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.
#testcases tree flat-fncache flat-nofncache
Tests narrow stream clones
$ . "$TESTDIR/narrow-library.sh"
#if tree
$ cat << EOF >> $HGRCPATH
> [experimental]
> treemanifest = 1
> EOF
#endif
#if flat-nofncache
$ cat << EOF >> $HGRCPATH
> [format]
> usefncache = 0
> EOF
#endif
Server setup
$ hg init master
$ cd master
$ mkdir dir
$ mkdir dir/src
$ cd dir/src
$ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done
$ cd ..
$ mkdir tests
$ cd tests
$ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done
$ cd ../../..
Trying to stream clone when the server does not support it
$ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
streaming all changes
remote: abort: server does not support narrow stream clones
abort: pull failed on remote
[100]
Enable stream clone on the server
$ echo "[experimental]" >> master/.hg/hgrc
$ echo "server.stream-narrow-clones=True" >> master/.hg/hgrc
Cloning a specific file when stream clone is supported
$ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
streaming all changes
* files to transfer, * KB of data (glob)
transferred * KB in * seconds (* */sec) (glob)
$ cd narrow
$ ls -A
.hg
$ hg tracked
I path:dir/src/F10
Making sure we have the correct set of requirements
$ hg debugrequires
dotencode (tree !)
dotencode (flat-fncache !)
dirstate-v2 (dirstate-v2 !)
fncache (tree !)
fncache (flat-fncache !)
generaldelta
narrowhg-experimental
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
share-safe
sparserevlog
store
treemanifest (tree !)
Making sure store has the required files
$ ls .hg/store/
00changelog-????????.nd (glob) (rust !)
00changelog.d
00changelog.i
00changelog.n (rust !)
00manifest.i
data
fncache (tree !)
fncache (flat-fncache !)
meta (tree !)
narrowspec
requires
undo
undo.backupfiles
Checking that repository has all the required data and not broken
$ hg verify
checking changesets
checking manifests
checking directory manifests (tree !)
crosschecking files in changesets and manifests
checking files
checking dirstate
checked 40 changesets with 1 changes to 1 files