tests/test-rebase-interruptions.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)

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
  > tglogp = log -G --template "{rev}:{phase} '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a

  $ echo A > A
  $ hg ci -Am A
  adding A

  $ echo B > B
  $ hg ci -Am B
  adding B

  $ echo C >> A
  $ hg ci -m C

  $ hg up -q -C 0

  $ echo D >> A
  $ hg ci -m D
  created new head

  $ echo E > E
  $ hg ci -Am E
  adding E

  $ cd ..


Changes during an interruption - continue:

  $ hg clone -q -u . a a1
  $ cd a1

  $ hg tglog
  @  4: 'E'
  |
  o  3: 'D'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
Rebasing B onto E:

  $ hg rebase -s 1 -d 4
  merging A
  warning: conflicts during merge.
  merging A incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Force a commit on C during the interruption:

  $ hg up -q -C 2 --config 'extensions.rebase=!'

  $ echo 'Extra' > Extra
  $ hg add Extra
  $ hg ci -m 'Extra' --config 'extensions.rebase=!'

Force this commit onto secret phase

  $ hg phase --force --secret 6

  $ hg tglogp
  @  6:secret 'Extra'
  |
  | o  5:draft 'B'
  | |
  | o  4:draft 'E'
  | |
  | o  3:draft 'D'
  | |
  o |  2:draft 'C'
  | |
  o |  1:draft 'B'
  |/
  o  0:draft 'A'
  
Resume the rebasing:

  $ hg rebase --continue
  merging A
  warning: conflicts during merge.
  merging A incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Solve the conflict and go on:

  $ echo 'conflict solved' > A
  $ rm A.orig
  $ hg resolve -m A

  $ hg rebase --continue
  warning: new changesets detected on source branch, not stripping

  $ hg tglogp
  o  7:draft 'C'
  |
  | o  6:secret 'Extra'
  | |
  o |  5:draft 'B'
  | |
  @ |  4:draft 'E'
  | |
  o |  3:draft 'D'
  | |
  | o  2:draft 'C'
  | |
  | o  1:draft 'B'
  |/
  o  0:draft 'A'
  
  $ cd ..


Changes during an interruption - abort:

  $ hg clone -q -u . a a2
  $ cd a2

  $ hg tglog
  @  4: 'E'
  |
  o  3: 'D'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
Rebasing B onto E:

  $ hg rebase -s 1 -d 4
  merging A
  warning: conflicts during merge.
  merging A incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Force a commit on B' during the interruption:

  $ hg up -q -C 5 --config 'extensions.rebase=!'

  $ echo 'Extra' > Extra
  $ hg add Extra
  $ hg ci -m 'Extra' --config 'extensions.rebase=!'

  $ hg tglog
  @  6: 'Extra'
  |
  o  5: 'B'
  |
  o  4: 'E'
  |
  o  3: 'D'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
Abort the rebasing:

  $ hg rebase --abort
  warning: new changesets detected on target branch, can't strip
  rebase aborted

  $ hg tglog
  @  6: 'Extra'
  |
  o  5: 'B'
  |
  o  4: 'E'
  |
  o  3: 'D'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..

Changes during an interruption - abort (again):

  $ hg clone -q -u . a a3
  $ cd a3

  $ hg tglogp
  @  4:draft 'E'
  |
  o  3:draft 'D'
  |
  | o  2:draft 'C'
  | |
  | o  1:draft 'B'
  |/
  o  0:draft 'A'
  
Rebasing B onto E:

  $ hg rebase -s 1 -d 4
  merging A
  warning: conflicts during merge.
  merging A incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Change phase on B and B'

  $ hg up -q -C 5 --config 'extensions.rebase=!'
  $ hg phase --public 1
  $ hg phase --public 5
  $ hg phase --secret -f 2

  $ hg tglogp
  @  5:public 'B'
  |
  o  4:public 'E'
  |
  o  3:public 'D'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
Abort the rebasing:

  $ hg rebase --abort
  warning: can't clean up immutable changesets 45396c49d53b
  rebase aborted

  $ hg tglogp
  @  5:public 'B'
  |
  o  4:public 'E'
  |
  o  3:public 'D'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
  $ cd ..