op.GREATER, CmpTarget.value(VALUE)),
- *    new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(2))
- * ).Then(
+ *     new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(2))).Then(
  *         Op.put(KEY2, VALUE2, PutOption.DEFAULT),
- *    Op.put(KEY3, VALUE3, PutOption.DEFAULT)
- * ).Else(
+ *         Op.put(KEY3, VALUE3, PutOption.DEFAULT))
+ *     .Else(
  *         Op.put(KEY4, VALUE4, PutOption.DEFAULT),
- *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
- * ).commit();
+ *         Op.put(KEY4, VALUE4, PutOption.DEFAULT))
+ *     .commit();
  * }
  * </pre>
  *
@@ -48,18 +47,17 @@ import io.etcd.jetcd.op.Op;
  * <pre>
  * {@code
  * txn.If(
- *    new Cmp(KEY, Cmp.Op.GREATER, CmpTarget.value(VALUE))
- * ).If(
- *    new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(VERSION))
- * ).Then(
- *    Op.put(KEY2, VALUE2, PutOption.DEFAULT)
- * ).Then(
- *    Op.put(KEY3, VALUE3, PutOption.DEFAULT)
- * ).Else(
- *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
- * ).Else(
- *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
- * ).commit();
+ *     new Cmp(KEY, Cmp.Op.GREATER, CmpTarget.value(VALUE))).If(
+ *         new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(VERSION)))
+ *     .Then(
+ *         Op.put(KEY2, VALUE2, PutOption.DEFAULT))
+ *     .Then(
+ *         Op.put(KEY3, VALUE3, PutOption.DEFAULT))
+ *     .Else(
+ *         Op.put(KEY4, VALUE4, PutOption.DEFAULT))
+ *     .Else(
+ *         Op.put(KEY4, VALUE4, PutOption.DEFAULT))
+ *     .commit();
  * }
  * </pre>
  */

jetcd-core/src/main/java/io/etcd/jetcd/Util.java

@@ -1,144 +0,0 @@
-/*
- * Copyright 2016-2020 The jetcd authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.etcd.jetcd;
-
-import java.net.URI;
-import java.net.URISyntaxException;
-import java.util.Collection;
-import java.util.List;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.Executor;
-import java.util.function.Function;
-import java.util.function.Supplier;
-import java.util.stream.Collectors;
-
-import com.google.common.util.concurrent.ListenableFuture;
-import com.google.protobuf.ByteString;
-import io.grpc.Metadata;
-import io.grpc.Status;
-import io.grpc.stub.AbstractStub;
-import io.grpc.stub.MetadataUtils;
-
-import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
-
-public final class Util {
-
-    private Util() {
-    }
-
-    public static List<URI> toURIs(Collection<String> uris) {
-        return uris.stream().map(uri -> {
-            try {
-                return new URI(uri);
-            } catch (URISyntaxException e) {
-                throw new IllegalArgumentException("Invalid endpoint URI: " + uri, e);
-            }
-        }).collect(Collectors.toList());
-    }
-
-    /**
-     * convert ListenableFuture of Type S to CompletableFuture of Type T.
-     */
-    static <S, T> CompletableFuture<T> toCompletableFuture(ListenableFuture<S> sourceFuture, Function<S, T> resultConvert,
-        Executor executor) {
-
-        CompletableFuture<T> targetFuture = new CompletableFuture<T>() {
-            // the cancel of targetFuture also cancels the sourceFuture.
-            @Override
-            public boolean cancel(boolean mayInterruptIfRunning) {
-                super.cancel(mayInterruptIfRunning);
-                return sourceFuture.cancel(mayInterruptIfRunning);
-            }
-        };
-
-        sourceFuture.addListener(() -> {
-            try {
-                targetFuture.complete(resultConvert.apply(sourceFuture.get()));
-            } catch (Exception e) {
-                targetFuture.completeExceptionally(toEtcdException(e));
-            }
-        }, executor);
-
-        return targetFuture;
-    }
-
-    static boolean isRetryable(Throwable e) {
-        return isInvalidTokenError(Status.fromThrowable(e));
-    }
-
-    static boolean isInvalidTokenError(Status status) {
-        return status.getCode() == Status.Code.UNAUTHENTICATED
-            && "etcdserver: invalid auth token".equals(status.getDescription());
-    }
-
-    static <T> T supplyIfNull(T target, Supplier<T> supplier) {
-        return target != null ? target : supplier.get();
-    }
-
-    public static ByteString prefixNamespace(ByteString key, ByteSequence namespace) {
-        return namespace.isEmpty() ? key : namespace.getByteString().concat(key);
-    }
-
-    public static ByteString prefixNamespaceToRangeEnd(ByteString end, ByteSequence namespace) {
-        if (namespace.isEmpty()) {
-            return end;
-        }
-
-        if (end.size() == 1 && end.toByteArray()[0] == 0) {
-            // range end is '\0', calculate the prefixed range end by (key + 1)
-            byte[] prefixedEndArray = namespace.getByteString().toByteArray();
-            boolean ok = false;
-            for (int i = (prefixedEndArray.length - 1); i >= 0; i--) {
-                prefixedEndArray[i] = (byte) (prefixedEndArray[i] + 1);
-                if (prefixedEndArray[i] != 0) {
-                    ok = true;
-                    break;
-                }
-            }
-            if (!ok) {
-                // 0xff..ff => 0x00
-                prefixedEndArray = new byte[] { 0 };
-            }
-            return ByteString.copyFrom(prefixedEndArray);
-        } else {
-            return namespace.getByteString().concat(end);
-        }
-    }
-
-    public static ByteString unprefixNamespace(ByteString key, ByteSequence namespace) {
-        return namespace.isEmpty() ? key : key.substring(namespace.size());
-    }
-
-    static <T extends AbstractStub<T>> T applyRequireLeader(boolean requireLeader, T stub) {
-        if (!requireLeader) {
-            return stub;
-        }
-        final Metadata md = new Metadata();
-        md.put(Constants.REQUIRE_LEADER_KEY, Constants.REQUIRE_LEADER_VALUE);
-        return MetadataUtils.attachHeaders(stub, md);
-    }
-
-    public static boolean isHaltError(final Status status) {
-        return status.getCode() != Status.Code.UNAVAILABLE && status.getCode() != Status.Code.INTERNAL;
-    }
-
-    static final String NO_LEADER_ERROR_MESSAGE = "etcdserver: no leader";
-
-    public static boolean isNoLeaderError(final Status status) {
-        return status.getCode() == Status.Code.UNAVAILABLE && NO_LEADER_ERROR_MESSAGE.equals(status.getDescription());
-    }
-}

