go中的非阻塞通道

Question

我有一些这样的代码：go func(ch chan bool) chan bool {    // some processing    ch <- true    return ch}(ch)for i := 0; i < TotalQuestions; i++ {    // check if channel ch has some value    // If it has then execute below statements, else break out of the loop    fmt.Println(questions[i])    answer, _ := InputReader.ReadString('\n')    // some processing}fmt.Println("Your Total score is " + strconv.Itoa(TotalScore) + " out of " + strconv.Itoa(TotalQuestions))现在我要做的是检查通道 ch 是否有值（在 for 循环中）。如果它有一个值，那么我想跳出 for 循环来打印最后一条语句。否则，我想继续我的循环。我试图插入选择块，但没有用（通道被阻塞，代码没有打印问题）。怎么做？

Answer 1

package main

    

import (

    "fmt"

    "log"

    "math/rand"

    "time"

)

func main() {

    // user score, no.of questions asked so far

    var score, num int

    var correct bool // temporary variable to decide if the answer is right

    // questions

    var questions = make([]string, 13)

    t1 := time.Tick(time.Second * 7) // timer loop:

    for {

        select {

        case <-t1:

            log.Println("ran out of time")

            break loop

        default:

            // have any questions further questions to ask

            if num < len(questions) {

                // simulate typing

                time.Sleep(time.Millisecond * 777)

                // correct or wrong answer

                correct = (rand.Intn(777)%2 == 0)

                if correct {

                    fmt.Println("you did it")

                    score++ //increase score

                } else {

                    fmt.Println("try again")

                }

            } else {

                // no questions, state and break

                log.Println("all questions were finished")

                break loop //break loop, all questions were finished

            }

            num++

        }

    }

    //print final score

    fmt.Println("your score is:", score)

}

Answer 2

以非阻塞方式从通道读取的功能方式：

func CollectChanOne[T any](ch <-chan T) (T, bool) {

    select {

    case val, stillOpen := <-ch:

        return val, stillOpen

    default:

        var zeroT T

        return zeroT, false

    }

}

示例： https: //go.dev/play/p/Njwyt32B4oT

注意此示例还有另一种方法 CollectChanRemaining() ，它读取通道中的所有缓冲元素。