Re: [PATCH 0/3] Teach Git about the patience diff algorithm

From: Pierre Habouzit <madcoder@debian.org>
Date: Jan 7, 2009, 22:45 UTC
Message-ID: <20090107224504.GA29537@artemis.corp>
In-Reply-To: <alpine.DEB.1.00.0901072213570.7496@intel-tinevez-2-302>

On Wed, Jan 07, 2009 at 10:00:07PM +0000, Johannes Schindelin wrote:

Show 25 quoted lines

> Therefore I counted the lines between conflict markers (actually, a perl 
> script did).  Of these 66 merges, on average patience merge produced 
> 4.46774193548387 _fewer_ lines between conflict markers.
> 
> Take that with a grain of salt, though: the standard deviation of this 
> difference is a hefty 121.163046639509 lines.
> 
> The worst case for patience diff was the merge 
> 4698ef555a1706fe322a68a02a21fb1087940ac3, where the --cc diff line counts 
> are 1300 (without) vs 1301 (with patience merge), but the lines between 
> conflict markers are 197 vs a ridiculous 826 lines!
> 
> But you should take that also with a grain of salt: this merge is a 
> _subtree_ merge, and my test redid it as a _non-subtree_ merge.
> 
> So I restricted the analysis to the non-subtree merges, and now 
> non-patience merge comes out 6.97297297297297 conflict lines fewer than 
> patience merge, with a standard deviation of 58.941106657867 (with a total 
> count of 37 merges).
> 
> Note that ~7 lines difference with a standard deviation of ~59 lines is 
> pretty close to ~0 lines difference.
> 
> In the end, the additional expense of patience merge might just not be 
> worth it.

Depends, if it can help generating nicer merges, it's good to have.

We could have an option to git-merge that tries hard to generate the smallest conflict possible. _that_ would really really be worth it. I mean, I've had really really tricky conflicts to work with where git-merge genrated ridiculously big conflicts, and where I hard to resort using UI tools to perform the merge (meld IIRC to name it), and given how slow and crappy those tools are, I would gladly restart a merge with a --generate-smallest-conflicts-as-possible if it can save me from those merge tools.

YMMV though.

PS: I never thought the patience diff is a silver bullet, it's just yet
    another tool in the toolbox.

-- 
·O·  Pierre Habouzit
··O                                                madcoder@debian.org
OOO                                                http://www.madism.org