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https://qcrao91.gitbook.io/go/channel/channel-fa-song-he-jie-shou-yuan-su-de-ben-zhi-shi-shi-mo

作者:互联网

Channel 发送和接收元素的本质是什么?

All transfer of value on the go channels happens with the copy of value.

就是说 channel 的发送和接收操作本质上都是 “值的拷贝”,无论是从 sender goroutine 的栈到 chan buf,还是从 chan buf 到 receiver goroutine,或者是直接从 sender goroutine 到 receiver goroutine。

举一个例子:

  type user struct { name string age int8 }   var u = user{name: "Ankur", age: 25} var g = &u   func modifyUser(pu *user) { fmt.Println("modifyUser Received Vaule", pu) pu.name = "Anand" }   func printUser(u <-chan *user) { time.Sleep(2 * time.Second) fmt.Println("printUser goRoutine called", <-u) }   func main() { c := make(chan *user, 5) c <- g fmt.Println(g) // modify g g = &user{name: "Ankur Anand", age: 100} go printUser(c) go modifyUser(g) time.Sleep(5 * time.Second) fmt.Println(g) }

运行结果:

  &{Ankur 25} modifyUser Received Vaule &{Ankur Anand 100} printUser goRoutine called &{Ankur 25} &{Anand 100}

这里就是一个很好的 share memory by communicating 的例子。

output

一开始构造一个结构体 u,地址是 0x56420,图中地址上方就是它的内容。接着把 &u 赋值给指针 g,g 的地址是 0x565bb0,它的内容就是一个地址,指向 u。

main 程序里,先把 g 发送到 c,根据 copy value 的本质,进入到 chan buf 里的就是 0x56420,它是指针 g 的值(不是它指向的内容),所以打印从 channel 接收到的元素时,它就是 &{Ankur 25}。因此,这里并不是将指针 g “发送” 到了 channel 里,只是拷贝它的值而已。

再强调一次:

Remember all transfer of value on the go channels happens with the copy of value.

 

 

参考:

https://qcrao91.gitbook.io/go/channel/channel-fa-song-he-jie-shou-yuan-su-de-ben-zhi-shi-shi-mo

https://www.cnblogs.com/bonelee/p/6056373.html

标签:25,jie,Ankur,value,go,shi,channel
来源: https://www.cnblogs.com/lovezbs/p/13906432.html