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

@@ -6,13 +6,17 @@ 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. 
-This section *must* be provided, if not, the issue may not get attention.
+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.

.github/dependabot.yml

@@ -1,11 +1,18 @@
 version: 2
 updates:
-- package-ecosystem: maven
+  - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: daily
-  open-pull-requests-limit: 10
+      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: org.codehaus.plexus:plexus-compiler-javac-errorprone
-    versions:
-    - "> 2.8.6, < 2.9"
+      - 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

@@ -1,46 +0,0 @@
-#
-# 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.
-#
-
-name: Build and Publish
-
-concurrency:
-  group: ${{ github.ref }}-${{ github.workflow }}
-  cancel-in-progress: true
-
-on:
-  push:
-    branches:
-      - master
-  workflow_dispatch:
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-      - name: Set Up Java
-        uses: actions/setup-java@v2
-        with:
-          java-version: 11
-          distribution: 'temurin'
-      - name: Build Project
-        env:
-          OSSRH_USERNAME: ${{ secrets.OSSRH_USERNAME }}
-          OSSRH_PASSWORD: ${{ secrets.OSSRH_PASSWORD }}
-        run: |
-          ./gradlew spotlessCheck
-          ./gradlew publishToSonatype

.github/workflows/build-pr.yml

@@ -1,5 +1,5 @@
 #
-# Copyright 2016-2021 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.
@@ -17,27 +17,35 @@
 name: Build PR
 
 concurrency:
-  group: ${{ github.ref }}-${{ github.workflow }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 on:
   pull_request:
     branches:
-      - master
+      - main
   workflow_dispatch:
 
 jobs:
+  checks:
+    uses: ./.github/workflows/checks.yml
+
   build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-      - name: Set Up Java
-        uses: actions/setup-java@v2
+    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:
-          java-version: 11
-          distribution: 'temurin'
-      - name: Build Project
-        run: |
-          ./gradlew spotlessCheck
-          ./gradlew test
+      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 2016-2021 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

@@ -15,3 +15,4 @@ logs/
 .sdkmanrc
 build/
 bin/
+out/

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

@@ -1,5 +1,5 @@
 # jetcd - A Java Client for etcd
-[![Build Status](https://github.com/etcd-io/jetcd/actions/workflows/build-master.yml/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)
 [![Javadocs](http://www.javadoc.io/badge/io/etcd/jetcd-core.svg)](https://javadoc.io/doc/io.etcd/jetcd-core)
@@ -23,13 +23,13 @@ Java 11 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"
 }
 ```
 
@@ -63,6 +63,7 @@ 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 the [official API documentation](https://etcd.io/docs/current/learning/api/).
 
@@ -98,7 +99,7 @@ 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/):
 
 ```
 ./gradlew compileJava
@@ -110,7 +111,7 @@ The project is tested against a three node `etcd` setup started with the Launche
 
 ```sh
 $ ./gradlew test
-````
+```
 
 ### Troubleshooting
 
@@ -118,7 +119,7 @@ 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)
+* Mailing list: [etcd-dev](https://groups.google.com/g/etcd-dev)
 
 ## Contributing
 
@@ -127,3 +128,5 @@ See [CONTRIBUTING](https://github.com/etcd-io/jetcd/blob/master/CONTRIBUTING.md)
 ## 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

@@ -19,13 +19,13 @@ buildscript {
         gradlePluginPortal()
     }
     dependencies {
-        classpath "com.github.ben-manes:gradle-versions-plugin:$versionsPluginVersion"
-        classpath "com.diffplug.spotless:spotless-plugin-gradle:$spotlessPluginVersion"
-        classpath "net.ltgt.gradle:gradle-errorprone-plugin:$errorPronePluginVersion"
-        classpath "io.github.gradle-nexus:publish-plugin:$nexusPublishPluginVersion"
-        classpath "com.adarshr:gradle-test-logger-plugin:$testLoggerPluginVersion"
-        classpath "se.ascp.gradle:gradle-versions-filter:$versionsFilterPluginVersion"
-        classpath "pl.allegro.tech.build:axion-release-plugin:$axionReleasePluginVersion"
+        classpath "com.github.ben-manes:gradle-versions-plugin:${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()}"
     }
 }
 
@@ -49,25 +49,52 @@ subprojects {
     apply from: "${rootProject.projectDir}/gradle/publishing-release-tasks.gradle"
 
     apply plugin: 'java-library'
-    apply plugin: "com.adarshr.test-logger"
+    apply plugin: 'com.adarshr.test-logger'
+    apply plugin: 'org.gradle.test-retry'
 
-    java {
-        toolchain {
-            languageVersion = JavaLanguageVersion.of(11)
+    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().intdiv(2) ?: 1
+        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

@@ -12,11 +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
+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), process cancel with [cancelWatch function](#cancelwatch-function) and request progress with [requestProgress function](#requestProgress-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
 

etc/eclipse-formatter-config.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright 2016-2021 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.
@@ -271,4 +271,3 @@
         <setting id="org.eclipse.jdt.core.formatter.enabling_tag" value="CHECKSTYLE:ON"/>
     </profile>
 </profiles>
-

etc/pmd-ruleset.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright 2016-2021 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.
@@ -23,6 +23,8 @@
 
     <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"/>
@@ -42,6 +44,7 @@
     <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>
@@ -71,15 +74,6 @@
         </properties>
     </rule>
 
-    <rule ref="category/java/errorprone.xml/EmptyFinallyBlock"/>
-    <rule ref="category/java/errorprone.xml/EmptyIfStmt"/>
-    <rule ref="category/java/errorprone.xml/EmptyInitializer"/>
-    <rule ref="category/java/errorprone.xml/EmptyStatementBlock"/>
-    <rule ref="category/java/errorprone.xml/EmptyStatementNotInLoop"/>
-    <rule ref="category/java/errorprone.xml/EmptySwitchStatements"/>
-    <rule ref="category/java/errorprone.xml/EmptySynchronizedBlock"/>
-    <rule ref="category/java/errorprone.xml/EmptyTryBlock"/>
-    <rule ref="category/java/errorprone.xml/EmptyWhileStmt"/>
     <rule ref="category/java/errorprone.xml/JumbledIncrementer"/>
     <rule ref="category/java/errorprone.xml/MisplacedNullCheck"/>
     <rule ref="category/java/errorprone.xml/OverrideBothEqualsAndHashcode"/>

gradle.properties

@@ -1,30 +1,10 @@
 #
 # project
 #
-gitProject  = 'https://github.com/etcd-io/jetcd'
-gitURL      = 'git@github.com/etcd-io/jetcd.git'
-
-#
-# dependencies
-#
-grpcVersion = 1.42.1
-protocVersion = 3.17.2
-
-#
-# plugins
-#
-versionsPluginVersion = 0.39.0
-versionsFilterPluginVersion = 0.1.10
-errorPronePluginVersion = 2.0.2
-spotlessPluginVersion = 6.0.0
-shadowPluginVersion =  7.1.0
-testLoggerPluginVersion = 3.1.0
-protobufPluginVersion = 0.8.18
-nexusPublishPluginVersion = 1.1.0
-axionReleasePluginVersion = 1.13.6
+gitProject  = https://github.com/etcd-io/jetcd
+gitURL      = git@github.com/etcd-io/jetcd.git
 
 #
 # gradle
 #
 org.gradle.parallel = true
-

gradle/libs.versions.toml

@@ -1,38 +1,46 @@
 [versions]
-grpc = "1.42.1"
-log4j = "2.14.1"
-mockito = "4.0.0"
-slf4j = "1.7.32"
-guava = "31.0.1-jre"
+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"
-spotbugs = "4.5.0"
-assertj = "3.21.0"
-junit = "5.8.1"
-testcontainers = "1.16.2"
-protoc = "3.19.1"
-failsafe = "2.4.4"
-awaitility = "4.1.1"
-commonsIo = "2.11.0"
-commonCompress = "1.21"
-autoService = "1.0.1"
-jool = "0.9.14"
-jcommander = "1.81"
-errorprone = "2.10.0"
+
+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" }
-javaxAnnotation = { module = "javax.annotation:javax.annotation-api", version.ref = "javaxAnnotation" }
-spotbugs = { module = "com.github.spotbugs:spotbugs-annotations", version.ref = "spotbugs" }
 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 = "net.jodah:failsafe", version.ref = "failsafe" }
+failsafe = { module = "dev.failsafe:failsafe", version.ref = "failsafe" }
 awaitility = { module = "org.awaitility:awaitility", version.ref = "awaitility" }
-jcommander = { module = "com.beust:jcommander", version.ref = "jcommander"}
-jool = { module = "org.jooq:jool-java-8", version.ref = "jool"}
+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" }
@@ -45,23 +53,34 @@ 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-slf4j-impl", 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" }
-errorproneJavac = { module = "com.google.errorprone:javac", version = "9+181-r4173-1" }
+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" ]
+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

@@ -20,10 +20,10 @@ apply plugin: "io.github.gradle-nexus.publish-plugin"
 
 ext {
     if (!project.hasProperty('nexusUsername')) {
-        nexusUsername = "$System.env.OSSRH_USERNAME"
+        nexusUsername = "$System.env.NEXUS_USERNAME"
     }
     if (!project.hasProperty('nexusPassword')) {
-        nexusPassword = "$System.env.OSSRH_PASSWORD"
+        nexusPassword = "$System.env.NEXUS_PASSWORD"
     }
 }
 

gradle/publishing-release-tasks.gradle

@@ -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.

gradle/publishing-release.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 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.
@@ -89,9 +89,12 @@ signing {
     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

@@ -19,6 +19,7 @@ apply plugin: "pmd"
 
 dependencies {
     errorprone(libs.errorprone)
+    errorprone(libs.errorproneAnnotations)
     errorproneJavac(libs.errorproneJavac)
 }
 
@@ -27,9 +28,10 @@ tasks.withType(JavaCompile).configureEach {
         excludedPaths = '.*/generated/.*'
         disableWarningsInGeneratedCode = true
     }
+    options.deprecation = true
 }
 
 pmd {
     consoleOutput = true
-    ruleSets = [ rootProject.file("etc/pmd-ruleset.xml") ]
+    ruleSets = [ "${project.rootDir}/etc/pmd-ruleset.xml" ]
 }

gradle/release.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 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.

gradle/style.gradle

@@ -24,7 +24,6 @@ spotless {
         endWithNewline()
         importOrderFile(rootProject.file('etc/eclipse.importorder'))
         eclipse().configFile(rootProject.file('etc/eclipse-formatter-config.xml'))
-        //licenseHeaderFile(rootProject.file('etc/license.txt'))
-        //licenseHeader 'Copyright $YEAR The jetcd authors'
+        targetExclude("build/generated/**/*.java")
     }
 }

gradle/versions.gradle

@@ -15,11 +15,16 @@
  */
 
 apply plugin: 'com.github.ben-manes.versions'
-apply plugin: 'se.ascp.gradle.gradle-versions-filter'
 
-versionsFilter {
-    exclusiveQualifiers = ['alpha', 'beta', 'rc', 'cr', 'm', 'ea']
-    log = false
+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 {

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       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/.
@@ -80,13 +82,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# 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"'
+# 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
@@ -114,7 +114,7 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -133,22 +133,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    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 $MAX_FD"
     esac
@@ -193,18 +200,28 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# 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" \
-        org.gradle.wrapper.GradleWrapperMain \
+        -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.

gradlew.bat

@@ -13,8 +13,10 @@
 @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
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +27,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,13 +43,13 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+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
 
@@ -56,32 +59,34 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+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=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+"%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%"=="0" goto mainEnd
+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!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+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

jetcd-api/build.gradle

@@ -17,6 +17,4 @@
 
 dependencies {
     api libs.slf4j
-    api libs.guava
-    api libs.grpcCore
 }

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/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

@@ -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.
@@ -27,7 +27,7 @@ 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");
     }
 
     /**

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

@@ -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

@@ -21,17 +21,17 @@ dependencies {
 
     api libs.slf4j
     api libs.guava
-    api libs.javaxAnnotation
-    api libs.bundles.grpc
-    api libs.spotbugs
     api libs.failsafe
 
-    api libs.autoServiceAnnotations
+    //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

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

@@ -17,11 +17,10 @@
 package io.etcd.jetcd;
 
 import java.nio.charset.Charset;
+import java.util.Objects;
 
 import com.google.protobuf.ByteString;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
 /**
  * Etcd binary bytes, easy to convert between byte[], String and ByteString.
