From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@9fans.net
Date: Wed, 30 Sep 2009 15:57:08 +0200
From: gdiaz@9grid.es
Message-ID: <b625c33fc26ec00a7dd0cf637f7c6197@9grid.es>
In-Reply-To: <8c0180e1040b5ab14761083fdd1b9600@brasstown.quanstro.net>
References: <9d12d327612343c13bd110253c2632c6@9grid.es>
	<8c0180e1040b5ab14761083fdd1b9600@brasstown.quanstro.net>
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Subject: Re: [9fans] exiting nicely
Topicbox-Message-UUID: 79c08cc4-ead5-11e9-9d60-3106f5b1d025

hello

i think i'll do the checkexit() and doublecheck again all exiting procs unlocks all the locks they had, as the only place to check is when a proc is waiting to read from the 9p pipe:

		qlock(&iorlock);
		n = read9pmsg(mfd[0], io->mdata, messagesize);
		qunlock(&iorlock);

thanks!

gabi

>> I have a couple of processes working together sharing memory and using locks, and when the program finish the job and exits, the proceses in Rendez state  does not exit, and i need to slay them.
>>
>> I'm using postnote(PNGROUP,...) call, should i write a postctl to slay the waiting proceses or is there a better way to accomplish this? (may be using canlock and wait for it with a loop and sleep instead of a qlock?)
>
> looping on canq?lock is not a good idea.
>
> i think what you want is to ensure that no proc is
> doing anything that shouldn't be interrupted when
> it is killed or quits.  for many programs, interrupting
> writes is a bad idea.  one would want a half-written
> upas index file, for instance.  rc checks a global sentinal at
> a few strategic points (where it can clean up easily)
> when it receives a signal.  perhaps you could borrow
> this technique, as in
>
> 	/*
> 	 * exit the building single file
> 	 */
> 	void
> 	chkexit(QLock *q)
> 	{
> 		if(!exiting)
> 			return;
> 		qunlock(q)
> 		cleanexit();
> 	}
> ...
> 	qlock(&resourcelk);
> 	chkexit(&resourcelk);
> 	...
> 	qunlock(&resourcelk);
>
> this might not be appropriate.  the bad things
> that might happen if your interrupted in the
> middle of something might not be bad enough
> to worry about or this might be difficult to implement
> with your program.
>
> - erik