先看下源碼，源碼位于src/runtime/chan.go中

type hchan struct {
    qcount   uint           // total data in the queue
    dataqsiz uint           // size of the circular queue
    buf      unsafe.Pointer // points to an array of dataqsiz elements
    elemsize uint16
    closed   uint32
    elemtype *_type // element type
    sendx    uint   // send index
    recvx    uint   // receive index
    recvq    waitq  // list of recv waiters
    sendq    waitq  // 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
}
type waitq struct {
    first *sudog
    last  *sudog
}
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

    // isSelect indicates g is participating in a select, so
    // g.selectDone must be CAS'd to win the wake-up race.
    isSelect bool
    next     *sudog
    prev     *sudog
    elem     unsafe.Pointer // 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
    parent      *sudog // semaRoot binary tree
    waitlink    *sudog // g.waiting list or semaRoot
    waittail    *sudog // semaRoot
    c           *hchan // channel
}

qcount uint // 當(dāng)前隊(duì)列中剩余元素個數(shù)
dataqsiz uint // 環(huán)形隊(duì)列長度涡驮，即緩沖區(qū)的大小评架，即make（chan T，N），N.
buf unsafe.Pointer // 環(huán)形隊(duì)列指針
elemsize uint16 // 每個元素的大小
closed uint32 // 表示當(dāng)前通道是否處于關(guān)閉狀態(tài)夭坪。創(chuàng)建通道后，該字段設(shè)置為0过椎，即通道打開; 通過調(diào)用close將其設(shè)置為1室梅，通道關(guān)閉。
elemtype *_type // 元素類型疚宇，用于數(shù)據(jù)傳遞過程中的賦值亡鼠；
sendx uint和recvx uint是環(huán)形緩沖區(qū)的狀態(tài)字段，它指示緩沖區(qū)的當(dāng)前索引 - 支持?jǐn)?shù)組敷待，它可以從中發(fā)送數(shù)據(jù)和接收數(shù)據(jù)间涵。
recvq waitq // 等待讀消息的goroutine隊(duì)列
sendq waitq // 等待寫消息的goroutine隊(duì)列
lock mutex // 互斥鎖，為每個讀寫操作鎖定通道榜揖，因?yàn)榘l(fā)送和接收必須是互斥操作勾哩。
這里sudog代表goroutine。
如創(chuàng)建帶緩沖的通道：ch := make(chan int, 3)举哟，思劳，底層的數(shù)據(jù)模型如下圖：

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向channel中寫入數(shù)據(jù)
ch <- 3。底層hchan數(shù)據(jù)流程如圖

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