tests/test-fastannotate-corrupt.t

dirstate-tree: Make Rust DirstateMap bindings go through a trait object

This changeset starts a series that adds an experiment to make status faster
by changing the dirstate (first only in memory and later also on disk) to
be shaped as a tree matching the directory structure, instead of the current
flat collection of entries. The status algorithm can then traverse this tree
dirstate at the same time as it traverses the filesystem.

We (Octobus) have made prototypes that show promising results but are prone
to bitrot. We would like to start upstreaming some experimental Rust code that
goes in this direction, but to avoid disrupting users it should only be
enabled by some run-time opt-in while keeping the existing dirstate structure
and status algorithm as-is.

The `DirstateMap` type and `status` function look like the appropriate
boundary. This adds a new trait that abstracts everything Python bindings need
and makes those bindings go through a `dyn` trait object. Later we’ll have two
implementations of this trait, and the same bindings can use either.

Differential Revision: https://phab.mercurial-scm.org/D10362

  $ 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