// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sync_test
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import (
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"fmt"
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"sync"
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)
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type httpPkg struct{}
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func (httpPkg) Get(url string) {}
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var http httpPkg
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// This example fetches several URLs concurrently,
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// using a WaitGroup to block until all the fetches are complete.
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func ExampleWaitGroup() {
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var wg sync.WaitGroup
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var urls = []string{
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"http://www.golang.org/",
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"http://www.google.com/",
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"http://www.somestupidname.com/",
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}
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for _, url := range urls {
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// Increment the WaitGroup counter.
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wg.Add(1)
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// Launch a goroutine to fetch the URL.
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go func(url string) {
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// Decrement the counter when the goroutine completes.
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defer wg.Done()
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// Fetch the URL.
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http.Get(url)
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}(url)
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}
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// Wait for all HTTP fetches to complete.
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wg.Wait()
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}
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func ExampleOnce() {
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var once sync.Once
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onceBody := func() {
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fmt.Println("Only once")
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}
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done := make(chan bool)
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for i := 0; i < 10; i++ {
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go func() {
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once.Do(onceBody)
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done <- true
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}()
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}
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for i := 0; i < 10; i++ {
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<-done
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}
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// Output:
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// Only once
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}
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