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outdated and unsupported repo format.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.
============================================
Testing obsolescence markers push: Cases D.4
============================================
Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).
This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.
Category D: Partial Information Case
TestCase 4: Unknown changeset in between known changesets
D.4 Unknown changeset in between known one
==========================================
.. Mostly a clarification case
..
.. {{{
.. B ø⇠◌⇠○ B''
.. | |
.. A ø⇠◌⇠◔ A'
.. \ /
.. ● O
..
.. }}}
..
.. Should be treated as A.3 case:
..
.. {{{
..
.. B ø⇠○ B''
.. | |
.. A ø⇠◔ A'
.. |/
.. ● O
..
.. }}}
Setup
-----
$ . $TESTDIR/testlib/exchange-obsmarker-util.sh
initial
$ setuprepos D.4
creating test repo for test case D.4
- pulldest
- main
- pushdest
cd into `main` and proceed with env setup
$ cd main
$ mkcommit A0
$ mkcommit B0
$ hg update -q 0
$ mkcommit A1
created new head
$ mkcommit B1
$ hg debugobsolete `getid 'desc(A0)'` aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
$ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A1)'`
$ hg debugobsolete `getid 'desc(B0)'` bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
$ hg debugobsolete bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb `getid 'desc(B1)'`
$ hg log -G --hidden
@ 069b05c3876d (draft): B1
|
o e5ea8f9c7314 (draft): A1
|
| x 6e72f0a95b5e (draft): B0
| |
| x 28b51eb45704 (draft): A0
|/
o a9bdc8b26820 (public): O
$ inspect_obsmarkers
obsstore content
================
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
$ cd ..
$ cd ..
Actual Test
-----------
$ dotest D.4 A1
## Running testcase D.4
# testing echange of "A1" (e5ea8f9c7314)
## initial state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
# obstore: pulldest
## pushing "A1" from main to pushdest
pushing to pushdest
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
remote: 2 new obsolescence markers
## post push state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
## pulling "e5ea8f9c7314" from main into pulldest
pulling from main
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
2 new obsolescence markers
(run 'hg update' to get a working copy)
## post pull state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}