如何在响应式上下文取消的情况下入睡？

Question

在 Go 中，我想要time.Sleep一段时间（例如在重试之间等待），但如果上下文被取消（不仅是从截止日期，而且是手动），我想快速返回。

这样做的正确或最佳方法是什么？谢谢！

Answer 1

您可以使用select它来实现：package mainimport (&nbsp; &nbsp; "fmt"&nbsp; &nbsp; "time"&nbsp; &nbsp; "context")func main() {&nbsp; &nbsp; fmt.Println("Hello, playground")&nbsp; &nbsp; ctx, cancel := context.WithCancel(context.Background())&nbsp; &nbsp; defer cancel()&nbsp; &nbsp; go func(){&nbsp; &nbsp; &nbsp; &nbsp; t := time.Now()&nbsp; &nbsp; &nbsp; &nbsp; select{&nbsp; &nbsp; &nbsp; &nbsp; case <-ctx.Done(): //context cancelled&nbsp; &nbsp; &nbsp; &nbsp; case <-time.After(2 * time.Second): //timeout&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; fmt.Printf("here after: %v\n", time.Since(t))&nbsp; &nbsp; }()&nbsp; &nbsp; cancel() //cancel manually, comment out to see timeout kick in&nbsp; &nbsp; time.Sleep(3 * time.Second)&nbsp; &nbsp; fmt.Println("done")}这是Go-playground 链接

Answer 2

select您可以像其他人提到的那样使用；但是，其他答案有一个错误，因为timer.After()如果不清理就会泄漏内存。func SleepWithContext(ctx context.Context, d time.Duration) {&nbsp; &nbsp; timer := time.NewTimer(d)&nbsp; &nbsp; select {&nbsp; &nbsp; case <-ctx.Done():&nbsp; &nbsp; &nbsp; &nbsp; if !timer.Stop() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <-timer.C&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; case <-timer.C:&nbsp; &nbsp; }}

Answer 3

这是一个sleepContext您可以用来代替的函数time.Sleep：func sleepContext(ctx context.Context, delay time.Duration) {&nbsp; &nbsp; select {&nbsp; &nbsp; case <-ctx.Done():&nbsp; &nbsp; case <-time.After(delay):&nbsp; &nbsp; }}以及一些示例用法（Go Playground 上的完整可运行代码）：func main() {&nbsp; &nbsp; ctx := context.Background()&nbsp; &nbsp; fmt.Println(time.Now())&nbsp; &nbsp; sleepContext(ctx, 1*time.Second)&nbsp; &nbsp; fmt.Println(time.Now())&nbsp; &nbsp; ctxTimeout, cancel := context.WithTimeout(ctx, 500*time.Millisecond)&nbsp; &nbsp; sleepContext(ctxTimeout, 1*time.Second)&nbsp; &nbsp; cancel()&nbsp; &nbsp; fmt.Println(time.Now())}