tests/test-rebase-detach.t

revlog: improve delta generation heuristics for generaldelta

Without this change, pulls (and clones) into a generaldelta repository could
generate very inefficient revlogs, the size of which could be at least twice
the original size.

This was caused by the generated delta chains covering too large distances,
causing new chains to be built far too often. This change addresses the
problem by forcing a delta against second parent or against the previous
revision, when the first parent delta is in danger of creating a long chain.

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


  $ 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)
  (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

  $ cd ..


Rebasing D onto H detaching from C:

  $ hg clone -q -u . a a1
  $ cd a1

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase --detach -s 3 -d 7
  saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  7: 'D'
  |
  o  6: 'H'
  |
  | o  5: 'G'
  |/|
  o |  4: 'F'
  | |
  | o  3: 'E'
  |/
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg manifest
  A
  D
  F
  H

  $ cd ..


Rebasing C onto H detaching from B:

  $ hg clone -q -u . a a2
  $ cd a2

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase --detach -s 2 -d 7
  saved backup bundle to $TESTTMP/a2/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  7: 'D'
  |
  o  6: 'C'
  |
  o  5: 'H'
  |
  | o  4: 'G'
  |/|
  o |  3: 'F'
  | |
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg manifest
  A
  C
  D
  F
  H

  $ cd ..


Rebasing B onto H using detach (same as not using it):

  $ hg clone -q -u . a a3
  $ cd a3

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase --detach -s 1 -d 7
  saved backup bundle to $TESTTMP/a3/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  7: 'D'
  |
  o  6: 'C'
  |
  o  5: 'B'
  |
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
  $ hg manifest
  A
  B
  C
  D
  F
  H

  $ cd ..


Rebasing C onto H detaching from B and collapsing:

  $ hg clone -q -u . a a4
  $ cd a4

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase --detach --collapse -s 2 -d 7
  saved backup bundle to $TESTTMP/a4/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  6: 'Collapsed revision
  |  * C
  |  * D'
  o  5: 'H'
  |
  | o  4: 'G'
  |/|
  o |  3: 'F'
  | |
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg manifest
  A
  C
  D
  F
  H

  $ cd ..

Rebasing across null as ancestor
  $ hg clone -q -U a a5

  $ cd a5

  $ echo x > x

  $ hg add x

  $ hg ci -m "extra branch"
  created new head

  $ hg tglog
  @  8: 'extra branch'
  
  o  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase --detach -s 1 -d tip
  saved backup bundle to $TESTTMP/a5/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  o  5: 'extra branch'
  
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'