view tests/test-convert-baz.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outdated and unsupported repo format.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.

#require baz symlink

  $ baz my-id "mercurial <[e-mail]>"

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert=" >> $HGRCPATH

create baz archive
  $ baz make-archive baz@mercurial--convert hg-test-convert-baz

initialize baz repo
  $ mkdir baz-repo
  $ cd baz-repo/
  $ baz init-tree baz@mercurial--convert/baz--test--0
  $ baz import
  * creating version baz@mercurial--convert/baz--test--0
  * imported baz@mercurial--convert/baz--test--0

create initial files
  $ echo 'this is a file' > a
  $ baz add a
  $ mkdir src
  $ baz add src
  $ cd src
  $ dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ baz add b
HACK: hide GNU tar-1.22 "tar: The --preserve option is deprecated, use --preserve-permissions --preserve-order instead"
  $ baz commit -s "added a file, src and src/b (binary)" 2>&1 | grep -v '^tar'
  * build pristine tree for baz@mercurial--convert/baz--test--0--base-0
  * Scanning for full-tree revision: .
  * from import revision: baz@mercurial--convert/baz--test--0--base-0
  A/ .arch-ids
  A/ src
  A/ src/.arch-ids
  A  .arch-ids/a.id
  A  a
  A  src/.arch-ids/=id
  A  src/.arch-ids/b.id
  A  src/b
  * update pristine tree (baz@mercurial--convert/baz--test--0--base-0 => baz--test--0--patch-1)
  * committed baz@mercurial--convert/baz--test--0--patch-1

create link file and modify a
  $ ln -s ../a a-link
  $ baz add a-link
  $ echo 'this a modification to a' >> ../a
  $ baz commit -s "added link to a and modify a"
  A  src/.arch-ids/a-link.id
  A  src/a-link
  M  a
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-1 => baz--test--0--patch-2)
  * committed baz@mercurial--convert/baz--test--0--patch-2

create second link and modify b
  $ ln -s ../a a-link-2
  $ baz add a-link-2
  $ dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ baz commit -s "added second link and modify b"
  A  src/.arch-ids/a-link-2.id
  A  src/a-link-2
  Mb src/b
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-2 => baz--test--0--patch-3)
  * committed baz@mercurial--convert/baz--test--0--patch-3

b file to link and a-link-2 to regular file
  $ rm -f a-link-2
  $ echo 'this is now a regular file' > a-link-2
  $ ln -sf ../a b
  $ baz commit -s "file to link and link to file test"
  fl src/b
  lf src/a-link-2
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-3 => baz--test--0--patch-4)
  * committed baz@mercurial--convert/baz--test--0--patch-4

move a-link-2 file and src directory
  $ cd ..
  $ baz mv src/a-link-2 c
  $ baz mv src test
  $ baz commit -s "move and rename a-link-2 file and src directory"
  D/ src/.arch-ids
  A/ test/.arch-ids
  /> src	test
  => src/.arch-ids/a-link-2.id	.arch-ids/c.id
  => src/a-link-2	c
  => src/.arch-ids/=id	test/.arch-ids/=id
  => src/.arch-ids/a-link.id	test/.arch-ids/a-link.id
  => src/.arch-ids/b.id	test/.arch-ids/b.id
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-4 => baz--test--0--patch-5)
  * committed baz@mercurial--convert/baz--test--0--patch-5

move and add the moved file again
  $ echo e > e
  $ baz add e
  $ baz commit -s "add e"
  A  .arch-ids/e.id
  A  e
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-5 => baz--test--0--patch-6)
  * committed baz@mercurial--convert/baz--test--0--patch-6
  $ baz mv e f
  $ echo ee > e
  $ baz add e
  $ baz commit -s "move e and recreate it again"
  A  .arch-ids/e.id
  A  e
  => .arch-ids/e.id	.arch-ids/f.id
  => e	f
  * update pristine tree (baz@mercurial--convert/baz--test--0--patch-6 => baz--test--0--patch-7)
  * committed baz@mercurial--convert/baz--test--0--patch-7
  $ cd ..

converting baz repo to Mercurial
  $ hg convert baz-repo baz-repo-hg
  initializing destination baz-repo-hg repository
  analyzing tree version baz@mercurial--convert/baz--test--0...
  scanning source...
  sorting...
  converting...
  7 initial import
  6 added a file, src and src/b (binary)
  5 added link to a and modify a
  4 added second link and modify b
  3 file to link and link to file test
  2 move and rename a-link-2 file and src directory
  1 add e
  0 move e and recreate it again

  $ baz register-archive -d baz@mercurial--convert

  $ glog()
  > {
  >     hg log -G --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
  > }

show graph log
  $ glog -R baz-repo-hg
  o  7 "move e and recreate it again" files: e f
  |
  o  6 "add e" files: e
  |
  o  5 "move and rename a-link-2 file and src directory" files: c src/a-link src/a-link-2 src/b test/a-link test/b
  |
  o  4 "file to link and link to file test" files: src/a-link-2 src/b
  |
  o  3 "added second link and modify b" files: src/a-link-2 src/b
  |
  o  2 "added link to a and modify a" files: a src/a-link
  |
  o  1 "added a file, src and src/b (binary)" files: a src/b
  |
  o  0 "initial import" files:
  
  $ hg up -q -R baz-repo-hg
  $ hg -R baz-repo-hg manifest --debug
  c4072c4b72e1cabace081888efa148ee80ca3cbb 644   a
  0201ac32a3a8e86e303dff60366382a54b48a72e 644   c
  1a4a864db0073705a11b1439f563bfa4b46d9246 644   e
  09e0222742fc3f75777fa9d68a5d8af7294cb5e7 644   f
  c0067ba5ff0b7c9a3eb17270839d04614c435623 644 @ test/a-link
  375f4263d86feacdea7e3c27100abd1560f2a973 644 @ test/b
  $ hg -R baz-repo-hg log -r 5 -r 7 -C --debug | grep copies
  copies:      c (src/a-link-2) test/a-link (src/a-link) test/b (src/b)
  copies:      f (e)