Re: [PATCH/RFC 0/3] faster inexact rename handling

On Tue, 30 Oct 2007, Jeff King wrote:

On Mon, Oct 29, 2007 at 10:06:11PM -0700, Linus Torvalds wrote:

quoted

Have you compared the results? IOW, does it find the *same* renames?

From my limited testing, it generally finds the same pairs. However,
there are a number of renames that it _doesn't_ find, because they are
composed of "uninteresting" lines, dropping them below the minimum
score. Try (in git.git):

  git-show --raw -M -l0 :/'Big tool rename'

with the old and new code. Pairs like Documentation/git-add-script.txt
-> Documentation/git-add.txt are not found, because the file is composed
almost entirely of boilerplate.

Ok, that does imply to me that we cannot just drop boilerplate text, 
because the fact is, lots of files contain boilerplate, but people still 
think they are "similar".

We do actually depend on the similarity analysis being "good" - because it 
matters a lot for things like merging. The old code was actually very 
careful indeed, and while it didn't care about things like the exact 
*ordering* of lines (ie moving functions around in the same file resulted 
in the *exact* same fingerprint for the file!) it cared about everything 
else.

Moving the size normalization into the similarity engine should probably
fix that, and will let us compare old and new results more accurately.
I'll try to work on that.

Hmm. I hope that is sufficient. But I suspect it may well not be. 
Especially since you ignore boiler-plate lines for *some* files but not 
others (ie it depends on which file you happen to find it in first).

			Linus