view tests/test-journal-exists.t @ 30441:3633403888ae

bdiff: give slight preference to appending lines

[This change could be folded into the previous changeset to minimize the repo
churn ...]

The general preference to matches in the middle of bdiff ranges helps getting
balanced recursion and efficient computation. But, as previous changes have
shown, it might also give diffs that seems "obviously wrong".

To mitigate that: If the best match on the A side starts at the beginning of
the bdiff range, don't aim for the middle-most B side match but for the
earliest.

This will make the matches balanced (by both sides being "early") even though
the bisection will be less balanced. Still, this case only apply if the *best*
and middle-most match was fully unbalanced on the A side. Each recursion will
thus even in this worst case reduce the problem significantly and we are not
re-introducing the problem that was fixed in f1ca249696ed.

The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from
22806817 to 22807275 bytes - a 0.002% increase.

This make the recent test-bdiff.py changes give a more pretty output ... but
they no longer show that the recursion is around middle matches (because it in
these cases isn't).

  $ hg init
  $ echo a > a
  $ hg ci -Am0
  adding a

  $ hg -q clone . foo

  $ touch .hg/store/journal

  $ echo foo > a
  $ hg ci -Am0
  abort: abandoned transaction found!
  (run 'hg recover' to clean up transaction)
  [255]

  $ hg recover
  rolling back interrupted transaction
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

Check that zero-size journals are correctly aborted:

#if unix-permissions no-root
  $ hg bundle -qa repo.hg
  $ chmod -w foo/.hg/store/00changelog.i

  $ hg -R foo unbundle repo.hg
  adding changesets
  abort: Permission denied: $TESTTMP/foo/.hg/store/.00changelog.i-* (glob)
  [255]

  $ if test -f foo/.hg/store/journal; then echo 'journal exists :-('; fi
#endif