tests/test-addremove-similar.t

obsolete: order of magnitude speedup in _computebumpedset

Reminder: a changeset is said "bumped" if it tries to obsolete a immutable
          changeset.


The previous algorithm for computing bumped changeset was:

    1) Get all public changesets
    2) Find all they successors
    3) Search for stuff that are eligible for being "bumped"
       (mutable and non obsolete)

The entry size of this algorithm is `O(len(public))` which is mostly the same as
`O(len(repo))`. Even this this approach mean fewer obsolescence marker are
traveled, this is not very scalable.

The new algorithm is:

    1) For each potential bumped changesets (non obsolete mutable)
    2) iterate over precursors
    3) if a precursors is public. changeset is bumped

We travel more obsolescence marker, but the entry size is much smaller since
the amount of potential bumped should remains mostly stable with time `O(1)`.

On some confidential gigantic repo this move bumped computation from 15.19s to
0.46s (×33 speedup…). On "smaller" repo (mercurial, cubicweb's review) no
significant gain were seen. The additional traversal of obsolescence marker is
probably probably counter balance the advantage of it.

Other optimisation could be done in the future (eg: sharing precursors cache
for divergence detection)

  $ hg init rep; cd rep

  $ touch empty-file
  $ python -c 'for x in range(10000): print x' > large-file

  $ hg addremove
  adding empty-file
  adding large-file

  $ hg commit -m A

  $ rm large-file empty-file
  $ python -c 'for x in range(10,10000): print x' > another-file

  $ hg addremove -s50
  adding another-file
  removing empty-file
  removing large-file
  recording removal of large-file as rename to another-file (99% similar)

  $ hg commit -m B

comparing two empty files caused ZeroDivisionError in the past

  $ hg update -C 0
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ rm empty-file
  $ touch another-empty-file
  $ hg addremove -s50
  adding another-empty-file
  removing empty-file

  $ cd ..

  $ hg init rep2; cd rep2

  $ python -c 'for x in range(10000): print x' > large-file
  $ python -c 'for x in range(50): print x' > tiny-file

  $ hg addremove
  adding large-file
  adding tiny-file

  $ hg commit -m A

  $ python -c 'for x in range(70): print x' > small-file
  $ rm tiny-file
  $ rm large-file

  $ hg addremove -s50
  removing large-file
  adding small-file
  removing tiny-file
  recording removal of tiny-file as rename to small-file (82% similar)

  $ hg commit -m B

should all fail

  $ hg addremove -s foo
  abort: similarity must be a number
  [255]
  $ hg addremove -s -1
  abort: similarity must be between 0 and 100
  [255]
  $ hg addremove -s 1e6
  abort: similarity must be between 0 and 100
  [255]

  $ cd ..

Issue1527: repeated addremove causes util.Abort

  $ hg init rep3; cd rep3
  $ mkdir d
  $ echo a > d/a
  $ hg add d/a
  $ hg commit -m 1

  $ mv d/a d/b
  $ hg addremove -s80
  removing d/a
  adding d/b
  recording removal of d/a as rename to d/b (100% similar) (glob)
  $ hg debugstate
  r   0          0 1970-01-01 00:00:00 d/a
  a   0         -1 unset               d/b
  copy: d/a -> d/b
  $ mv d/b c

no copies found here (since the target isn't in d

  $ hg addremove -s80 d
  removing d/b (glob)

copies here

  $ hg addremove -s80
  adding c
  recording removal of d/a as rename to c (100% similar) (glob)

  $ cd ..