tests/test-branch-change.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

Testing changing branch on commits
==================================

Setup

  $ cat >> $HGRCPATH << EOF
  > [alias]
  > glog = log -G -T "{rev}:{node|short} {desc}\n{branch} ({bookmarks})"
  > [experimental]
  > evolution = createmarkers
  > [extensions]
  > rebase=
  > EOF

  $ hg init repo
  $ cd repo
  $ for ch in a b c d e; do echo foo >> $ch; hg ci -Aqm "Added "$ch; done
  $ hg glog
  @  4:aa98ab95a928 Added e
  |  default ()
  o  3:62615734edd5 Added d
  |  default ()
  o  2:28ad74487de9 Added c
  |  default ()
  o  1:29becc82797a Added b
  |  default ()
  o  0:18d04c59bb5d Added a
     default ()

  $ hg branches
  default                        4:aa98ab95a928

Try without passing a new branch name

  $ hg branch -r .
  abort: no branch name specified for the revisions
  [255]

Setting an invalid branch name

  $ hg branch -r . a:b
  abort: ':' cannot be used in a name
  [255]
  $ hg branch -r . tip
  abort: the name 'tip' is reserved
  [255]
  $ hg branch -r . 1234
  abort: cannot use an integer as a name
  [255]

Change on non-linear set of commits

  $ hg branch -r 2 -r 4 foo
  abort: cannot change branch of non-linear revisions
  [255]

Change in middle of the stack (linear commits)

  $ hg branch -r 1::3 foo
  abort: cannot change branch of changeset with children
  [255]

Change with dirty working directory

  $ echo bar > a
  $ hg branch -r . foo
  abort: uncommitted changes
  [255]

  $ hg revert --all
  reverting a

Change on empty revision set

  $ hg branch -r 'draft() - all()' foo
  abort: empty revision set
  [255]

Changing branch on linear set of commits from head

Without obsmarkers

  $ hg branch -r 3:4 foo --config experimental.evolution=!
  changed branch on 2 changesets
  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/62615734edd5-e86bd13a-branch-change.hg
  $ hg glog
  @  4:3938acfb5c0f Added e
  |  foo ()
  o  3:9435da006bdc Added d
  |  foo ()
  o  2:28ad74487de9 Added c
  |  default ()
  o  1:29becc82797a Added b
  |  default ()
  o  0:18d04c59bb5d Added a
     default ()

  $ hg branches
  foo                            4:3938acfb5c0f
  default                        2:28ad74487de9 (inactive)

With obsmarkers

  $ hg branch -r 3::4 bar
  changed branch on 2 changesets
  $ hg glog
  @  6:7c1991464886 Added e
  |  bar ()
  o  5:1ea05e93925f Added d
  |  bar ()
  o  2:28ad74487de9 Added c
  |  default ()
  o  1:29becc82797a Added b
  |  default ()
  o  0:18d04c59bb5d Added a
     default ()

  $ hg branches
  bar                            6:7c1991464886
  default                        2:28ad74487de9 (inactive)

Change branch name to an existing branch

  $ hg branch -r . default
  abort: a branch of the same name already exists
  [255]

Changing on a branch head which is not topological head

  $ hg branch -r 2 stable
  abort: cannot change branch of changeset with children
  [255]

Enabling the allowunstable config and trying to change branch on a branch head
which is not a topological head

  $ echo "[experimental]" >> .hg/hgrc
  $ echo "evolution.allowunstable=yes" >> .hg/hgrc
  $ hg branch -r 2 foo
  changed branch on 1 changesets
  2 new orphan changesets

Changing branch of an obsoleted changeset

  $ hg branch -r 4 foobar
  abort: hidden revision '4' was rewritten as: 7c1991464886!
  (use --hidden to access hidden revisions)
  [255]

  $ hg branch -r 4 --hidden foobar
  abort: cannot change branch of a obsolete changeset
  [255]

