tests/test-manifest.t

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

Source bundle was generated with the following script:

# hg init
# echo a > a
# ln -s a l
# hg ci -Ama -d'0 0'
# mkdir b
# echo a > b/a
# chmod +x b/a
# hg ci -Amb -d'1 0'

  $ hg init
  $ hg unbundle "$TESTDIR/bundles/test-manifest.hg"
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 3 changes to 3 files
  new changesets b73562a03cfe:5bdc995175ba (2 drafts)
  (run 'hg update' to get a working copy)

The next call is expected to return nothing:

  $ hg manifest

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

  $ hg manifest
  a
  b/a
  l

  $ hg files -vr .
           2   a
           2 x b/a
           1 l l
  $ hg files -r . -X b
  a
  l
  $ hg files -T '{path} {size} {flags}\n'
  a 2 
  b/a 2 x
  l 1 l
  $ hg files -T '{path} {node|shortest}\n' -r.
  a 5bdc
  b/a 5bdc
  l 5bdc

  $ hg manifest -v
  644   a
  755 * b/a
  644 @ l
  $ hg manifest -T '{path} {rev}\n'
  a 1
  b/a 1
  l 1

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 755 * b/a
  047b75c6d7a3ef6a2243bd0e99f94f6ea6683597 644 @ l

  $ hg manifest -r 0
  a
  l

  $ hg manifest -r 1
  a
  b/a
  l

  $ hg manifest -r tip
  a
  b/a
  l

  $ hg manifest tip
  a
  b/a
  l

  $ hg manifest --all
  a
  b/a
  l

The next two calls are expected to abort:

  $ hg manifest -r 2
  abort: unknown revision '2'!
  [255]

  $ hg manifest -r tip tip
  abort: please specify just one revision
  [255]

Testing the manifest full text cache utility
--------------------------------------------

Reminder of the manifest log content

  $ hg log --debug | grep 'manifest:'
  manifest:    1:1e01206b1d2f72bd55f2a33fa8ccad74144825b7
  manifest:    0:fce2a30dedad1eef4da95ca1dc0004157aa527cf

Showing the content of the caches after the above operations

  $ hg debugmanifestfulltextcache
  cache contains 1 manifest entries, in order of most to least recent:
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 157 bytes, on-disk 157 bytes

(Clearing the cache in case of any content)

  $ hg debugmanifestfulltextcache --clear

Adding a new persistent entry in the cache

  $ hg debugmanifestfulltextcache --add 1e01206b1d2f72bd55f2a33fa8ccad74144825b7

  $ hg debugmanifestfulltextcache
  cache contains 1 manifest entries, in order of most to least recent:
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 157 bytes, on-disk 157 bytes

Check we don't duplicated entry (added from the debug command)

  $ hg debugmanifestfulltextcache --add 1e01206b1d2f72bd55f2a33fa8ccad74144825b7
  $ hg debugmanifestfulltextcache
  cache contains 1 manifest entries, in order of most to least recent:
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 157 bytes, on-disk 157 bytes

Adding a second entry

  $ hg debugmanifestfulltextcache --add fce2a30dedad1eef4da95ca1dc0004157aa527cf
  $ hg debugmanifestfulltextcache
  cache contains 2 manifest entries, in order of most to least recent:
  id: fce2a30dedad1eef4da95ca1dc0004157aa527cf, size 87 bytes
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 268 bytes, on-disk 268 bytes

Accessing the initial entry again, refresh their order

  $ hg debugmanifestfulltextcache --add 1e01206b1d2f72bd55f2a33fa8ccad74144825b7
  $ hg debugmanifestfulltextcache
  cache contains 2 manifest entries, in order of most to least recent:
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  id: fce2a30dedad1eef4da95ca1dc0004157aa527cf, size 87 bytes
  total cache data size 268 bytes, on-disk 268 bytes

Check cache clearing

  $ hg debugmanifestfulltextcache --clear
  $ hg debugmanifestfulltextcache
  cache empty

Check adding multiple entry in one go:

