tests/test-fastannotate-corrupt.t

documentation: add some internals documentation about bid merge

This is an important algorithm that was only documented on the wiki so far.

Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.

Differential Revision: https://phab.mercurial-scm.org/D8711

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > fastannotate=
  > EOF

  $ hg init repo
  $ cd repo
  $ for i in 0 1 2 3 4; do
  >   echo $i >> a
  >   echo $i >> b
  >   hg commit -A -m $i a b
  > done

use the "debugbuildannotatecache" command to build annotate cache at rev 0

  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=0
  fastannotate: a: 1 new changesets in the main branch
  fastannotate: b: 1 new changesets in the main branch

"debugbuildannotatecache" should work with broken cache (and other files would
be built without being affected). note: linelog being broken is only noticed
when we try to append to it.

  $ echo 'CORRUPT!' >> .hg/fastannotate/default/a.m
  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=1
  fastannotate: a: rebuilding broken cache
  fastannotate: a: 2 new changesets in the main branch
  fastannotate: b: 1 new changesets in the main branch

  $ echo 'CANNOT REUSE!' > .hg/fastannotate/default/a.l
  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=2
  fastannotate: a: rebuilding broken cache
  fastannotate: a: 3 new changesets in the main branch
  fastannotate: b: 1 new changesets in the main branch

  $ rm .hg/fastannotate/default/a.m
  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=3
  fastannotate: a: rebuilding broken cache
  fastannotate: a: 4 new changesets in the main branch
  fastannotate: b: 1 new changesets in the main branch

  $ rm .hg/fastannotate/default/a.l
  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=3
  $ hg debugbuildannotatecache --debug --config fastannotate.mainbranch=4
  fastannotate: a: rebuilding broken cache
  fastannotate: a: 5 new changesets in the main branch
  fastannotate: b: 1 new changesets in the main branch

"fastannotate" should deal with file corruption as well

  $ rm -rf .hg/fastannotate
  $ hg fastannotate --debug -r 0 a
  fastannotate: a: 1 new changesets in the main branch
  0: 0

  $ echo 'CORRUPT!' >> .hg/fastannotate/default/a.m
  $ hg fastannotate --debug -r 0 a
  fastannotate: a: cache broken and deleted
  fastannotate: a: 1 new changesets in the main branch
  0: 0

  $ echo 'CORRUPT!' > .hg/fastannotate/default/a.l
  $ hg fastannotate --debug -r 1 a
  fastannotate: a: cache broken and deleted
  fastannotate: a: 2 new changesets in the main branch
  0: 0
  1: 1

  $ rm .hg/fastannotate/default/a.l
  $ hg fastannotate --debug -r 1 a
  fastannotate: a: using fast path (resolved fctx: True)
  fastannotate: a: cache broken and deleted
  fastannotate: a: 2 new changesets in the main branch
  0: 0
  1: 1

  $ rm .hg/fastannotate/default/a.m
  $ hg fastannotate --debug -r 2 a
  fastannotate: a: cache broken and deleted
  fastannotate: a: 3 new changesets in the main branch
  0: 0
  1: 1
  2: 2