我想用來處理我發(fā)出外部請求的用例，如果請求的響應太長，它將返回錯誤。context.WithTimeout()我已經(jīng)實現(xiàn)了偽代碼，如下面附帶的 playground 鏈接：2 解決方案：主->未預料到預計main_1 ->package mainimport ( "context" "fmt" "time")// I just dummy sleep in this func to produce use case this func// need 10s to process and handle logic. // And this assume will be out of timeOut expect (5s)func makeHTTPRequest(ctx context.Context) (string, error) { time.Sleep(time.Duration(10) * time.Second) return "abc", nil}// In main Func, I will set timeout is 5 second. func main() { var strCh = make(chan string, 1) ctx, cancel := context.WithTimeout(context.Background(), time.Duration(5)*time.Second) defer cancel() fmt.Print("Begin make request\n") abc, err := makeHTTPRequest(ctx) if err != nil { fmt.Print("Return error\n") return } select { case <-ctx.Done(): fmt.Printf("Return ctx error: %s\n", ctx.Err()) return case strCh <- abc: fmt.Print("Return response\n") return }}func main_1() { var strCh = make(chan string, 1) var errCh = make(chan error, 1) ctx, cancel := context.WithTimeout(context.Background(), time.Duration(5)*time.Second) defer cancel() go func() { fmt.Print("Begin make request\n") abc, err := makeHTTPRequest(ctx) if err != nil { fmt.Print("Return error\n") errCh <- err return } strCh <- abc }() select { case err := <-errCh: fmt.Printf("Return error: %s\n", err.Error()) return case <-ctx.Done(): fmt.Printf("Return ctx error: %s\n", ctx.Err()) return case str := <-strCh: fmt.Printf("Return response: %s\n", str) return }}但是，如果使用該函數(shù)，則它無法按預期工作。但是，如果使用goroutine進行第二種實現(xiàn)，那么也許新的實現(xiàn)可以按預期工作。main()main_1()context.WithTimeout()你能幫我回答這個問題嗎？https://play.golang.org/p/kZdlm_Tvljy
2 回答
HUX布斯
TA貢獻1876條經(jīng)驗 獲得超6個贊
最好在函數(shù)中處理上下文，這樣就可以將其用作 中的同步函數(shù)。makeHTTPRequest()main()
https://play.golang.org/p/Bhl4qprIBgH
func makeHTTPRequest(ctx context.Context) (string, error) {
ch := make(chan string)
go func() {
time.Sleep(10 * time.Second)
select {
case ch <- "abc":
default:
// When context deadline exceeded, there is no receiver
// This case will prevent goroutine blocking forever
return
}
}()
select {
case <-ctx.Done():
return "", ctx.Err()
case result := <-ch:
return result, nil
}
}
func main() {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
fmt.Printf("[%v] Begin make request \n", time.Now())
abc, err := makeHTTPRequest(ctx)
if err != nil {
fmt.Printf("[%v] Return error: %v \n", time.Now(), err)
return
}
fmt.Printf("[%v] %s", time.Now(), abc)
}
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