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.
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > foo
$ echo y > bar
$ hg commit -qAm one
$ hg tag tag1
$ cd ..
# clone with tags
$ hg clone --shallow ssh://user@dummy/master shallow --noupdate --config remotefilelog.excludepattern=.hgtags
streaming all changes
4 files to transfer, 662 bytes of data (no-zstd !)
transferred 662 bytes in * seconds (* */sec) (glob) (no-zstd !)
4 files to transfer, 665 bytes of data (zstd no-rust !)
transferred 665 bytes in * seconds (* */sec) (glob) (zstd no-rust !)
6 files to transfer, 791 bytes of data (zstd rust !)
transferred 791 bytes in * seconds (*/sec) (glob) (zstd rust !)
searching for changes
no changes found
$ cat >> shallow/.hg/hgrc <<EOF
> [remotefilelog]
> cachepath=$PWD/hgcache
> debug=True
> reponame = master
> excludepattern=.hgtags
> [extensions]
> remotefilelog=
> EOF
$ cd shallow
$ ls .hg/store/data
~2ehgtags.i
$ hg tags
tip 1:6ce44dcfda68
tag1 0:e0360bc0d9e1
$ hg update
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
# pull with tags
$ cd ../master
$ hg tag tag2
$ cd ../shallow
$ hg pull
pulling from ssh://user@dummy/master
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files
new changesets 6a22dfa4fd34
(run 'hg update' to get a working copy)
$ hg tags
tip 2:6a22dfa4fd34
tag2 1:6ce44dcfda68
tag1 0:e0360bc0d9e1
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ ls .hg/store/data
~2ehgtags.i
$ hg log -l 1 --stat
changeset: 2:6a22dfa4fd34
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag tag2 for changeset 6ce44dcfda68
.hgtags | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)