view tests/test-generaldelta.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outdated and unsupported repo format.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.

Check whether size of generaldelta revlog is not bigger than its
regular equivalent. Test would fail if generaldelta was naive
implementation of parentdelta: third manifest revision would be fully
inserted due to big distance from its paren revision (zero).

  $ hg init repo --config format.generaldelta=no --config format.usegeneraldelta=no
  $ cd repo
  $ echo foo > foo
  $ echo bar > bar
  $ echo baz > baz
  $ hg commit -q -Am boo
  $ hg clone --pull . ../gdrepo -q --config format.generaldelta=yes
  $ for r in 1 2 3; do
  >   echo $r > foo
  >   hg commit -q -m $r
  >   hg up -q -r 0
  >   hg pull . -q -r $r -R ../gdrepo
  > done

  $ cd ..
  >>> from __future__ import print_function
  >>> import os
  >>> regsize = os.stat("repo/.hg/store/00manifest.i").st_size
  >>> gdsize = os.stat("gdrepo/.hg/store/00manifest.i").st_size
  >>> if regsize < gdsize:
  ...     print('generaldata increased size of manifest')

Verify rev reordering doesnt create invalid bundles (issue4462)
This requires a commit tree that when pulled will reorder manifest revs such
that the second manifest to create a file rev will be ordered before the first
manifest to create that file rev. We also need to do a partial pull to ensure
reordering happens. At the end we verify the linkrev points at the earliest
commit.

  $ hg init server --config format.generaldelta=True
  $ cd server
  $ touch a
  $ hg commit -Aqm a
  $ echo x > x
  $ echo y > y
  $ hg commit -Aqm xy
  $ hg up -q '.^'
  $ echo x > x
  $ echo z > z
  $ hg commit -Aqm xz
  $ hg up -q 1
  $ echo b > b
  $ hg commit -Aqm b
  $ hg merge -q 2
  $ hg commit -Aqm merge
  $ echo c > c
  $ hg commit -Aqm c
  $ hg log -G -T '{rev} {shortest(node)} {desc}'
  @  5 ebb8 c
  |
  o    4 baf7 merge
  |\
  | o  3 a129 b
  | |
  o |  2 958c xz
  | |
  | o  1 f00c xy
  |/
  o  0 3903 a
  
  $ cd ..
  $ hg init client --config format.generaldelta=false --config format.usegeneraldelta=false
  $ cd client
  $ hg pull -q ../server -r 4
  $ hg debugindex x
     rev    offset  length   base linkrev nodeid       p1           p2
       0         0       3      0       1 1406e7411862 000000000000 000000000000

  $ cd ..

Test "usegeneraldelta" config
(repo are general delta, but incoming bundle are not re-deltafied)

delta coming from the server base delta server are not recompressed.
(also include the aggressive version for comparison)

  $ hg clone repo --pull --config format.usegeneraldelta=1 usegd
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 6 changes to 3 files (+2 heads)
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone repo --pull --config format.generaldelta=1 full
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 6 changes to 3 files (+2 heads)
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R repo debugindex -m
     rev    offset  length   base linkrev nodeid       p1           p2
       0         0     104      0       0 cef96823c800 000000000000 000000000000
       1       104      57      0       1 58ab9a8d541d cef96823c800 000000000000
       2       161      57      0       2 134fdc6fd680 cef96823c800 000000000000
       3       218     104      3       3 723508934dad cef96823c800 000000000000
  $ hg -R usegd debugindex -m
     rev    offset  length  delta linkrev nodeid       p1           p2
       0         0     104     -1       0 cef96823c800 000000000000 000000000000
       1       104      57      0       1 58ab9a8d541d cef96823c800 000000000000
       2       161      57      1       2 134fdc6fd680 cef96823c800 000000000000
       3       218      57      0       3 723508934dad cef96823c800 000000000000
  $ hg -R full debugindex -m
     rev    offset  length  delta linkrev nodeid       p1           p2
       0         0     104     -1       0 cef96823c800 000000000000 000000000000
       1       104      57      0       1 58ab9a8d541d cef96823c800 000000000000
       2       161      57      0       2 134fdc6fd680 cef96823c800 000000000000
       3       218      57      0       3 723508934dad cef96823c800 000000000000

Test format.aggressivemergedeltas

  $ hg init --config format.generaldelta=1 aggressive
  $ cd aggressive
  $ cat << EOF >> .hg/hgrc
  > [format]
  > generaldelta = 1
  > EOF
  $ touch a b c d e
  $ hg commit -Aqm side1
  $ hg up -q null
  $ touch x y
  $ hg commit -Aqm side2

- Verify non-aggressive merge uses p1 (commit 1) as delta parent
  $ hg merge -q 0
  $ hg commit -q -m merge
  $ hg debugindex -m
     rev    offset  length  delta linkrev nodeid       p1           p2
       0         0      59     -1       0 8dde941edb6e 000000000000 000000000000
       1        59      61      0       1 315c023f341d 000000000000 000000000000
       2       120      65      1       2 2ab389a983eb 315c023f341d 8dde941edb6e

  $ hg strip -q -r . --config extensions.strip=

- Verify aggressive merge uses p2 (commit 0) as delta parent
  $ hg up -q -C 1
  $ hg merge -q 0
  $ hg commit -q -m merge --config format.aggressivemergedeltas=True
  $ hg debugindex -m
     rev    offset  length  delta linkrev nodeid       p1           p2
       0         0      59     -1       0 8dde941edb6e 000000000000 000000000000
       1        59      61      0       1 315c023f341d 000000000000 000000000000
       2       120      62      0       2 2ab389a983eb 315c023f341d 8dde941edb6e

Test that strip bundle use bundle2
  $ hg --config extensions.strip= strip .
  0 files updated, 0 files merged, 5 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/aggressive/.hg/strip-backup/1c5d4dc9a8b8-6c68e60c-backup.hg (glob)
  $ hg debugbundle .hg/strip-backup/*
  Stream params: sortdict([('Compression', 'BZ')])
  changegroup -- "sortdict([('version', '02'), ('nbchanges', '1')])"
      1c5d4dc9a8b8d6e1750966d343e94db665e7a1e9

  $ cd ..