go - 当 channel 接收到新值时无限循环被终止

Question

我有 2 个模块(模块 1 和模块 2)，我在模块 1 中生成一些随机数，并通过 main 中定义的 channel 将它们传递给模块 2。当值落在模块 2 中时，我希望它在循环中打印，直到新值再次从模块 1 到达。这是代码。
main.go文件内容

package main

import (
    "time"
    "example/module1"
    "example/module2"
)

func main() {
    ints := make(chan []int, 1)
    for {
        select {
        case <- time.After(5 * time.Second):
            go module1.GenerateRandint(ints)
        case  <- module2.Done:
            go module2.Start(ints)
        }
    }
}

module1的内容如下。

package module1

import (
    "math/rand"
    "time"
)

func GenerateRandint(a chan []int){
    var rint []int
    for  i:=0;i<1;i++ {
        rand.Seed(time.Now().UnixNano())
        rint = append(rint,  rand.Int())
    }
    a <- rint
}

module2是:

package module2

import (
    "fmt"
    "math/rand"
    "sync"
    "time"
)

var Done = make(chan struct{})
var quit = make(chan struct{})

type localData struct {
    nums []int
    Lock sync.RWMutex
}

var store localData

func init() {
    go func() {
        Done <- struct{}{}
        quit <- struct{}{}
    }()
    go printer(0, quit)
}

func printer(id int, quit chan struct{}) {

    for {
        select {
        case <-quit:
            return
        default:
            store.Lock.RLock()
            fmt.Println("ID:", id, "====", store.nums)
            time.Sleep(500 * time.Millisecond)
            store.Lock.RUnlock()

        }
    }
}

func Start(a chan []int) {
    rand.Seed(time.Now().UnixNano())
    d := <-a
    fmt.Println("RECEIVED DATA", d)
    store.Lock.Lock()
    go func() {
        quit <- struct{}{}
    }()
    store.nums = d
    store.Lock.Unlock()
    go printer(rand.Int(), quit)
    Done <- struct{}{}

}

在最终输出中，我没有看到 printer功能连续打印 slice 。它打印一次。我在下面粘贴一个示例输出。

ID: 0 ==== []
RECEIVED DATA [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
RECEIVED DATA [7203870927705193095]
RECEIVED DATA [1478549829208931483]
ID: 2311909806311895805 ==== [1478549829208931483]
RECEIVED DATA [3000658591728341557]

理想的输出应该是:

ID: 0 ==== []
RECEIVED DATA [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
ID: 2057228961822266542 ==== [5183630848712612481]
RECEIVED DATA [7203870927705193095]
ID: 3052382001843759201 ==== [7203870927705193095]
ID: 3052382001843759201 ==== [7203870927705193095]
ID: 3052382001843759201 ==== [7203870927705193095]
ID: 3052382001843759201 ==== [7203870927705193095]
ID: 3052382001843759201 ==== [7203870927705193095]
RECEIVED DATA [1478549829208931483]
ID: 3850200927174591249 ==== [1478549829208931483]
ID: 3850200927174591249 ==== [1478549829208931483]
ID: 3850200927174591249 ==== [1478549829208931483]
ID: 3850200927174591249 ==== [1478549829208931483]
ID: 3850200927174591249 ==== [1478549829208931483]
RECEIVED DATA [3000658591728341557]

Answer 1

我将假设您正在询问有关调用 go printer(0, quit) 的问题。在 init()功能。它只打印整个列表一次的原因是:

在 init() 函数中，您尝试将数据发送到 Done和 quit channel 。现在，它们显然会阻塞，直到接收器准备好。加载模块后，接收器尚未准备好，因此您转到 default打印机方法中的情况。因此，它打印该语句一次并休眠 500 毫秒。在此期间，main()启动并为 Done 创建一个接收器 channel 。这会解除对该 channel 的写入阻塞，随后会写入 quit。 channel 也是如此。现在，自从 quit也有数据，printer中的select语句方法简单地返回，不再打印。