revisionbranchcache: fall back to slow path if starting readonly (issue4531)
Transitioning to Mercurial versions with revision branch cache could be slow as
long as all operations were readonly (revset queries) and the cache would be
populated but not written back.
Instead, fall back to using the consistently slow path when readonly and the
cache doesn't exist yet. That avoids the overhead of populating the cache
without writing it back.
If not readonly, it will still populate all missing entries initially. That
avoids repeated writing of the cache file with small updates, and it also makes
sure a fully populated cache available for the readonly operations.
N.B. bzr 1.13 has a bug that breaks this test. If you see this
test fail, check your bzr version. Upgrading to bzr 1.13.1
should fix it.
$ . "$TESTDIR/bzr-definitions"
test multiple merges at once
$ mkdir test-multimerge
$ cd test-multimerge
$ bzr init -q source
$ cd source
$ echo content > file
$ bzr add -q file
$ bzr commit -q -m 'Initial add'
$ cd ..
$ bzr branch -q source source-branch1
$ cd source-branch1
$ echo morecontent >> file
$ echo evenmorecontent > file-branch1
$ bzr add -q file-branch1
$ bzr commit -q -m 'Added branch1 file'
$ cd ../source
$ sleep 1
$ echo content > file-parent
$ bzr add -q file-parent
$ bzr commit -q -m 'Added parent file'
$ cd ..
$ bzr branch -q source source-branch2
$ cd source-branch2
$ echo somecontent > file-branch2
$ bzr add -q file-branch2
$ bzr commit -q -m 'Added brach2 file'
$ sleep 1
$ cd ../source
$ bzr merge -q ../source-branch1
$ bzr merge -q --force ../source-branch2
$ bzr commit -q -m 'Merged branches'
$ cd ..
$ hg convert --datesort source source-hg
initializing destination source-hg repository
scanning source...
sorting...
converting...
4 Initial add
3 Added branch1 file
2 Added parent file
1 Added brach2 file
0 Merged branches
$ glog -R source-hg
o 5@source "(octopus merge fixup)" files:
|\
| o 4@source "Merged branches" files: file-branch2
| |\
o---+ 3@source-branch2 "Added brach2 file" files: file-branch2
/ /
| o 2@source "Added parent file" files: file-parent
| |
o | 1@source-branch1 "Added branch1 file" files: file file-branch1
|/
o 0@source "Initial add" files: file
$ manifest source-hg tip
% manifest of tip
644 file
644 file-branch1
644 file-branch2
644 file-parent
$ cd ..