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 > x
$ hg commit -qAm x
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cd master
$ echo xx > x
$ hg commit -qAm x2
$ cd ..
# Test cache misses with read only permissions on server
$ chmod -R a-w master/.hg/remotefilelogcache
$ cd shallow
$ hg pull -q
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cd ..
$ chmod -R u+w master/.hg/remotefilelogcache
#if suidbit
# Test setting up shared cache with the right permissions
# (this is hard to test in a cross platform way, so we just make sure nothing
# crashes)
$ rm -rf $CACHEDIR
$ umask 002
$ mkdir $CACHEDIR
$ hg -q clone --shallow ssh://user@dummy/master shallow2 --config remotefilelog.cachegroup="`id -g -n`"
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over * (glob)
$ ls -ld $CACHEDIR/11
drwxrws* $TESTTMP/hgcache/11 (glob)
#endif