  */
@@ -33,7 +32,7 @@ public final class ByteSequence {
     private final ByteString byteString;
 
     private ByteSequence(ByteString byteString) {
-        checkNotNull(byteString, "byteString should not be null");
+        Objects.requireNonNull(byteString, "byteString should not be null");
         this.byteString = byteString;
         this.hashVal = byteString.hashCode();
     }
@@ -49,9 +48,7 @@ public final class ByteSequence {
         if (prefix == null) {
             return false;
         }
-        ByteString baseByteString = this.getByteString();
-        ByteString prefixByteString = prefix.getByteString();
-        return baseByteString.startsWith(prefixByteString);
+        return byteString.startsWith(prefix.byteString);
     }
 
     /**
@@ -61,8 +58,19 @@ public final class ByteSequence {
      * @return       a new {@code ByteSequence} instance
      */
     public ByteSequence concat(ByteSequence other) {
-        checkNotNull(other, "other byteSequence should not be null");
-        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));
     }
 
     /**
@@ -114,10 +122,6 @@ public final class ByteSequence {
         return hashVal;
     }
 
-    ByteString getByteString() {
-        return this.byteString;
-    }
-
     public String toString(Charset charset) {
         return byteString.toString(charset);
     }
@@ -151,10 +155,22 @@ public final class ByteSequence {
         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

@@ -27,41 +27,57 @@ public interface Client extends AutoCloseable {
 
     /**
      * Returns the {@link Auth} client.
+     *
+     * @return the client.
      */
     Auth getAuthClient();
 
     /**
      * Returns the {@link KV} client.
+     *
+     * @return the client.
      */
     KV getKVClient();
 
     /**
      * Returns the {@link Cluster} client.
+     *
+     * @return the client.
      */
     Cluster getClusterClient();
 
     /**
      * Returns the {@link Maintenance} client.
+     *
+     * @return the client.
      */
     Maintenance getMaintenanceClient();
 
     /**
      * Returns the {@link Lease} client.
+     *
+     * @return the client.
      */
     Lease getLeaseClient();
 
     /**
      * Returns the {@link Watch} client.
+     *
+     * @return the client.
      */
     Watch getWatchClient();
 
     /**
      * Returns the {@link Lock} client.
+     *
+     * @return the client.
      */
     Lock getLockClient();
 
     /**
      * Returns the {@link Election} client.
+     *
+     * @return the client.
      */
     Election getElectionClient();
 
@@ -70,6 +86,8 @@ public interface Client extends AutoCloseable {
 
     /**
      * Returns a new {@link ClientBuilder}.
+     *
+     * @return the builder.
      */
     static ClientBuilder builder() {
         return new ClientBuilder();

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

@@ -19,37 +19,30 @@ 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.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+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 com.google.common.base.Strings;
-import com.google.common.collect.Streams;
-
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Preconditions.checkNotNull;
-import static com.google.common.base.Preconditions.checkState;
 
 /**
- * ClientBuilder knows how to create an Client instance.
+ * ClientBuilder knows how to create a Client instance.
  */
 public final class ClientBuilder implements Cloneable {
 
@@ -68,6 +61,7 @@ public final class ClientBuilder implements Cloneable {
     private ByteSequence namespace = ByteSequence.EMPTY;
     private long retryDelay = 500;
     private long retryMaxDelay = 2500;
+    private int retryMaxAttempts = 2;
     private ChronoUnit retryChronoUnit = ChronoUnit.MILLIS;
     private Duration keepaliveTime = Duration.ofSeconds(30L);
     private Duration keepaliveTimeout = Duration.ofSeconds(10L);
@@ -75,6 +69,7 @@ public final class ClientBuilder implements Cloneable {
     private Duration retryMaxDuration;
     private Duration connectTimeout;
     private boolean waitForReady = true;
+    private Vertx vertx;
 
     ClientBuilder() {
     }
@@ -96,7 +91,7 @@ public final class ClientBuilder implements Cloneable {
      * @throws NullPointerException if target is null or one of endpoint is null
      */
     public ClientBuilder target(String target) {
-        checkArgument(!Strings.isNullOrEmpty(target), "target can't be null or empty");
+        Preconditions.checkArgument(!Strings.isNullOrEmpty(target), "target can't be null or empty");
 
         this.target = target;
 
@@ -137,7 +132,7 @@ public final class ClientBuilder implements Cloneable {
      * @throws IllegalArgumentException if some endpoint is invalid
      */
     public ClientBuilder endpoints(Iterable<URI> endpoints) {
-        checkNotNull(endpoints, "endpoints can't be null");
+        Objects.requireNonNull(endpoints, "endpoints can't be null");
 
         endpoints.forEach(e -> {
             if (e.getHost() == null) {
@@ -145,8 +140,8 @@ public final class ClientBuilder implements Cloneable {
             }
         });
 
-        final String target = Streams.stream(endpoints)
-            .map(e -> e.getHost() + (e.getPort() != -1 ? (":" + e.getPort()) : ""))
+        final String target = StreamSupport.stream(endpoints.spliterator(), false)
+            .map(e -> e.getHost() + (e.getPort() != -1 ? ":" + e.getPort() : ""))
             .distinct()
             .collect(Collectors.joining(","));
 
@@ -164,6 +159,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the auth user
+     *
+     * @return the user.
      */
     public ByteSequence user() {
         return user;
@@ -177,13 +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;
     }
 
     /**
      * Returns the auth password
+     *
+     * @return the password.
      */
     public ByteSequence password() {
         return password;
@@ -197,13 +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;
     }
 
     /**
      * Returns the namespace of each key used
+     *
+     * @return the namespace.
      */
     public ByteSequence namespace() {
         return namespace;
@@ -218,13 +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;
     }
 
     /**
      * Returns the executor service
+     *
+     * @return the executor service.
      */
     public ExecutorService executorService() {
         return executorService;
@@ -238,7 +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;
     }
@@ -251,7 +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;
     }
@@ -267,6 +270,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the ssl context
+     *
+     * @return the ssl context.
      */
     public SslContext sslContext() {
         return sslContext;
@@ -300,6 +305,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns The authority used to authenticate connections to servers.
+     *
+     * @return the authority.
      */
     public String authority() {
         return authority;
@@ -318,6 +325,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the maximum message size allowed for a single gRPC frame.
+     *
+     * @return max inbound message size.
      */
     public Integer maxInboundMessageSize() {
         return maxInboundMessageSize;
@@ -336,6 +345,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * 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);
@@ -372,6 +383,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * 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);
@@ -408,6 +421,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the interceptors
+     *
+     * @return the interceptors.
      */
     public List<ClientInterceptor> interceptors() {
         return interceptors;
@@ -445,6 +460,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the auth interceptors
+     *
+     * @return the interceptors.
      */
     public List<ClientInterceptor> authInterceptors() {
         return authInterceptors;
@@ -482,6 +499,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns The delay between retries.
+     *
+     * @return the retry delay.
      */
     public long retryDelay() {
         return retryDelay;
@@ -500,6 +519,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the max backing off delay between retries
+     *
+     * @return max retry delay.
      */
     public long retryMaxDelay() {
         return retryMaxDelay;
@@ -516,6 +537,31 @@ public final class ClientBuilder implements Cloneable {
         return this;
     }
 
+    /**
+     * 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;
     }
@@ -534,6 +580,11 @@ public final class ClientBuilder implements Cloneable {
         return this;
     }
 
+    /**
+     * Returns the keep alive time out.
+     *
+     * @return keep alive time out.
+     */
     public Duration keepaliveTimeout() {
         return keepaliveTimeout;
     }
@@ -566,6 +617,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns he retries period unit.
+     *
+     * @return the chrono unit.
      */
     public ChronoUnit retryChronoUnit() {
         return retryChronoUnit;
@@ -584,6 +637,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the retries max duration.
+     *
+     * @return retry max duration.
      */
     public Duration retryMaxDuration() {
         return retryMaxDuration;
@@ -591,6 +646,8 @@ public final class ClientBuilder implements Cloneable {
 
     /**
      * Returns the connect timeout.
+     *
+     * @return connect timeout.
      */
     public Duration connectTimeout() {
         return connectTimeout;
@@ -652,6 +709,30 @@ public final class ClientBuilder implements Cloneable {
         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;
+    }
+
     /**
      * build a new Client.
      *
@@ -659,13 +740,15 @@ public final class ClientBuilder implements Cloneable {
      * @throws EtcdException if client experiences build error.
      */
     public Client build() {
-        checkState(target != null, "please configure etcd server endpoints before build.");
+        Preconditions.checkState(target != null, "please configure etcd server endpoints before build.");
 
         return new ClientImpl(this);
     }
 
     /**
      * Returns a copy of this builder
+     *
+     * @return a copy of the builder.
      */
     public ClientBuilder copy() {
         try {

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

@@ -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

@@ -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/ElectionImpl.java

@@ -1,185 +0,0 @@
-/*
- * 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;
-
-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

@@ -26,6 +26,7 @@ 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;
 
 /**
@@ -115,4 +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

@@ -1,181 +0,0 @@
-/*
- * 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;
-
-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.OptionsUtil;
-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);
-
-        if (!option.getEndKey().isPresent() && option.isPrefix()) {
-            ByteSequence endKey = OptionsUtil.prefixEndOf(key);
-            builder.setRangeEnd(Util.prefixNamespaceToRangeEnd(endKey.getByteString(), namespace));
-        }
-
-        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);
-
-        if (!option.getEndKey().isPresent() && option.isPrefix()) {
-            ByteSequence endKey = OptionsUtil.prefixEndOf(key);
-            builder.setRangeEnd(Util.prefixNamespaceToRangeEnd(endKey.getByteString(), namespace));
-        }
-
-        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);
-    }
-
-    @Override
-    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

@@ -16,6 +16,8 @@
 
 package io.etcd.jetcd;
 
+import io.etcd.jetcd.support.Util;
+
 /**
  * Etcd key value pair.
  */
@@ -27,13 +29,18 @@ 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));
     }
 
     /**
      * Returns the key
+     *
+     * @return the key.
      */
     public ByteSequence getKey() {
         return unprefixedKey;
@@ -41,6 +48,8 @@ public class KeyValue {
 
     /**
      * Returns the value
+     *
+     * @return the value.
      */
     public ByteSequence getValue() {
         return value;
@@ -48,6 +57,8 @@ public class KeyValue {
 
     /**
      * Returns the create revision.
+     *
+     * @return the create revision.
      */
     public long getCreateRevision() {
         return kv.getCreateRevision();
@@ -55,6 +66,8 @@ public class KeyValue {
 
     /**
      * Returns the mod revision.
+     *
+     * @return the mod revision.
      */
     public long getModRevision() {
         return kv.getModRevision();
@@ -62,6 +75,8 @@ public class KeyValue {
 
     /**
      * Returns the version.
+     *
+     * @return the version.
      */
     public long getVersion() {
         return kv.getVersion();
@@ -69,6 +84,8 @@ public class KeyValue {
 
     /**
      * Returns the lease.
+     *
+     * @return the lease.
      */
     public long getLease() {
         return kv.getLease();

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

@@ -1,354 +0,0 @@
-/*
- * 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;
-
-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 org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-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 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 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/LockImpl.java

@@ -1,71 +0,0 @@
-/*
- * 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;
-
-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

@@ -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;
 
@@ -68,16 +61,6 @@ public interface Maintenance extends CloseableClient {
      */
     CompletableFuture<AlarmResponse> alarmDisarm(AlarmMember member);
 
-    /**
-     * Defragment one member of the cluster by its endpoint.
-     *
-     * @param      endpoint the etcd server endpoint.
-     * @return              the response result
-     * @deprecated          use {@link #defragmentMember(String)}
-     */
-    @Deprecated
-    CompletableFuture<DefragmentResponse> defragmentMember(URI endpoint);
-
     /**
      * Defragment one member of the cluster by its endpoint.
      *
@@ -100,16 +83,6 @@ public interface Maintenance extends CloseableClient {
      */
     CompletableFuture<DefragmentResponse> defragmentMember(String target);
 
-    /**
-     * get the status of a member by its endpoint.
-     *
-     * @param      endpoint the etcd server endpoint.
-     * @return              the response result
-     * @deprecated          use {@link #statusMember(String)}
-     */
-    @Deprecated
-    CompletableFuture<StatusResponse> statusMember(URI endpoint);
-
     /**
      * get the status of a member by its endpoint.
      *
@@ -118,17 +91,6 @@ public interface Maintenance extends CloseableClient {
      */
     CompletableFuture<StatusResponse> statusMember(String target);
 
-    /**
-     * returns a hash of the KV state at the time of the RPC.
-     *
-     * @param      endpoint the etcd server endpoint.
