blockUntilReadable和select的问题，发生死锁...

[lius1984]

无法从网络收包，调试后找到错误处在blockUntilReadable函数，socket不可读所以阻塞了程序。但socket怎样才能设为可读，同时vlc一直在收数据并显示啊。 问题在blockUntilReadable中的select()函数，这个函数无法执行，我尝试删去select但blockUntilReadable会陷入死循环。 该怎么解决这个难题，高手请指教！欢迎大家讨论，谢谢！

static int blockUntilReadable(UsageEnvironment& env,
			      int socket, struct timeval* timeout) {
  int result = -1;
  do {
    fd_set rd_set;
    FD_ZERO(&rd_set);
    if (socket < 0) break;
    FD_SET((unsigned) socket, &rd_set);
    const unsigned numFds = socket+1;
    
    result = select(numFds, &rd_set, NULL, NULL, timeout);     //block here
    if (timeout != NULL && result == 0) {
      break; // this is OK - timeout occurred
    } else if (result <= 0) {
#if defined(__WIN32__) || defined(_WIN32)
#else
      if (errno == EINTR || errno == EAGAIN) continue;
#endif
      socketErr(env, "select() error: ");
      break;
    }
    
    if (!FD_ISSET(socket, &rd_set)) {
      socketErr(env, "select() error - !FD_ISSET");
      break;
    }
  } while (0);

  return result;
}

int readSocket(UsageEnvironment& env,
	       int socket, unsigned char* buffer, unsigned bufferSize,
	       struct sockaddr_in& fromAddress,
	       struct timeval* timeout) {
  int bytesRead = -1;
 
  while(1)
	  {
	  
	  	int result;

	    result = blockUntilReadable(env, socket, timeout);  
	    if(result > 0)
	    	{
	    	  break;
	    	}

	      if (timeout != NULL && result == 0) 
	      {
	        bytesRead = 0;
	        break;
	      } 

	      else if (timeout == NULL && result <= 0) 
	      {
	          sleep(10);        //break;   
	      }
	  
	  }
 
  
  do {
  	
    
    unsigned int addressSize = sizeof fromAddress;
    
   while(1)                 
    {
    	bytesRead = recvfrom(socket, (void*)buffer, bufferSize, 0,
    						(struct sockaddr*)&fromAddress,
    							&addressSize);
    	if(bytesRead > 0) break;              // added by lin 
    	if(bytesRead  == 0) break;         // added by lin 
    }
  ....
]
   return bytesRead;
}

[僵哥]

1.没有数据，当然不可读
2.设置timeout

[lius1984]

谢谢回复。

1. 怎么会没数据呢，我电脑一直在收来自服务器的数据包用vlc一直在播放。一直都是192.168.1.103:554/ch01。

我用ethereal抓包 程序运行时还是有数据的，但只有reply OK,description都没了（如下）。后附主要代码段。

2. 我注意到getResponse1中的readSocket(envir(), fInputSocketNum, &firstByte, 1, fromAddress)只有5个参数，是否应该加入timeout。 timeout的格式是怎么样的，表示什么含义呢？ 还请指教！

TCP 1542 > 40504 [ACK] Seq=1 Ack=1 Win=65535 Len=0
OPTIONS rtsp://skyewe:skyewe@192.168.1.103:40504/mo01 RTSP/1.0
40504 > 1542 [ACK] Seq=1 Ack=146 Win=6432 Len=0
RTSP Reply: RTSP/1.0 200 OK



//Get the URL from streamPlayer;
char url[]= "rtsp://skyewe:skyewe@192.168.1.103:40504/mo01";

//Create the Scheduler and enviornment;
scheduler = BasicTaskScheduler::createNew();
env = BasicUsageEnvironment::createNew(*scheduler);

const char *progName = "Skyewe RTSP client";

// Create our client object:
ourClient = RTSPClient::createNew(*env, 0, progName,0);

if (NULL == ourClient)
{
shutdown1();
return 0;
};

//Send Option

m_eState = RTSP_STATE_CONNECTING;
char* optionsResponse = ourClient->sendOptionsCmd(url, NULL, NULL); //返回为空

if (m_eState==RTSP_STATE_SHUTDOWN)
{
shutdown1();
return 0;
}

m_eState = RTSP_STATE_CONNECTED;

//07-09-16 yujianchun modify, when optionresponse is null, return it
if (NULL != optionsResponse)
{
delete[] optionsResponse;
optionsResponse = NULL;
}

else
{
shutdown1();
return 0;
}


// Open the URL, to get a SDP description:
char* sdpDescription= ourClient->describeURL(url);
int statusCode = ourClient->describeStatus();

if (NULL == sdpDescription)
{
//// TRACE(L"Failed to get a SDP description from URL.\n");
shutdown1();
return 0;
}