view tests/test-rebase-base.t @ 31793:69d8fcf20014

help: document bundle specifications

I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.

The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.

After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.

Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.

Given:

a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
   a user-facing feature
c) the list of available compression engines and their behavior isn't
   exposed
d) we need an extensible place to modify behavior of compression
   engines

I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > drawdag=$TESTDIR/drawdag.py
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {desc}"
  > EOF

  $ rebasewithdag() {
  >   N=`$PYTHON -c "print($N+1)"`
  >   hg init repo$N && cd repo$N
  >   hg debugdrawdag
  >   hg rebase "$@" > _rebasetmp
  >   r=$?
  >   grep -v 'saved backup bundle' _rebasetmp
  >   [ $r -eq 0 ] && hg tglog
  >   cd ..
  >   return $r
  > }

Single branching point, without merge:

  $ rebasewithdag -b D -d Z <<'EOS'
  >     D E
  >     |/
  > Z B C   # C: branching point, E should be picked
  >  \|/    # B should not be picked
  >   A
  >   |
  >   R
  > EOS
  rebasing 3:d6003a550c2c "C" (C)
  rebasing 5:4526cf523425 "D" (D)
  rebasing 6:b296604d9846 "E" (E tip)
  o  6: E
  |
  | o  5: D
  |/
  o  4: C
  |
  o  3: Z
  |
  | o  2: B
  |/
  o  1: A
  |
  o  0: R
  
Multiple branching points caused by selecting a single merge changeset:

  $ rebasewithdag -b E -d Z <<'EOS'
  >     E
  >    /|
  >   B C D  # B, C: multiple branching points
  >   | |/   # D should not be picked
  > Z | /
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d "B" (B)
  rebasing 3:d6003a550c2c "C" (C)
  rebasing 6:5251e0cb7302 "E" (E tip)
  o    6: E
  |\
  | o  5: C
  | |
  o |  4: B
  |/
  o  3: Z
  |
  | o  2: D
  |/
  o  1: A
  |
  o  0: R
  
Rebase should not extend the "--base" revset using "descendants":

  $ rebasewithdag -b B -d Z <<'EOS'
  >     E
  >    /|
  > Z B C  # descendants(B) = B+E. With E, C will be included incorrectly
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d "B" (B)
  rebasing 5:5251e0cb7302 "E" (E tip)
  o    5: E
  |\
  | o  4: B
  | |
  | o  3: Z
  | |
  o |  2: C
  |/
  o  1: A
  |
  o  0: R
  
Rebase should not simplify the "--base" revset using "roots":

  $ rebasewithdag -b B+E -d Z <<'EOS'
  >     E
  >    /|
  > Z B C  # roots(B+E) = B. Without E, C will be missed incorrectly
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d "B" (B)
  rebasing 3:d6003a550c2c "C" (C)
  rebasing 5:5251e0cb7302 "E" (E tip)
  o    5: E
  |\
  | o  4: C
  | |
  o |  3: B
  |/
  o  2: Z
  |
  o  1: A
  |
  o  0: R
  
The destination is one of the two branching points of a merge:

  $ rebasewithdag -b F -d Z <<'EOS'
  >     F
  >    / \
  >   E   D
  >  /   /
  > Z   C
  >  \ /
  >   B
  >   |
  >   A
  > EOS
  nothing to rebase
  [1]

Multiple branching points caused by multiple bases (issue5420):

  $ rebasewithdag -b E1+E2+C2+B1 -d Z <<'EOS'
  >   Z    E2
  >   |   /
  >   F E1 C2
  >   |/  /
  >   E C1 B2
  >   |/  /
  >   C B1
  >   |/
  >   B
  >   |
  >   A
  >   |
  >   R
  > EOS
  rebasing 3:a113dbaa660a "B1" (B1)
  rebasing 5:06ce7b1cc8c2 "B2" (B2)
  rebasing 6:0ac98cce32d3 "C1" (C1)
  rebasing 8:781512f5e33d "C2" (C2)
  rebasing 9:428d8c18f641 "E1" (E1)
  rebasing 11:e1bf82f6b6df "E2" (E2)
  o  12: E2
  |
  o  11: E1
  |
  | o  10: C2
  | |
  | o  9: C1
  |/
  | o  8: B2
  | |
  | o  7: B1
  |/
  o  6: Z
  |
  o  5: F
  |
  o  4: E
  |
  o  3: C
  |
  o  2: B
  |
  o  1: A
  |
  o  0: R
  
Multiple branching points with multiple merges:

