BTCD源码阅读笔记-connmgr

// ConnManager provides a manager to handle network connections.
type ConnManager struct {
        // The following variables must only be used atomically.
        connReqCount uint64  // 管理的连接数
        start        int32  // 启动标识
        stop         int32 // 停止标志

        cfg            Config  // 配置
        wg             sync.WaitGroup  // 并发连接管理
        failedAttempts uint64  // 记录失败次数，如果成功连接则归0
        requests       chan interface{}  // 用于消息传递
        quit           chan struct{} // 用于退出
}


// ConnReq is the connection request to a network address. If permanent, the
// connection will be retried on disconnection.
type ConnReq struct {
        // The following variables must only be used atomically.
        id uint64  // 连接id，采用connReqCoount +1 的方式生成

        Addr      net.Addr // 连接地址
        Permanent bool  // 是否是持久连接

        conn       net.Conn
        state      ConnState // 记录该连接的状态
        stateMtx   sync.RWMutex
        retryCount uint32   // 记录持久连接的失败重试次数，如果成功连接则归0
}


// Config holds the configuration options related to the connection manager.
type Config struct {
        // Listeners defines a slice of listeners for which the connection
        // manager will take ownership of and accept connections.  When a
        // connection is accepted, the OnAccept handler will be invoked with the
        // connection.  Since the connection manager takes ownership of these
        // listeners, they will be closed when the connection manager is
        // stopped.
        //
        // This field will not have any effect if the OnAccept field is not
        // also specified.  It may be nil if the caller does not wish to listen
        // for incoming connections.
        Listeners []net.Listener

        // OnAccept is a callback that is fired when an inbound connection is
        // accepted.  It is the caller's responsibility to close the connection.
        // Failure to close the connection will result in the connection manager
        // believing the connection is still active and thus have undesirable
        // side effects such as still counting toward maximum connection limits.
        //
        // This field will not have any effect if the Listeners field is not
        // also specified since there couldn't possibly be any accepted
        // connections in that case.
        OnAccept func(net.Conn)

        // TargetOutbound is the number of outbound network connections to
        // maintain. Defaults to 8.
        TargetOutbound uint32

        // RetryDuration is the duration to wait before retrying connection
        // requests. Defaults to 5s.
        RetryDuration time.Duration

        // OnConnection is a callback that is fired when a new outbound
        // connection is established.
        OnConnection func(*ConnReq, net.Conn)

        // OnDisconnection is a callback that is fired when an outbound
        // connection is disconnected.
        OnDisconnection func(*ConnReq)

        // GetNewAddress is a way to get an address to make a network connection
        // to.  If nil, no new connections will be made automatically.
        GetNewAddress func() (net.Addr, error)

        // Dial connects to the address on the named network. It cannot be nil.
        Dial func(net.Addr) (net.Conn, error)
}