  $ hg debugmanifestfulltextcache --add fce2a30dedad1eef4da95ca1dc0004157aa527cf  --add 1e01206b1d2f72bd55f2a33fa8ccad74144825b7
  $ hg debugmanifestfulltextcache
  cache contains 2 manifest entries, in order of most to least recent:
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  id: fce2a30dedad1eef4da95ca1dc0004157aa527cf, size 87 bytes
  total cache data size 268 bytes, on-disk 268 bytes
  $ hg debugmanifestfulltextcache --clear

Test caching behavior on actual operation
-----------------------------------------

Make sure we start empty

  $ hg debugmanifestfulltextcache
  cache empty

Commit should have the new node cached:

  $ echo a >> b/a
  $ hg commit -m 'foo'
  $ hg debugmanifestfulltextcache
  cache contains 2 manifest entries, in order of most to least recent:
  id: 26b8653b67af8c1a0a0317c4ee8dac50a41fdb65, size 133 bytes
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 314 bytes, on-disk 314 bytes
  $ hg log -r 'ancestors(., 1)' --debug | grep 'manifest:'
  manifest:    1:1e01206b1d2f72bd55f2a33fa8ccad74144825b7
  manifest:    2:26b8653b67af8c1a0a0317c4ee8dac50a41fdb65

hg update should warm the cache too

(force dirstate check to avoid flackiness in manifest order)
  $ hg debugrebuilddirstate

  $ hg update 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg debugmanifestfulltextcache
  cache contains 3 manifest entries, in order of most to least recent:
  id: fce2a30dedad1eef4da95ca1dc0004157aa527cf, size 87 bytes
  id: 26b8653b67af8c1a0a0317c4ee8dac50a41fdb65, size 133 bytes
  id: 1e01206b1d2f72bd55f2a33fa8ccad74144825b7, size 133 bytes
  total cache data size 425 bytes, on-disk 425 bytes
  $ hg log -r '0' --debug | grep 'manifest:'
  manifest:    0:fce2a30dedad1eef4da95ca1dc0004157aa527cf

Test file removal (especially with pure).  The tests are crafted such that there
will be contiguous spans of existing entries to ensure that is handled properly.
(In this case, a.txt, aa.txt and c.txt, cc.txt, and ccc.txt)

  $ cat > $TESTTMP/manifest.py <<EOF
  > from mercurial import (
  >     extensions,
  >     manifest,
  > )
  > def extsetup(ui):
  >     manifest.FASTDELTA_TEXTDIFF_THRESHOLD = 0
  > EOF
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > manifest = $TESTTMP/manifest.py
  > EOF

Pure removes should actually remove all dropped entries

  $ hg init repo
  $ cd repo
  $ echo a > a.txt
  $ echo aa > aa.txt
  $ echo b > b.txt
  $ echo c > c.txt
  $ echo c > cc.txt
  $ echo c > ccc.txt
  $ echo b > d.txt
  $ echo c > e.txt
  $ hg ci -Aqm 'a-e'

  $ hg rm b.txt d.txt
  $ hg ci -m 'remove b and d'

  $ hg debugdata -m 1
  a.txt\x00b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 (esc)
  aa.txt\x00a4bdc161c8fbb523c9a60409603f8710ff49a571 (esc)
  c.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  cc.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  ccc.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  e.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)

  $ hg up -qC .

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 8 changes to 8 files

  $ hg rollback -q --config ui.rollback=True
  $ hg rm b.txt d.txt
  $ echo bb > bb.txt

A mix of adds and removes should remove all dropped entries.

  $ hg ci -Aqm 'remove b and d; add bb'

  $ hg debugdata -m 1
  a.txt\x00b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 (esc)
  aa.txt\x00a4bdc161c8fbb523c9a60409603f8710ff49a571 (esc)
  bb.txt\x0004c6faf8a9fdd848a5304dfc1704749a374dff44 (esc)
  c.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  cc.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  ccc.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)
  e.txt\x00149da44f2a4e14f488b7bd4157945a9837408c00 (esc)

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 9 changes to 9 files