-     * @param      rev      the revision
-     * @return              the response result
-     * @deprecated          use {@link #hashKV(String, long)}
-     */
-    @Deprecated
-    CompletableFuture<HashKVResponse> hashKV(URI endpoint, long rev);
-
     /**
      * 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

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

@@ -1,213 +0,0 @@
-/*
- * 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;
-
-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);
-    }
-
-    @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());
-    }
-
-    @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());
-    }
-
-    @Override
-    public CompletableFuture<DefragmentResponse> defragmentMember(URI endpoint) {
-        return this.connectionManager.withNewChannel(
-            // TODO
-            endpoint.toString(),
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.defragment(DefragmentRequest.getDefaultInstance()),
-                DefragmentResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<DefragmentResponse> defragmentMember(String target) {
-        return this.connectionManager.withNewChannel(
-            target,
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.defragment(DefragmentRequest.getDefaultInstance()),
-                DefragmentResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<StatusResponse> statusMember(URI endpoint) {
-        return this.connectionManager.withNewChannel(
-            // TODO
-            endpoint.toString(),
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.status(StatusRequest.getDefaultInstance()),
-                StatusResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<StatusResponse> statusMember(String target) {
-        return this.connectionManager.withNewChannel(
-            target,
-            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(
-            // TODO
-            endpoint.toString(),
-            MaintenanceGrpc::newFutureStub,
-            stub -> Util.toCompletableFuture(
-                stub.hashKV(HashKVRequest.newBuilder().setRevision(rev).build()),
-                HashKVResponse::new,
-                this.connectionManager.getExecutorService()));
-    }
-
-    @Override
-    public CompletableFuture<HashKVResponse> hashKV(String target, long rev) {
-        return this.connectionManager.withNewChannel(
-            target,
-            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

@@ -23,6 +23,8 @@ public interface Response {
 
     /**
      * Returns the response header
+     *
+     * @return the header.
      */
     Header getHeader();
 
@@ -30,21 +32,29 @@ public interface Response {
 
         /**
          * Returns the cluster id
+         *
+         * @return the cluster id.
          */
         long getClusterId();
 
         /**
          * Returns the member id
+         *
+         * @return the member id.
          */
         long getMemberId();
 
         /**
          * Returns the revision id
+         *
+         * @return the revision.
          */
         long getRevision();
 
         /**
          * Returns the raft term
+         *
+         * @return theraft term.
          */
         long getRaftTerm();
     }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 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/Watch.java

@@ -226,6 +226,11 @@ 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
          */

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

@@ -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

@@ -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/AuthInterceptor.java

@@ -1,180 +0,0 @@
-/*
- * 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.auth;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.concurrent.ExecutionException;
-import java.util.function.BiConsumer;
-
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-
-import io.etcd.jetcd.ClientBuilder;
-import io.etcd.jetcd.api.AuthGrpc;
-import io.etcd.jetcd.api.AuthenticateRequest;
-import io.etcd.jetcd.api.AuthenticateResponse;
-import io.grpc.CallOptions;
-import io.grpc.Channel;
-import io.grpc.ClientCall;
-import io.grpc.ClientInterceptor;
-import io.grpc.ForwardingClientCall;
-import io.grpc.ForwardingClientCallListener;
-import io.grpc.Metadata;
-import io.grpc.MethodDescriptor;
-import io.grpc.Status;
-import io.grpc.stub.MetadataUtils;
-
-import com.google.common.util.concurrent.ListenableFuture;
-import com.google.protobuf.ByteString;
-
-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;
-
-/**
- * AuthTokenInterceptor fills header with Auth token of any rpc calls and
- * refreshes token if the rpc results an invalid Auth token error.
- */
-public class AuthInterceptor implements ClientInterceptor {
-    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 ClientInterceptor[] interceptors;
-    private volatile String token;
-
-    public AuthInterceptor(ClientBuilder builder) {
-        this.lock = new Object();
-        this.builder = builder;
-
-        List<ClientInterceptor> interceptorsChain = new ArrayList<>();
-        if (builder.authHeaders() != null) {
-            Metadata metadata = new Metadata();
-            builder.authHeaders().forEach((BiConsumer<Metadata.Key, Object>) metadata::put);
-
-            interceptorsChain.add(MetadataUtils.newAttachHeadersInterceptor(metadata));
-        }
-        if (builder.authInterceptors() != null) {
-            interceptorsChain.addAll(builder.authInterceptors());
-        }
-
-        this.interceptors = interceptorsChain.isEmpty() ? null : interceptorsChain.toArray(new ClientInterceptor[0]);
-    }
-
-    @Override
-    public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
-        MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
-
-        return new ForwardingClientCall.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 ForwardingClientCallListener.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);
-            }
-        };
-    }
-
-    public void refresh() {
-        synchronized (lock) {
-            token = null;
-        }
-    }
-
-    /**
-     * get token from etcd with name and password.
-     *
-     * @param  channel channel to etcd
-     * @return         authResp
-     */
-    @SuppressWarnings("rawtypes")
-    private ListenableFuture<AuthenticateResponse> authenticate(@Nonnull Channel channel) {
-
-        final ByteString user = ByteString.copyFrom(builder.user().getBytes());
-        final ByteString pass = ByteString.copyFrom(builder.password().getBytes());
-
-        checkArgument(!user.isEmpty(), "username can not be empty.");
-        checkArgument(!pass.isEmpty(), "password can not be empty.");
-
-        AuthGrpc.AuthFutureStub authFutureStub = AuthGrpc.newFutureStub(channel);
-        if (interceptors != null) {
-            authFutureStub = authFutureStub.withInterceptors(interceptors);
-        }
-
-        return authFutureStub.authenticate(
-            AuthenticateRequest.newBuilder()
-                .setNameBytes(user)
-                .setPasswordBytes(pass)
-                .build());
-    }
-
-    @Nullable
-    private String getToken(Channel channel) {
-        if (token == null) {
-            synchronized (lock) {
-                if (token == null) {
-                    token = generateToken(channel);
-                }
-            }
-        }
-
-        return token;
-    }
-
-    private void refreshToken(Channel channel) {
-        synchronized (lock) {
-            token = generateToken(channel);
-        }
-    }
-
-    /**
-     * 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).get().getToken();
-            } catch (InterruptedException ite) {
-                throw handleInterrupt(ite);
-            } catch (ExecutionException exee) {
-                throw toEtcdException(exee);
-            }
-        }
-        return null;
-    }
-}

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

@@ -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

@@ -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

@@ -19,11 +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.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> {

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

@@ -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

@@ -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
@@ -33,6 +33,8 @@ public class AuthRoleListResponse extends AbstractResponse<io.etcd.jetcd.api.Aut
 
     /**
      * 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

@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthRoleRevokePermissionResponse returned by
- * {@link io.etcd.jetcd.Auth#roleRevokePermission(io.etcd.jetcd.ByteSequence.ByteSequence,
- * io.etcd.jetcd.ByteSequence.ByteSequence, io.etcd.jetcd.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

@@ -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

@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserChangePasswordResponse returned by
- * {@link io.etcd.jetcd.Auth#userChangePassword(io.etcd.jetcd.ByteSequence.ByteSequence,
- * io.etcd.jetcd.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

@@ -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

@@ -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> {
@@ -33,6 +34,8 @@ public class AuthUserGetResponse extends AbstractResponse<io.etcd.jetcd.api.Auth
 
     /**
      * 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

@@ -16,12 +16,10 @@
 
 package io.etcd.jetcd.auth;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * AuthUserGrantRoleResponse returned by
- * {@link io.etcd.jetcd.Auth#userGrantRole(io.etcd.jetcd.ByteSequence.ByteSequence,
- * io.etcd.jetcd.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

@@ -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> {
@@ -32,6 +33,8 @@ public class AuthUserListResponse extends AbstractResponse<io.etcd.jetcd.api.Aut
 
     /**
      * 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

@@ -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

@@ -39,6 +39,8 @@ public class Permission {
 
     /**
      * 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

@@ -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 {
 
@@ -31,6 +31,8 @@ public class Member {
 
     /**
      * Returns the member ID for this member.
+     *
+     * @return the id.
      */
     public long getId() {
         return member.getID();
@@ -38,6 +40,8 @@ public class Member {
 
     /**
      * 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();
@@ -45,6 +49,8 @@ public class Member {
 
     /**
      * 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());
@@ -53,8 +59,19 @@ public class Member {
     /**
      * 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();
+    }
 }

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

@@ -18,10 +18,11 @@ package io.etcd.jetcd.cluster;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Cluster;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * MemberAddResponse returned by {@link io.etcd.jetcd.Cluster#addMember(List)}
+ * MemberAddResponse returned by {@link Cluster#addMember(List, boolean)}
  * contains a header, added member, and list of members after adding the new member.
  */
 public class MemberAddResponse extends AbstractResponse<io.etcd.jetcd.api.MemberAddResponse> {

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

@@ -18,8 +18,8 @@ package io.etcd.jetcd.cluster;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
 import io.etcd.jetcd.Cluster;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
  * MemberListResponse returned by {@link Cluster#listMember()}

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

@@ -18,10 +18,11 @@ package io.etcd.jetcd.cluster;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Cluster;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * MemberRemoveResponse returned by {@link io.etcd.jetcd.Cluster#removeMember(long)}
+ * MemberRemoveResponse returned by {@link Cluster#removeMember(long)}
  * contains a header and a list of member the removal of the member.
  */
 public class MemberRemoveResponse extends AbstractResponse<io.etcd.jetcd.api.MemberRemoveResponse> {

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

@@ -18,10 +18,11 @@ package io.etcd.jetcd.cluster;
 
 import java.util.List;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.Cluster;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 /**
- * MemberUpdateResponse returned by {@link io.etcd.jetcd.Cluster#updateMember(long, List)}
+ * MemberUpdateResponse returned by {@link Cluster#updateMember(long, List)}
  * contains a header and a list of members after the member update.
  */
 public class MemberUpdateResponse extends AbstractResponse<io.etcd.jetcd.api.MemberUpdateResponse> {

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

@@ -22,7 +22,9 @@ import java.util.stream.Collectors;
 /**
  * Util class for Cluster models.
  */
-public class Util {
+final class Util {
+    private Util() {
+    }
 
     /**
      * Converts a list of API member to a List of client side member.

jetcd-core/src/main/java/io/etcd/jetcd/election/CampaignResponse.java

@@ -16,22 +16,26 @@
 
 package io.etcd.jetcd.election;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 public class CampaignResponse extends AbstractResponse<io.etcd.jetcd.api.CampaignResponse> {
     private final LeaderKey leaderKey;
 
     public CampaignResponse(io.etcd.jetcd.api.CampaignResponse response) {
         super(response, response.getHeader());
-        this.leaderKey = toLeaderKey(getResponse().getLeader());
-    }
 
-    private static LeaderKey toLeaderKey(io.etcd.jetcd.api.LeaderKey leader) {
-        return new LeaderKey(leader.getName(), leader.getKey(), leader.getRev(), leader.getLease());
+        this.leaderKey = new LeaderKey(
+            ByteSequence.from(getResponse().getLeader().getName()),
+            ByteSequence.from(getResponse().getLeader().getKey()),
+            getResponse().getLeader().getRev(),
+            getResponse().getLeader().getLease());
     }
 
     /**
      * Returns the resources used for holding leadership of the election.
+     *
+     * @return the leader.
      */
     public LeaderKey getLeader() {
         return leaderKey;

jetcd-core/src/main/java/io/etcd/jetcd/election/LeaderKey.java

@@ -16,15 +16,15 @@
 
 package io.etcd.jetcd.election;
 
-import com.google.protobuf.ByteString;
+import io.etcd.jetcd.ByteSequence;
 
 public class LeaderKey {
-    private final ByteString name;
-    private final ByteString key;
+    private final ByteSequence name;
+    private final ByteSequence key;
     private final long revision;
     private final long lease;
 
-    public LeaderKey(ByteString name, ByteString key, long revision, long lease) {
+    public LeaderKey(ByteSequence name, ByteSequence key, long revision, long lease) {
         this.name = name;
         this.key = key;
         this.revision = revision;
@@ -32,17 +32,21 @@ public class LeaderKey {
     }
 
     /**
-     * Returns the election identifier that corresponds to the leadership key. *
+     * Returns the election identifier that corresponds to the leadership key.
+     *
+     * @return the name.
      */
-    public ByteString getName() {
+    public ByteSequence getName() {
         return name;
     }
 
     /**
      * Returns the opaque key representing the ownership of the election. If the key
      * is deleted, then leadership is lost.
+     *
+     * @return the key.
      */
-    public ByteString getKey() {
+    public ByteSequence getKey() {
         return key;
     }
 
@@ -50,6 +54,8 @@ public class LeaderKey {
      * Returns the creation revision of the key. It can be used to test for ownership
      * of an election during transactions by testing the key's creation revision
      * matches rev.
+     *
+     * @return the revision.
      */
     public long getRevision() {
         return revision;
@@ -57,6 +63,8 @@ public class LeaderKey {
 
     /**
      * Returns the lease ID of the election leader.
+     *
+     * @return the lese id.
