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outdated and unsupported repo format.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

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > share =
  > EOF

store and revlogv1 are required in source

  $ hg --config format.usestore=false init no-store
  $ hg -R no-store debugupgraderepo
  abort: cannot upgrade repository; requirement missing: store
  [255]

  $ hg init no-revlogv1
  $ cat > no-revlogv1/.hg/requires << EOF
  > dotencode
  > fncache
  > generaldelta
  > store
  > EOF

  $ hg -R no-revlogv1 debugupgraderepo
  abort: cannot upgrade repository; requirement missing: revlogv1
  [255]

Cannot upgrade shared repositories

  $ hg init share-parent
  $ hg -q share share-parent share-child

  $ hg -R share-child debugupgraderepo
  abort: cannot upgrade repository; unsupported source requirement: shared
  [255]

Do not yet support upgrading manifestv2 and treemanifest repos

  $ hg --config experimental.manifestv2=true init manifestv2
  $ hg -R manifestv2 debugupgraderepo
  abort: cannot upgrade repository; unsupported source requirement: manifestv2
  [255]

  $ hg --config experimental.treemanifest=true init treemanifest
  $ hg -R treemanifest debugupgraderepo
  abort: cannot upgrade repository; unsupported source requirement: treemanifest
  [255]

Cannot add manifestv2 or treemanifest requirement during upgrade

  $ hg init disallowaddedreq
  $ hg -R disallowaddedreq --config experimental.manifestv2=true --config experimental.treemanifest=true debugupgraderepo
  abort: cannot upgrade repository; do not support adding requirement: manifestv2, treemanifest
  [255]

An upgrade of a repository created with recommended settings only suggests optimizations

  $ hg init empty
  $ cd empty
  $ hg debugupgraderepo
  (no feature deficiencies found in existing repository)
  performing an upgrade with "--run" will make the following changes:
  
  requirements
     preserved: dotencode, fncache, generaldelta, revlogv1, store
  
  additional optimizations are available by specifying "--optimize <name>":
  
  redeltaparent
     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
  
  redeltamultibase
     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
  
  redeltaall
     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
  

--optimize can be used to add optimizations

  $ hg debugupgrade --optimize redeltaparent
  (no feature deficiencies found in existing repository)
  performing an upgrade with "--run" will make the following changes:
  
  requirements
     preserved: dotencode, fncache, generaldelta, revlogv1, store
  
  redeltaparent
     deltas within internal storage will choose a new base revision if needed
  
  additional optimizations are available by specifying "--optimize <name>":
  
  redeltamultibase
     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
  
  redeltaall
     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
  

Various sub-optimal detections work

  $ cat > .hg/requires << EOF
  > revlogv1
  > store
  > EOF

  $ hg debugupgraderepo
  repository lacks features recommended by current config options:
  
  fncache
     long and reserved filenames may not work correctly; repository performance is sub-optimal
  
  dotencode
     storage of filenames beginning with a period or space may not work correctly
  
  generaldelta
     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
  
  
  performing an upgrade with "--run" will make the following changes:
  
  requirements
     preserved: revlogv1, store
     added: dotencode, fncache, generaldelta
  
  fncache
     repository will be more resilient to storing certain paths and performance of certain operations should be improved
  
  dotencode
     repository will be better able to store files beginning with a space or period
  
  generaldelta
     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
  
  additional optimizations are available by specifying "--optimize <name>":
  
  redeltaparent
     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
  
  redeltamultibase
     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
  
  redeltaall
     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
  

  $ hg --config format.dotencode=false debugupgraderepo
  repository lacks features recommended by current config options:
  
  fncache
     long and reserved filenames may not work correctly; repository performance is sub-optimal
  
  generaldelta
     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
  
  repository lacks features used by the default config options:
  
  dotencode
     storage of filenames beginning with a period or space may not work correctly
  
  
  performing an upgrade with "--run" will make the following changes:
  
  requirements
     preserved: revlogv1, store
     added: fncache, generaldelta
  
  fncache
     repository will be more resilient to storing certain paths and performance of certain operations should be improved
  
  generaldelta
     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
  
  additional optimizations are available by specifying "--optimize <name>":
  
  redeltaparent
     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
  
  redeltamultibase
     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
  
  redeltaall
     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
  

  $ cd ..

Upgrading a repository that is already modern essentially no-ops

  $ hg init modern
  $ hg -R modern debugupgraderepo --run
  upgrade will perform the following actions:
  
  requirements
     preserved: dotencode, fncache, generaldelta, revlogv1, store
  
  beginning upgrade...
  repository locked and read-only
  creating temporary repository to stage migrated data: $TESTTMP/modern/.hg/upgrade.* (glob)
  (it is safe to interrupt this process any time before data migration completes)
  data fully migrated to temporary repository
  marking source repository as being upgraded; clients will be unable to read from repository
  starting in-place swap of repository data
  replaced files will be backed up at $TESTTMP/modern/.hg/upgradebackup.* (glob)
  replacing store...
  store replacement complete; repository was inconsistent for *s (glob)
  finalizing requirements file and making repository readable again
  removing temporary repository $TESTTMP/modern/.hg/upgrade.* (glob)
  copy of old repository backed up at $TESTTMP/modern/.hg/upgradebackup.* (glob)
  the old repository will not be deleted; remove it to free up disk space once the upgraded repository is verified

