127 lines
2.9 KiB
Go
127 lines
2.9 KiB
Go
// Copyright 2017 The etcd 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 concurrency_test
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import (
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"context"
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"fmt"
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"log"
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"go.etcd.io/etcd/clientv3"
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"go.etcd.io/etcd/clientv3/concurrency"
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)
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func ExampleMutex_TryLock() {
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cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
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if err != nil {
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log.Fatal(err)
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}
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defer cli.Close()
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// create two separate sessions for lock competition
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s1, err := concurrency.NewSession(cli)
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if err != nil {
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log.Fatal(err)
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}
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defer s1.Close()
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m1 := concurrency.NewMutex(s1, "/my-lock")
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s2, err := concurrency.NewSession(cli)
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if err != nil {
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log.Fatal(err)
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}
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defer s2.Close()
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m2 := concurrency.NewMutex(s2, "/my-lock")
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// acquire lock for s1
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if err = m1.Lock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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fmt.Println("acquired lock for s1")
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if err = m2.TryLock(context.TODO()); err == nil {
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log.Fatal("should not acquire lock")
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}
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if err == concurrency.ErrLocked {
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fmt.Println("cannot acquire lock for s2, as already locked in another session")
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}
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if err = m1.Unlock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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fmt.Println("released lock for s1")
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if err = m2.TryLock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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fmt.Println("acquired lock for s2")
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// Output:
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// acquired lock for s1
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// cannot acquire lock for s2, as already locked in another session
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// released lock for s1
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// acquired lock for s2
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}
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func ExampleMutex_Lock() {
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cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
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if err != nil {
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log.Fatal(err)
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}
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defer cli.Close()
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// create two separate sessions for lock competition
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s1, err := concurrency.NewSession(cli)
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if err != nil {
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log.Fatal(err)
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}
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defer s1.Close()
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m1 := concurrency.NewMutex(s1, "/my-lock/")
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s2, err := concurrency.NewSession(cli)
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if err != nil {
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log.Fatal(err)
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}
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defer s2.Close()
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m2 := concurrency.NewMutex(s2, "/my-lock/")
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// acquire lock for s1
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if err := m1.Lock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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fmt.Println("acquired lock for s1")
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m2Locked := make(chan struct{})
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go func() {
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defer close(m2Locked)
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// wait until s1 is locks /my-lock/
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if err := m2.Lock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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}()
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if err := m1.Unlock(context.TODO()); err != nil {
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log.Fatal(err)
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}
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fmt.Println("released lock for s1")
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<-m2Locked
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fmt.Println("acquired lock for s2")
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// Output:
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// acquired lock for s1
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// released lock for s1
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// acquired lock for s2
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}
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