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.
$ . "$TESTDIR/narrow-library.sh"
create full repo
$ hg init master
$ cd master
$ echo init > init
$ hg ci -Aqm 'initial'
$ mkdir inside
$ echo inside > inside/f1
$ mkdir outside
$ echo outside > outside/f1
$ hg ci -Aqm 'add inside and outside'
$ echo modified > inside/f1
$ hg ci -qm 'modify inside'
$ echo modified > outside/f1
$ hg ci -qm 'modify outside'
$ cd ..
$ hg clone --narrow ssh://user@dummy/master narrow --include inside
requesting all changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 2 changes to 1 files
new changesets *:* (glob)
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd narrow
$ hg debugindex -c
rev linkrev nodeid p1-nodeid p2-nodeid
0 0 9958b1af2add 000000000000 000000000000
1 1 2db4ce2a3bfe 9958b1af2add 000000000000
2 2 0980ee31a742 2db4ce2a3bfe 000000000000
3 3 4410145019b7 0980ee31a742 000000000000
$ hg update -q 0
Can update to revision with changes inside
$ hg update -q 'desc("add inside and outside")'
$ hg update -q 'desc("modify inside")'
$ find *
inside
inside/f1
$ cat inside/f1
modified
Can update to revision with changes outside
$ hg update -q 'desc("modify outside")'
$ find *
inside
inside/f1
$ cat inside/f1
modified
Can update with a deleted file inside
$ hg rm inside/f1
$ hg update -q 'desc("modify inside")'
$ hg update -q 'desc("modify outside")'
$ hg update -q 'desc("initial")'
$ hg update -q 'desc("modify inside")'
Can update with a moved file inside
$ hg mv inside/f1 inside/f2
$ hg update -q 'desc("modify outside")'
$ hg update -q 'desc("add inside and outside")'
$ hg update -q 'desc("modify inside")'