      */
     public long getLease() {
         return lease;

jetcd-core/src/main/java/io/etcd/jetcd/election/LeaderResponse.java

@@ -16,9 +16,9 @@
 
 package io.etcd.jetcd.election;
 
-import io.etcd.jetcd.AbstractResponse;
 import io.etcd.jetcd.ByteSequence;
 import io.etcd.jetcd.KeyValue;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 public class LeaderResponse extends AbstractResponse<io.etcd.jetcd.api.LeaderResponse> {
     private final KeyValue kv;
@@ -30,6 +30,8 @@ public class LeaderResponse extends AbstractResponse<io.etcd.jetcd.api.LeaderRes
 
     /**
      * Returns the key-value pair representing the latest leader update.
+     *
+     * @return the kv.
      */
     public KeyValue getKv() {
         return kv;

jetcd-core/src/main/java/io/etcd/jetcd/election/NoLeaderException.java

@@ -20,5 +20,4 @@ package io.etcd.jetcd.election;
  * Signals that leader for given election does not exist.
  */
 public class NoLeaderException extends RuntimeException {
-    public static final NoLeaderException INSTANCE = new NoLeaderException();
 }

jetcd-core/src/main/java/io/etcd/jetcd/election/NotLeaderException.java

@@ -20,5 +20,4 @@ package io.etcd.jetcd.election;
  * Signals that candidate is not a leader at the moment.
  */
 public class NotLeaderException extends RuntimeException {
-    public static final NotLeaderException INSTANCE = new NotLeaderException();
 }

jetcd-core/src/main/java/io/etcd/jetcd/election/ProclaimResponse.java

@@ -16,7 +16,7 @@
 
 package io.etcd.jetcd.election;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 public class ProclaimResponse extends AbstractResponse<io.etcd.jetcd.api.ProclaimResponse> {
     public ProclaimResponse(io.etcd.jetcd.api.ProclaimResponse response) {

jetcd-core/src/main/java/io/etcd/jetcd/election/ResignResponse.java

@@ -16,7 +16,7 @@
 
 package io.etcd.jetcd.election;
 
-import io.etcd.jetcd.AbstractResponse;
+import io.etcd.jetcd.impl.AbstractResponse;
 
 public class ResignResponse extends AbstractResponse<io.etcd.jetcd.api.ResignResponse> {
     public ResignResponse(io.etcd.jetcd.api.ResignResponse response) {

jetcd-core/src/main/java/io/etcd/jetcd/impl/AbstractResponse.java

@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd;
+package io.etcd.jetcd.impl;
 
+import io.etcd.jetcd.Response;
 import io.etcd.jetcd.api.ResponseHeader;
 
 public class AbstractResponse<R> implements Response {

jetcd-core/src/main/java/io/etcd/jetcd/impl/AuthCredential.java

@@ -0,0 +1,113 @@
+/*
+ * 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.impl;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.function.BiConsumer;
+
+import io.etcd.jetcd.api.AuthenticateRequest;
+import io.etcd.jetcd.api.VertxAuthGrpc;
+import io.grpc.CallCredentials;
+import io.grpc.ClientInterceptor;
+import io.grpc.Metadata;
+import io.grpc.Status;
+import io.grpc.stub.MetadataUtils;
+
+import com.google.protobuf.ByteString;
+
+import static io.etcd.jetcd.Preconditions.checkArgument;
+
+/**
+ * AuthTokenInterceptor fills header with Auth token of any rpc calls and
+ * refreshes token if the rpc results an invalid Auth token error.
+ */
+class AuthCredential extends CallCredentials {
+    public static final Metadata.Key<String> TOKEN = Metadata.Key.of("token", Metadata.ASCII_STRING_MARSHALLER);
+
+    private final ClientConnectionManager manager;
+    private volatile Metadata meta;
+
+    public AuthCredential(ClientConnectionManager manager) {
+        this.manager = manager;
+    }
+
+    @Override
+    public void applyRequestMetadata(RequestInfo requestInfo, Executor appExecutor, MetadataApplier applier) {
+        final Metadata meta = this.meta;
+
+        if (meta != null) {
+            applier.apply(meta);
+        } else {
+            authenticate(applier);
+        }
+    }
+
+    public void refresh() {
+        meta = null;
+    }
+
+    @SuppressWarnings("rawtypes")
+    private void authenticate(MetadataApplier applier) {
+        checkArgument(!manager.builder().user().isEmpty(), "username can not be empty.");
+        checkArgument(!manager.builder().password().isEmpty(), "password can not be empty.");
+
+        VertxAuthGrpc.AuthVertxStub authFutureStub = VertxAuthGrpc.newVertxStub(this.manager.getChannel());
+
+        List<ClientInterceptor> interceptorsChain = new ArrayList<>();
+        if (manager.builder().authHeaders() != null) {
+            Metadata metadata = new Metadata();
+            manager.builder().authHeaders().forEach((BiConsumer<Metadata.Key, Object>) metadata::put);
+
+            interceptorsChain.add(MetadataUtils.newAttachHeadersInterceptor(metadata));
+        }
+        if (manager.builder().authInterceptors() != null) {
+            interceptorsChain.addAll(manager.builder().authInterceptors());
+        }
+
+        if (!interceptorsChain.isEmpty()) {
+            authFutureStub = authFutureStub.withInterceptors(
+                interceptorsChain.toArray(new ClientInterceptor[0]));
+        }
+
+        final ByteString user = ByteString.copyFrom(this.manager.builder().user().getBytes());
+        final ByteString pass = ByteString.copyFrom(this.manager.builder().password().getBytes());
+
+        AuthenticateRequest request = AuthenticateRequest.newBuilder()
+            .setNameBytes(user)
+            .setPasswordBytes(pass)
+            .build();
+
+        try {
+            authFutureStub.authenticate(request)
+                .onFailure(t -> {
+                    applier.fail(Status.UNAUTHENTICATED.withCause(t));
+                })
+                .onSuccess(h -> {
+                    Metadata meta = new Metadata();
+                    meta.put(TOKEN, h.getToken());
+
+                    this.meta = meta;
+
+                    applier.apply(this.meta);
+                });
+        } catch (Exception e) {
+            applier.fail(Status.UNAUTHENTICATED.withCause(e));
+        }
+    }
+}

jetcd-core/src/main/java/io/etcd/jetcd/impl/AuthImpl.java

@@ -14,13 +14,14 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd;
+package io.etcd.jetcd.impl;
 
 import java.util.concurrent.CompletableFuture;
 
+import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.ByteSequence;
 import io.etcd.jetcd.api.AuthDisableRequest;
 import io.etcd.jetcd.api.AuthEnableRequest;
-import io.etcd.jetcd.api.AuthGrpc;
 import io.etcd.jetcd.api.AuthRoleAddRequest;
 import io.etcd.jetcd.api.AuthRoleDeleteRequest;
 import io.etcd.jetcd.api.AuthRoleGetRequest;
@@ -34,6 +35,7 @@ import io.etcd.jetcd.api.AuthUserGetRequest;
 import io.etcd.jetcd.api.AuthUserGrantRoleRequest;
 import io.etcd.jetcd.api.AuthUserListRequest;
 import io.etcd.jetcd.api.AuthUserRevokeRoleRequest;
+import io.etcd.jetcd.api.VertxAuthGrpc;
 import io.etcd.jetcd.auth.AuthDisableResponse;
 import io.etcd.jetcd.auth.AuthEnableResponse;
 import io.etcd.jetcd.auth.AuthRoleAddResponse;
@@ -51,120 +53,153 @@ import io.etcd.jetcd.auth.AuthUserListResponse;
 import io.etcd.jetcd.auth.AuthUserRevokeRoleResponse;
 import io.etcd.jetcd.auth.Permission;
 
-import static com.google.common.base.Preconditions.checkNotNull;
+import com.google.protobuf.ByteString;
+
+import static java.util.Objects.requireNonNull;
 
 /**
  * Implementation of etcd auth client.
  */
-final class AuthImpl implements Auth {
+final class AuthImpl extends Impl implements Auth {
 
-    private final AuthGrpc.AuthFutureStub stub;
-    private final ClientConnectionManager connectionManager;
+    private final VertxAuthGrpc.AuthVertxStub stub;
 
     AuthImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(AuthGrpc::newFutureStub);
+        super(connectionManager);
+
+        this.stub = connectionManager.newStub(VertxAuthGrpc::newVertxStub);
     }
 
     @Override
     public CompletableFuture<AuthEnableResponse> authEnable() {
         AuthEnableRequest enableRequest = AuthEnableRequest.getDefaultInstance();
-        return Util.toCompletableFuture(this.stub.authEnable(enableRequest), AuthEnableResponse::new,
-            this.connectionManager.getExecutorService());
+        return completable(
+            this.stub.authEnable(enableRequest),
+            AuthEnableResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthDisableResponse> authDisable() {
         AuthDisableRequest disableRequest = AuthDisableRequest.getDefaultInstance();
-        return Util.toCompletableFuture(this.stub.authDisable(disableRequest), AuthDisableResponse::new,
-            this.connectionManager.getExecutorService());
+        return completable(
+            this.stub.authDisable(disableRequest),
+            AuthDisableResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserAddResponse> userAdd(ByteSequence user, ByteSequence password) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(password, "password can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(password, "password can't be null");
 
-        AuthUserAddRequest addRequest = AuthUserAddRequest.newBuilder().setNameBytes(user.getByteString())
-            .setPasswordBytes(password.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userAdd(addRequest), AuthUserAddResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthUserAddRequest addRequest = AuthUserAddRequest.newBuilder()
+            .setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .setPasswordBytes(ByteString.copyFrom(password.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userAdd(addRequest),
+            AuthUserAddResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserDeleteResponse> userDelete(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
-        AuthUserDeleteRequest deleteRequest = AuthUserDeleteRequest.newBuilder().setNameBytes(user.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userDelete(deleteRequest), AuthUserDeleteResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthUserDeleteRequest deleteRequest = AuthUserDeleteRequest.newBuilder()
+            .setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userDelete(deleteRequest),
+            AuthUserDeleteResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserChangePasswordResponse> userChangePassword(ByteSequence user, ByteSequence password) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(password, "password can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(password, "password can't be null");
 
         AuthUserChangePasswordRequest changePasswordRequest = AuthUserChangePasswordRequest.newBuilder()
-            .setNameBytes(user.getByteString()).setPasswordBytes(password.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userChangePassword(changePasswordRequest),
-            AuthUserChangePasswordResponse::new, this.connectionManager.getExecutorService());
+            .setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .setPasswordBytes(ByteString.copyFrom(password.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userChangePassword(changePasswordRequest),
+            AuthUserChangePasswordResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserGetResponse> userGet(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
-        AuthUserGetRequest userGetRequest = AuthUserGetRequest.newBuilder().setNameBytes(user.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userGet(userGetRequest), AuthUserGetResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthUserGetRequest userGetRequest = AuthUserGetRequest.newBuilder()
+            .setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userGet(userGetRequest),
+            AuthUserGetResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserListResponse> userList() {
         AuthUserListRequest userListRequest = AuthUserListRequest.getDefaultInstance();
-        return Util.toCompletableFuture(this.stub.userList(userListRequest), AuthUserListResponse::new,
-            this.connectionManager.getExecutorService());
+
+        return completable(
+            this.stub.userList(userListRequest),
+            AuthUserListResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserGrantRoleResponse> userGrantRole(ByteSequence user, ByteSequence role) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(role, "key can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(role, "key can't be null");
 
-        AuthUserGrantRoleRequest userGrantRoleRequest = AuthUserGrantRoleRequest.newBuilder().setUserBytes(user.getByteString())
-            .setRoleBytes(role.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userGrantRole(userGrantRoleRequest), AuthUserGrantRoleResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthUserGrantRoleRequest userGrantRoleRequest = AuthUserGrantRoleRequest.newBuilder()
+            .setUserBytes(ByteString.copyFrom(user.getBytes()))
+            .setRoleBytes(ByteString.copyFrom(role.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userGrantRole(userGrantRoleRequest),
+            AuthUserGrantRoleResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthUserRevokeRoleResponse> userRevokeRole(ByteSequence user, ByteSequence role) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(role, "key can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(role, "key can't be null");
 
         AuthUserRevokeRoleRequest userRevokeRoleRequest = AuthUserRevokeRoleRequest.newBuilder()
-            .setNameBytes(user.getByteString()).setRoleBytes(role.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.userRevokeRole(userRevokeRoleRequest), AuthUserRevokeRoleResponse::new,
-            this.connectionManager.getExecutorService());
+            .setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .setRoleBytes(ByteString.copyFrom(role.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.userRevokeRole(userRevokeRoleRequest),
+            AuthUserRevokeRoleResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleAddResponse> roleAdd(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
