Re: Git on Windows, CRLF issues

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi,

On Wed, 23 Apr 2008, Jeff King wrote:

> On Tue, Apr 22, 2008 at 12:51:14PM -0400, Avery Pennarun wrote:
> 
> > Do you think git would benefit from having a generalized version of 
> > this script?  Basically, the user provides a "munge" script on the 
> > command line, and there's a git-filter-branch mode for auto-munging 
> > (with a cache) every file in every checkin.  Even if it's *only* ever 
> > used for CRLF, I can imagine this being useful to a lot of people.
> 
> It was easy enough to work up the patch below, which allows
> 
>   git filter-branch --blob-filter 'tr a-z A-Z'
> 
> However, it's _still_ horribly slow.

You create a quite huge blob-cache, so you are pretty heavy on disk-I/O.  
Have you tried (as suggested in the man page) to run this on a huge RAM 
disk?  That should blow you away.

> Shell script is nice and flexible, but running a tight loop like this is 
> just painful. I suspect filter-branch in something like perl would be a 
> lot faster and just as flexible (you could even do it in C, but you'd 
> probably have to invent a little domain-specific scripting language).

I hoped that the rewrite-commits attempt was more than just that: an 
attempt.  So there is a point you could start from, doing things in C.

But I doubt that you get any joy: either your language is too limited, or 
you will get the same problems (fork() overhead) again.

> Anyway, here is the patch. I don't know if it is even worth applying, 
> since it is still painfully slow.

I like your patch:

Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Ciao,
Dscho