tests/test-histedit-base.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

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > tglog = log -G --template "{rev}:{node}:{phase} '{desc}'\n"
  > [extensions]
  > histedit=
  > EOF

Create repo a:

  $ hg init a
  $ cd a
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  new changesets cd010b8cd998:02de42196ebe (8 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg tglog
  @  7:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  |
  | o  6:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  |/|
  o |  5:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  | |
  | o  4:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  | o  3:32af7686d403cf45b5d95f2d70cebea587ac806a:draft 'D'
  | |
  | o  2:5fddd98957c8a54a4d436dfe1da9d87f21a1b97b:draft 'C'
  | |
  | o  1:42ccdea3bb16d28e1848c95fe2e44c000f3f21b1:draft 'B'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Verify that implicit base command and help are listed

  $ HGEDITOR=cat hg histedit |grep base
  #  b, base = checkout changeset and apply further changesets from there

Go to D
  $ hg update 3
  3 files updated, 0 files merged, 2 files removed, 0 files unresolved
edit the history to rebase B onto H


Rebase B onto H
  $ hg histedit 1 --commands - 2>&1 << EOF | fixbundle
  > base 02de42196ebe
  > pick 42ccdea3bb16 B
  > pick 5fddd98957c8 C
  > pick 32af7686d403 D
  > EOF

  $ hg tglog
  @  7:0937e82309df47d14176ee15e45dbec5fbdef340:draft 'D'
  |
  o  6:f778d1cbddac4ab679d9983c9bb92e4c5e09e7fa:draft 'C'
  |
  o  5:3d41b7cc708545206213a842f96d812d2e73d818:draft 'B'
  |
  o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  |
  | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  |/|
  o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  | |
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Rebase back and drop something
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > base cd010b8cd998
  > pick 3d41b7cc7085 B
  > drop f778d1cbddac C
  > pick 0937e82309df D
  > EOF

  $ hg tglog
  @  6:476cc3e4168da2d036b141f7f7dcff7f8e3fe846:draft 'D'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Split stack
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > base cd010b8cd998
  > pick d273e35dcdf2 B
  > base cd010b8cd998
  > pick 476cc3e4168d D
  > EOF

  $ hg tglog
  @  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Abort
  $ echo x > B
  $ hg add B
  $ hg commit -m "X"
  $ hg tglog
  @  7:591369deedfdcbf57471e894999a70d7f676186d:draft 'X'
  |
  o  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
  $ hg histedit 6 --commands - 2>&1 << EOF | fixbundle
  > base d273e35dcdf2 B
  > drop d7a6f907a822 D
  > pick 591369deedfd X
  > EOF
  merging B
  warning: conflicts while merging B! (edit, then use 'hg resolve --mark')
  Fix up the change (pick 591369deedfd)
  (hg histedit --continue to resume)
  $ hg histedit --abort | fixbundle
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tglog
  @  7:591369deedfdcbf57471e894999a70d7f676186d:draft 'X'
  |
  o  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Continue
  $ hg histedit 6 --commands - 2>&1 << EOF | fixbundle
  > base d273e35dcdf2 B
  > drop d7a6f907a822 D
  > pick 591369deedfd X
  > EOF
  merging B
  warning: conflicts while merging B! (edit, then use 'hg resolve --mark')
  Fix up the change (pick 591369deedfd)
  (hg histedit --continue to resume)
  $ echo b2 > B
  $ hg resolve --mark B
  (no more unresolved files)
  continue: hg histedit --continue
  $ hg histedit --continue | fixbundle
  $ hg tglog
  @  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  

base on a previously picked changeset
  $ echo i > i
  $ hg add i
  $ hg commit -m "I"
  $ echo j > j
  $ hg add j
  $ hg commit -m "J"
  $ hg tglog
  @  8:e8c55b19d366b335626e805484110d1d5f6f2ea3:draft 'J'
  |
  o  7:b2f90fd8aa85db5569e3cfc30cd1d7739546368e:draft 'I'
  |
  o  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > pick d273e35dcdf2 B
  > pick 03772da75548 X
  > base d273e35dcdf2 B
  > pick e8c55b19d366 J
  > base d273e35dcdf2 B
  > pick b2f90fd8aa85 I
  > EOF
  hg: parse error: base "d273e35dcdf2" changeset was an edited list candidate
  (base must only use unlisted changesets)

  $ hg tglog
  @  8:e8c55b19d366b335626e805484110d1d5f6f2ea3:draft 'J'
  |
  o  7:b2f90fd8aa85db5569e3cfc30cd1d7739546368e:draft 'I'
  |
  o  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'