Upgrading a repository to generaldelta works

  $ hg --config format.usegeneraldelta=false init upgradegd
  $ cd upgradegd
  $ touch f0
  $ hg -q commit -A -m initial
  $ touch f1
  $ hg -q commit -A -m 'add f1'
  $ hg -q up -r 0
  $ touch f2
  $ hg -q commit -A -m 'add f2'

  $ hg debugupgraderepo --run
  upgrade will perform the following actions:
  
  requirements
     preserved: dotencode, fncache, revlogv1, store
     added: generaldelta
  
  generaldelta
     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
  
  beginning upgrade...
  repository locked and read-only
  creating temporary repository to stage migrated data: $TESTTMP/upgradegd/.hg/upgrade.* (glob)
  (it is safe to interrupt this process any time before data migration completes)
  migrating 9 total revisions (3 in filelogs, 3 in manifests, 3 in changelog)
  migrating 341 bytes in store; 401 bytes tracked data
  migrating 3 filelogs containing 3 revisions (0 bytes in store; 0 bytes tracked data)
  finished migrating 3 filelog revisions across 3 filelogs; change in size: 0 bytes
  migrating 1 manifests containing 3 revisions (157 bytes in store; 220 bytes tracked data)
  finished migrating 3 manifest revisions across 1 manifests; change in size: 0 bytes
  migrating changelog containing 3 revisions (184 bytes in store; 181 bytes tracked data)
  finished migrating 3 changelog revisions; change in size: 0 bytes
  finished migrating 9 total revisions; total change in store size: 0 bytes
  copying phaseroots
  data fully migrated to temporary repository
  marking source repository as being upgraded; clients will be unable to read from repository
  starting in-place swap of repository data
  replaced files will be backed up at $TESTTMP/upgradegd/.hg/upgradebackup.* (glob)
  replacing store...
  store replacement complete; repository was inconsistent for *s (glob)
  finalizing requirements file and making repository readable again
  removing temporary repository $TESTTMP/upgradegd/.hg/upgrade.* (glob)
  copy of old repository backed up at $TESTTMP/upgradegd/.hg/upgradebackup.* (glob)
  the old repository will not be deleted; remove it to free up disk space once the upgraded repository is verified

Original requirements backed up

  $ cat .hg/upgradebackup.*/requires
  dotencode
  fncache
  revlogv1
  store

generaldelta added to original requirements files

  $ cat .hg/requires
  dotencode
  fncache
  generaldelta
  revlogv1
  store

store directory has files we expect

  $ ls .hg/store
  00changelog.i
  00manifest.i
  data
  fncache
  phaseroots
  undo
  undo.backupfiles
  undo.phaseroots

manifest should be generaldelta

  $ hg debugrevlog -m | grep flags
  flags  : inline, generaldelta

verify should be happy

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 3 changesets, 3 total revisions

old store should be backed up

  $ ls .hg/upgradebackup.*/store
  00changelog.i
  00manifest.i
  data
  fncache
  phaseroots
  undo
  undo.backup.fncache
  undo.backupfiles
  undo.phaseroots

  $ cd ..

store files with special filenames aren't encoded during copy

  $ hg init store-filenames
  $ cd store-filenames
  $ touch foo
  $ hg -q commit -A -m initial
  $ touch .hg/store/.XX_special_filename

  $ hg debugupgraderepo --run
  upgrade will perform the following actions:
  
  requirements
     preserved: dotencode, fncache, generaldelta, revlogv1, store
  
  beginning upgrade...
  repository locked and read-only
  creating temporary repository to stage migrated data: $TESTTMP/store-filenames/.hg/upgrade.* (glob)
  (it is safe to interrupt this process any time before data migration completes)
  migrating 3 total revisions (1 in filelogs, 1 in manifests, 1 in changelog)
  migrating 109 bytes in store; 107 bytes tracked data
  migrating 1 filelogs containing 1 revisions (0 bytes in store; 0 bytes tracked data)
  finished migrating 1 filelog revisions across 1 filelogs; change in size: 0 bytes
  migrating 1 manifests containing 1 revisions (46 bytes in store; 45 bytes tracked data)
  finished migrating 1 manifest revisions across 1 manifests; change in size: 0 bytes
  migrating changelog containing 1 revisions (63 bytes in store; 62 bytes tracked data)
  finished migrating 1 changelog revisions; change in size: 0 bytes
  finished migrating 3 total revisions; total change in store size: 0 bytes
  copying .XX_special_filename
  copying phaseroots
  data fully migrated to temporary repository
  marking source repository as being upgraded; clients will be unable to read from repository
  starting in-place swap of repository data
  replaced files will be backed up at $TESTTMP/store-filenames/.hg/upgradebackup.* (glob)
  replacing store...
  store replacement complete; repository was inconsistent for *s (glob)
  finalizing requirements file and making repository readable again
  removing temporary repository $TESTTMP/store-filenames/.hg/upgrade.* (glob)
  copy of old repository backed up at $TESTTMP/store-filenames/.hg/upgradebackup.* (glob)
  the old repository will not be deleted; remove it to free up disk space once the upgraded repository is verified

  $ cd ..