tests/test-rebase-mq.t

revlog: change generaldelta delta parent heuristic

The old generaldelta heuristic was "if p1 (or p2) was closer than the last full text,
use it, otherwise use prev". This was problematic when a repo contained multiple
branches that were very different. If commits to branch A were pushed, and the
last full text was branch B, it would generate a fulltext. Then if branch B was
pushed, it would generate another fulltext. The problem is that the last
fulltext (and delta'ing against `prev` in general) has no correlation with the
contents of the incoming revision, and therefore will always have degenerate
cases.

According to the blame, that algorithm was chosen to minimize the chain length.
Since there is already code that protects against that (the delta-vs-fulltext
code), and since it has been improved since the original generaldelta algorithm
went in (2011), I believe the chain length criteria will still be preserved.

The new algorithm always diffs against p1 (or p2 if it's closer), unless the
resulting delta will fail the delta-vs-fulltext check, in which case we delta
against prev.

Some before and after stats on manifest.d size.

internal large repo
old heuristic - 2.0 GB
new heuristic - 1.2 GB

mozilla-central
old heuristic - 242 MB
new heuristic - 261 MB

The regression in mozilla central is due to the new heuristic choosing p2r as
the delta when it's closer to the tip. Switching the algorithm to always prefer
p1r brings the size back down (242 MB). This is result of the way in which
mozilla does merges and pushes, and the result could easily swing the other
direction in other repos (depending on if they merge X into Y or Y into X), but
will never be as degenerate as before.

I future patch will address the regression by introducing an optional, even more
aggressive delta heuristic which will knock the mozilla manifest size down
dramatically.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > mq=
  > 
  > [mq]
  > plain=true
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' tags: {tags}\n"
  > EOF


  $ hg init a
  $ cd a
  $ hg qinit -c

  $ echo c1 > f
  $ hg add f
  $ hg ci -m C1

  $ echo r1 > f
  $ hg ci -m R1

  $ hg up -q 0

  $ hg qnew f.patch -d '1 0'
  $ echo mq1 > f
  $ hg qref -m P0

  $ hg qnew f2.patch
  $ echo mq2 > f
  $ hg qref -m P1 -d '2 0'

  $ hg tglog
  @  3: 'P1' tags: f2.patch qtip tip
  |
  o  2: 'P0' tags: f.patch qbase
  |
  | o  1: 'R1' tags:
  |/
  o  0: 'C1' tags: qparent
  

Rebase - try to rebase on an applied mq patch:

  $ hg rebase -s 1 -d 3
  abort: cannot rebase onto an applied mq patch
  [255]

Rebase - same thing, but mq patch is default dest:

  $ hg up -q 1
  $ hg rebase
  abort: cannot rebase onto an applied mq patch
  [255]
  $ hg up -q qtip

Rebase - generate a conflict:

  $ hg rebase -s 2 -d 1
  rebasing 2:3504f44bffc0 "P0" (f.patch qbase)
  merging f
  warning: conflicts during merge.
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Fix the 1st conflict:

  $ echo mq1r1 > f
  $ hg resolve -m f
  (no more unresolved files)
  $ hg rebase -c
  rebasing 2:3504f44bffc0 "P0" (f.patch qbase)
  rebasing 3:929394423cd3 "P1" (f2.patch qtip tip)
  merging f
  warning: conflicts during merge.
  merging f incomplete! (edit conflicts, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Fix the 2nd conflict:

  $ echo mq1r1mq2 > f
  $ hg resolve -m f
  (no more unresolved files)
  $ hg rebase -c
  already rebased 2:3504f44bffc0 "P0" (f.patch qbase) as ebe9914c0d1c
  rebasing 3:929394423cd3 "P1" (f2.patch qtip)
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/3504f44bffc0-30595b40-backup.hg (glob)

  $ hg tglog
  @  3: 'P1' tags: f2.patch qtip tip
  |
  o  2: 'P0' tags: f.patch qbase
  |
  o  1: 'R1' tags: qparent
  |
  o  0: 'C1' tags:
  
  $ hg up -q qbase

  $ cat f
  mq1r1

  $ cat .hg/patches/f.patch
  # HG changeset patch
  # User test
  # Date 1 0
  #      Thu Jan 01 00:00:01 1970 +0000
  # Node ID ebe9914c0d1c3f60096e952fa4dbb3d377dea3ab
  # Parent  bac9ed9960d8992bcad75864a879fa76cadaf1b0
  P0
  
  diff -r bac9ed9960d8 -r ebe9914c0d1c f
  --- a/f	Thu Jan 01 00:00:00 1970 +0000
  +++ b/f	Thu Jan 01 00:00:01 1970 +0000
  @@ -1,1 +1,1 @@
  -r1
  +mq1r1

Update to qtip:

  $ hg up -q qtip

  $ cat f
  mq1r1mq2

  $ cat .hg/patches/f2.patch
  # HG changeset patch
  # User test
  # Date 2 0
  #      Thu Jan 01 00:00:02 1970 +0000
  # Node ID 462012cf340c97d44d62377c985a423f6bb82f07
  # Parent  ebe9914c0d1c3f60096e952fa4dbb3d377dea3ab
  P1
  
  diff -r ebe9914c0d1c -r 462012cf340c f
  --- a/f	Thu Jan 01 00:00:01 1970 +0000
  +++ b/f	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,1 +1,1 @@
  -mq1r1
  +mq1r1mq2

Adding one git-style patch and one normal:

