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outdated and unsupported repo format.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.
Tests for the journal extension; records bookmark locations.
$ cat >> testmocks.py << EOF
> # mock out util.getuser() and util.makedate() to supply testable values
> import os
> from mercurial import util
> def mockgetuser():
> return 'foobar'
>
> def mockmakedate():
> filename = os.path.join(os.environ['TESTTMP'], 'testtime')
> try:
> with open(filename, 'rb') as timef:
> time = float(timef.read()) + 1
> except IOError:
> time = 0.0
> with open(filename, 'wb') as timef:
> timef.write(str(time))
> return (time, 0)
>
> util.getuser = mockgetuser
> util.makedate = mockmakedate
> EOF
$ cat >> $HGRCPATH << EOF
> [extensions]
> journal=
> testmocks=`pwd`/testmocks.py
> EOF
Setup repo
$ hg init repo
$ cd repo
Test empty journal
$ hg journal
previous locations of '.':
no recorded locations
$ hg journal foo
previous locations of 'foo':
no recorded locations
Test that working copy changes are tracked
$ echo a > a
$ hg commit -Aqm a
$ hg journal
previous locations of '.':
cb9a9f314b8b commit -Aqm a
$ echo b > a
$ hg commit -Aqm b
$ hg journal
previous locations of '.':
1e6c11564562 commit -Aqm b
cb9a9f314b8b commit -Aqm a
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg journal
previous locations of '.':
cb9a9f314b8b up 0
1e6c11564562 commit -Aqm b
cb9a9f314b8b commit -Aqm a
Test that bookmarks are tracked
$ hg book -r tip bar
$ hg journal bar
previous locations of 'bar':
1e6c11564562 book -r tip bar
$ hg book -f bar
$ hg journal bar
previous locations of 'bar':
cb9a9f314b8b book -f bar
1e6c11564562 book -r tip bar
$ hg up
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
updating bookmark bar
$ hg journal bar
previous locations of 'bar':
1e6c11564562 up
cb9a9f314b8b book -f bar
1e6c11564562 book -r tip bar
Test that bookmarks and working copy tracking is not mixed
$ hg journal
previous locations of '.':
1e6c11564562 up
cb9a9f314b8b up 0
1e6c11564562 commit -Aqm b
cb9a9f314b8b commit -Aqm a
Test that you can list all entries as well as limit the list or filter on them
$ hg book -r tip baz
$ hg journal --all
previous locations of the working copy and bookmarks:
1e6c11564562 baz book -r tip baz
1e6c11564562 bar up
1e6c11564562 . up
cb9a9f314b8b bar book -f bar
1e6c11564562 bar book -r tip bar
cb9a9f314b8b . up 0
1e6c11564562 . commit -Aqm b
cb9a9f314b8b . commit -Aqm a
$ hg journal --limit 2
previous locations of '.':
1e6c11564562 up
cb9a9f314b8b up 0
$ hg journal bar
previous locations of 'bar':
1e6c11564562 up
cb9a9f314b8b book -f bar
1e6c11564562 book -r tip bar
$ hg journal foo
previous locations of 'foo':
no recorded locations
$ hg journal .
previous locations of '.':
1e6c11564562 up
cb9a9f314b8b up 0
1e6c11564562 commit -Aqm b
cb9a9f314b8b commit -Aqm a
$ hg journal "re:ba."
previous locations of 're:ba.':
1e6c11564562 baz book -r tip baz
1e6c11564562 bar up
cb9a9f314b8b bar book -f bar
1e6c11564562 bar book -r tip bar
Test that verbose, JSON, template and commit output work
$ hg journal --verbose --all
previous locations of the working copy and bookmarks:
000000000000 -> 1e6c11564562 foobar baz 1970-01-01 00:00 +0000 book -r tip baz
cb9a9f314b8b -> 1e6c11564562 foobar bar 1970-01-01 00:00 +0000 up
cb9a9f314b8b -> 1e6c11564562 foobar . 1970-01-01 00:00 +0000 up
1e6c11564562 -> cb9a9f314b8b foobar bar 1970-01-01 00:00 +0000 book -f bar
000000000000 -> 1e6c11564562 foobar bar 1970-01-01 00:00 +0000 book -r tip bar
1e6c11564562 -> cb9a9f314b8b foobar . 1970-01-01 00:00 +0000 up 0
cb9a9f314b8b -> 1e6c11564562 foobar . 1970-01-01 00:00 +0000 commit -Aqm b
000000000000 -> cb9a9f314b8b foobar . 1970-01-01 00:00 +0000 commit -Aqm a
$ hg journal --verbose -Tjson
[
{
"command": "up",
"date": [5.0, 0],
"name": ".",
"newhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"],
"oldhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
"user": "foobar"
},
{
"command": "up 0",
"date": [2.0, 0],
"name": ".",
"newhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
"oldhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"],
"user": "foobar"
},
{
"command": "commit -Aqm b",
"date": [1.0, 0],
"name": ".",
"newhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"],
"oldhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
"user": "foobar"
},
{
"command": "commit -Aqm a",
"date": [0.0, 0],
"name": ".",
"newhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
"oldhashes": ["0000000000000000000000000000000000000000"],
"user": "foobar"
}
]
$ cat <<EOF >> $HGRCPATH
> [templates]
> j = "{oldhashes % '{node|upper}'} -> {newhashes % '{node|upper}'}
> - user: {user}
> - command: {command}
> - date: {date|rfc3339date}
> - newhashes: {newhashes}
> - oldhashes: {oldhashes}
> "
> EOF
$ hg journal -Tj -l1
previous locations of '.':
CB9A9F314B8B07BA71012FCDBC544B5A4D82FF5B -> 1E6C11564562B4ED919BACA798BC4338BD299D6A
- user: foobar
- command: up
- date: 1970-01-01T00:00:05+00:00
- newhashes: 1e6c11564562b4ed919baca798bc4338bd299d6a
- oldhashes: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b
$ hg journal --commit
previous locations of '.':
1e6c11564562 up
changeset: 1:1e6c11564562
bookmark: bar
bookmark: baz
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
cb9a9f314b8b up 0
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
1e6c11564562 commit -Aqm b
changeset: 1:1e6c11564562
bookmark: bar
bookmark: baz
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
cb9a9f314b8b commit -Aqm a
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Test for behaviour on unexpected storage version information
$ printf '42\0' > .hg/namejournal
$ hg journal
previous locations of '.':
abort: unknown journal file version '42'
[255]
$ hg book -r tip doomed
unsupported journal file version '42'