Make sure bookmark movement is correct

  $ hg bookmark b1
  $ hg glog -r '.^::'
  @  6:7c1991464886 Added e
  |  bar (b1)
  *  5:1ea05e93925f Added d
  |  bar ()
  ~

  $ hg branch -r '(.^)::' wat --debug
  changing branch of '1ea05e93925f806d875a2163f9b76764be644636' from 'bar' to 'wat'
  committing files:
  d
  committing manifest
  committing changelog
  new node id is 343660ccab7400da637bd6a211d07f413536d718
  changing branch of '7c19914648869f5b02fc7fed31ddee9783fdd680' from 'bar' to 'wat'
  committing files:
  e
  committing manifest
  committing changelog
  new node id is de1404b45a69f8cc6437d7679033ee33e9efb4ba
  moving bookmarks ['b1'] from 7c19914648869f5b02fc7fed31ddee9783fdd680 to de1404b45a69f8cc6437d7679033ee33e9efb4ba
  resolving manifests
   branchmerge: False, force: False, partial: False
   ancestor: 7c1991464886, local: 7c1991464886+, remote: de1404b45a69
  starting 4 threads for background file closing (?)
  changed branch on 2 changesets
  updating the branch cache
  invalid branch cache (served): tip differs

  $ hg glog -r '(.^)::'
  @  9:de1404b45a69 Added e
  |  wat (b1)
  *  8:343660ccab74 Added d
  |  wat ()
  ~

Make sure phase handling is correct

  $ echo foo >> bar
  $ hg ci -Aqm "added bar" --secret
  1 new orphan changesets
  $ hg glog -r .
  @  10:8ad1294c1660 added bar
  |  wat (b1)
  ~
  $ hg branch -r . secret
  changed branch on 1 changesets
  $ hg phase -r .
  11: secret

  $ hg branches
  secret                        11:38a9b2d53f98
  foo                            7:8a4729a5e2b8
  wat                            9:de1404b45a69 (inactive)
  default                        2:28ad74487de9 (inactive)
  $ hg branch
  secret

Changing branch of another head, different from one on which we are

  $ hg glog
  @  11:38a9b2d53f98 added bar
  |  secret (b1)
  *  9:de1404b45a69 Added e
  |  wat ()
  *  8:343660ccab74 Added d
  |  wat ()
  | o  7:8a4729a5e2b8 Added c
  | |  foo ()
  x |  2:28ad74487de9 Added c
  |/   default ()
  o  1:29becc82797a Added b
  |  default ()
  o  0:18d04c59bb5d Added a
     default ()

  $ hg branch
  secret

  $ hg branch -r 7 foobar
  changed branch on 1 changesets

The current branch must be preserved
  $ hg branch
  secret

Changing branch on multiple heads at once

  $ hg rebase -s 8 -d 12 --keepbranches -q

  $ hg rebase -s 14 -d 1 --keepbranches -q

  $ hg branch -r 0: stable
  changed branch on 6 changesets
  $ hg glog
  @  23:6a5ddbcfb870 added bar
  |  stable (b1)
  o  22:baedc6e98a67 Added e
  |  stable ()
  | o  21:99ac7bf8aad1 Added d
  | |  stable ()
  | o  20:0ecb4d39c4bd Added c
  |/   stable ()
  o  19:fd45b986b109 Added b
  |  stable ()
  o  18:204d2769eca2 Added a
     stable ()

  $ hg branches
  stable                        23:6a5ddbcfb870

  $ hg branch
  stable

Changing to same branch is no-op

  $ hg branch -r 19::21 stable
  changed branch on 0 changesets

Changing branch name to existing branch name if the branch of parent of root of
revs is same as the new branch name

