go.etcd.io/etcd@v3.3.27+incompatible/clientv3/concurrency/example_mutex_test.go (about) 1 // Copyright 2017 The etcd Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package concurrency_test 16 17 import ( 18 "context" 19 "fmt" 20 "log" 21 22 "github.com/coreos/etcd/clientv3" 23 "github.com/coreos/etcd/clientv3/concurrency" 24 ) 25 26 func ExampleMutex_Lock() { 27 cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints}) 28 if err != nil { 29 log.Fatal(err) 30 } 31 defer cli.Close() 32 33 // create two separate sessions for lock competition 34 s1, err := concurrency.NewSession(cli) 35 if err != nil { 36 log.Fatal(err) 37 } 38 defer s1.Close() 39 m1 := concurrency.NewMutex(s1, "/my-lock/") 40 41 s2, err := concurrency.NewSession(cli) 42 if err != nil { 43 log.Fatal(err) 44 } 45 defer s2.Close() 46 m2 := concurrency.NewMutex(s2, "/my-lock/") 47 48 // acquire lock for s1 49 if err := m1.Lock(context.TODO()); err != nil { 50 log.Fatal(err) 51 } 52 fmt.Println("acquired lock for s1") 53 54 m2Locked := make(chan struct{}) 55 go func() { 56 defer close(m2Locked) 57 // wait until s1 is locks /my-lock/ 58 if err := m2.Lock(context.TODO()); err != nil { 59 log.Fatal(err) 60 } 61 }() 62 63 if err := m1.Unlock(context.TODO()); err != nil { 64 log.Fatal(err) 65 } 66 fmt.Println("released lock for s1") 67 68 <-m2Locked 69 fmt.Println("acquired lock for s2") 70 71 // Output: 72 // acquired lock for s1 73 // released lock for s1 74 // acquired lock for s2 75 }