mirror of https://github.com/tikv/client-go.git
134 lines
3.4 KiB
Go
134 lines
3.4 KiB
Go
// Copyright 2021 TiKV Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package main
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import (
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"context"
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"flag"
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"fmt"
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"os"
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"github.com/tikv/client-go/v2/kv"
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"github.com/tikv/client-go/v2/txnkv"
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)
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// KV represents a Key-Value pair.
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type KV struct {
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K, V []byte
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}
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func (kv KV) String() string {
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return fmt.Sprintf("%s => %s (%v)", kv.K, kv.V, kv.V)
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}
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var (
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client *txnkv.Client
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pdAddr = flag.String("pd", "127.0.0.1:2379", "pd address")
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)
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// Init initializes information.
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func initStore() {
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var err error
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client, err = txnkv.NewClient([]string{*pdAddr})
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if err != nil {
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panic(err)
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}
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}
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func begin_pessimistic_txn() (txn *txnkv.KVTxn) {
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txn, err := client.Begin()
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if err != nil {
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panic(err)
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}
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txn.SetPessimistic(true)
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return txn
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}
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func exampleForPessimisticTXN() {
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// k1 is the primary lock of txn1
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k1 := []byte("k1")
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// k2 is a secondary lock of txn1 and a key txn2 wants to lock
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k2 := []byte("k2")
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txn1 := begin_pessimistic_txn()
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//txn1: lock the primary key
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err := txn1.LockKeysWithWaitTime(context.Background(), kv.LockAlwaysWait, k1)
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if err != nil {
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panic(err)
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}
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fmt.Println("txn1: lock k1 success.")
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// txn1:lock the secondary key
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err = txn1.LockKeysWithWaitTime(context.Background(), kv.LockAlwaysWait, k2)
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if err != nil {
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panic(err)
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}
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fmt.Println("txn1: lock k2 success.")
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// begin txn2
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txn2 := begin_pessimistic_txn()
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// txn2: lock k2 no wait
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err = txn2.LockKeysWithWaitTime(context.Background(), kv.LockNoWait, k2)
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// cannot acquire lock immediately thus error:ErrLockAcquireFailAndNoWaitSet
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fmt.Println("txn2: acquire lock for k2 (while txn1 has this lock) should be failed with error: ", err)
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// txn2:lock k2 for wait limited time (200ms),less than k2's lock TTL by txn1,should failed with timeout.
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err = txn2.LockKeysWithWaitTime(context.Background(), 200, k2)
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// txn2: cannot acquire lock k2 in time should failed with timeout.
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fmt.Println("txn2: acquire lock for k1(while txn1 has this lock) should be failed with error: ", err)
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// commit txn1 should be success.
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txn1.Set(k1, k1)
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err = txn1.Commit(context.Background())
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if err != nil {
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panic(err)
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} else {
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fmt.Println("tnx1: commit txn1 success!")
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}
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// txn2: lock k2 in txn2 with new forUpdateTS should success.
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err = txn2.LockKeysWithWaitTime(context.Background(), kv.LockNoWait, k2)
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if err != nil {
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// cannot acquire lock , should success.
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fmt.Println("txn2: acquire lock for k2 should be success while meet err:", err)
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} else {
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fmt.Println("txn2: acquire lock for k2 success!")
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}
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// txn2: do some write.
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txn2.Set(k1, k1)
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txn2.Set(k2, k2)
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txn2.Delete(k1)
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txn2.Delete(k2)
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// commit txn2 should success.
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err = txn2.Commit(context.Background())
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if err != nil {
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fmt.Println("txn2: commit should success while meet err ", err)
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} else {
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fmt.Println("txn2: commit success.")
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}
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}
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func main() {
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pdAddr := os.Getenv("PD_ADDR")
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if pdAddr != "" {
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os.Args = append(os.Args, "-pd", pdAddr)
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}
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flag.Parse()
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initStore()
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exampleForPessimisticTXN()
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}
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