jetcd-core/src/main/java/io/etcd/jetcd/Watch.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,6 +53,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key.
+     *
      * @param  key    key to be watched on.
      * @param  onNext the on next consumer
      * @return        this watcher
@@ -62,6 +64,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key.
+     *
      * @param  key     key to be watched on.
      * @param  onNext  the on next consumer
      * @param  onError the on error consumer
@@ -72,6 +76,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key.
+     *
      * @param  key         key to be watched on.
      * @param  onNext      the on next consumer
      * @param  onError     the on error consumer
@@ -83,6 +89,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key.
+     *
      * @param  key         key to be watched on.
      * @param  onNext      the on next consumer
      * @param  onCompleted the on completion consumer
@@ -94,6 +102,7 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key with option.
      *
      * @param  key    key to be watched on.
      * @param  option the options
@@ -105,6 +114,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key with option.
+     *
      * @param  key     key to be watched on.
      * @param  option  the options
      * @param  onNext  the on next consumer
@@ -116,6 +127,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key with option.
+     *
      * @param  key         key to be watched on.
      * @param  option      the options
      * @param  onNext      the on next consumer
@@ -128,6 +141,8 @@ public interface Watch extends CloseableClient {
     }
 
     /**
+     * Watch key with option.
+     *
      * @param  key         key to be watched on.
      * @param  option      the options
      * @param  onNext      the on next consumer
@@ -140,6 +155,11 @@ public interface Watch extends CloseableClient {
         return watch(key, option, listener(onNext, onError, onCompleted));
     }
 
+    /**
+     * Requests the latest revision processed for all watcher instances
+     */
+    void requestProgress();
+
     static Listener listener(Consumer<WatchResponse> onNext) {
         return listener(onNext, t -> {
         }, () -> {
@@ -205,5 +225,15 @@ public interface Watch extends CloseableClient {
          */
         @Override
         void close();
+
+        /**
+         * Returns if watcher is already closed
+         */
+        boolean isClosed();
+
+        /**
+         * Requests the latest revision processed and propagates it to listeners
+         */
+        void requestProgress();
     }
 }