-        AuthRoleAddRequest roleAddRequest = AuthRoleAddRequest.newBuilder().setNameBytes(user.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.roleAdd(roleAddRequest), AuthRoleAddResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthRoleAddRequest roleAddRequest = AuthRoleAddRequest.newBuilder().setNameBytes(ByteString.copyFrom(user.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.roleAdd(roleAddRequest),
+            AuthRoleAddResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleGrantPermissionResponse> roleGrantPermission(ByteSequence role, ByteSequence key,
         ByteSequence rangeEnd, Permission.Type permType) {
-        checkNotNull(role, "role can't be null");
-        checkNotNull(key, "key can't be null");
-        checkNotNull(rangeEnd, "rangeEnd can't be null");
-        checkNotNull(permType, "permType can't be null");
+        requireNonNull(role, "role can't be null");
+        requireNonNull(key, "key can't be null");
+        requireNonNull(rangeEnd, "rangeEnd can't be null");
+        requireNonNull(permType, "permType can't be null");
 
         io.etcd.jetcd.api.Permission.Type type;
         switch (permType) {
@@ -183,54 +218,70 @@ final class AuthImpl implements Auth {
         }
 
         io.etcd.jetcd.api.Permission perm = io.etcd.jetcd.api.Permission.newBuilder()
-            .setKey(key.getByteString())
-            .setRangeEnd(rangeEnd.getByteString())
+            .setKey(ByteString.copyFrom(key.getBytes()))
+            .setRangeEnd(ByteString.copyFrom(rangeEnd.getBytes()))
             .setPermType(type)
             .build();
+
         AuthRoleGrantPermissionRequest roleGrantPermissionRequest = AuthRoleGrantPermissionRequest.newBuilder()
-            .setNameBytes(role.getByteString())
+            .setNameBytes(ByteString.copyFrom(role.getBytes()))
             .setPerm(perm)
             .build();
 
-        return Util.toCompletableFuture(this.stub.roleGrantPermission(roleGrantPermissionRequest),
-            AuthRoleGrantPermissionResponse::new, this.connectionManager.getExecutorService());
+        return completable(
+            this.stub.roleGrantPermission(roleGrantPermissionRequest),
+            AuthRoleGrantPermissionResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleGetResponse> roleGet(ByteSequence role) {
-        checkNotNull(role, "role can't be null");
+        requireNonNull(role, "role can't be null");
 
-        AuthRoleGetRequest roleGetRequest = AuthRoleGetRequest.newBuilder().setRoleBytes(role.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.roleGet(roleGetRequest), AuthRoleGetResponse::new,
-            this.connectionManager.getExecutorService());
+        AuthRoleGetRequest roleGetRequest = AuthRoleGetRequest.newBuilder()
+            .setRoleBytes(ByteString.copyFrom(role.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.roleGet(roleGetRequest),
+            AuthRoleGetResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleListResponse> roleList() {
         AuthRoleListRequest roleListRequest = AuthRoleListRequest.getDefaultInstance();
-        return Util.toCompletableFuture(this.stub.roleList(roleListRequest), AuthRoleListResponse::new,
-            this.connectionManager.getExecutorService());
+
+        return completable(
+            this.stub.roleList(roleListRequest),
+            AuthRoleListResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleRevokePermissionResponse> roleRevokePermission(ByteSequence role, ByteSequence key,
         ByteSequence rangeEnd) {
-        checkNotNull(role, "role can't be null");
-        checkNotNull(key, "key can't be null");
-        checkNotNull(rangeEnd, "rangeEnd can't be null");
+        requireNonNull(role, "role can't be null");
+        requireNonNull(key, "key can't be null");
+        requireNonNull(rangeEnd, "rangeEnd can't be null");
 
         AuthRoleRevokePermissionRequest roleRevokePermissionRequest = AuthRoleRevokePermissionRequest.newBuilder()
-            .setRoleBytes(role.getByteString()).setKeyBytes(key.getByteString()).setRangeEndBytes(rangeEnd.getByteString())
+            .setRoleBytes(ByteString.copyFrom(role.getBytes()))
+            .setKey(ByteString.copyFrom(key.getBytes()))
+            .setRangeEnd(ByteString.copyFrom(rangeEnd.getBytes()))
             .build();
-        return Util.toCompletableFuture(this.stub.roleRevokePermission(roleRevokePermissionRequest),
-            AuthRoleRevokePermissionResponse::new, this.connectionManager.getExecutorService());
+
+        return completable(
+            this.stub.roleRevokePermission(roleRevokePermissionRequest),
+            AuthRoleRevokePermissionResponse::new);
     }
 
     @Override
     public CompletableFuture<AuthRoleDeleteResponse> roleDelete(ByteSequence role) {
-        checkNotNull(role, "role can't be null");
-        AuthRoleDeleteRequest roleDeleteRequest = AuthRoleDeleteRequest.newBuilder().setRoleBytes(role.getByteString()).build();
-        return Util.toCompletableFuture(this.stub.roleDelete(roleDeleteRequest), AuthRoleDeleteResponse::new,
-            this.connectionManager.getExecutorService());
+        requireNonNull(role, "role can't be null");
+        AuthRoleDeleteRequest roleDeleteRequest = AuthRoleDeleteRequest.newBuilder()
+            .setRoleBytes(ByteString.copyFrom(role.getBytes()))
+            .build();
+
+        return completable(
+            this.stub.roleDelete(roleDeleteRequest),
+            AuthRoleDeleteResponse::new);
     }
 }

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

@@ -14,50 +14,35 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd;
+package io.etcd.jetcd.impl;
 
-import java.util.concurrent.Callable;
 import java.util.concurrent.CompletableFuture;
 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 org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import io.etcd.jetcd.auth.AuthInterceptor;
-import io.grpc.CallOptions;
-import io.grpc.Channel;
-import io.grpc.ClientCall;
-import io.grpc.ClientInterceptor;
+import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.ClientBuilder;
+import io.etcd.jetcd.support.Util;
+import io.grpc.*;
 import io.grpc.ForwardingClientCall.SimpleForwardingClientCall;
-import io.grpc.ManagedChannel;
-import io.grpc.ManagedChannelBuilder;
-import io.grpc.Metadata;
-import io.grpc.MethodDescriptor;
 import io.grpc.netty.NegotiationType;
-import io.grpc.netty.NettyChannelBuilder;
 import io.grpc.stub.AbstractStub;
 import io.netty.channel.ChannelOption;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.util.concurrent.ListenableFuture;
-
-import net.jodah.failsafe.Failsafe;
-import net.jodah.failsafe.RetryPolicy;
+import io.vertx.core.Vertx;
+import io.vertx.core.VertxOptions;
+import io.vertx.grpc.VertxChannelBuilder;
 
 import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
 
 final class ClientConnectionManager {
-    private static final Logger LOGGER = LoggerFactory.getLogger(ClientConnectionManager.class);
-
     private final Object lock;
     private final ClientBuilder builder;
     private final ExecutorService executorService;
-    private final AuthInterceptor authInterceptor;
+    private final AuthCredential credential;
+    private volatile Vertx vertx;
     private volatile ManagedChannel managedChannel;
 
     ClientConnectionManager(ClientBuilder builder) {
@@ -67,14 +52,19 @@ final class ClientConnectionManager {
     ClientConnectionManager(ClientBuilder builder, ManagedChannel managedChannel) {
         this.lock = new Object();
         this.builder = builder;
-        this.authInterceptor = new AuthInterceptor(builder);
         this.managedChannel = managedChannel;
+        this.credential = new AuthCredential(this);
 
         if (builder.executorService() == null) {
-            this.executorService = Executors.newCachedThreadPool();
+            // default to daemon
+            this.executorService = Executors.newCachedThreadPool(Util.createThreadFactory("jetcd-", true));
         } else {
             this.executorService = builder.executorService();
         }
+
+        if (builder.vertx() != null) {
+            this.vertx = builder.vertx();
+        }
     }
 
     ManagedChannel getChannel() {
@@ -97,8 +87,12 @@ final class ClientConnectionManager {
         return executorService;
     }
 
-    AuthInterceptor authInterceptor() {
-        return authInterceptor;
+    ClientBuilder builder() {
+        return builder;
+    }
+
+    AuthCredential authCredential() {
+        return this.credential;
     }
 
     /**
@@ -113,12 +107,15 @@ final class ClientConnectionManager {
     }
 
     private <T extends AbstractStub<T>> T newStub(Function<ManagedChannel, T> stubCustomizer, ManagedChannel channel) {
-        final T stub = stubCustomizer.apply(channel);
+        T stub = stubCustomizer.apply(channel);
         if (builder.waitForReady()) {
-            return stub.withWaitForReady();
-        } else {
-            return stub;
+            stub = stub.withWaitForReady();
         }
+        if (builder.user() != null && builder.password() != null) {
+            stub = stub.withCallCredentials(this.authCredential());
+        }
+
+        return stub;
     }
 
     void close() {
@@ -126,6 +123,9 @@ final class ClientConnectionManager {
             if (managedChannel != null) {
                 managedChannel.shutdownNow();
             }
+            if (vertx != null) {
+                vertx.close();
+            }
         }
 
         if (builder.executorService() == null) {
@@ -133,7 +133,8 @@ final class ClientConnectionManager {
         }
     }
 
-    <T extends AbstractStub<T>, R> CompletableFuture<R> withNewChannel(String target,
+    <T extends AbstractStub<T>, R> CompletableFuture<R> withNewChannel(
+        String target,
         Function<ManagedChannel, T> stubCustomizer,
         Function<T, CompletableFuture<R>> stubConsumer) {
 
@@ -148,19 +149,17 @@ final class ClientConnectionManager {
         }
     }
 
-    @VisibleForTesting
     ManagedChannelBuilder<?> defaultChannelBuilder() {
         return defaultChannelBuilder(builder.target());
     }
 
-    @VisibleForTesting
     @SuppressWarnings("rawtypes")
     ManagedChannelBuilder<?> defaultChannelBuilder(String target) {
         if (target == null) {
             throw new IllegalArgumentException("At least one endpoint should be provided");
         }
 
-        final NettyChannelBuilder channelBuilder = NettyChannelBuilder.forTarget(target);
+        final VertxChannelBuilder channelBuilder = VertxChannelBuilder.forTarget(vertx(), target);
 
         if (builder.authority() != null) {
             channelBuilder.overrideAuthority(builder.authority());
@@ -169,10 +168,10 @@ final class ClientConnectionManager {
             channelBuilder.maxInboundMessageSize(builder.maxInboundMessageSize());
         }
         if (builder.sslContext() != null) {
-            channelBuilder.negotiationType(NegotiationType.TLS);
-            channelBuilder.sslContext(builder.sslContext());
+            channelBuilder.nettyBuilder().negotiationType(NegotiationType.TLS);
+            channelBuilder.nettyBuilder().sslContext(builder.sslContext());
         } else {
-            channelBuilder.negotiationType(NegotiationType.PLAINTEXT);
+            channelBuilder.nettyBuilder().negotiationType(NegotiationType.PLAINTEXT);
         }
 
         if (builder.keepaliveTime() != null) {
@@ -185,22 +184,24 @@ final class ClientConnectionManager {
             channelBuilder.keepAliveWithoutCalls(builder.keepaliveWithoutCalls());
         }
         if (builder.connectTimeout() != null) {
-            channelBuilder.withOption(ChannelOption.CONNECT_TIMEOUT_MILLIS, (int) builder.connectTimeout().toMillis());
+            channelBuilder.nettyBuilder().withOption(ChannelOption.CONNECT_TIMEOUT_MILLIS,
+                (int) builder.connectTimeout().toMillis());
         }
 
         if (builder.loadBalancerPolicy() != null) {
             channelBuilder.defaultLoadBalancingPolicy(builder.loadBalancerPolicy());
         } else {
-            channelBuilder.defaultLoadBalancingPolicy("pick_first");
+            channelBuilder.defaultLoadBalancingPolicy("round_robin");
         }
 
-        channelBuilder.intercept(authInterceptor);
-
         if (builder.headers() != null) {
             channelBuilder.intercept(new ClientInterceptor() {
                 @Override
-                public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method,
-                    CallOptions callOptions, Channel next) {
+                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) {
@@ -219,59 +220,15 @@ final class ClientConnectionManager {
         return channelBuilder;
     }
 
-    /**
-     * 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(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());
-                        execution.complete(wrappedFuture);
-                    } catch (Exception error) {
-                        if (!execution.retryOn(error)) {
-                            // permanent failure
-                            wrappedFuture.completeExceptionally(error);
+    Vertx vertx() {
+        if (this.vertx == null) {
+            synchronized (this.lock) {
+                if (this.vertx == null) {
+                    this.vertx = Vertx.vertx(new VertxOptions().setUseDaemonThread(true));
                 }
             }
-                }, executorService);
-            }).thenCompose(f -> f.thenApply(resultConvert));
         }
 
+        return this.vertx;
+    }
 }

jetcd-core/src/main/java/io/etcd/jetcd/impl/ClientImpl.java

@@ -14,35 +14,45 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd;
+package io.etcd.jetcd.impl;
 
-import io.etcd.jetcd.support.MemoizingClientSupplier;
+import io.etcd.jetcd.Auth;
+import io.etcd.jetcd.Client;
+import io.etcd.jetcd.ClientBuilder;
+import io.etcd.jetcd.Cluster;
+import io.etcd.jetcd.Election;
+import io.etcd.jetcd.KV;
+import io.etcd.jetcd.Lease;
+import io.etcd.jetcd.Lock;
+import io.etcd.jetcd.Maintenance;
+import io.etcd.jetcd.Watch;
+import io.etcd.jetcd.support.MemorizingClientSupplier;
 
 /**
  * Etcd Client.
