golang context与sync.WaitGroup

最新推荐文章于 2022-11-28 19:12:40 发布

gdut17

最新推荐文章于 2022-11-28 19:12:40 发布

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分类专栏： golang

本文链接：https://blog.youkuaiyun.com/beyond706/article/details/112861692

本文介绍了Golang中用于协程同步的sync.WaitGroup和context包。sync.WaitGroup允许主协程等待所有子goroutine完成其任务，而context包则提供了协程启动者可以主动取消子协程的能力，包括withCancel、withDeadline、withTimeout和withValue四种用法的示例。

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sync.WaitGroup 等待组，协程同步

// A WaitGroup must not be copied after first use.
type WaitGroup struct {
   
   
	noCopy noCopy

	// 64-bit value: high 32 bits are counter, low 32 bits are waiter count.
	// 64-bit atomic operations require 64-bit alignment, but 32-bit
	// compilers do not ensure it. So we allocate 12 bytes and then use
	// the aligned 8 bytes in them as state, and the other 4 as storage
	// for the sema.
	state1 [3]uint32
}
func (wg *WaitGroup) Add(delta int)
func (wg *WaitGroup) Done() {
   
   
	wg.Add(-1)
}
func (wg *WaitGroup) Wait()

主协程等待(wg.Wait())所有子goroutine结束(wg.Done()),主动权在子goroutine，什么时候子goroutine调用wg.Done()了，主协程才能结束wg.Wait()。

context
标志库的context包从golang.org/x/net/context而来的
提供四个接口

func WithCancel(parent Context) (ctx Context, cancel CancelFunc)
func WithDeadline(parent Context, d time.Time) (Context, CancelFunc)
func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc)
func WithValue(parent Context, key, val in