[Scummvm-devel] Threading issues and mutexes :-)

[Lionel Ulmer]

Hi all,

My streaming patch does not fix yet all the problems that can be found
between the main thread and the sound playing thread (mainly because there
is no way I can see to differentiate a buffer underrun from a stream
'normally' finishing playing). The patch may even get worse results on some
platforms :-/ (as in some cases, it will append stuff to a buffer that was
already deleted by free).

The only way to fix this is to add some mutex capabilities in the OSystem
interface (thus adding a mutex to all sound objects to be able to do
operations on them being sure that the sound thread will not destroy it
while we play with it :-) ).

So does everyone agree with it ? I ask here because I know how to do it in
the X11 port, it should not be that hard to do in the SDL port (as SDL
proposes mutex services), but I have no idea if other porters will find it
difficult to do or not :-)

Quick interface :

 - OSystem::create_mutex : returns a void * being the handle to the mutex
 - OSystem::lock_mutex : locks the given mutex
 - OSystem::free_mutex : frees the given mutex
 - OSystem::delete_mutex : deletes the given mutex
 
If nobody objects, I will start on this tomorrow evening (or the day after
depending of my free time :-) ).

                 Lionel

-- 
		 Lionel Ulmer - http://www.bbrox.org/