view tests/test-flags.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

  $ "$TESTDIR/hghave" execbit || exit 80

  $ umask 027

  $ hg init test1
  $ cd test1
  $ touch a b
  $ hg add a b
  $ hg ci -m "added a b"

  $ cd ..
  $ hg clone test1 test3
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg init test2
  $ cd test2
  $ hg pull ../test1
  pulling from ../test1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files
  (run 'hg update' to get a working copy)
  $ hg co
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ chmod +x a
  $ hg ci -m "chmod +x a"

the changelog should mention file a:

  $ hg tip --template '{files}\n'
  a

  $ cd ../test1
  $ echo 123 >>a
  $ hg ci -m "a updated"

  $ hg pull ../test2
  pulling from ../test2
  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 heads
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:c6ecefc45368
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a updated
  
  $ hg history
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:c6ecefc45368
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a updated
  
  changeset:   0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     added a b
  

  $ hg -v merge
  resolving manifests
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cd ../test3
  $ echo 123 >>b
  $ hg ci -m "b updated"

  $ hg pull ../test2
  pulling from ../test2
  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 heads
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:dc57ead75f79
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b updated
  
  $ hg history
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:dc57ead75f79
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b updated
  
  changeset:   0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     added a b
  

  $ hg -v merge
  resolving manifests
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ ls -l ../test[123]/a > foo
  $ cut -b 1-10 < foo
  -rwxr-x---
  -rwxr-x---
  -rwxr-x---

  $ hg debugindex a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
  $ hg debugindex -R ../test2 a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
  $ hg debugindex -R ../test1 a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
       1         0       5  .....       1 7fe919cc0336 b80de5d13875 000000000000 (re)

  $ cd ..