Mercurial > hg
view tests/test-merge6.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 | 2428e8ec0793 |
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$ cat <<EOF > merge > import sys, os > print "merging for", os.path.basename(sys.argv[1]) > EOF $ HGMERGE="python ../merge"; export HGMERGE $ hg init A1 $ cd A1 $ echo This is file foo1 > foo $ echo This is file bar1 > bar $ hg add foo bar $ hg commit -m "commit text" $ cd .. $ hg clone A1 B1 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd A1 $ rm bar $ hg remove bar $ hg commit -m "commit test" $ cd ../B1 $ echo This is file foo22 > foo $ hg commit -m "commit test" $ cd .. $ hg clone A1 A2 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg clone B1 B2 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd A1 $ hg pull ../B1 pulling from ../B1 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg merge 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -m "commit test" bar should remain deleted. $ hg manifest --debug f9b0e817f6a48de3564c6b2957687c5e7297c5a0 644 foo $ cd ../B2 $ hg pull ../A2 pulling from ../A2 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 merge 0 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -m "commit test" bar should remain deleted. $ hg manifest --debug f9b0e817f6a48de3564c6b2957687c5e7297c5a0 644 foo $ cd ..