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthDisableResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,11 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthDisableResponse returned by {@link io.etcd.jetcd.Auth#authDisable()} contains a header.
+ * AuthDisableResponse returned by {@link Auth#authDisable()} contains a header.
  */
 public class AuthDisableResponse extends AbstractResponse<io.etcd.jetcd.api.AuthDisableResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthEnableResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,11 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthEnableResponse returned by {@link io.etcd.jetcd.Auth#authEnable()} call contains a header.
+ * AuthEnableResponse returned by {@link Auth#authEnable()} call contains a header.
  */
 public class AuthEnableResponse extends AbstractResponse<io.etcd.jetcd.api.AuthEnableResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleAddResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,12 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthRoleAddResponse returned by {@link io.etcd.jetcd.Auth#roleAdd(ByteSequence)} contains
+ * AuthRoleAddResponse returned by {@link Auth#roleAdd(ByteSequence)} contains
  * a header.
  */
 public class AuthRoleAddResponse extends AbstractResponse<io.etcd.jetcd.api.AuthRoleAddResponse> {

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleDeleteResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,12 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthRoleDeleteResponse returned by {@link io.etcd.jetcd.Auth#roleDelete(ByteSequence)}
+ * AuthRoleDeleteResponse returned by {@link Auth#roleDelete(ByteSequence)}
  * contains a header.
  */
 public class AuthRoleDeleteResponse extends AbstractResponse<io.etcd.jetcd.api.AuthRoleDeleteResponse> {

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleGetResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,12 +19,12 @@ package io.etcd.jetcd.auth;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
-import io.etcd.jetcd.auth.Permission.Type;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthRoleGetResponse returned by {@link io.etcd.jetcd.Auth#roleGet(ByteSequence)} contains
+ * AuthRoleGetResponse returned by {@link Auth#roleGet(ByteSequence)} contains
  * a header and a list of permissions.
  */
 public class AuthRoleGetResponse extends AbstractResponse<io.etcd.jetcd.api.AuthRoleGetResponse> {
@@ -42,16 +42,16 @@ public class AuthRoleGetResponse extends AbstractResponse<io.etcd.jetcd.api.Auth
         Permission.Type type;
         switch (perm.getPermType()) {
             case READ:
-                type = Type.READ;
+                type = Permission.Type.READ;
                 break;
             case WRITE:
-                type = Type.WRITE;
+                type = Permission.Type.WRITE;
                 break;
             case READWRITE:
-                type = Type.READWRITE;
+                type = Permission.Type.READWRITE;
                 break;
             default:
-                type = Type.UNRECOGNIZED;
+                type = Permission.Type.UNRECOGNIZED;
         }
 
         return new Permission(type, key, rangeEnd);

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleGrantPermissionResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,13 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
  * AuthRoleGrantPermissionResponse returned by
- * {@link io.etcd.jetcd.Auth#roleGrantPermission(ByteSequence, ByteSequence, ByteSequence, Permission.Type)} contains a
+ * {@link Auth#roleGrantPermission(ByteSequence, ByteSequence, ByteSequence, Permission.Type)} contains a
  * header.
  */
 public class AuthRoleGrantPermissionResponse extends AbstractResponse<io.etcd.jetcd.api.AuthRoleGrantPermissionResponse> {

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleListResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,8 +18,8 @@ package io.etcd.jetcd.auth;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
 import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
  * AuthRoleListResponse returned by {@link Auth#roleList()} contains a header and
@@ -32,7 +32,9 @@ public class AuthRoleListResponse extends AbstractResponse<io.etcd.jetcd.api.Aut
     }
 
     /**
-     * @return a list of roles.
+     * Returns a list of roles.
+     *
+     * @return the roles.
      */
     public List<String> getRoles() {
         return getResponse().getRolesList();

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthRoleRevokePermissionResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
-import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthRoleRevokePermissionResponse returned by {@link io.etcd.jetcd.Auth#roleRevokePermission(ByteSequence,
- * ByteSequence, ByteSequence)} contains a header.
+ * AuthRoleRevokePermissionResponse
  */
 public class AuthRoleRevokePermissionResponse extends AbstractResponse<io.etcd.jetcd.api.AuthRoleRevokePermissionResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserAddResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,12 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserAddResponse returned by {@link io.etcd.jetcd.Auth#userAdd(ByteSequence, ByteSequence)} contains a
+ * AuthUserAddResponse returned by {@link Auth#userAdd(ByteSequence, ByteSequence)} contains a
  * header.
  */
 public class AuthUserAddResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserAddResponse> {

