view tests/test-exchange-obsmarkers-case-B1.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 B.1
============================================

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 B: pruning case
TestCase 1: Prune on non-targeted common changeset

B.1 Prune on non-targeted common changeset
==========================================

.. {{{
..     ⊗ B
..     |
..     ◕ A
..     |
..     ● O
.. }}}
..
.. Marker exist from:
..
..  * B (prune)
..
.. Command runs:
..
..  * hg push -r O
..
.. Expected exclude:
..
..  * B (prune)

Setup
-----

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

Initial

  $ setuprepos B.1
  creating test repo for test case B.1
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ mkcommit B

make both changeset known in remote

  $ hg push -qf ../pushdest
  $ hg push -qf ../pulldest

create prune marker

  $ hg prune -qd '0 0' .
  $ hg log -G --hidden
  x  f6fbb35d8ac9 (draft): B
  |
  @  f5bc6836db60 (draft): A
  |
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

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

  $ dotest B.1 O
  ## Running testcase B.1
  # testing echange of "O" (a9bdc8b26820)
  ## initial state
  # obstore: main
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (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
  ## post push state
  # obstore: main
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pulling "a9bdc8b26820" from main into pulldest
  pulling from main
  no changes found
  ## post pull state
  # obstore: main
  f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest