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outdated and unsupported repo format.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

This test makes sure that we don't mark a file as merged with its ancestor
when we do a merge.

  $ cat <<EOF > merge
  > import sys, os
  > print "merging for", os.path.basename(sys.argv[1])
  > EOF
  $ HGMERGE="python ../merge"; export HGMERGE

Creating base:

  $ hg init a
  $ cd a
  $ echo 1 > foo
  $ echo 1 > bar
  $ echo 1 > baz
  $ echo 1 > quux
  $ hg add foo bar baz quux
  $ hg commit -m "base"

  $ cd ..
  $ hg clone a b
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved

Creating branch a:

  $ cd a
  $ echo 2a > foo
  $ echo 2a > bar
  $ hg commit -m "branch a"

Creating branch b:

  $ cd ..
  $ cd b
  $ echo 2b > foo
  $ echo 2b > baz
  $ hg commit -m "branch b"

We shouldn't have anything but n state here:

  $ hg debugstate --nodates | grep -v "^n"
  [1]

Merging:

  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg merge -v
  resolving manifests
  getting bar
  merging foo
  merging for foo
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ echo 2m > foo
  $ echo 2b > baz
  $ echo new > quux

  $ hg ci -m "merge"

main: we should have a merge here:

  $ hg debugindex --changelog
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      73  .....       0 cdca01651b96 000000000000 000000000000 (re)
       1        73      68  .....       1 f6718a9cb7f3 cdca01651b96 000000000000 (re)
       2       141      68  .....       2 bdd988058d16 cdca01651b96 000000000000 (re)
       3       209      66  .....       3 d8a521142a3c f6718a9cb7f3 bdd988058d16 (re)

log should show foo and quux changed:

  $ hg log -v -r tip
  changeset:   3:d8a521142a3c
  tag:         tip
  parent:      1:f6718a9cb7f3
  parent:      2:bdd988058d16
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       foo quux
  description:
  merge
  
  

foo: we should have a merge here:

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       1 2ffeddde1b65 b8e02f643373 000000000000 (re)
       2         7       4  .....       2 33d1fb69067a b8e02f643373 000000000000 (re)
       3        11       4  .....       3 aa27919ee430 2ffeddde1b65 33d1fb69067a (re)

bar: we should not have a merge here:

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       2 33d1fb69067a b8e02f643373 000000000000 (re)

baz: we should not have a merge here:

  $ hg debugindex baz
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       1 2ffeddde1b65 b8e02f643373 000000000000 (re)

quux: we should not have a merge here:

  $ hg debugindex quux
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       5  .....       3 6128c0f33108 b8e02f643373 000000000000 (re)

Manifest entries should match tips of all files:

  $ hg manifest --debug
  33d1fb69067a0139622a3fa3b7ba1cdb1367972e 644   bar
  2ffeddde1b65b4827f6746174a145474129fa2ce 644   baz
  aa27919ee4303cfd575e1fb932dd64d75aa08be4 644   foo
  6128c0f33108e8cfbb4e0824d13ae48b466d7280 644   quux

Everything should be clean now:

  $ hg status

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 4 changesets, 10 total revisions

  $ cd ..