[Libevent-users] Proper time to request port from a listener.

["Kelly Brock" <Kerby@xxxxxxxxxxx>]

Hi Folks,

	Maybe someone has done this before so figured I'd ask while I'm
still experimenting with possible solutions.  In the process of finishing up
some porting to OsX I noticed that I have a race condition in my code
related to listener sockets.  Previously I would just bring up the listener
socket, bind it, make it non-blocking, call accept once (dropping any
success which should never happen anyway) and then query the port before
moving on.

	Now, with libevent I'm curious if there is a better method of doing
this.  I started out just using the evconnlistener_new_bind but this is
obviously not calling accept immediately on the socket since OsX is
functional only if I insert a couple calls to libevent_loop into the code
prior to requesting the bound port.  (NOTE: Win32 works fine but I assume
that is because it calls AcceptEx immediately on the socket.)  In a single
threaded system this is not a problem but much of this portion of my code is
actually running in a worker thread owned by a multi-cast dns (i.e.
bonjour/avahi) wrapper.

	Currently my best guess is to go back to the old method and just use
evconnlistener_new instead of the '_bind' variation passing in the socket
after I've gotten the required information out of it.

	Any suggestions are welcome.  Preferably in the future, listener
might be able to do this fully asynchronously with an event callback or
something and then it would all work without any extra front end work or
portability issues.

KB

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