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outdated and unsupported repo format.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.
#require serve
$ hg init test
$ cd test
$ echo foo>foo
$ hg addremove
adding foo
$ hg commit -m 1
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ hg serve -p $HGPORT -d --pid-file=hg.pid
$ cat hg.pid >> $DAEMON_PIDS
$ cd ..
$ hg clone --pull http://foo:bar@localhost:$HGPORT/ copy
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd copy
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ hg co
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cat foo
foo
$ hg manifest --debug
2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 foo
$ hg pull
pulling from http://foo@localhost:$HGPORT/
searching for changes
no changes found
$ hg rollback --dry-run --verbose
repository tip rolled back to revision -1 (undo pull: http://foo:***@localhost:$HGPORT/)
Test pull of non-existing 20 character revision specification, making sure plain ascii identifiers
not are encoded like a node:
$ hg pull -r 'xxxxxxxxxxxxxxxxxxxy'
pulling from http://foo@localhost:$HGPORT/
abort: unknown revision 'xxxxxxxxxxxxxxxxxxxy'!
[255]
$ hg pull -r 'xxxxxxxxxxxxxxxxxx y'
pulling from http://foo@localhost:$HGPORT/
abort: unknown revision '7878787878787878787878787878787878782079'!
[255]
Issue622: hg init && hg pull -u URL doesn't checkout default branch
$ cd ..
$ hg init empty
$ cd empty
$ hg pull -u ../test
pulling from ../test
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Test 'file:' uri handling:
$ hg pull -q file://../test-does-not-exist
abort: file:// URLs can only refer to localhost
[255]
$ hg pull -q file://../test
abort: file:// URLs can only refer to localhost
[255]
MSYS changes 'file:' into 'file;'
#if no-msys
$ hg pull -q file:../test # no-msys
#endif
It's tricky to make file:// URLs working on every platform with
regular shell commands.
$ URL=`$PYTHON -c "import os; print 'file://foobar' + ('/' + os.getcwd().replace(os.sep, '/')).replace('//', '/') + '/../test'"`
$ hg pull -q "$URL"
abort: file:// URLs can only refer to localhost
[255]
$ URL=`$PYTHON -c "import os; print 'file://localhost' + ('/' + os.getcwd().replace(os.sep, '/')).replace('//', '/') + '/../test'"`
$ hg pull -q "$URL"
$ cd ..