Re: comparing file contents in is_exact_match?

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 18, 2006, 10:20 UTC
Message-ID: <Pine.LNX.4.63.0607181216290.29667@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <f36b08ee0607180238i34cde4deib17426f121ae269e@mail.gmail.com>

Hi,

On Tue, 18 Jul 2006, Yakov Lerner wrote:

> How about making this parameter (do-use-mmap  vs  not-use-mmap)
> a *runtime*  parameter  ? (Env. var. $GIT_MMAP or $GIT_USE_MMAP ?).
> What do you think ? I see two benefits:
> (1) much easier to benchmark two methods against each other

You will benchmark it only once, right? No need to have this in git for one-time use.

> (2) will always work on cygwin (automatic fallback to working
>    method at runtime; say depending on filesystem)

I think it is too complicated to depend on the filesystem, and too system specific (but hey, those who submit a patch are more right than others...).

But an automatic fallback is not feasible: you would try to mmap(), and it would throw an "Access violation", which is MS speak for "Segmentation fault".

Besides, if you would be able to detect a failed mmap(), it would be too late: the rename() or unlink() would already have taken place.

Ciao, Dscho