RTSP连接服务器和从服务器接收数据的处理流程

RTSP连接服务器是否成功，以及是否从服务器接收到实际播放的数据，主要是判断两个linux select函数的执行结果。
1.连接服务器的处理过程

ARTSPConnection::onConnect(const sp<AMessage> &msg)    int err = ::connect(            mSocket, (const struct sockaddr *)&remote, sizeof(remote));    LOGE("%s L%d err = %d", __FUNCTION__, __LINE__, err);        if (err < 0) {        if (errno == EINPROGRESS) { // 正在连接中            sp<AMessage> msg = new AMessage(kWhatCompleteConnection, id());            msg->setMessage("reply", reply);            msg->setInt32("connection-id", mConnectionID);            msg->post();

调用---------->

void ARTSPConnection::onMessageReceived(const sp<AMessage> &msg) {case kWhatCompleteConnection:            onCompleteConnection(msg);

调用----------> 

ARTSPConnection::onCompleteConnection    int res = select(mSocket + 1, NULL, &ws, NULL, &tv);    CHECK_GE(res, 0);        if (res == 0) {        // Timed out. Not yet connected.        LOGE("%s L%d -ECONNABORTED", __FUNCTION__, __LINE__);        msg->post(); // 循环执行此函数检查是否connected        return;    }

2.是否接收到服务器发送的播放数据的处理

2.1 在ARTSPConnection::onCompleteConnection成功连接后，发送检查接收数据的event

void ARTSPConnection::postReceiveReponseEvent() {    if (mReceiveResponseEventPending) {        return;    }    sp<AMessage> msg = new AMessage(kWhatReceiveResponse, id());    msg->post();    mReceiveResponseEventPending = true;}

调用---------->

2.2 void ARTSPConnection::onMessageReceived(const sp<AMessage> &msg) {
        case kWhatReceiveResponse:
            onReceiveResponse();
            break;
继续调用---------->
2.3

 void ARTSPConnection::onReceiveResponse() {    int res = select(mSocket + 1, &rs, NULL, NULL, &tv);     //   LOGE("%s L%d select res = %d", __FUNCTION__, __LINE__, res);    CHECK_GE(res, 0);    if (res == 1) {        MakeSocketBlocking(mSocket, true);                bool success = receiveRTSPReponse(); // 2.3.1        MakeSocketBlocking(mSocket, false);        LOGE("%s L%d select ==== success = %d", __FUNCTION__, __LINE__, success);        if (!success) {            // Something horrible, irreparable has happened.            flushPendingRequests();            LOGE("%s L%d return ", __FUNCTION__, __LINE__);            return;        }    }    postReceiveReponseEvent(); // 循环执行此函数}

继续调用……

2.3.1 bool ARTSPConnection::receiveRTSPReponse() {

--->
  2.3.1.1 bool ARTSPConnection::receiveLine(AString *line) {
  --->
    2.3.1.1.1 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读一个字符
    --->
      2.3.1.1.1.1 ssize_t n = recv(mSocket, (uint8_t *)data + offset, size - offset, 0); // 从TCP连接的另一端接收数据
--->  
  2.3.1.2 sp<ABuffer> ARTSPConnection::receiveBinaryData()
  --->
    2.3.1.2.1 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读3个字符
    --->
      recv()
    2.3.1.2.2 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读buffer->size()个字符
    --->
      recv()      
--->
  2.3.1.3 new ARTSPResponse
--->
  2.3.1.4 receiveLine()
--->
  2.3.1.5 recv() // while (numBytesRead < contentLength)
--->
  2.3.1.6 函数返回
  return isRequest
        ? handleServerRequest(response)
        : notifyResponseListener(response);
        
 附：
SDP: Session Description Protocol
[RFC4566]
http://www.ietf.org/rfc/rfc4566.txt