[Live-devel] multi-threaded connect() and EBADF

[Janus, Karl]

Hello!

I work on a win32-based project that consumes live555 (client-side only) and recently upgraded from an older synchronous API revision of live555 to the latest (2015-06-11 at the time of this writing).  Also, possibly of note, this project is multi-threaded and consumes multiple instances of RTSPClient (with separate UsageEnvironment(s), MediaSink(s), and MediaSession(s) per derived RTSPClient instance).

My main concern is that the timeout parameter is missing from the calls and I was previously using the timeout parameter to solve a silly win32 bug (as far as I know it's win32-only).  After the first connect(), subsequent calls to connect() with a non-blocking socket will fail most of the time with EBADF (-9) in a multi-threaded environment (e.g., in a thread-pool environment).  To combat this in the older API I specified a -1 on the first call (e.g., sendOptionsCmd) so that the initial socket would be in blocking mode upon first connect().  The socket could then be made non-blocking after that point.

I can 'remedy' this problem by making RTSPClient::connectToServer() virtual and using makeSocketBlocking() with an arbitrary timeout and then makeSocketNonBlocking() after successful return from RTSPClient::connectToServer().  I understand that this probably violates the license agreement and in order to comply with the license, I ask: Is there a way that live555 could be modified by making RTSPClient::connectToServer a virtual method?  Another way could be to allow a timeout per request, but at the expense of more code and possibly more API changes.

My end-goal is that the connect() method can be called with a blocking socket and a specifiable timeout.  Simple example assuming the method was virtual and MyRtspClient derives from RTSPClient:

<code>
int MyRtspClient::connectToServer(int socketNum, portNumBits remotePortNum) {
        ...
        makeSocketBlocking(socketNum, myOwnTimeoutValue);
        ...
        int result = RTSPClient::connectToServer(socketNum, remotePortNum);
        ...
        if(result >=0){
                makeSocketNonBlocking(socketNum);
        }
        ...
        return result;
}
</code>

Side note: this is one of the few instances of this issue outside of Live555 that I could find while researching:  http://acsutoday.blogspot.com/2009/02/connect-returns-ebadf-when-run-in.html

Thanks for the great RTSP library and thanks in advance for your time.
-karl

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