Mercurial > hg
view tests/test-merge-remove.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 | 0a63e91c519d |
children | e4d7cbc94219 |
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$ hg init $ echo foo > foo $ echo bar > bar $ hg ci -qAm 'add foo bar' $ echo foo2 >> foo $ echo bleh > bar $ hg ci -m 'change foo bar' $ hg up -qC 0 $ hg mv foo foo1 $ echo foo1 > foo1 $ hg cat foo >> foo1 $ hg ci -m 'mv foo foo1' created new head $ hg merge merging foo1 and foo to foo1 1 files updated, 1 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg debugstate --nodates n 0 -2 bar m 644 14 foo1 copy: foo -> foo1 $ hg st -q M bar M foo1 Removing foo1 and bar: $ cp foo1 F $ cp bar B $ hg rm -f foo1 bar $ hg debugstate --nodates r 0 -2 bar r 0 -1 foo1 copy: foo -> foo1 $ hg st -qC R bar R foo1 Re-adding foo1 and bar: $ cp F foo1 $ cp B bar $ hg add -v foo1 bar adding bar adding foo1 $ hg debugstate --nodates n 0 -2 bar m 644 14 foo1 copy: foo -> foo1 $ hg st -qC M bar M foo1 foo Reverting foo1 and bar: $ hg revert -vr . foo1 bar saving current version of bar as bar.orig reverting bar saving current version of foo1 as foo1.orig reverting foo1 $ hg debugstate --nodates n 0 -2 bar m 644 14 foo1 copy: foo -> foo1 $ hg st -qC M bar M foo1 foo $ hg diff