I have a multi-threaded C++ app using lib event. The receive all happens in the libevent process and then a flag is set so that the data received is processed later. On the send tho, things go wrong. I am in a "main thread" and the data to send is assembled and then the following function is invoked.
int SocketWrapper :: SendData( const U8* buffer, int length )
{
if( m_useLibeventToSend )
{
bufferevent* bev = GetBufferEvent();
struct evbuffer* outputBuffer = bufferevent_get_output( bev );
evbuffer_lock( outputBuffer );
int result = evbuffer_add( outputBuffer, buffer, length );
evbuffer_unlock( outputBuffer );
return result;
}
return send( m_socketId, (const char* )buffer, length, 0 );
}
This function crashes on occasion at the point of the evbuffer_add invocation but 99.9% of the time it works fine. This smells like a concurrency bug and it may be related to clients crashing or coming-and-going. I made sure that during the initial creation of the socket by libevent, I did the following:
struct evbuffer* outputBuffer = bufferevent_get_output( GetBufferEvent() );
evbuffer_enable_locking( outputBuffer, NULL );
Do you have any notion of some other special initialization I should be doing? Should I not invoke "SendData" from my main thread and instead send an event to the bufferevent so that the send should happen in the same process as libevent?
All design ideas are open. So far, my workaround is to not use libevent for the send, but to write directly to the socket.
This crash happens in both release and debug, VS 2008, libevent 2.0. It's deep in the library so I will be resorting to including the c files in my project to try and track down my problem, but maybe someone here knows instantly what's wrong. :-)
