what is golang channel

The channel in the Go language is the key mechanism to achieve lock-free communication between goroutines. It makes writing multi-threaded concurrent programs simple, flexible and accessible.

Channel is a core type in Go. You can think of it as a pipe, through which the concurrent core unit can send or receive data for communication. (Recommended learning: go)

Its operator is the arrow <-.

ch <- v    // 发送值v到Channel ch中
v := <-ch  // 从Channel ch中接收数据，并将数据赋值给v

channel structure

type hchan struct {
   qcount   uint           // total data in the queue 队列中存在的个数
   dataqsiz uint           // size of the circular queue buffer大小 实现看起来是个循环数组
   buf      unsafe.Pointer // points to an array of dataqsiz elements 数组指针
   elemsize uint16       //channel类型的大小
   closed   uint32      //channel是否关闭
   elemtype *_type // element type //channel 类型
   sendx    uint   // send index  //发送index
   recvx    uint   // receive index //接收index
   recvq    waitq  // list of recv waiters //接收链表 即读channel的goroutine
   sendq    waitq  // list of send waiters //发送链表 即写channel的goroutine

   // lock protects all fields in hchan, as well as several
   // fields in sudogs blocked on this channel.
   //
   // Do not change another G's status while holding this lock
   // (in particular, do not ready a G), as this can deadlock
   // with stack shrinking.
   lock mutex
}

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