  */
-final class ClientImpl implements Client {
+public final class ClientImpl implements Client {
 
     private final ClientConnectionManager connectionManager;
-    private final MemoizingClientSupplier<KV> kvClient;
-    private final MemoizingClientSupplier<Auth> authClient;
-    private final MemoizingClientSupplier<Maintenance> maintenanceClient;
-    private final MemoizingClientSupplier<Cluster> clusterClient;
-    private final MemoizingClientSupplier<Lease> leaseClient;
-    private final MemoizingClientSupplier<Watch> watchClient;
-    private final MemoizingClientSupplier<Lock> lockClient;
-    private final MemoizingClientSupplier<Election> electionClient;
+    private final MemorizingClientSupplier<KV> kvClient;
+    private final MemorizingClientSupplier<Auth> authClient;
+    private final MemorizingClientSupplier<Maintenance> maintenanceClient;
+    private final MemorizingClientSupplier<Cluster> clusterClient;
+    private final MemorizingClientSupplier<Lease> leaseClient;
+    private final MemorizingClientSupplier<Watch> watchClient;
+    private final MemorizingClientSupplier<Lock> lockClient;
+    private final MemorizingClientSupplier<Election> electionClient;
 
     public ClientImpl(ClientBuilder clientBuilder) {
         this.connectionManager = new ClientConnectionManager(clientBuilder.copy());
-        this.kvClient = new MemoizingClientSupplier<>(() -> new KVImpl(this.connectionManager));
-        this.authClient = new MemoizingClientSupplier<>(() -> new AuthImpl(this.connectionManager));
-        this.maintenanceClient = new MemoizingClientSupplier<>(() -> new MaintenanceImpl(this.connectionManager));
-        this.clusterClient = new MemoizingClientSupplier<>(() -> new ClusterImpl(this.connectionManager));
-        this.leaseClient = new MemoizingClientSupplier<>(() -> new LeaseImpl(this.connectionManager));
-        this.watchClient = new MemoizingClientSupplier<>(() -> new WatchImpl(this.connectionManager));
-        this.lockClient = new MemoizingClientSupplier<>(() -> new LockImpl(this.connectionManager));
-        this.electionClient = new MemoizingClientSupplier<>(() -> new ElectionImpl(this.connectionManager));
+        this.kvClient = new MemorizingClientSupplier<>(() -> new KVImpl(this.connectionManager));
+        this.authClient = new MemorizingClientSupplier<>(() -> new AuthImpl(this.connectionManager));
+        this.maintenanceClient = new MemorizingClientSupplier<>(() -> new MaintenanceImpl(this.connectionManager));
+        this.clusterClient = new MemorizingClientSupplier<>(() -> new ClusterImpl(this.connectionManager));
+        this.leaseClient = new MemorizingClientSupplier<>(() -> new LeaseImpl(this.connectionManager));
+        this.watchClient = new MemorizingClientSupplier<>(() -> new WatchImpl(this.connectionManager));
+        this.lockClient = new MemorizingClientSupplier<>(() -> new LockImpl(this.connectionManager));
+        this.electionClient = new MemorizingClientSupplier<>(() -> new ElectionImpl(this.connectionManager));
     }
 
     @Override

jetcd-core/src/main/java/io/etcd/jetcd/impl/ClusterImpl.java

@@ -14,18 +14,19 @@
  * limitations under the License.
  */
 
-package io.etcd.jetcd;
+package io.etcd.jetcd.impl;
 
 import java.net.URI;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Collectors;
 
-import io.etcd.jetcd.api.ClusterGrpc;
+import io.etcd.jetcd.Cluster;
 import io.etcd.jetcd.api.MemberAddRequest;
 import io.etcd.jetcd.api.MemberListRequest;
 import io.etcd.jetcd.api.MemberRemoveRequest;
 import io.etcd.jetcd.api.MemberUpdateRequest;
+import io.etcd.jetcd.api.VertxClusterGrpc;
 import io.etcd.jetcd.cluster.MemberAddResponse;
 import io.etcd.jetcd.cluster.MemberListResponse;
 import io.etcd.jetcd.cluster.MemberRemoveResponse;
@@ -34,14 +35,14 @@ import io.etcd.jetcd.cluster.MemberUpdateResponse;
 /**
  * Implementation of cluster client.
  */
-final class ClusterImpl implements Cluster {
+final class ClusterImpl extends Impl implements Cluster {
 
-    private final ClusterGrpc.ClusterFutureStub stub;
-    private final ClientConnectionManager connectionManager;
+    private final VertxClusterGrpc.ClusterVertxStub stub;
 
     ClusterImpl(ClientConnectionManager connectionManager) {
-        this.connectionManager = connectionManager;
-        this.stub = connectionManager.newStub(ClusterGrpc::newFutureStub);
+        super(connectionManager);
+
+        this.stub = connectionManager.newStub(VertxClusterGrpc::newVertxStub);
     }
 
     /**
@@ -49,27 +50,37 @@ final class ClusterImpl implements Cluster {
      */
     @Override
     public CompletableFuture<MemberListResponse> listMember() {
-        return Util.toCompletableFuture(
+        return completable(
             this.stub.memberList(MemberListRequest.getDefaultInstance()),
-            MemberListResponse::new,
-            this.connectionManager.getExecutorService());
+            MemberListResponse::new);
+    }
+
+    /**
+     * add a non-learner new member into the cluster.
+     *
+     * @param peerAddrs the peer addresses of the new member
+     */
+    @Override
+    public CompletableFuture<MemberAddResponse> addMember(List<URI> peerAddrs) {
+        return addMember(peerAddrs, false);
     }
 
     /**
      * add a new member into the cluster.
      *
      * @param peerAddrs the peer addresses of the new member
+     * @param isLearner whether the member is raft learner
      */
     @Override
-    public CompletableFuture<MemberAddResponse> addMember(List<URI> peerAddrs) {
+    public CompletableFuture<MemberAddResponse> addMember(List<URI> peerAddrs, boolean isLearner) {
         MemberAddRequest memberAddRequest = MemberAddRequest.newBuilder()
             .addAllPeerURLs(peerAddrs.stream().map(URI::toString).collect(Collectors.toList()))
+            .setIsLearner(isLearner)
             .build();
 
-        return Util.toCompletableFuture(
+        return completable(
             this.stub.memberAdd(memberAddRequest),
-            MemberAddResponse::new,
-            this.connectionManager.getExecutorService());
+            MemberAddResponse::new);
     }
 
     /**
@@ -83,10 +94,9 @@ final class ClusterImpl implements Cluster {
             .setID(memberID)
             .build();
 
-        return Util.toCompletableFuture(
+        return completable(
             this.stub.memberRemove(memberRemoveRequest),
-            MemberRemoveResponse::new,
-            this.connectionManager.getExecutorService());
+            MemberRemoveResponse::new);
     }
 
     /**
@@ -98,12 +108,12 @@ final class ClusterImpl implements Cluster {
     @Override
     public CompletableFuture<MemberUpdateResponse> updateMember(long memberID, List<URI> peerAddrs) {
         MemberUpdateRequest memberUpdateRequest = MemberUpdateRequest.newBuilder()
-            .addAllPeerURLs(peerAddrs.stream().map(URI::toString).collect(Collectors.toList())).setID(memberID)
+            .addAllPeerURLs(peerAddrs.stream().map(URI::toString).collect(Collectors.toList()))
+            .setID(memberID)
             .build();
 
-        return Util.toCompletableFuture(
+        return completable(
             this.stub.memberUpdate(memberUpdateRequest),
-            MemberUpdateResponse::new,
-            this.connectionManager.getExecutorService());
+            MemberUpdateResponse::new);
     }
 }

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

@@ -0,0 +1,199 @@
+/*
+ * 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.impl;
+
+import java.util.concurrent.CompletableFuture;
+
+import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.Election;
+import io.etcd.jetcd.api.CampaignRequest;
+import io.etcd.jetcd.api.LeaderRequest;
+import io.etcd.jetcd.api.ProclaimRequest;
+import io.etcd.jetcd.api.ResignRequest;
+import io.etcd.jetcd.api.VertxElectionGrpc;
+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.etcd.jetcd.support.Errors;
+import io.etcd.jetcd.support.Util;
+import io.grpc.StatusRuntimeException;
+
+import com.google.protobuf.ByteString;
+
+import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;
+import static java.util.Objects.requireNonNull;
+
+final class ElectionImpl extends Impl implements Election {
+    private final VertxElectionGrpc.ElectionVertxStub stub;
+    private final ByteSequence namespace;
+
+    ElectionImpl(ClientConnectionManager connectionManager) {
+        super(connectionManager);
+
+        this.stub = connectionManager.newStub(VertxElectionGrpc::newVertxStub);
+        this.namespace = connectionManager.getNamespace();
+    }
+
+    // Election operations are done in a context where a client is trying to implement
+    // some fault tolerance related use case; in that type of context, it makes sense to always
+    // apply require leader, since we don't want a client connected to a non-raft-leader server
+    // have an election method just go silent if the server the client happens to be connected to
+    // becomes partitioned from the actual raft-leader server in the etcd servers cluster:
+    // in that scenario and without required leader, an attempt to campaign could block forever
+    // not because some other client is already an election leader, but because the server the client
+    // is connected to is partitioned and can't tell.
+    // With require leader, in that case the call will fail and we give
+    // the client the ability to (a) know (b) retry on a different server.
+    // The retry on a different server should happen automatically if the connection manager is using
+    // a round robin strategy.
+    //
+    // Beware in the context of this election API, the word "leader" is overloaded.
+    // In the paragraph above when we say "raft-leader" we are talking about the etcd server that is a leader
+    // of the etcd servers cluster according to raft, we are not talking about the client that
+    // happens to be the leader of an election using the election API in this file.
+    private VertxElectionGrpc.ElectionVertxStub stubWithLeader() {
+        return Util.applyRequireLeader(true, stub);
+    }
+
+    @Override
+    public CompletableFuture<CampaignResponse> campaign(ByteSequence electionName, long leaseId, ByteSequence proposal) {
+        requireNonNull(electionName, "election name should not be null");
+        requireNonNull(proposal, "proposal should not be null");
+
+        CampaignRequest request = CampaignRequest.newBuilder()
+            .setName(Util.prefixNamespace(electionName, namespace))
+            .setValue(ByteString.copyFrom(proposal.getBytes()))
+            .setLease(leaseId)
+            .build();
+
+        return wrapConvertException(
+            execute(
+                () -> stubWithLeader().campaign(request),
+                CampaignResponse::new,
+                Errors::isRetryableForNoSafeRedoOp));
+    }
+
+    @Override
+    public CompletableFuture<ProclaimResponse> proclaim(LeaderKey leaderKey, ByteSequence proposal) {
+        requireNonNull(leaderKey, "leader key should not be null");
+        requireNonNull(proposal, "proposal should not be null");
+
+        ProclaimRequest request = ProclaimRequest.newBuilder()
+            .setLeader(
+                io.etcd.jetcd.api.LeaderKey.newBuilder()
+                    .setKey(ByteString.copyFrom(leaderKey.getKey().getBytes()))
+                    .setName(ByteString.copyFrom(leaderKey.getName().getBytes()))
+                    .setLease(leaderKey.getLease())
+                    .setRev(leaderKey.getRevision())
+                    .build())
+            .setValue(ByteString.copyFrom(proposal.getBytes()))
+            .build();
+
+        return wrapConvertException(
+            execute(
+                () -> stubWithLeader().proclaim(request),
+                ProclaimResponse::new,
+                Errors::isRetryableForNoSafeRedoOp));
+    }
+
+    @Override
+    public CompletableFuture<LeaderResponse> leader(ByteSequence electionName) {
+        requireNonNull(electionName, "election name should not be null");
+
+        LeaderRequest request = LeaderRequest.newBuilder()
+            .setName(Util.prefixNamespace(electionName, namespace))
+            .build();
+
+        return wrapConvertException(
+            execute(
+                () -> stubWithLeader().leader(request),
+                response -> new LeaderResponse(response, namespace),
+                Errors::isRetryableForNoSafeRedoOp));
+    }
+
+    @Override
+    public void observe(ByteSequence electionName, Listener listener) {
+        requireNonNull(electionName, "election name should not be null");
+        requireNonNull(listener, "listener should not be null");
+
+        LeaderRequest request = LeaderRequest.newBuilder()
+            .setName(Util.prefixNamespace(electionName, namespace))
+            .build();
+
+        stubWithLeader().observeWithHandler(request,
+            value -> listener.onNext(new LeaderResponse(value, namespace)),
+            ignored -> listener.onCompleted(),
+            error -> listener.onError(toEtcdException(error)));
+    }
+
+    @Override
+    public CompletableFuture<ResignResponse> resign(LeaderKey leaderKey) {
+        requireNonNull(leaderKey, "leader key should not be null");
+
+        ResignRequest request = ResignRequest.newBuilder()
+            .setLeader(
+                io.etcd.jetcd.api.LeaderKey.newBuilder()
+                    .setKey(ByteString.copyFrom(leaderKey.getKey().getBytes()))
+                    .setName(ByteString.copyFrom(leaderKey.getName().getBytes()))
+                    .setLease(leaderKey.getLease())
+                    .setRev(leaderKey.getRevision())
+                    .build())
+            .build();
+
+        return wrapConvertException(
+            execute(
+                () -> stubWithLeader().resign(request),
+                ResignResponse::new,
+                Errors::isRetryableForNoSafeRedoOp));
+    }
+
+    private <S> CompletableFuture<S> wrapConvertException(CompletableFuture<S> future) {
+        return future.exceptionally(e -> {
+            throw convertException(e);
+        });
+    }
+
+    private RuntimeException convertException(Throwable e) {
+        Throwable cause = e;
+        while (cause != null) {
+            if (cause instanceof StatusRuntimeException) {
+                StatusRuntimeException exception = (StatusRuntimeException) cause;
+                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)) {
+                    // Candidate is not a leader at the moment.
