43 lines
895 B
Go
43 lines
895 B
Go
package main
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import (
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"context"
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"fmt"
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"time"
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)
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func subTask(ctx context.Context, name string, d time.Duration) {
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select {
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case <-ctx.Done():
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fmt.Println(name, "提前被取消:", ctx.Err())
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case <-time.After(d):
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fmt.Println(name, "完成，用时", d)
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}
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}
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func mainTask(ctx context.Context) {
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// 从上游 ctx 派生两个子 context
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ctx1, cancel1 := context.WithCancel(ctx)
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defer cancel1()
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ctx2, cancel2 := context.WithTimeout(ctx, 2*time.Second)
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defer cancel2()
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go subTask(ctx1, "subTask-1", 5*time.Second)
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go subTask(ctx2, "subTask-2", 5*time.Second)
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time.Sleep(1 * time.Second)
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fmt.Println("mainTask: 主动取消 subTask-1 的 ctx1")
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cancel1()
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// 等待一会儿，看 subTask-2 是否因超时被取消
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time.Sleep(3 * time.Second)
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}
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func main() {
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root := context.Background()
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fmt.Println("开始 mainTask...")
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mainTask(root)
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fmt.Println("main 结束")
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}
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