Re: A question on discardEventsMatchingMask:beforeEvent:

[David Chisnall]

On 31 Jan 2011, at 09:51, SPUeNTRUP - Kai Henningsen wrote:

>> When I was looking at it, I found it hard to see how best to make a fast 
>> allocation/deallocation scheme thread-safe.
> 
> I learned this from ptmalloc3


ptmalloc() is very heavily optimised for the case in which malloc() and free() 
are both called in the same thread.  For NSEvent, this may well not be the 
case, as the event is delivered to a run loop, which may pass it off to another 
thread.

Of course, if you want really fast NSEvent allocation and deallocation, then 
you should take advantage of the fact that NSEvents are inserted at the bottom 
of the run loop, are immutable, and rarely persist beyond a single run loop 
iteration.  You can then allocate an NSEvent subclass on the stack, inject 
this, and have its -retain method return a copy of itself on the heap, so you 
are only calling malloc() at all when someone tries to keep the event beyond 
the run loop iteration.

This would require some tweaking of the current code, I think, because NSEvents 
are queued by the run loop.  Something for Banlu to play with...

David

-- Send from my Jacquard Loom