Mercurial > hg
view tests/test-diff-newlines.t @ 17970:0b03454abae7
ancestor: faster algorithm for difference of ancestor sets
One of the major reasons rebase is slow in large repositories is
the computation of the detach set: the set of ancestors of the
changesets to rebase not in the destination parent. This is currently
done via a revset that does two walks all the way to the root of
the DAG. Instead of doing that, to find ancestors of a set <revs>
not in another set <common> we walk up the tree in reverse revision
number order, maintaining sets of nodes visited from <revs>, <common>
or both.
For the common case where the sets are close both topologically and
in revision number (relative to repository size), this has been
found to speed up rebase by around 15-20%. When the nodes are farther
apart and the DAG is highly branching, it is harder to say which
would win.
Here's how long computing the detach set takes in a linear repository
with over 400000 changesets, rebasing near tip:
Rebasing across 4 changesets
Revset method: 2.2s
New algorithm: 0.00015s
Rebasing across 250 changesets
Revset method: 2.2s
New algorithm: 0.00069s
Rebasing across 10000 changesets
Revset method: 2.4s
New algorithm: 0.019s
author | Siddharth Agarwal <sid0@fb.com> |
---|---|
date | Mon, 26 Nov 2012 11:46:51 -0800 |
parents | 405b6bd015df |
children | c63a09b6b337 |
line wrap: on
line source
$ hg init $ python -c 'file("a", "wb").write("confuse str.splitlines\nembedded\rnewline\n")' $ hg ci -Ama -d '1 0' adding a $ echo clean diff >> a $ hg ci -mb -d '2 0' $ hg diff -r0 -r1 diff -r 107ba6f817b5 -r 310ce7989cdc a --- a/a Thu Jan 01 00:00:01 1970 +0000 +++ b/a Thu Jan 01 00:00:02 1970 +0000 @@ -1,2 +1,3 @@ confuse str.splitlines embedded\r (no-eol) (esc) newline +clean diff