55 lines
1.1 KiB
Go
55 lines
1.1 KiB
Go
// Copyright 2012 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 sync_test
|
|
|
|
import (
|
|
"fmt"
|
|
"net/http"
|
|
"sync"
|
|
)
|
|
|
|
// This example fetches several URLs concurrently,
|
|
// using a WaitGroup to block until all the fetches are complete.
|
|
func ExampleWaitGroup() {
|
|
var wg sync.WaitGroup
|
|
var urls = []string{
|
|
"http://www.golang.org/",
|
|
"http://www.google.com/",
|
|
"http://www.somestupidname.com/",
|
|
}
|
|
for _, url := range urls {
|
|
// Increment the WaitGroup counter.
|
|
wg.Add(1)
|
|
// Launch a goroutine to fetch the URL.
|
|
go func(url string) {
|
|
// Decrement the counter when the goroutine completes.
|
|
defer wg.Done()
|
|
// Fetch the URL.
|
|
http.Get(url)
|
|
}(url)
|
|
}
|
|
// Wait for all HTTP fetches to complete.
|
|
wg.Wait()
|
|
}
|
|
|
|
func ExampleOnce() {
|
|
var once sync.Once
|
|
onceBody := func() {
|
|
fmt.Println("Only once")
|
|
}
|
|
done := make(chan bool)
|
|
for i := 0; i < 10; i++ {
|
|
go func() {
|
|
once.Do(onceBody)
|
|
done <- true
|
|
}()
|
|
}
|
|
for i := 0; i < 10; i++ {
|
|
<-done
|
|
}
|
|
// Output:
|
|
// Only once
|
|
}
|