[Mac-emacs-devel] 10.2 and C-g (was: 'Fatal error (6).Abort' (with fix))

[Steven T. <ste...@ma...>]

Yes it would.  I'm not sure I've posted this to the list, but it makes 
sense.

The main problem is that C-g does not interrupt synchronous processes.  
This is because C-g does not generate an interrupt at all.  The only way 
to get keyboard input is to be in a call to WaitNextEvent or 
ReceiveNextEvent.  The carbon event manager allows the event loop to run 
asynchronously in its own thread, so C-g could be recieved and then 
passed into emacs-lisp.   So in order to fix the problem, we can place 
event handling in one thread, and the emacs lisp loop in a separate 
thread.  Then when C-g comes into the UI, we can immediately post an 
interrupt to the lisp loop and it will work just like X windows.  
However due to other restrictions, this event handling thread can only 
be the "main" thread.  This, I think, is a bug in Mac OS X, but it's 
documented quite explicitly.  In addition, interrupt signals like SIGINT 
and SIGPIPE are also only sent to the main thread.  This means that both 
the lisp loop and the event loop need to be in the main thread for emacs 
to work.

10.2 includes thread-specific signal masks (specifically it includes 
pthread_kill and pthread_).  This means that SIGINT and SIGPIPE can be 
sent to a thread other than the main thread.  Therefore in 10.2 (and 
darwin build 6.0), the Carbon Event Manager's asynchronous event 
handling can be used and C-g will work like on w32 or x.  And emacs will 
be more efficient and responsive.

-Steven

On Friday, August 9, 2002, at 01:54  AM, dm...@dm... wrote:

> * ste...@ma... [2002-08-09 06:59:27]
>> When 10.2 comes around and the multithreaded UI can be used, a call
>> to add_keyboard_wait_descriptor would fix the select problem that
>> this patch concerns.
>
> Forgive my ignorance, but would this also be an opportunity to make
> ctrl-g work better ?  It's one of main irritations which remains for
> me.
>
>
>
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