From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Date: Thu, 06 Jan 2011 17:28:48 GMT
Subject: Re: Concurrent pushes updating the same ref
Message-ID: <20110106172848.GA15729@LK-Perkele-VI.localdomain>
In-Reply-To: <AANLkTinGYjExrnHCqcTPu-APzk9WynxwWoKVOLaSkZ2y@mail.gmail.com>

On Thu, Jan 06, 2011 at 08:48:11AM -0800, Shawn Pearce wrote:
> On Thu, Jan 6, 2011 at 08:30, Jeff King <peff@peff.net> wrote:
> >
> >     Right now you are getting contention on the lock itself. But may
> >     you not also run afoul of step (6) above? That is, one push updates
> >     the ref from A to B, then the other one in attempting to go from A
> >     to B sees that it has already changed to B under our feet and
> >     complains?
> 
> Not if its a force push.  :-)

IIRC, there are no wire protocol bits to denote a forced push, the
force option only overrides client-side checks. Thus, even forced pushes
can fail due to race conditions...

-Ilari