view tests/test-journal-share.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outdated and unsupported repo format.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.

Journal extension test: tests the share extension support

  $ 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=
  > share=
  > testmocks=`pwd`/testmocks.py
  > [remotenames]
  > rename.default=remote
  > EOF

  $ hg init repo
  $ cd repo
  $ hg bookmark bm
  $ touch file0
  $ hg commit -Am file0-added
  adding file0
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         commit -Am file0-added
  0fd3805711f9  bm        commit -Am file0-added

A shared working copy initially receives the same bookmarks and working copy

  $ cd ..
  $ hg share repo shared1
  updating working directory
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd shared1
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1

unless you explicitly share bookmarks

  $ cd ..
  $ hg share --bookmarks repo shared2
  updating working directory
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

Moving the bookmark in the original repository is only shown in the repository
that shares bookmarks

  $ cd ../repo
  $ touch file1
  $ hg commit -Am file1-added
  adding file1
  $ cd ../shared1
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1
  $ cd ../shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

But working copy changes are always 'local'

  $ cd ../repo
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark bm)
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         up 0
  4f354088b094  .         commit -Am file1-added
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         commit -Am file0-added
  0fd3805711f9  bm        commit -Am file0-added
  $ cd ../shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added
  $ hg up tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg journal
  previous locations of '.':
  0fd3805711f9  up 0
  4f354088b094  up tip
  0fd3805711f9  share --bookmarks repo shared2

Unsharing works as expected; the journal remains consistent

  $ cd ../shared1
  $ hg unshare
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1
  $ cd ../shared2
  $ hg unshare
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         up 0
  4f354088b094  .         up tip
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

New journal entries in the source repo no longer show up in the other working copies

  $ cd ../repo
  $ hg bookmark newbm -r tip
  $ hg journal newbm
  previous locations of 'newbm':
  4f354088b094  bookmark newbm -r tip
  $ cd ../shared2
  $ hg journal newbm
  previous locations of 'newbm':
  no recorded locations

This applies for both directions

  $ hg bookmark shared2bm -r tip
  $ hg journal shared2bm
  previous locations of 'shared2bm':
  4f354088b094  bookmark shared2bm -r tip
  $ cd ../repo
  $ hg journal shared2bm
  previous locations of 'shared2bm':
  no recorded locations