  $ hg branch -r 20::21 bugfix
  changed branch on 2 changesets
  $ hg glog
  o  25:714defe1cf34 Added d
  |  bugfix ()
  o  24:98394def28fc Added c
  |  bugfix ()
  | @  23:6a5ddbcfb870 added bar
  | |  stable (b1)
  | o  22:baedc6e98a67 Added e
  |/   stable ()
  o  19:fd45b986b109 Added b
  |  stable ()
  o  18:204d2769eca2 Added a
     stable ()

  $ hg branch -r 24:25 stable
  changed branch on 2 changesets
  $ hg glog
  o  27:4ec342341562 Added d
  |  stable ()
  o  26:83f48859c2de Added c
  |  stable ()
  | @  23:6a5ddbcfb870 added bar
  | |  stable (b1)
  | o  22:baedc6e98a67 Added e
  |/   stable ()
  o  19:fd45b986b109 Added b
  |  stable ()
  o  18:204d2769eca2 Added a
     stable ()

Changing branch of a merge commit

  $ hg branch -q ghi
  $ echo f > f
  $ hg ci -qAm 'Added f'
  $ hg up -q 27
  $ hg branch -q jkl
  $ echo g > g
  $ hg ci -qAm 'Added g'
  $ hg glog -r 'heads(:)'
  @  29:6bc1c6c2c9da Added g
  |  jkl ()
  ~
  o  28:2f1019bd29d2 Added f
  |  ghi (b1)
  ~

  $ hg branch -q default
  $ hg merge -r 28
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg branch -r . abcd
  abort: outstanding uncommitted merge
  [255]

  $ hg ci -m "Merge commit"
  $ hg glog -r 'parents(.)::'
  @    30:4d56e6b1eb6b Merge commit
  |\   default ()
  | o  29:6bc1c6c2c9da Added g
  | |  jkl ()
  | ~
  o  28:2f1019bd29d2 Added f
  |  ghi (b1)
  ~

  $ hg branch -r . ghi
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  changed branch on 1 changesets
  $ hg branch -r . jkl
  changed branch on 1 changesets
  $ hg branch -r . default
  changed branch on 1 changesets
  $ hg branch -r . stable
  abort: a branch of the same name already exists
  [255]

Changing branch on public changeset

  $ hg phase -r . -p
  $ hg branch -r . def
  abort: cannot change branch of public changesets
  (see 'hg help phases' for details)
  [255]

Merge commit with conflicts, with evolution and without

  $ mklozenge() {
  >   echo foo > a
  >   hg ci -qAm foo
  >   echo bar > a
  >   hg ci -qm bar
  >   hg up -q '.^'
  >   echo baz > a
  >   hg ci -qm baz
  >   hg merge -q -t :local
  >   echo neither > a
  >   hg ci -qm neither
  > }

  $ cd ..
  $ hg init merge-with-evolution
  $ cd merge-with-evolution
  $ mklozenge

  $ hg branch -r '(.^)::' abc
  changed branch on 2 changesets
  $ hg glog
  @    5:c07fa8b34d54 neither
  |\   abc ()
  | o  4:f2aa51777cc9 baz
  | |  abc ()
  o |  1:2e33c4f0856b bar
  |/   default ()
  o  0:91cfb6004abf foo
     default ()
  $ hg cat a
  neither

  $ cd ..
  $ hg init merge-without-evolution
  $ cd merge-without-evolution
  $ mklozenge
  $ cat > .hg/hgrc << EOF
  > [experimental]
  > evolution = no
  > evolution.allowunstable = no
  > EOF

  $ hg branch -r '(.^)::' abc
  changed branch on 2 changesets
  saved backup bundle to $TESTTMP/merge-without-evolution/.hg/strip-backup/9a3a2af368f4-8db1a361-branch-change.hg
  $ hg glog
  @    3:c07fa8b34d54 neither
  |\   abc ()
  | o  2:f2aa51777cc9 baz
  | |  abc ()
  o |  1:2e33c4f0856b bar
  |/   default ()
  o  0:91cfb6004abf foo
     default ()
  $ hg cat a
  neither