  $ hg qpop -a
  popping f2.patch
  popping f.patch
  patch queue now empty

  $ rm -fr .hg/patches
  $ hg qinit -c

  $ hg up -q 0

  $ hg qnew --git f_git.patch -d '3 0'
  $ echo mq1 > p
  $ hg add p
  $ hg qref --git -m 'P0 (git)'

  $ hg qnew f.patch -d '4 0'
  $ echo mq2 > p
  $ hg qref -m P1
  $ hg qci -m 'save patch state'

  $ hg qseries -s
  f_git.patch: P0 (git)
  f.patch: P1

  $ hg -R .hg/patches manifest
  .hgignore
  f.patch
  f_git.patch
  series

  $ cat .hg/patches/f_git.patch
  Date: 3 0
  
  P0 (git)
  
  diff --git a/p b/p
  new file mode 100644
  --- /dev/null
  +++ b/p
  @@ -0,0 +1,1 @@
  +mq1

  $ cat .hg/patches/f.patch
  Date: 4 0
  
  P1
  
  diff -r ???????????? p (glob)
  --- a/p	??? ??? ?? ??:??:?? ???? ????? (glob)
  +++ b/p	??? ??? ?? ??:??:?? ???? ????? (glob)
  @@ -1,1 +1,1 @@
  -mq1
  +mq2


Rebase the applied mq patches:

  $ hg rebase -s 2 -d 1
  rebasing 2:0c587ffcb480 "P0 (git)" (f_git.patch qbase)
  rebasing 3:c7f18665e4bc "P1" (f.patch qtip tip)
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/0c587ffcb480-0ea5695f-backup.hg (glob)

  $ hg qci -m 'save patch state'

  $ hg qseries -s
  f_git.patch: P0 (git)
  f.patch: P1

  $ hg -R .hg/patches manifest
  .hgignore
  f.patch
  f_git.patch
  series

  $ cat .hg/patches/f_git.patch
  # HG changeset patch
  # User test
  # Date 3 0
  #      Thu Jan 01 00:00:03 1970 +0000
  # Node ID 12d9f6a3bbe560dee50c7c454d434add7fb8e837
  # Parent  bac9ed9960d8992bcad75864a879fa76cadaf1b0
  P0 (git)
  
  diff --git a/p b/p
  new file mode 100644
  --- /dev/null
  +++ b/p
  @@ -0,0 +1,1 @@
  +mq1

  $ cat .hg/patches/f.patch
  # HG changeset patch
  # User test
  # Date 4 0
  #      Thu Jan 01 00:00:04 1970 +0000
  # Node ID c77a2661c64c60d82f63c4f7aefd95b3a948a557
  # Parent  12d9f6a3bbe560dee50c7c454d434add7fb8e837
  P1
  
  diff -r 12d9f6a3bbe5 -r c77a2661c64c p
  --- a/p	Thu Jan 01 00:00:03 1970 +0000
  +++ b/p	Thu Jan 01 00:00:04 1970 +0000
  @@ -1,1 +1,1 @@
  -mq1
  +mq2

  $ cd ..

Rebase with guards

  $ hg init foo
  $ cd foo
  $ echo a > a
  $ hg ci -Am a
  adding a

Create mq repo with guarded patches foo and bar and empty patch:

  $ hg qinit
  $ echo guarded > guarded
  $ hg add guarded
  $ hg qnew guarded
  $ hg qnew empty-important -m 'important commit message' -d '1 0'
  $ echo bar > bar
  $ hg add bar
  $ hg qnew bar -d '2 0'
  $ echo foo > foo
  $ hg add foo
  $ hg qnew foo
  $ hg qpop -a
  popping foo
  popping bar
  popping empty-important
  popping guarded
  patch queue now empty
  $ hg qguard guarded +guarded
  $ hg qguard bar +baz
  $ hg qguard foo +baz
  $ hg qselect baz
  number of unguarded, unapplied patches has changed from 1 to 3
  $ hg qpush bar
  applying empty-important
  patch empty-important is empty
  applying bar
  now at: bar

  $ hg qguard -l
  guarded: +guarded
  empty-important: unguarded
  bar: +baz
  foo: +baz

  $ hg tglog
  @  2: 'imported patch bar' tags: bar qtip tip
  |
  o  1: 'important commit message' tags: empty-important qbase
  |
  o  0: 'a' tags: qparent
  
Create new head to rebase bar onto:

  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b > b
  $ hg add b
  $ hg ci -m b
  created new head
  $ hg up -C 2
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a >> a
  $ hg qref

  $ hg tglog
  @  3: '[mq]: bar' tags: bar qtip tip
  |
  | o  2: 'b' tags:
  | |
  o |  1: 'important commit message' tags: empty-important qbase
  |/
  o  0: 'a' tags: qparent
  

Rebase bar (make sure series order is preserved and empty-important also is
removed from the series):

  $ hg qseries
  guarded
  empty-important
  bar
  foo
  $ [ -f .hg/patches/empty-important ]
  $ hg -q rebase -d 2
  note: rebase of 1:0aaf4c3af7eb created no changes to commit
  $ hg qseries
  guarded
  bar
  foo
  $ [ -f .hg/patches/empty-important ]
  [1]

  $ hg qguard -l
  guarded: +guarded
  bar: +baz
  foo: +baz

  $ hg tglog
  @  2: '[mq]: bar' tags: bar qbase qtip tip
  |
  o  1: 'b' tags: qparent
  |
  o  0: 'a' tags:
  
  $ cd ..