view tests/test-status-tracked-key.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

===============================
Test the "tracked hint" feature
===============================

The tracked hint feature provide a file that get updated when the set of tracked
files get updated.

basic setup

  $ cat << EOF >> $HGRCPATH
  > [format]
  > use-dirstate-tracked-hint=yes
  > EOF

  $ hg init tracked-hint-test
  $ cd tracked-hint-test
  $ hg debugbuilddag '.+10' -n
  $ hg log -G -T '{rev} {desc} {files}\n'
  o  10 r10 nf10
  |
  o  9 r9 nf9
  |
  o  8 r8 nf8
  |
  o  7 r7 nf7
  |
  o  6 r6 nf6
  |
  o  5 r5 nf5
  |
  o  4 r4 nf4
  |
  o  3 r3 nf3
  |
  o  2 r2 nf2
  |
  o  1 r1 nf1
  |
  o  0 r0 nf0
  
  $ hg up tip
  11 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg files
  nf0
  nf1
  nf10
  nf2
  nf3
  nf4
  nf5
  nf6
  nf7
  nf8
  nf9

key-file exists
-----------

The tracked hint file should exist

  $ ls -1 .hg/dirstate*
  .hg/dirstate
  .hg/dirstate-tracked-hint

key-file stay the same if the tracked set is unchanged
------------------------------------------------------

(copy its content for later comparison)

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ echo foo >> nf0
  $ sleep 1
  $ hg status
  M nf0
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  $ hg revert -C nf0
  $ sleep 1
  $ hg status
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck

key-file change if the tracked set is changed manually
------------------------------------------------------

adding a file to tracking

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ echo x > x
  $ hg add x
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]

remove a file from tracking
(forget)

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg forget x
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]

(remove)

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg remove nf1
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]

key-file changes on revert (when applicable)
--------------------------------------------

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg status
  R nf1
  ? x
  $ hg revert --all
  undeleting nf1
  $ hg status
  ? x
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]


`hg update` does affect the key-file (when needed)
--------------------------------------------------

update changing the tracked set

(removing)

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg status --rev . --rev '.#generations[-1]'
  R nf10
  $ hg up '.#generations[-1]'
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]

(adding)

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg status --rev . --rev '.#generations[1]'
  A nf10
  $ hg up '.#generations[1]'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck
  Files .hg/dirstate-tracked-hint and ../key-bck differ
  [1]

update not affecting the tracked set

  $ echo foo >> nf0
  $ hg commit -m foo

  $ cp .hg/dirstate-tracked-hint ../key-bck
  $ hg status --rev . --rev '.#generations[-1]'
  M nf0
  $ hg up '.#generations[-1]'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ diff --brief .hg/dirstate-tracked-hint ../key-bck

Test upgrade and downgrade
==========================

  $ ls .hg/dirstate-tracked-hint
  .hg/dirstate-tracked-hint
  $ hg debugrequires | grep 'tracked'
  dirstate-tracked-key-v1

downgrade

  $ hg debugupgraderepo --config format.use-dirstate-tracked-hint=no --run --quiet
  upgrade will perform the following actions:
  
  requirements
     preserved: * (glob)
     removed: dirstate-tracked-key-v1
  
  no revlogs to process
  
  $ ls -1 .hg/dirstate-tracked-hint
  ls: *.hg/dirstate-tracked-hint*: $ENOENT$ (glob)
  [2]
  $ hg debugrequires | grep 'tracked'
  [1]

upgrade

  $ hg debugupgraderepo --config format.use-dirstate-tracked-hint=yes --run --quiet
  upgrade will perform the following actions:
  
  requirements
     preserved: * (glob)
     added: dirstate-tracked-key-v1
  
  no revlogs to process
  
  $ ls -1 .hg/dirstate-tracked-hint
  .hg/dirstate-tracked-hint
  $ hg debugrequires | grep 'tracked'
  dirstate-tracked-key-v1