view tests/test-i18n.t @ 34824:e2ad93bcc084

revlog: introduce an experimental flag to slice chunks reads when too sparse

Delta chains can become quite sparse if there is a lot of unrelated data between
relevant pieces. Right now, revlog always reads all the necessary data for the
delta chain in one single read. This can lead to a lot of unrelated data to be
read (see issue5482 for more details).
One can use the `experimental.maxdeltachainspan` option with a large value
(or -1) to easily produce a very sparse delta chain.

This change introduces the ability to slice the chunks retrieval into  multiple
reads, skipping large sections of unrelated data. Preliminary testing shows
interesting results. For example the peak memory consumption to read a manifest
on a large repository is reduced from 600MB to 250MB (200MB without
maxdeltachainspan). However, the slicing itself and the multiple reads can have
an negative impact on performance. This is why the new feature is hidden behind
an experimental flag.

Future changesets will add various parameters to control the slicing heuristics.
We hope to experiment a wide variety of repositories during 4.4 and hopefully
turn the feature on by default in 4.5.
As a first try, the algorithm itself is prone to deep changes. However, we wish
to define APIs and have a baseline to work on.

(Translations are optional)

#if gettext no-outer-repo

Test that translations are compiled and installed correctly.

Default encoding in tests is "ascii" and the translation is encoded
using the "replace" error handler:

  $ LANGUAGE=pt_BR hg tip
  abortado: n?o foi encontrado um reposit?rio em '$TESTTMP' (.hg n?o encontrado)!
  [255]

Using a more accommodating encoding:

  $ HGENCODING=UTF-8 LANGUAGE=pt_BR hg tip
  abortado: n\xc3\xa3o foi encontrado um reposit\xc3\xb3rio em '$TESTTMP' (.hg n\xc3\xa3o encontrado)! (esc)
  [255]

Different encoding:

  $ HGENCODING=Latin-1 LANGUAGE=pt_BR hg tip
  abortado: n\xe3o foi encontrado um reposit\xf3rio em '$TESTTMP' (.hg n\xe3o encontrado)! (esc)
  [255]

#endif

#if gettext

Test keyword search in translated help text:

  $ HGENCODING=UTF-8 LANGUAGE=de hg help -k Aktualisiert
  Themen:
  
   subrepos Unterarchive
  
  Befehle:
  
   pull   Ruft \xc3\x84nderungen von der angegebenen Quelle ab (esc)
   update Aktualisiert das Arbeitsverzeichnis (oder wechselt die Version)

#endif

Check Mercurial specific translation problems in each *.po files, and
tool itself by doctest

  $ cd "$TESTDIR"/../i18n
  $ $PYTHON check-translation.py *.po
  $ $PYTHON check-translation.py --doctest
  $ cd $TESTTMP

#if gettext

Check i18n cache isn't reused after encoding change:

  $ cat > $TESTTMP/encodingchange.py << EOF
  > from mercurial import encoding, registrar
  > from mercurial.i18n import _
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'encodingchange', norepo=True)
  > def encodingchange(ui):
  >     for encode in (b'ascii', b'UTF-8', b'ascii', b'UTF-8'):
  >         encoding.encoding = encode
  >         ui.write(b'%s\n' % _(b'(EXPERIMENTAL)'))
  > EOF

  $ LANGUAGE=ja hg --config extensions.encodingchange=$TESTTMP/encodingchange.py encodingchange
  (?????)
  (\xe5\xae\x9f\xe9\xa8\x93\xe7\x9a\x84\xe5\xae\x9f\xe8\xa3\x85) (esc)
  (?????)
  (\xe5\xae\x9f\xe9\xa8\x93\xe7\x9a\x84\xe5\xae\x9f\xe8\xa3\x85) (esc)

#endif