view tests/test-drawdag.t @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

  $ cat >> $HGRCPATH<<EOF
  > [extensions]
  > drawdag=$TESTDIR/drawdag.py
  > [experimental]
  > evolution=true
  > EOF

  $ reinit () {
  >   rm -rf .hg && hg init
  > }

  $ hg init

Test what said in drawdag.py docstring

  $ hg debugdrawdag <<'EOS'
  > c d
  > |/
  > b
  > |
  > a
  > EOS

  $ hg log -G -T '{rev} {desc} ({tags})'
  o  3 d (d tip)
  |
  | o  2 c (c)
  |/
  o  1 b (b)
  |
  o  0 a (a)
  
  $ hg debugdrawdag <<'EOS'
  >  foo    bar       bar  foo
  >   |     /          |    |
  >  ancestor(c,d)     a   baz
  > EOS

  $ hg log -G -T '{desc}'
  o    foo
  |\
  +---o  bar
  | | |
  | o |  baz
  |  /
  +---o  d
  | |
  +---o  c
  | |
  o |  b
  |/
  o  a
  
  $ reinit

  $ hg debugdrawdag <<'EOS'
  > o    foo
  > |\
  > +---o  bar
  > | | |
  > | o |  baz
  > |  /
  > +---o  d
  > | |
  > +---o  c
  > | |
  > o |  b
  > |/
  > o  a
  > EOS

  $ hg log -G -T '{desc}'
  o    foo
  |\
  | | o  d
  | |/
  | | o  c
  | |/
  | | o  bar
  | |/|
  | o |  b
  | |/
  o /  baz
   /
  o  a
  
  $ reinit

  $ hg debugdrawdag <<'EOS'
  > o    foo
  > |\
  > | | o  d
  > | |/
  > | | o  c
  > | |/
  > | | o  bar
  > | |/|
  > | o |  b
  > | |/
  > o /  baz
  >  /
  > o  a
  > EOS

  $ hg log -G -T '{desc}'
  o    foo
  |\
  | | o  d
  | |/
  | | o  c
  | |/
  | | o  bar
  | |/|
  | o |  b
  | |/
  o /  baz
   /
  o  a
  
  $ hg manifest -r a
  a
  $ hg manifest -r b
  a
  b
  $ hg manifest -r bar
  a
  b
  $ hg manifest -r foo
  a
  b
  baz

Edges existed in repo are no-ops

  $ reinit
  $ hg debugdrawdag <<'EOS'
  > B C C
  > | | |
  > A A B
  > EOS

  $ hg log -G -T '{desc}'
  o    C
  |\
  | o  B
  |/
  o  A
  

  $ hg debugdrawdag <<'EOS'
  > C D C
  > | | |
  > B B A
  > EOS

  $ hg log -G -T '{desc}'
  o  D
  |
  | o  C
  |/|
  o |  B
  |/
  o  A
  

Node with more than 2 parents are disallowed

  $ hg debugdrawdag <<'EOS'
  >   A
  >  /|\
  > D B C
  > EOS
  abort: A: too many parents: C D B
  [255]

Cycles are disallowed

  $ hg debugdrawdag <<'EOS'
  > A
  > |
  > A
  > EOS
  abort: the graph has cycles
  [255]

  $ hg debugdrawdag <<'EOS'
  > A
  > |
  > B
  > |
  > A
  > EOS
  abort: the graph has cycles
  [255]

Create obsmarkers via comments

  $ reinit

  $ hg debugdrawdag <<'EOS'
  >       G
  >       |
  > I D C F   # split: B -> E, F, G
  >  \ \| |   # replace: C -> D -> H
  >   H B E   # prune: F, I
  >    \|/
  >     A
  > EOS
  1 new orphan changesets

  $ hg log -r 'sort(all(), topo)' -G --hidden -T '{desc} {node}'
  *  G 711f53bbef0bebd12eb6f0511d5e2e998b984846
  |
  x  F 64a8289d249234b9886244d379f15e6b650b28e3
  |
  o  E 7fb047a69f220c21711122dfd94305a9efb60cba
  |
  | x  D be0ef73c17ade3fc89dc41701eb9fc3a91b58282
  | |
  | | x  C 26805aba1e600a82e93661149f2313866a221a7b
  | |/
  | x  B 112478962961147124edd43549aedd1a335e44bf
  |/
  | x  I 58e6b987bf7045fcd9c54f496396ca1d1fc81047
  | |
  | o  H 575c4b5ec114d64b681d33f8792853568bfb2b2c
  |/
  o  A 426bada5c67598ca65036d57d9e4b64b0c1ce7a0
  
  $ hg debugobsolete
  112478962961147124edd43549aedd1a335e44bf 7fb047a69f220c21711122dfd94305a9efb60cba 64a8289d249234b9886244d379f15e6b650b28e3 711f53bbef0bebd12eb6f0511d5e2e998b984846 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '0', 'operation': 'split', 'user': 'test'}
  26805aba1e600a82e93661149f2313866a221a7b be0ef73c17ade3fc89dc41701eb9fc3a91b58282 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '9', 'operation': 'replace', 'user': 'test'}
  be0ef73c17ade3fc89dc41701eb9fc3a91b58282 575c4b5ec114d64b681d33f8792853568bfb2b2c 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '13', 'operation': 'replace', 'user': 'test'}
  64a8289d249234b9886244d379f15e6b650b28e3 0 {7fb047a69f220c21711122dfd94305a9efb60cba} (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '0', 'operation': 'prune', 'user': 'test'}
  58e6b987bf7045fcd9c54f496396ca1d1fc81047 0 {575c4b5ec114d64b681d33f8792853568bfb2b2c} (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '0', 'operation': 'prune', 'user': 'test'}

Change file contents via comments

  $ reinit
  $ hg debugdrawdag <<'EOS'
  > C       # A/dir1/a = 1\n2
  > |\      # B/dir2/b = 34
  > A B     # C/dir1/c = 5
  >         # C/dir2/c = 6
  >         # C/A = a
  >         # C/B = b
  > EOS

  $ hg log -G -T '{desc} {files}'
  o    C A B dir1/c dir2/c
  |\
  | o  B B dir2/b
  |
  o  A A dir1/a
  
  $ for f in `hg files -r C`; do
  >   echo FILE "$f"
  >   hg cat -r C "$f"
  >   echo
  > done
  FILE A
  a
  FILE B
  b
  FILE dir1/a
  1
  2
  FILE dir1/c
  5
  FILE dir2/b
  34
  FILE dir2/c
  6