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view tests/test-contrib.t @ 32697:19b9fc40cc51
revlog: skeleton support for version 2 revlogs
There are a number of improvements we want to make to revlogs
that will require a new version - version 2. It is unclear what the
full set of improvements will be or when we'll be done with them.
What I do know is that the process will likely take longer than a
single release, will require input from various stakeholders to
evaluate changes, and will have many contentious debates and
bikeshedding.
It is unrealistic to develop revlog version 2 up front: there
are just too many uncertainties that we won't know until things
are implemented and experiments are run. Some changes will also
be invasive and prone to bit rot, so sitting on dozens of patches
is not practical.
This commit introduces skeleton support for version 2 revlogs in
a way that is flexible and not bound by backwards compatibility
concerns.
An experimental repo requirement for denoting revlog v2 has been
added. The requirement string has a sub-version component to it.
This will allow us to declare multiple requirements in the course
of developing revlog v2. Whenever we change the in-development
revlog v2 format, we can tweak the string, creating a new
requirement and locking out old clients. This will allow us to
make as many backwards incompatible changes and experiments to
revlog v2 as we want. In other words, we can land code and make
meaningful progress towards revlog v2 while still maintaining
extreme format flexibility up until the point we freeze the
format and remove the experimental labels.
To enable the new repo requirement, you must supply an experimental
and undocumented config option. But not just any boolean flag
will do: you need to explicitly use a value that no sane person
should ever type. This is an additional guard against enabling
revlog v2 on an installation it shouldn't be enabled on. The
specific scenario I'm trying to prevent is say a user with a
4.4 client with a frozen format enabling the option but then
downgrading to 4.3 and accidentally creating repos with an
outdated and unsupported repo format. Requiring a "challenge"
string should prevent this.
Because the format is not yet finalized and I don't want to take
any chances, revlog v2's version is currently 0xDEAD. I figure
squatting on a value we're likely never to use as an actual revlog
version to mean "internal testing only" is acceptable. And
"dead" is easily recognized as something meaningful.
There is a bunch of cleanup that is needed before work on revlog
v2 begins in earnest. I plan on doing that work once this patch
is accepted and we're comfortable with the idea of starting down
this path.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 19 May 2017 20:29:11 -0700 |
parents | c3e9269d9602 |
children | 8e6f4939a69a |
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Set vars: $ CONTRIBDIR="$TESTDIR/../contrib" Prepare repo-a: $ hg init repo-a $ cd repo-a $ echo this is file a > a $ hg add a $ hg commit -m first $ echo adding to file a >> a $ hg commit -m second $ echo adding more to file a >> a $ hg commit -m third $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions Dumping revlog of file a to stdout: $ python "$CONTRIBDIR/dumprevlog" .hg/store/data/a.i file: .hg/store/data/a.i node: 183d2312b35066fb6b3b449b84efc370d50993d0 linkrev: 0 parents: 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 length: 15 -start- this is file a -end- node: b1047953b6e6b633c0d8197eaa5116fbdfd3095b linkrev: 1 parents: 183d2312b35066fb6b3b449b84efc370d50993d0 0000000000000000000000000000000000000000 length: 32 -start- this is file a adding to file a -end- node: 8c4fd1f7129b8cdec6c7f58bf48fb5237a4030c1 linkrev: 2 parents: b1047953b6e6b633c0d8197eaa5116fbdfd3095b 0000000000000000000000000000000000000000 length: 54 -start- this is file a adding to file a adding more to file a -end- Dump all revlogs to file repo.dump: $ find .hg/store -name "*.i" | sort | xargs python "$CONTRIBDIR/dumprevlog" > ../repo.dump $ cd .. Undumping into repo-b: $ hg init repo-b $ cd repo-b $ python "$CONTRIBDIR/undumprevlog" < ../repo.dump .hg/store/00changelog.i .hg/store/00manifest.i .hg/store/data/a.i $ cd .. Rebuild fncache with clone --pull: $ hg clone --pull -U repo-b repo-c requesting all changes adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files Verify: $ hg -R repo-c verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions Compare repos: $ hg -R repo-c incoming repo-a comparing with repo-a searching for changes no changes found [1] $ hg -R repo-a incoming repo-c comparing with repo-c searching for changes no changes found [1] Test simplemerge command: $ cp "$CONTRIBDIR/simplemerge" . $ echo base > base $ echo local > local $ cat base >> local $ cp local orig $ cat base > other $ echo other >> other changing local directly $ python simplemerge local base other && echo "merge succeeded" merge succeeded $ cat local local base other $ cp orig local printing to stdout $ python simplemerge -p local base other local base other local: $ cat local local base conflicts $ cp base conflict-local $ cp other conflict-other $ echo not other >> conflict-local $ echo end >> conflict-local $ echo end >> conflict-other $ python simplemerge -p conflict-local base conflict-other base <<<<<<< conflict-local not other ======= other >>>>>>> conflict-other end [1] 1 label $ python simplemerge -p -L foo conflict-local base conflict-other base <<<<<<< foo not other ======= other >>>>>>> conflict-other end [1] 2 labels $ python simplemerge -p -L foo -L bar conflict-local base conflict-other base <<<<<<< foo not other ======= other >>>>>>> bar end [1] 3 labels $ python simplemerge -p -L foo -L bar -L base conflict-local base conflict-other base <<<<<<< foo not other end ||||||| base ======= other end >>>>>>> bar [1] too many labels $ python simplemerge -p -L foo -L bar -L baz -L buz conflict-local base conflict-other abort: can only specify three labels. [255] binary file $ $PYTHON -c "f = file('binary-local', 'w'); f.write('\x00'); f.close()" $ cat orig >> binary-local $ python simplemerge -p binary-local base other warning: binary-local looks like a binary file. [1] binary file --text $ python simplemerge -a -p binary-local base other 2>&1 warning: binary-local looks like a binary file. \x00local (esc) base other help $ python simplemerge --help simplemerge [OPTS] LOCAL BASE OTHER Simple three-way file merge utility with a minimal feature set. Apply to LOCAL the changes necessary to go from BASE to OTHER. By default, LOCAL is overwritten with the results of this operation. options: -L --label labels to use on conflict markers -a --text treat all files as text -p --print print results instead of overwriting LOCAL --no-minimal no effect (DEPRECATED) -h --help display help and exit -q --quiet suppress output wrong number of arguments $ python simplemerge simplemerge: wrong number of arguments simplemerge [OPTS] LOCAL BASE OTHER Simple three-way file merge utility with a minimal feature set. Apply to LOCAL the changes necessary to go from BASE to OTHER. By default, LOCAL is overwritten with the results of this operation. options: -L --label labels to use on conflict markers -a --text treat all files as text -p --print print results instead of overwriting LOCAL --no-minimal no effect (DEPRECATED) -h --help display help and exit -q --quiet suppress output [1] bad option $ python simplemerge --foo -p local base other simplemerge: option --foo not recognized simplemerge [OPTS] LOCAL BASE OTHER Simple three-way file merge utility with a minimal feature set. Apply to LOCAL the changes necessary to go from BASE to OTHER. By default, LOCAL is overwritten with the results of this operation. options: -L --label labels to use on conflict markers -a --text treat all files as text -p --print print results instead of overwriting LOCAL --no-minimal no effect (DEPRECATED) -h --help display help and exit -q --quiet suppress output [1]