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.
Force revlog max inline value to be smaller than default
$ mkdir $TESTTMP/ext
$ cat << EOF > $TESTTMP/ext/small_inline.py
> from mercurial import revlog
> revlog._maxinline = 8
> EOF
$ cat << EOF >> $HGRCPATH
> [extensions]
> small_inline=$TESTTMP/ext/small_inline.py
> EOF
$ hg init repo
$ cd repo
Try on an empty repository
$ hg debug-revlog-stats
rev-count data-size inl type target
$ mkdir folder
$ touch a b folder/c folder/d
$ hg commit -Aqm 0
$ echo "text" > a
$ hg rm b
$ echo "longer string" > folder/d
$ hg commit -Aqm 1
Differences in data size observed with pure is due to different compression
algorithms
$ hg debug-revlog-stats
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)
2 6 yes file a
1 0 yes file b
1 0 yes file folder/c
2 15 no file folder/d
Test 'changelog' command argument
$ hg debug-revlog-stats -c
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
Test 'manifest' command argument
$ hg debug-revlog-stats -m
rev-count data-size inl type target
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)
Test 'file' command argument
$ hg debug-revlog-stats -f
rev-count data-size inl type target
2 6 yes file a
1 0 yes file b
1 0 yes file folder/c
2 15 no file folder/d
Test multiple command arguments
$ hg debug-revlog-stats -cm
rev-count data-size inl type target
2 138 no changelog (no-pure !)
2 137 no changelog (pure !)
2 177 no manifest (no-pure !)
2 168 no manifest (pure !)