Mercurial > hg
view tests/test-issue1802.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 | f2719b387380 |
children | 44bda93df90e |
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$ "$TESTDIR/hghave" execbit || exit 80 Create extension that can disable exec checks: $ cat > noexec.py <<EOF > from mercurial import extensions, util > def setflags(orig, f, l, x): > pass > def checkexec(orig, path): > return False > def extsetup(ui): > extensions.wrapfunction(util, 'setflags', setflags) > extensions.wrapfunction(util, 'checkexec', checkexec) > EOF $ hg init unix-repo $ cd unix-repo $ touch a $ hg add a $ hg commit -m 'unix: add a' $ hg clone . ../win-repo updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ chmod +x a $ hg commit -m 'unix: chmod a' $ hg manifest -v 755 * a $ cd ../win-repo $ touch b $ hg add b $ hg commit -m 'win: add b' $ hg manifest -v 644 a 644 b $ hg pull pulling from $TESTTMP/unix-repo searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 0 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg manifest -v -r tip 755 * a Simulate a Windows merge: $ hg --config extensions.n=$TESTTMP/noexec.py merge --debug searching for copies back to rev 1 unmatched files in local: b resolving manifests overwrite: False, partial: False ancestor: a03b0deabf2b, local: d6fa54f68ae1+, remote: 2d8bcf2dda39 a: update permissions -> e updating: a 1/1 files (100.00%) 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) Simulate a Windows commit: $ hg --config extensions.n=$TESTTMP/noexec.py commit -m 'win: merge' $ hg manifest -v 755 * a 644 b $ cd ..