Re: Finding file revisions

From: Linus Torvalds <torvalds@osdl.org>
Date: Apr 27, 2005, 17:34 UTC
Message-ID: <Pine.LNX.4.58.0504271027460.18901@ppc970.osdl.org>
In-Reply-To: <200504271251.00635.mason@suse.com>

On Wed, 27 Apr 2005, Chris Mason wrote:

Show 9 quoted lines

> 
> I haven't seen a tool yet to find which changeset modified a given file, so 
> I whipped up something.  The basic idea is to:
> 
> for each changeset in rev-list
> 	for each file in diff-tree -r parent changeset
> 		match against desired files
> 
> Is there a faster way?

Yes. Tell "diff-tree" what your desired files are, and it will cut down the amount of work by a _lot_ (because then diff-tree doesn't need to recurse into subdirectories that don't matter).

So you should just do

	for each changeset in rev-list
	do 
		diff-tree -r parent changeset <file-list>
	...

instead.

> This will scale pretty badly as the tree grows, but 
> I usually only want to search back a few months in the history.  So, it 
> might make sense to limit the results by date or commit/tag.

With more history, "rev-list" should do basically the right thing: it will be constant-time for _recent_ commits, and it is linear time in how far back you want to go. Which seems quite reasonable.

And diff-tree is obviously constant-time (and very fast at that, especially if you limit it to just a few files, since then it won't even bother with any other subdirectories).

		Linus