tests/test-obsolete-tag-cache.t

obsolete: explicitly track folds inside the markers

We now record information to be able to recognize "fold" event from
obsolescence markers. To do so, we track the following pieces of information:

a) a fold ID. Unique to that fold (per successor),
b) the number of predecessors,
c) the index of the predecessor in that fold.

We will now be able to create an algorithm able to find "predecessorssets".

We now store this data in the generic "metadata" field of the markers.
Updating the format to have a more compact storage for this would be useful.

This way of tracking a fold through multiple markers could be applied to split
too. This would have two advantages:

1) We get a simpler format, since number of successors is limited to [0-1].
2) We can better deal with situations where only some of the split successors
   are pushed to a remote repository.

We should look into the relevance of such a change before updating the on-disk
format.

note: unlike splits, folds do not have to deal with cases where only some of
the markers have been synchronized. As they all share the same successor
changesets, they are all relevant to the same nodes.

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > blackbox=
  > rebase=
  > mock=$TESTDIR/mockblackbox.py
  > 
  > [experimental]
  > evolution.createmarkers=True
  > EOF

Create a repo with some tags

  $ hg init repo
  $ cd repo
  $ echo initial > foo
  $ hg -q commit -A -m initial
  $ hg tag -m 'test tag' test1
  $ echo first > first
  $ hg -q commit -A -m first
  $ hg tag -m 'test2 tag' test2
  $ hg -q up -r 0
  $ echo newhead > newhead
  $ hg commit -A -m newhead
  adding newhead
  created new head
  $ hg tag -m 'test head 2 tag' head2

  $ hg log -G -T '{rev}:{node|short} {tags} {desc}\n'
  @  5:2942a772f72a tip test head 2 tag
  |
  o  4:042eb6bfcc49 head2 newhead
  |
  | o  3:c3cb30f2d2cd  test2 tag
  | |
  | o  2:d75775ffbc6b test2 first
  | |
  | o  1:5f97d42da03f  test tag
  |/
  o  0:55482a6fb4b1 test1 initial
  

Trigger tags cache population by doing something that accesses tags info

  $ hg tags
  tip                                5:2942a772f72a
  head2                              4:042eb6bfcc49
  test2                              2:d75775ffbc6b
  test1                              0:55482a6fb4b1

  $ cat .hg/cache/tags2-visible
  5 2942a772f72a444bef4bef13874d515f50fa27b6
  042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2
  55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1
  d75775ffbc6bca1794d300f5571272879bd280da test2

Hiding a non-tip changeset should change filtered hash and cause tags recompute

  $ hg debugobsolete -d '0 0' c3cb30f2d2cd0aae008cc91a07876e3c5131fd22 -u dummyuser
  obsoleted 1 changesets

  $ hg tags
  tip                                5:2942a772f72a
  head2                              4:042eb6bfcc49
  test1                              0:55482a6fb4b1

  $ cat .hg/cache/tags2-visible
  5 2942a772f72a444bef4bef13874d515f50fa27b6 f34fbc9a9769ba9eff5aff3d008a6b49f85c08b1
  042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2
  55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1

  $ hg blackbox -l 5
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 2/2 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2-visible with 2 tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5

Hiding another changeset should cause the filtered hash to change

  $ hg debugobsolete -d '0 0' d75775ffbc6bca1794d300f5571272879bd280da -u dummyuser
  obsoleted 1 changesets
  $ hg debugobsolete -d '0 0' 5f97d42da03fd56f3b228b03dfe48af5c0adf75b -u dummyuser
  obsoleted 1 changesets

  $ hg tags
  tip                                5:2942a772f72a
  head2                              4:042eb6bfcc49

  $ cat .hg/cache/tags2-visible
  5 2942a772f72a444bef4bef13874d515f50fa27b6 2fce1eec33263d08a4d04293960fc73a555230e4
  042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2

  $ hg blackbox -l 5
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 1/1 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2-visible with 1 tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5

Resolving tags on an unfiltered repo writes a separate tags cache

  $ hg --hidden tags
  tip                                5:2942a772f72a
  head2                              4:042eb6bfcc49
  test2                              2:d75775ffbc6b
  test1                              0:55482a6fb4b1

  $ cat .hg/cache/tags2
  5 2942a772f72a444bef4bef13874d515f50fa27b6
  042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2
  55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1
  d75775ffbc6bca1794d300f5571272879bd280da test2

  $ hg blackbox -l 5
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> --hidden tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 2/2 cache hits/lookups in * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2 with 3 tags
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> --hidden tags exited 0 after * seconds (glob)
  1970/01/01 00:00:00 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5