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserChangePasswordResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
-import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserChangePasswordResponse returned by {@link io.etcd.jetcd.Auth#userChangePassword(ByteSequence,
- * ByteSequence)} contains a header.
+ * AuthUserChangePasswordResponse
  */
 public class AuthUserChangePasswordResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserChangePasswordResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserDeleteResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,12 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserDeleteResponse returned by {@link io.etcd.jetcd.Auth#userDelete(ByteSequence)} contains a header.
+ * AuthUserDeleteResponse returned by {@link Auth#userDelete(ByteSequence)} contains a header.
  */
 public class AuthUserDeleteResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserDeleteResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserGetResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,11 +18,12 @@ package io.etcd.jetcd.auth;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserGetResponse returned by {@link io.etcd.jetcd.Auth#userGet(ByteSequence)} contains a header and
+ * AuthUserGetResponse returned by {@link Auth#userGet(ByteSequence)} contains a header and
  * a list of roles associated with the user.
  */
 public class AuthUserGetResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserGetResponse> {
@@ -32,7 +33,9 @@ public class AuthUserGetResponse extends AbstractResponse<io.etcd.jetcd.api.Auth
     }
 
     /**
-     * @return a list of roles.
+     * Returns a list of roles.
+     *
+     * @return the roles.
      */
     public List<String> getRoles() {
         return getResponse().getRolesList();

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserGrantRoleResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
-import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserGrantRoleResponse returned by {@link io.etcd.jetcd.Auth#userGrantRole(ByteSequence,
- * ByteSequence)} contains a header.
+ * AuthUserGrantRoleResponse
  */
 public class AuthUserGrantRoleResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserGrantRoleResponse> {
 

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserListResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,10 +18,11 @@ package io.etcd.jetcd.auth;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserListResponse returned by {@link io.etcd.jetcd.Auth#userList()} contains a header and
+ * AuthUserListResponse returned by {@link Auth#userList()} contains a header and
  * a list of users.
  */
 public class AuthUserListResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserListResponse> {
@@ -31,7 +32,9 @@ public class AuthUserListResponse extends AbstractResponse<io.etcd.jetcd.api.Aut
     }
 
     /**
-     * @return a list of users.
+     * Returns a list of users.
+     *
+     * @return the users.
      */
     public List<String> getUsers() {
         return getResponse().getUsersList();

jetcd-core/src/main/java/io/etcd/jetcd/auth/AuthUserRevokeRoleResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,12 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Auth;
 import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserRevokeRoleResponse returned by {@link io.etcd.jetcd.Auth#userRevokeRole(ByteSequence, ByteSequence)}
+ * AuthUserRevokeRoleResponse returned by {@link Auth#userRevokeRole(ByteSequence, ByteSequence)}
  * contains a header.
  */
 public class AuthUserRevokeRoleResponse extends AbstractResponse<io.etcd.jetcd.api.AuthUserRevokeRoleResponse> {

jetcd-core/src/main/java/io/etcd/jetcd/auth/Permission.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,9 @@ public class Permission {
     }
 
     /**
-     * @return the type of Permission: READ, WRITE, READWRITE, or UNRECOGNIZED.
+     * Returns the type of Permission: READ, WRITE, READWRITE, or UNRECOGNIZED.
+     *
+     * @return the permission type.
      */
     public Type getPermType() {
         return permType;

jetcd-core/src/main/java/io/etcd/jetcd/cluster/Member.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 The jetcd authors
+ * Copyright 2016-2021 The jetcd authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package io.etcd.jetcd.cluster;
 import java.net.URI;
 import java.util.List;
 
-import io.etcd.jetcd.Util;
+import io.etcd.jetcd.support.Util;
 
 public class Member {
 
@@ -30,31 +30,48 @@ public class Member {
     }
 
     /**
-     * @return the member ID for this member.
+     * Returns the member ID for this member.
+     *
+     * @return the id.
      */
     public long getId() {
         return member.getID();
     }
 
     /**
-     * @return the human-readable name of the member, ff the member is not started, the name will be an empty string.
+     * Returns the human-readable name of the member, ff the member is not started, the name will be an empty string.
+     *
+     * @return the name.
      */
     public String getName() {
         return member.getName();
     }
 
     /**
-     * @return the list of URLs the member exposes to the cluster for communication.
+     * Returns the list of URLs the member exposes to the cluster for communication.
+     *
+     * @return the peer url
      */
     public List<URI> getPeerURIs() {
         return Util.toURIs(member.getPeerURLsList());
     }
 
     /**
-     * @return list of URLs the member exposes to clients for communication, if the member is not started, clientURLs will
+     * Returns list of URLs the member exposes to clients for communication, if the member is not started, clientURLs will
      * be empty.
+     *
+     * @return the client URIs.
      */
     public List<URI> getClientURIs() {
         return Util.toURIs(member.getClientURLsList());
     }
+
+    /**
+     * Returns if the member is raft learner
+     *
+     * @return if the member is raft learner
+     */
+    public boolean isLearner() {
+        return member.getIsLearner();
+    }
 }