  $ rebasewithdag -b G+P -d Z <<'EOS'
  > G   H   P
  > |\ /|   |\
  > F E D   M N
  >  \|/|  /| |\
  > Z C B I J K L
  >  \|/  |/  |/
  >   A   A   A
  > EOS
  rebasing 2:dc0947a82db8 "C" (C)
  rebasing 8:215e7b0814e1 "D" (D)
  rebasing 9:03ca77807e91 "E" (E)
  rebasing 10:afc707c82df0 "F" (F)
  rebasing 13:018caa673317 "G" (G)
  rebasing 14:4f710fbd68cb "H" (H)
  rebasing 3:08ebfeb61bac "I" (I)
  rebasing 4:a0a5005cec67 "J" (J)
  rebasing 5:83780307a7e8 "K" (K)
  rebasing 6:e131637a1cb6 "L" (L)
  rebasing 11:d6fe3d11d95d "M" (M)
  rebasing 12:fa1e02269063 "N" (N)
  rebasing 15:448b1a498430 "P" (P tip)
  o    15: P
  |\
  | o    14: N
  | |\
  o \ \    13: M
  |\ \ \
  | | | o  12: L
  | | | |
  | | o |  11: K
  | | |/
  | o /  10: J
  | |/
  o /  9: I
  |/
  | o    8: H
  | |\
  | | | o  7: G
  | | |/|
  | | | o  6: F
  | | | |
  | | o |  5: E
  | | |/
  | o |  4: D
  | |\|
  +---o  3: C
  | |
  o |  2: Z
  | |
  | o  1: B
  |/
  o  0: A
  
Slightly more complex merge case (mentioned in https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-November/091074.html):

  $ rebasewithdag -b A3+B3 -d Z <<'EOF'
  > Z     C1    A3     B3
  > |    /     / \    / \
  > M3 C0     A1  A2 B1  B2
  > | /       |   |  |   |
  > M2        M1  C1 C1  M3
  > |
  > M1
  > |
  > M0
  > EOF
  rebasing 4:8817fae53c94 "C0" (C0)
  rebasing 6:06ca5dfe3b5b "B2" (B2)
  rebasing 7:73508237b032 "C1" (C1)
  rebasing 9:fdb955e2faed "A2" (A2)
  rebasing 11:1b2f368c3cb5 "A3" (A3)
  rebasing 10:0a33b0519128 "B1" (B1)
  rebasing 12:bd6a37b5b67a "B3" (B3 tip)
  o    12: B3
  |\
  | o  11: B1
  | |
  | | o    10: A3
  | | |\
  | +---o  9: A2
  | | |
  | o |  8: C1
  | | |
  o | |  7: B2
  | | |
  | o |  6: C0
  |/ /
  o |  5: Z
  | |
  o |  4: M3
  | |
  o |  3: M2
  | |
  | o  2: A1
  |/
  o  1: M1
  |
  o  0: M0
  
Mixed rebasable and non-rebasable bases (unresolved, issue5422):

  $ rebasewithdag -b C+D -d B <<'EOS'
  >   D
  >  /
  > B C
  > |/
  > A
  > EOS
  nothing to rebase
  [1]

Disconnected graph:

  $ rebasewithdag -b B -d Z <<'EOS'
  >   B
  >   |
  > Z A
  > EOS
  nothing to rebase from 112478962961 to 48b9aae0607f
  [1]

Multiple roots. Roots are ancestors of dest:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > D Z B
  >  \|\|
  >   C A
  > EOF
  rebasing 2:112478962961 "B" (B)
  rebasing 3:b70f76719894 "D" (D)
  o  4: D
  |
  | o  3: B
  |/
  o    2: Z
  |\
  | o  1: C
  |
  o  0: A
  
Multiple roots. One root is not an ancestor of dest:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > Z B D
  >  \|\|
  >   A C
  > EOF
  nothing to rebase from 86d01f49c0d9+b70f76719894 to 262e37e34f63
  [1]

Multiple roots. One root is not an ancestor of dest. Select using a merge:

  $ rebasewithdag -b E -d Z <<'EOF'
  >   E
  >   |\
  > Z B D
  >  \|\|
  >   A C
  > EOF
  rebasing 2:86d01f49c0d9 "B" (B)
  rebasing 5:539a0ff83ea9 "E" (E tip)
  o    5: E
  |\
  | o    4: B
  | |\
  | | o  3: Z
  | | |
  o | |  2: D
  |/ /
  o /  1: C
   /
  o  0: A
  
Multiple roots. Two children share two parents while dest has only one parent:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > Z B D
  >  \|\|\
  >   A C A
  > EOF
  rebasing 2:86d01f49c0d9 "B" (B)
  rebasing 3:b7df2ca01aa8 "D" (D)
  o    4: D
  |\
  +---o  3: B
  | |/
  | o  2: Z
  | |
  o |  1: C
   /
  o  0: A