+                    // Note there is a one letter difference, but this exception type is not the same as
+                    // NoLeaderException.
+                    return new NotLeaderException();
+                }
+                if ("election: no leader".equals(description)) {
+                    // Leader for given election does not exist.
+                    // Note there is a one letter difference, but this exception type is not the same as
+                    // NotLeaderException.
+                    return new NoLeaderException();
+                }
+            }
+            cause = cause.getCause();
+        }
+        return toEtcdException(e);
+    }
+}

jetcd-core/src/main/java/io/etcd/jetcd/impl/Impl.java

@@ -0,0 +1,160 @@
+package io.etcd.jetcd.impl;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.etcd.jetcd.common.exception.EtcdExceptionFactory;
+import io.etcd.jetcd.support.Errors;
+import io.grpc.Status;
+import io.vertx.core.Future;
+
+import dev.failsafe.Failsafe;
+import dev.failsafe.RetryPolicy;
+import dev.failsafe.RetryPolicyBuilder;
+
+import static io.etcd.jetcd.support.Errors.isAuthStoreExpired;
+import static io.etcd.jetcd.support.Errors.isInvalidTokenError;
+
+abstract class Impl {
+    private final Logger logger;
+    private final ClientConnectionManager connectionManager;
+
+    protected Impl(ClientConnectionManager connectionManager) {
+        this.connectionManager = connectionManager;
+        this.logger = LoggerFactory.getLogger(getClass());
+    }
+
+    protected ClientConnectionManager connectionManager() {
+        return this.connectionManager;
+    }
+
+    protected Logger logger() {
+        return this.logger;
+    }
+
+    /**
+     * Converts Future of Type S to CompletableFuture of Type T.
+     *
+     * @param  sourceFuture  the Future to wrap
+     * @param  resultConvert the result converter
+     * @return               a {@link CompletableFuture} wrapping the given {@link Future}
+     */
+    protected <S, T> CompletableFuture<T> completable(Future<S> sourceFuture, Function<S, T> resultConvert) {
+        return completable(sourceFuture, resultConvert, EtcdExceptionFactory::toEtcdException);
+    }
+
+    /**
+     * Converts Future of Type S to CompletableFuture of Type T.
+     *
+     * @param  sourceFuture       the Future to wrap
+     * @param  resultConvert      the result converter
+     * @param  exceptionConverter the exception mapper
+     * @return                    a {@link CompletableFuture} wrapping the given {@link Future}
+     */
+    protected <S, T> CompletableFuture<T> completable(
+        Future<S> sourceFuture,
+        Function<S, T> resultConvert,
+        Function<Throwable, Throwable> exceptionConverter) {
+
+        return completable(
+            sourceFuture.compose(
+                r -> Future.succeededFuture(resultConvert.apply(r)),
+                e -> Future.failedFuture(exceptionConverter.apply(e))));
+    }
+
+    /**
+     * Converts Future of Type S to CompletableFuture of Type T.
+     *
+     * @param  sourceFuture the Future to wrap
+     * @return              a {@link CompletableFuture} wrapping the given {@link Future}
+     */
+    protected <S> CompletableFuture<S> completable(
+        Future<S> sourceFuture) {
+        return sourceFuture.toCompletionStage().toCompletableFuture();
+    }
+
+    /**
+     * execute the task and retry it in case of failure.
+     *
+     * @param  supplier      a function that returns a new Future.
+     * @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.
+     */
+    protected <S, T> CompletableFuture<T> execute(
+        Supplier<Future<S>> supplier,
+        Function<S, T> resultConvert,
+        boolean autoRetry) {
+
+        return execute(supplier, resultConvert,
+            autoRetry ? Errors::isRetryableForSafeRedoOp : Errors::isRetryableForNoSafeRedoOp);
+    }
+
+    /**
+     * execute the task and retry it in case of failure.
+     *
+     * @param  supplier      a function that returns a new Future.
+     * @param  resultConvert a function that converts Type S to Type T.
+     * @param  doRetry       a predicate to determine if a failure has to be retried
+     * @param  <S>           Source type
+     * @param  <T>           Converted Type.
+     * @return               a CompletableFuture with type T.
+     */
+    protected <S, T> CompletableFuture<T> execute(
+        Supplier<Future<S>> supplier,
+        Function<S, T> resultConvert,
+        Predicate<Status> doRetry) {
+
+        return Failsafe
+            .with(retryPolicy(doRetry))
+            .with(connectionManager.getExecutorService())
+            .getStageAsync(() -> supplier.get().toCompletionStage())
+            .thenApply(resultConvert);
+    }
+
+    protected <S> RetryPolicy<S> retryPolicy(Predicate<Status> doRetry) {
+        RetryPolicyBuilder<S> policy = RetryPolicy.<S> builder()
+            .onFailure(e -> {
+                logger.warn("retry failure (attempt: {}, error: {})",
+                    e.getAttemptCount(),
+                    e.getException() != null ? e.getException().getMessage() : "<none>");
+            })
+            .onRetry(e -> {
+                logger.debug("retry (attempt: {}, error: {})",
+                    e.getAttemptCount(),
+                    e.getLastException() != null ? e.getLastException().getMessage() : "<none>");
+            })
+            .onRetriesExceeded(e -> {
+                logger.warn("maximum number of auto retries reached (attempt: {}, error: {})",
+                    e.getAttemptCount(),
+                    e.getException() != null ? e.getException().getMessage() : "<none>");
+            })
+            .handleIf(throwable -> {
+                Status status = Status.fromThrowable(throwable);
+                if (isInvalidTokenError(status)) {
+                    connectionManager.authCredential().refresh();
+                }
+                if (isAuthStoreExpired(status)) {
+                    connectionManager.authCredential().refresh();
+                }
+                return doRetry.test(status);
+            })
+            .withMaxRetries(connectionManager.builder().retryMaxAttempts())
+            .withBackoff(
+                connectionManager.builder().retryDelay(),
+                connectionManager.builder().retryMaxDelay(),
+                connectionManager.builder().retryChronoUnit());
+
+        if (connectionManager.builder().retryMaxDuration() != null) {
+            policy = policy.withMaxDuration(connectionManager.builder().retryMaxDuration());
+        }
+
+        return policy.build();
+    }
+}

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

@@ -0,0 +1,137 @@
+/*
+ * 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.impl;
+
+import java.util.concurrent.CompletableFuture;
+
+import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.KV;
+import io.etcd.jetcd.Txn;
+import io.etcd.jetcd.api.CompactionRequest;
+import io.etcd.jetcd.api.VertxKVGrpc;
+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 io.etcd.jetcd.options.TxnOption;
+import io.etcd.jetcd.support.Errors;
+import io.etcd.jetcd.support.Requests;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Implementation of etcd kv client.
+ */
+final class KVImpl extends Impl implements KV {
+    private final VertxKVGrpc.KVVertxStub stub;
+    private final ByteSequence namespace;
+
+    KVImpl(ClientConnectionManager connectionManager) {
+        super(connectionManager);
+
+        this.stub = connectionManager.newStub(VertxKVGrpc::newVertxStub);
+        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) {
+        requireNonNull(key, "key should not be null");
+        requireNonNull(value, "value should not be null");
+        requireNonNull(option, "option should not be null");
+        return execute(
+            () -> stub.put(Requests.mapPutRequest(key, value, option, namespace)),
+            response -> new PutResponse(response, namespace),
+            option.isAutoRetry() ? Errors::isRetryableForSafeRedoOp : Errors::isRetryableForNoSafeRedoOp);
+    }
+
+    @Override
+    public CompletableFuture<GetResponse> get(ByteSequence key) {
+        return this.get(key, GetOption.DEFAULT);
+    }
+
+    @Override
+    public CompletableFuture<GetResponse> get(ByteSequence key, GetOption option) {
+        requireNonNull(key, "key should not be null");
+        requireNonNull(option, "option should not be null");
+
+        return execute(
+            () -> stub.range(Requests.mapRangeRequest(key, option, namespace)),
+            response -> new GetResponse(response, namespace),
+            Errors::isRetryableForSafeRedoOp);
+    }
+
+    @Override
+    public CompletableFuture<DeleteResponse> delete(ByteSequence key) {
+        return this.delete(key, DeleteOption.DEFAULT);
+    }
+
+    @Override
+    public CompletableFuture<DeleteResponse> delete(ByteSequence key, DeleteOption option) {
+        requireNonNull(key, "key should not be null");
+        requireNonNull(option, "option should not be null");
+
+        return execute(
+            () -> stub.deleteRange(Requests.mapDeleteRequest(key, option, namespace)),
+            response -> new DeleteResponse(response, namespace),
+            option.isAutoRetry() ? Errors::isRetryableForSafeRedoOp : Errors::isRetryableForNoSafeRedoOp);
+    }
+
+    @Override
+    public CompletableFuture<CompactResponse> compact(long rev) {
+        return this.compact(rev, CompactOption.DEFAULT);
+    }
+
+    @Override
+    public CompletableFuture<CompactResponse> compact(long rev, CompactOption option) {
+        requireNonNull(option, "option should not be null");
+
+        CompactionRequest request = CompactionRequest.newBuilder()
+            .setRevision(rev).setPhysical(option.isPhysical())
+            .build();
+
+        return execute(
+            () -> stub.compact(request),
+            CompactResponse::new,
+            Errors::isRetryableForSafeRedoOp);
+    }
+
+    @Override
+    public Txn txn() {
+        return txn(TxnOption.DEFAULT);
+    }
+
+    @Override
+    public Txn txn(TxnOption option) {
+        return TxnImpl.newTxn(
+            request -> execute(
+                () -> stub.txn(request),
+                response -> new TxnResponse(response, namespace),
+                option.isAutoRetry() ? Errors::isRetryableForSafeRedoOp : Errors::isRetryableForNoSafeRedoOp),
+            namespace);
+    }
+}

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

@@ -0,0 +1,404 @@
+/*
+ * 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.impl;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import io.etcd.jetcd.Lease;
+import io.etcd.jetcd.api.LeaseGrantRequest;
+import io.etcd.jetcd.api.LeaseKeepAliveRequest;
+import io.etcd.jetcd.api.LeaseRevokeRequest;
+import io.etcd.jetcd.api.LeaseTimeToLiveRequest;
+import io.etcd.jetcd.api.VertxLeaseGrpc;
+import io.etcd.jetcd.common.Service;
+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.Util;
+import io.grpc.stub.StreamObserver;
+import io.vertx.core.streams.WriteStream;
+
+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;
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Implementation of lease client.
