go - 在一个goroutine中将项目添加到 channel ，在另一个goroutine中进行处理

Question

真正的围棋世界，尝试边干边学。我想看看如何使用go例程在一个go例程中将项目添加到“队列”中，而另一个go例程监听队列并在它们进入时对其进行处理。在这种情况下，我有一个函数，可以在int []中添加定义数量的项，而其他尝试在添加时打印它们。.我假设将需要发送一个标志来发出信号，表明一个go例程已停止添加队列中的项目。我为菜鸟问题表示歉意，但正在努力理解新的术语和语法。

package main

import "fmt"


func printFromSlice(c chan []int){
    i := <-c
    // wait for item to be added to channel
    fmt.Print(i)
}

func addToSlice (c chan []int, i int)  {
    for n := 0; n < i; n++{
        c <- n //I know this isnt right
    }

    // How do we signal this is complete??
}

func main(){
    c := make(chan []int)
    //add things to []i int
    go addToSlice(c, 25)
    //do something from []int
    go printFromSlice(c)



}

  **UPDATE**

修改为使用以下代码，但是现在它将仅以〜printFromSlice`函数的形式在关闭之前执行单个打印...

package main

func printFromSlice(c chan int){
    i := <-c
    // wait for item to be added to channel
    println("read")
    println(i)
}

func addToSlice (c chan int)  {
    for n := 0; n < 100; n++{
        println("add")
        println(n)
        c <- n
    }

    close(c)

}

func main(){
    println("starting...")
    c := make(chan int)

    //add things to []i int
    go addToSlice(c)
    //do something from []int
    go printFromSlice(c)

    <-c


}

Answer 1

您需要添加sync.WaitGroup来阻塞主线程，直到两个goroutine完成。您可以引用此Go by Example。

package main

import "sync"

func printFromSlice(c chan int, wg *sync.WaitGroup) {
    defer wg.Done() // Decrement the waitgroup counter by 1 after `printFromSlice` returns

    // wait for item to be added to channel
    // i := <-c // this only waits / blocks 1 time

    // For each message arriving at c, read and print
    for i := range c { // this would read all messages until channel is closed
        println("read")
        println(i)
    }
}

func addToSlice(c chan int, wg *sync.WaitGroup) {
    defer wg.Done() // Decrement the waitgroup counter by 1 after `addToSlice` returns

    for n := 0; n < 100; n++ {
        println("add")
        println(n)
        c <- n
    }

    close(c)

}

func main() {
    var wg sync.WaitGroup

    println("starting...")
    c := make(chan int)

    wg.Add(2) // Adds 2 to the waitgroup counter

    //add things to []i int
    go addToSlice(c, &wg) // Pass the wait group as reference so they can call wg.Done()
    //do something from []int
    go printFromSlice(c, &wg) // Pass the wait group as reference so they can call wg.Done()

    // <-c // No need for this to block the code

    wg.Wait() // Waits / blocks until waitgroup counter is 0
}