view tests/test-exchange-obsmarkers-case-C4.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

============================================
Testing obsolescence markers push: Cases C.4
============================================

Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).

This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.

Category C: advanced case
TestCase 4: multiple successors, one is pruned

C.4 multiple successors, one is pruned
======================================

.. (A similarish situation can appends with split markers see the Z section)
..
.. {{{
..        A
..    B ○⇢ø⇠⊗ C
..       \|/
..        ● O
.. }}}
..
.. Marker exist from:
..
..  * `A ø⇠○ B`
..  * `A ø⇠○ C`
..  * C (prune)
..
.. Command run:
..
..  * hg push -r O
..
.. Expected exchange:
..
..  * `A ø⇠○ C`
..  * C (prune)
..
.. Expected exclude:
..
..  * `A ø⇠○ B`

Setup
-----

  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh

Implemented as the non-split version

  $ setuprepos C.4
  creating test repo for test case C.4
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ hg update -q 0
  $ mkcommit B
  created new head
  $ hg update -q 0
  $ mkcommit C
  created new head
  $ hg debugobsolete --hidden `getid 'desc(A)'` `getid 'desc(B)'`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg debugobsolete --hidden `getid 'desc(A)'` `getid 'desc(C)'`
  1 new obsolescence markers
  2 new content-divergent changesets
  $ hg prune -qd '0 0' .
  $ hg log -G --hidden
  x  7f7f229b13a6 (draft): C
  |
  | o  35b183996678 (draft): B
  |/
  | x  f5bc6836db60 (draft): A
  |/
  @  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 35b1839966785d5703a01607229eea932db42f87 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

Actual Test
-----------

  $ dotest C.4 O
  ## Running testcase C.4
  # testing echange of "O" (a9bdc8b26820)
  ## initial state
  # obstore: main
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 35b1839966785d5703a01607229eea932db42f87 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "O" from main to pushdest
  pushing to pushdest
  searching for changes
  no changes found
  remote: 2 new obsolescence markers
  ## post push state
  # obstore: main
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 35b1839966785d5703a01607229eea932db42f87 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling "a9bdc8b26820" from main into pulldest
  pulling from main
  no changes found
  2 new obsolescence markers
  ## post pull state
  # obstore: main
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 35b1839966785d5703a01607229eea932db42f87 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  f5bc6836db60e308a17ba08bf050154ba9c4fad7 7f7f229b13a629a5b20581c6cb723f4e2ca54bed 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}