+ */
+final class LeaseImpl extends Impl implements Lease {
+
+    /**
+     * if there is no user-provided keep-alive timeout from ClientBuilder, then DEFAULT_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 DEFAULT_FIRST_KEEPALIVE_TIMEOUT_MS = 5000;
+
+    private final VertxLeaseGrpc.LeaseVertxStub stub;
+    private final VertxLeaseGrpc.LeaseVertxStub leaseStub;
+    private final Map<Long, KeepAliveObserver> keepAlives;
+    private final KeepAlive keepAlive;
+    private final DeadLine deadLine;
+    private volatile boolean closed;
+
+    LeaseImpl(ClientConnectionManager connectionManager) {
+        super(connectionManager);
+
+        this.stub = connectionManager().newStub(VertxLeaseGrpc::newVertxStub);
+        this.leaseStub = Util.applyRequireLeader(true, connectionManager().newStub(VertxLeaseGrpc::newVertxStub));
+        this.keepAlives = new ConcurrentHashMap<>();
+        this.keepAlive = new KeepAlive();
+        this.deadLine = new DeadLine();
+    }
+
+    @Override
+    public CompletableFuture<LeaseGrantResponse> grant(long ttl) {
+        return execute(
+            () -> this.stub.leaseGrant(
+                LeaseGrantRequest.newBuilder()
+                    .setTTL(ttl)
+                    .build()),
+            LeaseGrantResponse::new,
+            true);
+    }
+
+    @Override
+    public CompletableFuture<LeaseGrantResponse> grant(long ttl, long timeout, TimeUnit unit) {
+        return execute(
+            () -> this.stub.withDeadlineAfter(timeout, unit).leaseGrant(
+                LeaseGrantRequest.newBuilder()
+                    .setTTL(ttl)
+                    .build()),
+            LeaseGrantResponse::new,
+            true);
+    }
+
+    @Override
+    public CompletableFuture<LeaseRevokeResponse> revoke(long leaseId) {
+        return execute(
+            () -> this.stub.leaseRevoke(
+                LeaseRevokeRequest.newBuilder()
+                    .setID(leaseId)
+                    .build()),
+            LeaseRevokeResponse::new,
+            true);
+    }
+
+    @Override
+    public CompletableFuture<LeaseTimeToLiveResponse> timeToLive(long leaseId, LeaseOption option) {
+        requireNonNull(option, "LeaseOption should not be null");
+
+        LeaseTimeToLiveRequest leaseTimeToLiveRequest = LeaseTimeToLiveRequest.newBuilder()
+            .setID(leaseId)
+            .setKeys(option.isAttachedKeys())
+            .build();
+
+        return execute(
+            () -> this.stub.leaseTimeToLive(leaseTimeToLiveRequest),
+            LeaseTimeToLiveResponse::new,
+            true);
+    }
+
+    @Override
+    public synchronized CloseableClient keepAlive(long leaseId, StreamObserver<LeaseKeepAliveResponse> observer) {
+        if (this.closed) {
+            throw newClosedLeaseClientException();
+        }
+
+        KeepAliveObserver keepAlive = this.keepAlives.computeIfAbsent(leaseId, KeepAliveObserver::new);
+        keepAlive.addObserver(observer);
+
+        this.keepAlive.start();
+        this.deadLine.start();
+
+        return new CloseableClient() {
+            @Override
+            public void close() {
+                keepAlive.removeObserver(observer);
+            }
+        };
+    }
+
+    @Override
+    public CompletableFuture<LeaseKeepAliveResponse> keepAliveOnce(long leaseId) {
+        final AtomicReference<WriteStream<LeaseKeepAliveRequest>> ref = new AtomicReference<>();
+        final CompletableFuture<LeaseKeepAliveResponse> future = new CompletableFuture<>();
+        final LeaseKeepAliveRequest req = LeaseKeepAliveRequest.newBuilder().setID(leaseId).build();
+
+        leaseStub
+            .leaseKeepAliveWithHandler(
+                s -> {
+                    ref.set(s);
+                    s.write(req);
+                },
+                r -> {
+                    if (r.getTTL() != 0) {
+                        future.complete(new LeaseKeepAliveResponse(r));
+                    } else {
+                        future.completeExceptionally(
+                            newEtcdException(ErrorCode.NOT_FOUND, "etcdserver: requested lease not found"));
+                    }
+                },
+                null,
+                future::completeExceptionally);
+
+        return future.whenComplete((r, t) -> ref.get().end(req));
+    }
+
+    @Override
+    public synchronized void close() {
+        if (this.closed) {
+            return;
+        }
+        this.closed = true;
+
+        this.keepAlive.close();
+        this.deadLine.close();
+
+        final Throwable errResp = newClosedLeaseClientException();
+
+        this.keepAlives.values().forEach(v -> v.onError(errResp));
+        this.keepAlives.clear();
+    }
+
+    /**
+     * The KeepAliver hold a background task and stream for keep aliaves.
+     */
+    private final class KeepAlive extends Service {
+        private volatile Long task;
+        private volatile Long restart;
+        private volatile WriteStream<LeaseKeepAliveRequest> requestStream;
+
+        public KeepAlive() {
+        }
+
+        @Override
+        public void doStart() {
+            leaseStub.leaseKeepAliveWithHandler(
+                this::writeHandler,
+                this::handleResponse,
+                null,
+                this::handleException);
+        }
+
+        @Override
+        public void doStop() {
+            if (requestStream != null) {
+                requestStream.end();
+            }
+            if (this.restart != null) {
+                connectionManager().vertx().cancelTimer(this.restart);
+            }
+            if (this.task != null) {
+                connectionManager().vertx().cancelTimer(this.task);
+            }
+        }
+
+        @Override
+        public void close() {
+            super.close();
+
+            this.task = null;
+            this.restart = null;
+        }
+
+        private void writeHandler(WriteStream<LeaseKeepAliveRequest> stream) {
+            requestStream = stream;
+
+            task = connectionManager().vertx().setPeriodic(
+                0,
+                500,
+                l -> {
+                    keepAlives.values().forEach(element -> sendKeepAlive(element, stream));
+                });
+        }
+
+        private void sendKeepAlive(KeepAliveObserver observer, WriteStream<LeaseKeepAliveRequest> stream) {
+            if (observer.getNextKeepAlive() < System.currentTimeMillis()) {
+                stream.write(
+                    LeaseKeepAliveRequest.newBuilder().setID(observer.getLeaseId()).build());
+            }
+        }
+
+        private synchronized void handleResponse(io.etcd.jetcd.api.LeaseKeepAliveResponse leaseKeepAliveResponse) {
+            if (!this.isRunning()) {
+                return;
+            }
+
+            final long leaseID = leaseKeepAliveResponse.getID();
+            final long ttl = leaseKeepAliveResponse.getTTL();
+            final KeepAliveObserver ka = keepAlives.get(leaseID);
+
+            if (ka == null) {
+                return;
+            }
+
+            if (ttl > 0) {
+                long nextKeepAlive = System.currentTimeMillis() + ttl * 1000 / 3;
+                ka.setNextKeepAlive(nextKeepAlive);
+                ka.setDeadLine(System.currentTimeMillis() + ttl * 1000);
+                ka.onNext(leaseKeepAliveResponse);
+            } else {
+                keepAlives.remove(leaseID);
+                ka.onError(newEtcdException(ErrorCode.NOT_FOUND, "etcdserver: requested lease not found"));
+            }
+        }
+
+        private synchronized void handleException(Throwable throwable) {
+            if (!this.isRunning()) {
+                return;
+            }
+
+            keepAlives.values().forEach(ka -> ka.onError(throwable));
+
+            restart = connectionManager().vertx().setTimer(
+                500,
+                l -> {
+                    if (isRunning()) {
+                        restart();
+                    }
+                });
+        }
+    }
+
+    /**
+     * The DeadLiner hold a background task to check deadlines.
+     */
+    private class DeadLine extends Service {
+        private volatile Long task;
+
+        public DeadLine() {
+        }
+
+        @Override
+        public void doStart() {
+            this.task = connectionManager().vertx().setPeriodic(
+                0,
+                1000,
+                l -> {
+                    long now = System.currentTimeMillis();
+
+                    keepAlives.values().removeIf(ka -> {
+                        if (ka.getDeadLine() < now) {
+                            ka.onCompleted();
+                            return true;
+                        }
+                        return false;
+                    });
+                });
+        }
+
+        @Override
+        public void doStop() {
+            if (this.task != null) {
+                connectionManager().vertx().cancelTimer(this.task);
+            }
+        }
+    }
+
+    /**
+     * The KeepAlive hold the keepAlive information for lease.
+     */
+    private final class KeepAliveObserver implements StreamObserver<io.etcd.jetcd.api.LeaseKeepAliveResponse> {
+        private final List<StreamObserver<LeaseKeepAliveResponse>> observers;
+        private final long leaseId;
+
+        private long deadLine;
+        private long nextKeepAlive;
+
+        public KeepAliveObserver(long leaseId) {
+            this(leaseId, Collections.emptyList());
+        }
+
+        public KeepAliveObserver(long leaseId, Collection<StreamObserver<LeaseKeepAliveResponse>> observers) {
+            this.nextKeepAlive = System.currentTimeMillis();
+
+            // Use user-provided timeout if present to avoid removing KeepAlive before first response from server
+            int initialKeepAliveTimeoutMs = connectionManager().builder().keepaliveTimeout() != null
+                ? Math.toIntExact(connectionManager().builder().keepaliveTimeout().toMillis())
+                : DEFAULT_FIRST_KEEPALIVE_TIMEOUT_MS;
+            this.deadLine = nextKeepAlive + initialKeepAliveTimeoutMs;
+
+            this.observers = new CopyOnWriteArrayList<>(observers);
+            this.leaseId = leaseId;
+        }
+
+        public long getLeaseId() {
+            return leaseId;
+        }
+
+        public long getDeadLine() {
+            return deadLine;
+        }
+
+        public void setDeadLine(long deadLine) {
+            this.deadLine = deadLine;
+        }
+
+        public void addObserver(StreamObserver<LeaseKeepAliveResponse> observer) {
+            this.observers.add(observer);
+        }
+
+        public void removeObserver(StreamObserver<LeaseKeepAliveResponse> listener) {
+            this.observers.remove(listener);
+
+            if (this.observers.isEmpty()) {
+                keepAlives.remove(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/impl/LockImpl.java

@@ -0,0 +1,88 @@
+/*
+ * 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.impl;
+
+import java.util.concurrent.CompletableFuture;
+
+import io.etcd.jetcd.ByteSequence;
+import io.etcd.jetcd.Lock;
+import io.etcd.jetcd.api.lock.LockRequest;
+import io.etcd.jetcd.api.lock.UnlockRequest;
+import io.etcd.jetcd.api.lock.VertxLockGrpc;
+import io.etcd.jetcd.lock.LockResponse;
+import io.etcd.jetcd.lock.UnlockResponse;
+import io.etcd.jetcd.support.Errors;
+import io.etcd.jetcd.support.Util;
+
+import static java.util.Objects.requireNonNull;
+
+final class LockImpl extends Impl implements Lock {
+    private final VertxLockGrpc.LockVertxStub stub;
+    private final ByteSequence namespace;
+
+    // Lock operations are done in a context where a client is trying to implement
+    // some strict mutual exclusion use case; in that type of context, it makes sense to always
+    // apply require leader, since we don't want a client connected to a non-raft-leader server
+    // to have a lock method just go silent if the server the client happens to be connected to
+    // becomes partitioned from the actual raft-leader server in the etcd servers cluster:
+    // in that scenario and without required leader, an attempt to lock could block forever
+    // not because some other client is already holding a lock, but because the server the client
+    // is connected to is partitioned and can't tell.
+    // With require leader, in that case the call will fail and the client has the ability to
+    // (a) know (b) retry on a different server.
+    // The retry on a different server should happen automatically if the connection manager is using
+    // a round robin strategy.
+    private VertxLockGrpc.LockVertxStub stubWithLeader() {
+        return Util.applyRequireLeader(true, stub);
+    }
+
+    LockImpl(ClientConnectionManager connectionManager) {
+        super(connectionManager);
+
+        this.stub = connectionManager.newStub(VertxLockGrpc::newVertxStub);
+        this.namespace = connectionManager.getNamespace();
+    }
+
+    @Override
+    public CompletableFuture<LockResponse> lock(ByteSequence name, long leaseId) {
+        requireNonNull(name);
+
+        LockRequest request = LockRequest.newBuilder()
+            .setName(Util.prefixNamespace(name, namespace))
+            .setLease(leaseId)
+            .build();
+
+        return execute(
+            () -> stubWithLeader().lock(request),
+            response -> new LockResponse(response, namespace),
+            Errors::isRetryableForSafeRedoOp);
+    }
+
+    @Override
+    public CompletableFuture<UnlockResponse> unlock(ByteSequence lockKey) {
+        requireNonNull(lockKey);
+
+        UnlockRequest request = UnlockRequest.newBuilder()
+            .setKey(Util.prefixNamespace(lockKey, namespace))
+            .build();
+
+        return execute(
+            () -> stubWithLeader().unlock(request),
+            UnlockResponse::new,
+            Errors::isRetryableForSafeRedoOp);
+    }
+}