view tests/test-issue1175.t @ 30745:c1b7b2285522

revlog: flag processor

Add the ability for revlog objects to process revision flags and apply
registered transforms on read/write operations.

This patch introduces:
- the 'revlog._processflags()' method that looks at revision flags and applies
  flag processors registered on them. Due to the need to handle non-commutative
  operations, flag transforms are applied in stable order but the order in which
  the transforms are applied is reversed between read and write operations.
- the 'addflagprocessor()' method allowing to register processors on flags.
  Flag processors are defined as a 3-tuple of (read, write, raw) functions to be
  applied depending on the operation being performed.
- an update on 'revlog.addrevision()' behavior. The current flagprocessor design
  relies on extensions to wrap around 'addrevision()' to set flags on revision
  data, and on the flagprocessor to perform the actual transformation of its
  contents. In the lfs case, this means we need to process flags before we meet
  the 2GB size check, leading to performing some operations before it happens:
  - if flags are set on the revision data, we assume some extensions might be
    modifying the contents using the flag processor next, and we compute the
    node for the original revision data (still allowing extension to override
    the node by wrapping around 'addrevision()').
  - we then invoke the flag processor to apply registered transforms (in lfs's
    case, drastically reducing the size of large blobs).
  - finally, we proceed with the 2GB size check.

Note: In the case a cachedelta is passed to 'addrevision()' and we detect the
flag processor modified the revision data, we chose to trust the flag processor
and drop the cachedelta.

https://bz.mercurial-scm.org/1175

  $ hg init
  $ touch a
  $ hg ci -Am0
  adding a

  $ hg mv a a1
  $ hg ci -m1

  $ hg co 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ hg mv a a2
  $ hg up
  note: possible conflict - a was renamed multiple times to:
   a2
   a1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg ci -m2

  $ touch a
  $ hg ci -Am3
  adding a

  $ hg mv a b
  $ hg ci -Am4 a

  $ hg ci --debug --traceback -Am5 b
  committing files:
  b
  warning: can't find ancestor for 'b' copied from 'a'!
  committing manifest
  committing changelog
  committed changeset 5:83a687e8a97c80992ba385bbfd766be181bfb1d1

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 6 changesets, 4 total revisions

  $ hg export --git tip
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID 83a687e8a97c80992ba385bbfd766be181bfb1d1
  # Parent  1d1625283f71954f21d14c3d44d0ad3c019c597f
  5
  
  diff --git a/b b/b
  new file mode 100644

https://bz.mercurial-scm.org/show_bug.cgi?id=4476

  $ hg init foo
  $ cd foo
  $ touch a && hg ci -Aqm a
  $ hg mv a b
  $ echo b1 >> b
  $ hg ci -Aqm b1
  $ hg up 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg mv a b
  $ echo b2 >> b
  $ hg ci -Aqm b2
  $ hg graft 1
  grafting 1:5974126fad84 "b1"
  merging b
  warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]
  $ echo a > b
  $ echo b3 >> b
  $ hg resolve --mark b
  (no more unresolved files)
  continue: hg graft --continue
  $ hg graft --continue
  grafting 1:5974126fad84 "b1"
  warning: can't find ancestor for 'b' copied from 'a'!
  $ hg log -f b -T 'changeset:   {rev}:{node|short}\nsummary:     {desc}\n\n'
  changeset:   3:376d30ccffc0
  summary:     b1
  
  changeset:   2:416baaa2e5e4
  summary:     b2
  
  changeset:   0:3903775176ed
  summary:     a