[PATCH 2/4] X event queue mutex

[Keith Packard]

On Thu, 2008-10-02 at 19:10 -0300, Tiago Vignatti wrote:
> Simon Thum escreveu:
> > I believe tiagos words are a bit misleading: The mutex makes it possible 
> > to block event enqueuing, which is needed to guarantee order of events 
> > enqueued on the main thread. If I got it right, the intent is to 
> > 'emulate' OsBlockSignals(), though I'm missing that bit.
> 
> Good point, Simon. I forgot about this discussion which we had in XDS.
> 
> Given that there's only one thread to take care about all the input 
> devices this would not be a problem with *devices*. Events will be 
> serialized is this case. But the problems eventually can happen if the 
> others guys that enqueue events (nested servers, DGA, maybe also XTest) 
> try to do it at the same time with the devices. A mutex is needed in 
> this situation.

Ah, yes indeed -- we need a mutex to protect writes to the tail pointer
in mieqEnqueue. But, not the tail reads from mieqProcessInputEvents.

That is what the signal blocking stuff was for, after all.

-- 
keith.packard at intel.com
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