view tests/test-mq-merge.t @ 42621:99ebde4fec99

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

Setup extension:

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [mq]
  > git = keep
  > EOF

Test merge with mq changeset as the second parent:

  $ hg init m
  $ cd m
  $ touch a b c
  $ hg add a
  $ hg commit -m a
  $ hg add b
  $ hg qnew -d "0 0" b
  $ hg update 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg add c
  $ hg commit -m c
  created new head
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m merge
  abort: cannot commit over an applied mq patch
  [255]
  $ cd ..

Issue529: mq aborts when merging patch deleting files

  $ checkundo()
  > {
  >     if [ -f .hg/store/undo ]; then
  >         echo ".hg/store/undo still exists"
  >     fi
  > }

Commit two dummy files in "init" changeset:

  $ hg init t
  $ cd t
  $ echo a > a
  $ echo b > b
  $ hg ci -Am init
  adding a
  adding b
  $ hg tag -l init

Create a patch removing a:

  $ hg qnew rm_a
  $ hg rm a
  $ hg qrefresh -m "rm a"

Save the patch queue so we can merge it later:

  $ hg qsave -c -e
  copy $TESTTMP/t/.hg/patches to $TESTTMP/t/.hg/patches.1
  $ checkundo

Update b and commit in an "update" changeset:

  $ hg up -C init
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b >> b
  $ hg st
  M b
  $ hg ci -m update
  created new head

# Here, qpush used to abort with :
# The system cannot find the file specified => a
  $ hg manifest
  a
  b

  $ hg qpush -a -m
  merging with queue at: $TESTTMP/t/.hg/patches.1
  applying rm_a
  now at: rm_a

  $ checkundo
  $ hg manifest
  b

Ensure status is correct after merge:

  $ hg qpop -a
  popping rm_a
  popping .hg.patches.merge.marker
  patch queue now empty

  $ cd ..

Classic MQ merge sequence *with an explicit named queue*:

  $ hg init t2
  $ cd t2
  $ echo '[diff]' > .hg/hgrc
  $ echo 'nodates = 1' >> .hg/hgrc
  $ echo a > a
  $ hg ci -Am init
  adding a
  $ echo b > a
  $ hg ci -m changea
  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg cp a aa
  $ echo c >> a
  $ hg qnew --git -f -e patcha
  $ echo d >> a
  $ hg qnew -d '0 0' -f -e patcha2

Create the reference queue:

  $ hg qsave -c -e -n refqueue
  copy $TESTTMP/t2/.hg/patches to $TESTTMP/t2/.hg/refqueue
  $ hg up -C 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

Merge:

  $ HGMERGE=internal:other hg qpush -a -m -n refqueue
  merging with queue at: $TESTTMP/t2/.hg/refqueue
  applying patcha
  patching file a
  Hunk #1 succeeded at 2 with fuzz 1 (offset 0 lines).
  fuzz found when applying patch, stopping
  patch didn't work out, merging patcha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  0 files updated, 2 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  applying patcha2
  now at: patcha2

Check patcha is still a git patch:

  $ cat .hg/patches/patcha
  # HG changeset patch
  # Parent  d3873e73d99ef67873dac33fbcc66268d5d2b6f4
  
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,1 +1,2 @@
  -b
  +a
  +c
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,1 +1,1 @@
  -b
  +a

Check patcha2 is still a regular patch:

  $ cat .hg/patches/patcha2
  # HG changeset patch
  # Date 0 0
  # Parent  ???????????????????????????????????????? (glob)
  
  diff -r ???????????? -r ???????????? a (glob)
  --- a/a
  +++ b/a
  @@ -1,2 +1,3 @@
   a
   c
  +d

  $ cd ..