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.
$ cat >> $HGRCPATH << EOF
> [extensions]
> fastannotate=
> EOF
$ hg init repo
$ cd repo
$ for i in 0 1 2 3 4; do
> echo $i >> a
> echo $i >> b
> hg commit -A -m $i a b
> done
use the "debugbuildannotatecache" command to build annotate cache at rev 0
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=0
fastannotate: a: 1 new changesets in the main branch
fastannotate: b: 1 new changesets in the main branch
"debugbuildannotatecache" should work with broken cache (and other files would
be built without being affected). note: linelog being broken is only noticed
when we try to append to it.
$ echo 'CORRUPT!' >> .hg/fastannotate/default/a.m
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=1
fastannotate: a: rebuilding broken cache
fastannotate: a: 2 new changesets in the main branch
fastannotate: b: 1 new changesets in the main branch
$ echo 'CANNOT REUSE!' > .hg/fastannotate/default/a.l
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=2
fastannotate: a: rebuilding broken cache
fastannotate: a: 3 new changesets in the main branch
fastannotate: b: 1 new changesets in the main branch
$ rm .hg/fastannotate/default/a.m
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=3
fastannotate: a: rebuilding broken cache
fastannotate: a: 4 new changesets in the main branch
fastannotate: b: 1 new changesets in the main branch
$ rm .hg/fastannotate/default/a.l
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=3
$ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=4
fastannotate: a: rebuilding broken cache
fastannotate: a: 5 new changesets in the main branch
fastannotate: b: 1 new changesets in the main branch
"fastannotate" should deal with file corruption as well
$ rm -rf .hg/fastannotate
$ hg fastannotate --debug -r 0 a
fastannotate: a: 1 new changesets in the main branch
0: 0
$ echo 'CORRUPT!' >> .hg/fastannotate/default/a.m
$ hg fastannotate --debug -r 0 a
fastannotate: a: cache broken and deleted
fastannotate: a: 1 new changesets in the main branch
0: 0
$ echo 'CORRUPT!' > .hg/fastannotate/default/a.l
$ hg fastannotate --debug -r 1 a
fastannotate: a: cache broken and deleted
fastannotate: a: 2 new changesets in the main branch
0: 0
1: 1
$ rm .hg/fastannotate/default/a.l
$ hg fastannotate --debug -r 1 a
fastannotate: a: using fast path (resolved fctx: True)
fastannotate: a: cache broken and deleted
fastannotate: a: 2 new changesets in the main branch
0: 0
1: 1
$ rm .hg/fastannotate/default/a.m
$ hg fastannotate --debug -r 2 a
fastannotate: a: cache broken and deleted
fastannotate: a: 3 new changesets in the main branch
0: 0
1: 1
2: 2