view tests/test-issue1175.t @ 26945:8a256cee72c8 stable

tags: create new sortdict for performance reasons

sortdict internally maintains a list of keys in insertion order. When a
key is replaced via __setitem__, we .remove() from this list. This
involves a linear scan and array adjustment. This is an expensive
operation.

The tags reading code was calling into sortdict.__setitem__ for each tag
in a read .hgtags revision. For repositories with thousands of tags or
thousands of .hgtags revisions, the overhead from list.remove()
noticeable.

This patch creates a new sortdict() so __setitem__ calls don't incur a
list.remove.

This doesn't appear to have any performance impact on my Firefox
repository. But that's only because tags reading doesn't show up in
profiles to begin with. I'm still waiting to hear from a user with over
10,000 tags and hundreds of heads on the impact of this patch.

https://bz.mercurial-scm.org/1175

  $ hg init
  $ touch a
  $ hg ci -Am0
  adding a

  $ hg mv a a1
  $ hg ci -m1

  $ hg co 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ hg mv a a2
  $ hg up
  note: possible conflict - a was renamed multiple times to:
   a2
   a1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg ci -m2

  $ touch a
  $ hg ci -Am3
  adding a

  $ hg mv a b
  $ hg ci -Am4 a

  $ hg ci --debug --traceback -Am5 b
  committing files:
  b
  warning: can't find ancestor for 'b' copied from 'a'!
  committing manifest
  committing changelog
  committed changeset 5:83a687e8a97c80992ba385bbfd766be181bfb1d1

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 6 changesets, 4 total revisions

  $ hg export --git tip
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID 83a687e8a97c80992ba385bbfd766be181bfb1d1
  # Parent  1d1625283f71954f21d14c3d44d0ad3c019c597f
  5
  
  diff --git a/b b/b
  new file mode 100644

http://bz.selenic.com/show_bug.cgi?id=4476

  $ hg init foo
  $ cd foo
  $ touch a && hg ci -Aqm a
  $ hg mv a b
  $ echo b1 >> b
  $ hg ci -Aqm b1
  $ hg up 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg mv a b
  $ echo b2 >> b
  $ hg ci -Aqm b2
  $ hg graft 1
  grafting 1:5974126fad84 "b1"
  merging b
  warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
  abort: unresolved conflicts, can't continue
  (use hg resolve and hg graft --continue)
  [255]
  $ echo a > b
  $ echo b3 >> b
  $ hg resolve --mark b
  (no more unresolved files)
  $ hg graft --continue
  grafting 1:5974126fad84 "b1"
  warning: can't find ancestor for 'b' copied from 'a'!
  $ hg log -f b -T 'changeset:   {rev}:{node|short}\nsummary:     {desc}\n\n'
  changeset:   3:376d30ccffc0
  summary:     b1
  
  changeset:   2:416baaa2e5e4
  summary:     b2
  
  changeset:   0:3903775176ed
  summary:     a