obsolete: order of magnitude speedup in _computebumpedset
Reminder: a changeset is said "bumped" if it tries to obsolete a immutable
changeset.
The previous algorithm for computing bumped changeset was:
1) Get all public changesets
2) Find all they successors
3) Search for stuff that are eligible for being "bumped"
(mutable and non obsolete)
The entry size of this algorithm is `O(len(public))` which is mostly the same as
`O(len(repo))`. Even this this approach mean fewer obsolescence marker are
traveled, this is not very scalable.
The new algorithm is:
1) For each potential bumped changesets (non obsolete mutable)
2) iterate over precursors
3) if a precursors is public. changeset is bumped
We travel more obsolescence marker, but the entry size is much smaller since
the amount of potential bumped should remains mostly stable with time `O(1)`.
On some confidential gigantic repo this move bumped computation from 15.19s to
0.46s (×33 speedup…). On "smaller" repo (mercurial, cubicweb's review) no
significant gain were seen. The additional traversal of obsolescence marker is
probably probably counter balance the advantage of it.
Other optimisation could be done in the future (eg: sharing precursors cache
for divergence detection)
$ "$TESTDIR/hghave" hardlink || exit 80
$ echo "[extensions]" >> $HGRCPATH
$ echo "relink=" >> $HGRCPATH
$ fix_path() {
> tr '\\' /
> }
$ cat > arelinked.py <<EOF
> import sys, os
> from mercurial import util
> path1, path2 = sys.argv[1:3]
> if util.samefile(path1, path2):
> print '%s == %s' % (path1, path2)
> else:
> print '%s != %s' % (path1, path2)
> EOF
create source repository
$ hg init repo
$ cd repo
$ echo a > a
$ echo b > b
$ hg ci -Am addfile
adding a
adding b
$ cat "$TESTDIR/binfile.bin" >> a
$ cat "$TESTDIR/binfile.bin" >> b
$ hg ci -Am changefiles
make another commit to create files larger than 1 KB to test
formatting of final byte count
$ cat "$TESTDIR/binfile.bin" >> a
$ cat "$TESTDIR/binfile.bin" >> b
$ hg ci -m anotherchange
don't sit forever trying to double-lock the source repo
$ hg relink .
relinking $TESTTMP/repo/.hg/store to $TESTTMP/repo/.hg/store (glob)
there is nothing to relink
Test files are read in binary mode
$ python -c "file('.hg/store/data/dummy.i', 'wb').write('a\r\nb\n')"
$ cd ..
clone and pull to break links
$ hg clone --pull -r0 repo clone
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd clone
$ hg pull -q
$ echo b >> b
$ hg ci -m changeb
created new head
$ python -c "file('.hg/store/data/dummy.i', 'wb').write('a\nb\r\n')"
relink
$ hg relink --debug | fix_path
relinking $TESTTMP/repo/.hg/store to $TESTTMP/clone/.hg/store
tip has 2 files, estimated total number of files: 3
collecting: 00changelog.i 1/3 files (33.33%)
collecting: 00manifest.i 2/3 files (66.67%)
collecting: a.i 3/3 files (100.00%)
collecting: b.i 4/3 files (133.33%)
collecting: dummy.i 5/3 files (166.67%)
collected 5 candidate storage files
not linkable: 00changelog.i
not linkable: 00manifest.i
pruning: data/a.i 3/5 files (60.00%)
not linkable: data/b.i
pruning: data/dummy.i 5/5 files (100.00%)
pruned down to 2 probably relinkable files
relinking: data/a.i 1/2 files (50.00%)
not linkable: data/dummy.i
relinked 1 files (1.37 KB reclaimed)
$ cd ..
check hardlinks
$ python arelinked.py repo/.hg/store/data/a.i clone/.hg/store/data/a.i
repo/.hg/store/data/a.i == clone/.hg/store/data/a.i
$ python arelinked.py repo/.hg/store/data/b.i clone/.hg/store/data/b.i
repo/.hg/store/data/b.i != clone/.hg/store/data/b.i