[PATCH] client: Add acquire-fd API to avoid requiring a polling main thread

[Bill Spitzak]

Kristian Høgsberg wrote:

> This patch introduces new API to solve both problems.  We add
> 
> 	int wl_display_acquire_fd(struct wl_display *display);

I'm a little confused, some sample source code showing where the acquire 
call goes would help. My guess is each thread should do this:

	wl_display_acquire_fd(display);
	for (;;) {
	    wl_display_dispatch_pending(display);
	    poll(fds, nfds, -1);
	    wl_display_dispatch(display);
	    if (needToDoExpensiveCalculation) {
	        wl_display_release_fd(display);
	        doExpensiveCalculation();
	        wl_display_acquire_fd(display);
	    }
	}

This is based on reading the patch. The description made it sound like 
dispatch() drops the lock, but it actually drops & regains it, right?

Also it is very unclear what to do if acquire returns EBUSY. The only 
thing that looks like it will work is to busy-loop until it works?