branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
https://bz.mercurial-scm.org/672
# 0-2-4
# \ \ \
# 1-3-5
#
# rename in #1, content change in #4.
$ hg init repo
$ cd repo
$ touch 1
$ touch 2
$ hg commit -Am init # 0
adding 1
adding 2
$ hg rename 1 1a
$ hg commit -m rename # 1
$ hg co -C 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo unrelated >> 2
$ hg ci -m unrelated1 # 2
created new head
$ hg merge --debug 1
unmatched files in other:
1a
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
on remote side:
src: '1' -> dst: '1a'
checking for directory renames
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 81f4b099af3d, local: c64f439569a9+, remote: c12dcd37c90a
1: other deleted -> r
removing 1
1a: remote created -> g
getting 1a
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -m merge1 # 3
$ hg co -C 2
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo hello >> 1
$ hg ci -m unrelated2 # 4
created new head
$ hg co -C 3
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge -y --debug 4
unmatched files in local:
1a
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
on local side:
src: '1' -> dst: '1a' *
checking for directory renames
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c64f439569a9, local: f4a9cff3cd0b+, remote: 746e9549ea96
starting 4 threads for background file closing (?)
preserving 1a for resolve of 1a
1a: local copied/moved from 1 -> m
picked tool ':merge' for 1a (binary False symlink False changedelete False)
merging 1a and 1 to 1a
my 1a@f4a9cff3cd0b+ other 1@746e9549ea96 ancestor 1@c64f439569a9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg co -C 4
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge -y --debug 3
unmatched files in other:
1a
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
on remote side:
src: '1' -> dst: '1a' *
checking for directory renames
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: c64f439569a9, local: 746e9549ea96+, remote: f4a9cff3cd0b
starting 4 threads for background file closing (?)
preserving 1 for resolve of 1a
removing 1
1a: remote moved from 1 -> m
picked tool ':merge' for 1a (binary False symlink False changedelete False)
merging 1 and 1a to 1a
my 1a@746e9549ea96+ other 1a@f4a9cff3cd0b ancestor 1@c64f439569a9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)