Mercurial > hg
view tests/test-impexp-branch.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 | db6b958c4f35 |
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$ echo '[extensions]' >> $HGRCPATH $ echo 'mq =' >> $HGRCPATH $ cat >findbranch.py <<EOF > import re, sys > > head_re = re.compile('^#(?:(?:\\s+([A-Za-z][A-Za-z0-9_]*)(?:\\s.*)?)|(?:\\s*))$') > > for line in sys.stdin: > hmatch = head_re.match(line) > if not hmatch: > sys.exit(1) > if hmatch.group(1) == 'Branch': > sys.exit(0) > sys.exit(1) > EOF $ hg init a $ cd a $ echo "Rev 1" >rev $ hg add rev $ hg commit -m "No branch." $ hg branch abranch marked working directory as branch abranch (branches are permanent and global, did you want a bookmark?) $ echo "Rev 2" >rev $ hg commit -m "With branch." $ hg export 0 > ../r0.patch $ hg export 1 > ../r1.patch $ cd .. $ if python findbranch.py < r0.patch; then > echo "Export of default branch revision has Branch header" 1>&2 > exit 1 > fi $ if python findbranch.py < r1.patch; then > : # Do nothing > else > echo "Export of branch revision is missing Branch header" 1>&2 > exit 1 > fi Make sure import still works with branch information in patches. $ hg init b $ cd b $ hg import ../r0.patch applying ../r0.patch $ hg import ../r1.patch applying ../r1.patch $ cd .. $ hg init c $ cd c $ hg import --exact ../r0.patch applying ../r0.patch $ hg import --exact ../r1.patch applying ../r1.patch Test --exact and patch header separators (issue3356) $ hg strip --no-backup . 1 files updated, 0 files merged, 0 files removed, 0 files unresolved >>> import re >>> p = file('../r1.patch', 'rb').read() >>> p = re.sub(r'Parent\s+', 'Parent ', p) >>> file('../r1-ws.patch', 'wb').write(p) $ hg import --exact ../r1-ws.patch applying ../r1-ws.patch $ cd ..