view tests/test-hgk.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.

Minimal hgk check

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "hgk=" >> $HGRCPATH
  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ hg debug-cat-file commit 0
  tree a0c8bcbbb45c
  parent 000000000000
  author test 0 0
  revision 0
  branch default
  phase draft
  
  adda
  $ echo b > b
  $ hg ci -Am addb
  adding b
  $ hg log -T '{node}\n'
  102a90ea7b4a3361e4082ed620918c261189a36a
  07f4944404050f47db2e5c5071e0e84e7a27bba9

  $ hg debug-diff-tree 07f494440405 102a90ea7b4a
  :000000 100664 000000000000 1e88685f5dde N	b	b
  $ hg debug-diff-tree 07f494440405 102a90ea7b4a --patch
  diff --git a/b b/b
  new file mode 100644
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +b

Ensure that diff-tree output isn't affected by diffopts
  $ hg --config diff.noprefix=True debug-diff-tree 07f494440405 102a90ea7b4a
  :000000 100664 000000000000 1e88685f5dde N	b	b
  $ hg --config diff.noprefix=True debug-diff-tree --patch 07f494440405 102a90ea7b4a
  diff --git a/b b/b
  new file mode 100644
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +b

  $ cd ..