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From: Kim Gybels <kgybels@infogroep.be>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Jeff King <peff@peff.net>
Subject: Re: [PATCH 1/2] daemon: use timeout for uninterruptible poll
Date: Sun, 15 Apr 2018 19:08:59 +0200	[thread overview]
Message-ID: <20180415170859.GA30197@infogroep.be> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1804131433250.65@ZVAVAG-6OXH6DA.rhebcr.pbec.zvpebfbsg.pbz>

On (13/04/18 14:36), Johannes Schindelin wrote:
> > The poll provided in compat/poll.c is not interrupted by receiving
> > SIGCHLD. Use a timeout for cleaning up dead children in a timely manner.
> 
> Maybe say "When using this poll emulation, use a timeout ..."?

I will rewrite the commit message when I reroll the patch. Calling the
poll "uninterruptible" might be wrong as well, although the poll
doesn't return with EINTR when a child process terminates, it might
still be interruptible in other ways. On a related note, the handler
for SIGCHLD is simply not called in Git-for-Windows' daemon.

> > diff --git a/daemon.c b/daemon.c
> > index fe833ea7de..6dc95c1b2f 100644
> > --- a/daemon.c
> > +++ b/daemon.c
> > @@ -1147,6 +1147,7 @@ static int service_loop(struct socketlist *socklist)
> >  {
> >  	struct pollfd *pfd;
> >  	int i;
> > +	int poll_timeout = -1;
> 
> Just reuse the line above:
> 
> 	int poll_timeout = -1, i;

Sure.

> > @@ -1161,8 +1162,13 @@ static int service_loop(struct socketlist *socklist)
> >  		int i;
> >  
> >  		check_dead_children();
> > -
> > -		if (poll(pfd, socklist->nr, -1) < 0) {
> > +#ifdef NO_POLL
> > +		poll_timeout = live_children ? 100 : -1;
> > +#endif
> > +		int ret = poll(pfd, socklist->nr, poll_timeout);
> > +		if  (ret == 0) {
> > +			continue;
> > +		} else if (ret < 0) {
> 
> I would find it a bit easier on the eyes if this did not use curlies, and
> dropped the unnecessary `else` (`continue` will take care of that):
> 
> 		if (!ret)
> 			continue;
> 		if (ret < 0)
> 			[...]

Funny, that's how I would normally write it, if I wasn't so focused on
trying to follow the coding quidelines. While I'm at it, I will also
fix that sneaky double space after the if.

Is it ok to add the timeout for all platforms using the poll
emulation, since I only tested for Windows?

Best regards,
Kim

  reply	other threads:[~2018-04-15 17:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-12 21:07 [PATCH 0/2] Fix early EOF with GfW daemon Kim Gybels
2018-04-12 21:07 ` [PATCH 1/2] daemon: use timeout for uninterruptible poll Kim Gybels
2018-04-13 12:36   ` Johannes Schindelin
2018-04-15 17:08     ` Kim Gybels [this message]
2018-04-18 21:16       ` Johannes Schindelin
2018-04-15 21:54   ` Junio C Hamano
2018-04-15 22:16     ` Junio C Hamano
2018-04-18 21:07     ` Johannes Schindelin
2018-04-18 21:51       ` Junio C Hamano
2018-04-19 21:33         ` Kim Gybels
2018-04-19 23:18           ` Junio C Hamano
2018-04-12 21:07 ` [PATCH 2/2] daemon: graceful shutdown of client connection Kim Gybels
2018-04-13 13:03   ` Johannes Schindelin
2018-04-15 20:21     ` Kim Gybels
2018-04-18 21:48       ` Johannes Schindelin

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