zmq源码阅读 —— zmq_send()和zmq_recv()

int zmq_recv (void *s_, void *buf_, size_t len_, int flags_){    if (!s_ || !((zmq::socket_base_t*) s_)->check_tag ()) {        errno = ENOTSOCK;        return -1;    }    zmq_msg_t msg; // 创建消息结构    int rc = zmq_msg_init (&msg); // 初始化空消息    errno_assert (rc == 0);    zmq::socket_base_t *s = (zmq::socket_base_t *) s_;    int nbytes = s_recvmsg (s, &msg, flags_); // 接收消息    if (unlikely (nbytes < 0)) {        int err = errno;        rc = zmq_msg_close (&msg);        errno_assert (rc == 0);        errno = err;        return -1;    }    //  At the moment an oversized message is silently truncated.    //  TODO: Build in a notification mechanism to report the overflows.    size_t to_copy = size_t (nbytes) < len_ ? size_t (nbytes) : len_; //计算消息大小    memcpy (buf_, zmq_msg_data (&msg), to_copy); // 通过zmq_msg_data()获得消息的data地址，拷贝到buf_中    rc = zmq_msg_close (&msg); // 释放或销毁消息    errno_assert (rc == 0);    return nbytes;}---------------------------------------------------------------------int zmq_recvmsg (void *s_, zmq_msg_t *msg_, int flags_){    return zmq_msg_recv (msg_, s_, flags_);}----------------------------------------------------------------------int zmq_msg_recv (zmq_msg_t *msg_, void *s_, int flags_){    if (!s_ || !((zmq::socket_base_t*) s_)->check_tag ()) {        errno = ENOTSOCK;        return -1;    }    zmq::socket_base_t *s = (zmq::socket_base_t *) s_;    int result = s_recvmsg (s, msg_, flags_);    return result;}-----------------------------------------------------------------------static ints_recvmsg (zmq::socket_base_t *s_, zmq_msg_t *msg_, int flags_){    int rc = s_->recv ((zmq::msg_t*) msg_, flags_);     if (unlikely (rc < 0))        return -1;    return (int) zmq_msg_size (msg_);// 计算消息的大小}---------------------------------------------------------------------------------=================================================================================---------------------------------------------------------------------------------int zmq_send (void *s_, const void *buf_, size_t len_, int flags_){    if (!s_ || !((zmq::socket_base_t*) s_)->check_tag ()) {        errno = ENOTSOCK;        return -1;    }    zmq_msg_t msg; // 创建消息结构    int rc = zmq_msg_init_size (&msg, len_); // 以buf长度初始化成消息    if (rc != 0)        return -1;    memcpy (zmq_msg_data (&msg), buf_, len_); // 将buf的内容拷贝给消息    zmq::socket_base_t *s = (zmq::socket_base_t *) s_;    rc = s_sendmsg (s, &msg, flags_); // 发送消息    if (unlikely (rc < 0)) {        int err = errno;        int rc2 = zmq_msg_close (&msg); // 释放和销毁消息        errno_assert (rc2 == 0);        errno = err;        return -1;    }        //  Note the optimisation here. We don't close the msg object as it is    //  empty anyway. This may change when implementation of zmq_msg_t changes.    return rc;}从注释中可以看出消息发送的流程，czmq,jzmq等已经做了封装，也可以自己做封装。