tests/test-mq-qfold.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

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [mq]
  > git = keep
  > [diff]
  > nodates = 1
  > EOF

init:

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg qnew -f p1
  $ echo b >> a
  $ hg qnew -f p2
  $ echo c >> a
  $ hg qnew -f p3

Fold in the middle of the queue:
(this tests also that editor is not invoked if '--edit' is not
specified)

  $ hg qpop p1
  popping p3
  popping p2
  now at: p1

  $ hg qdiff
  diff -r 07f494440405 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,2 @@
   a
  +a

  $ HGEDITOR=cat hg qfold p2
  $ grep git .hg/patches/p1 && echo 'git patch found!'
  [1]

  $ hg qser
  p1
  p3

  $ hg qdiff
  diff -r 07f494440405 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,3 @@
   a
  +a
  +b

Fold with local changes:

  $ echo d >> a
  $ hg qfold p3
  abort: local changes found, qrefresh first
  [255]

  $ hg diff -c .
  diff -r 07f494440405 -r ???????????? a (glob)
  --- a/a
  +++ b/a
  @@ -1,1 +1,3 @@
   a
  +a
  +b

  $ hg revert -a --no-backup
  reverting a

Fold git patch into a regular patch, expect git patch:

  $ echo a >> a
  $ hg qnew -f regular
  $ hg cp a aa
  $ hg qnew --git -f git

  $ hg qpop
  popping git
  now at: regular

  $ hg qfold git

  $ cat .hg/patches/regular
  # HG changeset patch
  # Parent  ???????????????????????????????????????? (glob)
  
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,3 +1,4 @@
   a
   a
   b
  +a
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,3 +1,4 @@
   a
   a
   b
  +a

  $ hg qpop
  popping regular
  now at: p1

  $ hg qdel regular

Fold regular patch into a git patch, expect git patch:

  $ hg cp a aa
  $ hg qnew --git -f git
  $ echo b >> aa
  $ hg qnew -f regular

  $ hg qpop
  popping regular
  now at: git

  $ hg qfold regular

  $ cat .hg/patches/git
  # HG changeset patch
  # Parent  ???????????????????????????????????????? (glob)
  
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,3 +1,4 @@
   a
   a
   b
  +b

Test saving last-message.txt:

  $ hg qrefresh -m "original message"

  $ cat > $TESTTMP/commitfailure.py <<EOF
  > from mercurial import error
  > def reposetup(ui, repo):
  >     class commitfailure(repo.__class__):
  >         def commit(self, *args, **kwargs):
  >             raise error.Abort('emulating unexpected abort')
  >     repo.__class__ = commitfailure
  > EOF

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > # this failure occurs before editor invocation
  > commitfailure = $TESTTMP/commitfailure.py
  > EOF

  $ cat > $TESTTMP/editor.sh << EOF
  > echo "==== before editing"
  > cat \$1
  > echo "===="
  > (echo; echo "test saving last-message.txt") >> \$1
  > EOF

  $ hg qapplied
  p1
  git
  $ hg tip --template "{files}\n"
  aa

(test that editor is not invoked before transaction starting,
and that combination of '--edit' and '--message' doesn't abort execution)

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e -m MESSAGE p3
  qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
  abort: emulating unexpected abort
  [255]
  $ test -f .hg/last-message.txt
  [1]

(reset applied patches and directory status)

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > # this failure occurs after editor invocation
  > commitfailure = !
  > EOF

  $ hg qapplied
  p1
  $ hg status -A aa
  ? aa
  $ rm aa
  $ hg status -m
  M a
  $ hg revert --no-backup -q a
  $ hg qpush -q git
  now at: git

(test that editor is invoked and commit message is saved into
"last-message.txt")

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > # this failure occurs after editor invocation
  > pretxncommit.unexpectedabort = false
  > EOF

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e p3
  ==== before editing
  original message
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to use default message.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added aa
  HG: changed a
  ====
  note: commit message saved in .hg/last-message.txt
  transaction abort!
  rollback completed
  qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
  abort: pretxncommit.unexpectedabort hook exited with status 1
  [255]
  $ cat .hg/last-message.txt
  original message
  
  
  
  test saving last-message.txt

(confirm whether files listed up in the commit message editing are correct)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > pretxncommit.unexpectedabort =
  > EOF
  $ hg status -u | while read f; do rm ${f}; done
  $ hg revert --no-backup -q --all
  $ hg qpush -q git
  now at: git
  $ hg qpush -q --move p3
  now at: p3

  $ hg status --rev "git^1" --rev . -arm
  M a
  A aa

  $ cd ..