From: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: "Jeff King" <peff@peff.net>, "Junio C Hamano" <gitster@pobox.com>,
"Torsten Bögershausen" <tboegi@web.de>,
"Johannes Sixt" <j6t@kdbg.org>,
"Shawn O. Pearce" <spearce@spearce.org>,
mlevedahl@gmail.com, dpotapov@gmail.com,
"GIT Mailing-list" <git@vger.kernel.org>
Subject: Re: [RFC/PATCH 0/1] cygwin: Remove the Win32 l/stat() functions
Date: Fri, 28 Jun 2013 00:09:55 +0100 [thread overview]
Message-ID: <51CCC643.1050702@ramsay1.demon.co.uk> (raw)
In-Reply-To: <51CBD2FD.5070905@alum.mit.edu>
Michael Haggerty wrote:
> On 06/27/2013 12:35 AM, Jeff King wrote:
[ ... ]
>> I think Michael's assessment above is missing one thing.
>
> Peff is absolutely right; for some unknown reason I was thinking of the
> consistency check as having been already fixed.
Well, the "cygwin: Remove the Win32 l/stat() functions" patch *does* fix
the problem. :-D It's just a pity we can't use it on performance grounds. :(
>> [...#ifdef out consistency check on cygwin when lock is held...]
>
> Yes, this would work.
>
> But, taking a step back, I think it is a bad idea to have an unreliable
> stat() masquerading as a real stat(). If we want to allow the use of an
> unreliable stat for certain purposes, let's have two stat() interfaces:
>
> * the true stat() (in this case I guess cygwin's slow-but-correct
> implementation)
>
> * some fast_but_maybe_unreliable_stat(), which would map to stat() on
> most platforms but might map to the Windows stat() on cygwin when so
> configured.
>
> By default the true stat() would always be used. It should have to be a
> conscious decision, taken only in specific, vetted scenarios, to use the
> unreliable stat.
You have just described my second patch! :D
>
> For example, I can't imagine that checking the freshness of the index or
> of the packed-refs file is ever going to be a bottleneck, so there is no
> reason at all to use an unreliable stat() here.
>
> On the other hand, stat() seems definitely to be a bottleneck when
> testing for changes in a 100,000 file working tree, and here occasional
> mistakes might be considered acceptable. So for this purpose the
> unreliable stat() might be used.
I have already written the first pass at this patch, but I'm having
difficulty with naming (get_cached_stat_data, get_index_stat_data,
get_stat_data, ... ;-)
ATB,
Ramsay Jones
next prev parent reply other threads:[~2013-06-27 23:21 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <51C5FD28.1070004@ramsay1.demon.co.uk>
[not found] ` <51C7A875.6020205@gmail.com>
[not found] ` <7va9mf6txq.fsf@alter.siamese.dyndns.org>
2013-06-25 19:23 ` [RFC/PATCH 0/1] cygwin: Remove the Win32 l/stat() functions Johannes Sixt
2013-06-25 20:23 ` Torsten Bögershausen
2013-06-25 21:18 ` Junio C Hamano
2013-06-26 14:19 ` Torsten Bögershausen
2013-06-26 21:54 ` Ramsay Jones
2013-06-27 15:19 ` Torsten Bögershausen
2013-06-27 23:18 ` Ramsay Jones
2013-06-27 2:37 ` Mark Levedahl
[not found] ` <51C6BC4B.9030905@web.de>
[not found] ` <51C8BF2C.2050203@ramsay1.demon.co.uk>
[not found] ` <7vy59y4w3r.fsf@alter.siamese.dyndns.org>
2013-06-26 21:39 ` Ramsay Jones
[not found] ` <51C94425.7050006@alum.mit.edu>
2013-06-26 21:45 ` Ramsay Jones
2013-06-26 22:35 ` Jeff King
2013-06-26 22:43 ` Jeff King
2013-06-27 22:58 ` Ramsay Jones
2013-06-28 2:31 ` Mark Levedahl
2013-06-27 5:51 ` Michael Haggerty
2013-06-27 19:58 ` Jeff King
2013-06-27 21:04 ` Junio C Hamano
2013-06-27 23:09 ` Ramsay Jones [this message]
2013-06-30 17:28 ` Ramsay Jones
2013-06-30 19:50 ` Junio C Hamano
2013-07-04 18:18 ` Ramsay Jones
2013-07-09 11:02 ` Torsten Bögershausen
2013-07-11 17:31 ` Ramsay Jones
2013-06-27 22:17 ` Ramsay Jones
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