view tests/test-revlog-v2.t @ 38737:913ca175c4ae

aggressivemergedelta: document rename and move to `revlog` section

The config does not follow our naming guideline and "Aggressive" is probably a
word to keep away from users.

The option does not truly fit in the `format` section. It can be turned on and
off for existing repository without much consequence regarding compatibility.

A new `revlog` option is created to control behavior related to revlog writing
and reading. We can see multiple other config options that could be migrated
there.

* format.maxchainlen
* experimental.mmapindexthreshold
* experimental.sparse-read.density-threshold (in an updated form)
* experimental.sparse-read.min-gap-size (in an updated form)

In addition, we can foresee at least a couple of sparse-revlog related option
coming too (to reduce delta chain length and increase snapshot reuse)

These two extra options might fit there too. Unless we want to create a
section dedicated to caches and performance.

* format.chunkcachesize
* format.manifestcachesize

For now, we only migrate `optimize-delta-parent-choice` since it is getting
out of experimental. It is too close to the release to move the other one. In
addition, we still lack proper the prioritization of alias that would help
renaming them without bad consequence for users.

(Not fully happy about the `revlog` name but could not find better).

#require reporevlogstore

A repo with unknown revlogv2 requirement string cannot be opened

  $ hg init invalidreq
  $ cd invalidreq
  $ echo exp-revlogv2.unknown >> .hg/requires
  $ hg log
  abort: repository requires features unknown to this Mercurial: exp-revlogv2.unknown!
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]
  $ cd ..

Can create and open repo with revlog v2 requirement

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > revlogv2 = enable-unstable-format-and-corrupt-my-data
  > EOF

  $ hg init empty-repo
  $ cd empty-repo
  $ cat .hg/requires
  dotencode
  exp-revlogv2.0
  fncache
  store

  $ hg log

Unknown flags to revlog are rejected

  >>> with open('.hg/store/00changelog.i', 'wb') as fh:
  ...     fh.write(b'\x00\x04\xde\xad') and None

  $ hg log
  abort: unknown flags (0x04) in version 57005 revlog 00changelog.i!
  [255]

  $ cd ..

Writing a simple revlog v2 works

  $ hg init simple
  $ cd simple
  $ touch foo
  $ hg -q commit -A -m initial

  $ hg log
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  
Header written as expected (changelog always disables generaldelta)

  $ f --hexdump --bytes 4 .hg/store/00changelog.i
  .hg/store/00changelog.i:
  0000: 00 01 de ad                                     |....|

  $ f --hexdump --bytes 4 .hg/store/data/foo.i
  .hg/store/data/foo.i:
  0000: 00 03 de ad                                     |....|