hchan

type hchan struct {
 qcount   uint           // 通道中的总数据 total data in the queue
 dataqsiz uint           // 循环队列的大小 size of the circular queue
 buf      unsafe.Pointer // 指向dataqsiz元素数组  points to an array of dataqsiz elements
 elemsize uint16 // 大小
 closed   uint32 // 是否关闭
 elemtype *_type // 节点类型 element type
 sendx    uint   // 发送数据 send index
 recvx    uint   // 接受 receive index
 recvq    waitq  // 等待接受 list of recv waiters
 sendq    waitq  //  等待发送 list of send waiters

 // 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 // 锁
}

type waitq struct {
 first *sudog // 第一个
 last  *sudog // 最后一个
}

type sudog struct {
 // The following fields are protected by the hchan.lock of the
 // channel this sudog is blocking on. shrinkstack depends on
 // this for sudogs involved in channel ops.

 g *g

 next *sudog // 下一个
 prev *sudog // 上一个
 elem unsafe.Pointer // 数据元素(可能指向堆栈)  data element (may point to stack)

 // The following fields are never accessed concurrently.
 // For channels, waitlink is only accessed by g.
 // For semaphores, all fields (including the ones above)
 // are only accessed when holding a semaRoot lock.

 acquiretime int64 // 
 releasetime int64 // 
 ticket      uint32 //

 // isSelect indicates g is participating in a select, so
 // g.selectDone must be CAS'd to win the wake-up race.
 isSelect bool

 // success indicates whether communication over channel c
 // succeeded. It is true if the goroutine was awoken because a
 // value was delivered over channel c, and false if awoken
 // because c was closed.
 success bool //是否成功

 parent   *sudog // semaRoot二叉树  semaRoot binary tree
 waitlink *sudog // g.等待列表或semaRoot  g.waiting list or semaRoot
 waittail *sudog // 等待 semaRoot
 c        *hchan // 通道 channel
}