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Diffstat (limited to 'src/sync/atomic/example_test.go')
-rw-r--r-- | src/sync/atomic/example_test.go | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/src/sync/atomic/example_test.go b/src/sync/atomic/example_test.go new file mode 100644 index 0000000..09ae0aa --- /dev/null +++ b/src/sync/atomic/example_test.go @@ -0,0 +1,76 @@ +// Copyright 2018 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package atomic_test + +import ( + "sync" + "sync/atomic" + "time" +) + +func loadConfig() map[string]string { + return make(map[string]string) +} + +func requests() chan int { + return make(chan int) +} + +// The following example shows how to use Value for periodic program config updates +// and propagation of the changes to worker goroutines. +func ExampleValue_config() { + var config atomic.Value // holds current server configuration + // Create initial config value and store into config. + config.Store(loadConfig()) + go func() { + // Reload config every 10 seconds + // and update config value with the new version. + for { + time.Sleep(10 * time.Second) + config.Store(loadConfig()) + } + }() + // Create worker goroutines that handle incoming requests + // using the latest config value. + for i := 0; i < 10; i++ { + go func() { + for r := range requests() { + c := config.Load() + // Handle request r using config c. + _, _ = r, c + } + }() + } +} + +// The following example shows how to maintain a scalable frequently read, +// but infrequently updated data structure using copy-on-write idiom. +func ExampleValue_readMostly() { + type Map map[string]string + var m atomic.Value + m.Store(make(Map)) + var mu sync.Mutex // used only by writers + // read function can be used to read the data without further synchronization + read := func(key string) (val string) { + m1 := m.Load().(Map) + return m1[key] + } + // insert function can be used to update the data without further synchronization + insert := func(key, val string) { + mu.Lock() // synchronize with other potential writers + defer mu.Unlock() + m1 := m.Load().(Map) // load current value of the data structure + m2 := make(Map) // create a new value + for k, v := range m1 { + m2[k] = v // copy all data from the current object to the new one + } + m2[key] = val // do the update that we need + m.Store(m2) // atomically replace the current object with the new one + // At this point all new readers start working with the new version. + // The old version will be garbage collected once the existing readers + // (if any) are done with it. + } + _, _ = read, insert +} |