Re: Supressing sorting of trees

From: Sal Mangano <smangano@into-technology.com>
Date: Oct 12, 2009, 15:43 UTC
Message-ID: <loom.20091012T171550-239@post.gmane.org>
In-Reply-To: <20091012142032.GG9261@spearce.org>

Shawn O. Pearce <spearce <at> spearce.org> writes:

> 
> Sal Mangano <smangano <at> into-technology.com> wrote:
> > I am using Git in a non-standard way and need to make a few twaeks in my 
> > custom build. I have added a --nosort option to git mktree which will

suppress

Show 27 quoted lines

> > the qsort of the tree. 
> > 
> > Will this break any other git functions? Are there any commands that assume 
> > trees are always sorted?
> 
> _YES IT BREAKS GIT_.
> 
> You cannot do this.
> 
> A Git repository whose trees are not sorted according to the Git
> specific sort ordering is severly broken and most tools will fail
> horribly on it.
> 
> Almost all code which reads trees assumes the names are sorted in a
> specific order.  These tools perform sorted merges against other tree
> like structures.  If the names are out of order the merge will fail.
> `git fsck` will complain that the tree is not sorted properly.
> Tools like `git log -- foo.c` will fail randomly because they break
> out of the entry lookup as soon as they find a name that is after
> foo.c, as they assume the tree is sorted.
> 
> I could go on.  But there is no point.
> 
> Oh, and trust me when I say this, the tree sorting matters.  Long ago
> JGit had a bug where it didn't sort trees correctly all of the time
> and we had a devil of a time tracking down that corruption.
>

Thanks Shawn. I get the picture.

Now, let's assume I am stubborn, crazy or both :-)

I can modify fsck to ignore unsorted and at the moment I don't care about merging trees. If I hunt down all usage of base_name_compare will that identify all code with the sort assumption or is there other places as well? I can go through the entire source to figure this out myself but I need to get something hacked up very quickly and would appreciate help even if you think I am nuts!