view tests/test-repo-compengines.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).

A new repository uses zlib storage, which doesn't need a requirement

  $ hg init default
  $ cd default
  $ cat .hg/requires
  dotencode
  fncache
  generaldelta
  revlogv1
  store
  testonly-simplestore (reposimplestore !)

  $ touch foo
  $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text to trigger compression'
  $ hg debugrevlog -c | grep 0x78
      0x78 (x)  :   1 (100.00%)
      0x78 (x)  : 110 (100.00%)

  $ cd ..

Unknown compression engine to format.compression aborts

  $ hg --config experimental.format.compression=unknown init unknown
  abort: compression engine unknown defined by experimental.format.compression not available
  (run "hg debuginstall" to list available compression engines)
  [255]

A requirement specifying an unknown compression engine results in bail

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

  $ cd ..

#if zstd

  $ hg --config experimental.format.compression=zstd init zstd
  $ cd zstd
  $ cat .hg/requires
  dotencode
  exp-compression-zstd
  fncache
  generaldelta
  revlogv1
  store
  testonly-simplestore (reposimplestore !)

  $ touch foo
  $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text'

  $ hg debugrevlog -c | grep 0x28
      0x28      :  1 (100.00%)
      0x28      : 98 (100.00%)

  $ cd ..

Specifying a new format.compression on an existing repo won't introduce data
with that engine or a requirement

  $ cd default
  $ touch bar
  $ hg --config experimental.format.compression=zstd -q commit -A -m 'add bar with a lot of repeated repeated repeated text'

  $ cat .hg/requires
  dotencode
  fncache
  generaldelta
  revlogv1
  store
  testonly-simplestore (reposimplestore !)

  $ hg debugrevlog -c | grep 0x78
      0x78 (x)  :   2 (100.00%)
      0x78 (x)  : 199 (100.00%)

#endif