Mercurial > hg
view tests/test-obsolete-tag-cache.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
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | abbecb5cd6f3 |
children |
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$ cat >> $HGRCPATH << EOF > [extensions] > blackbox= > rebase= > mock=$TESTDIR/mockblackbox.py > > [blackbox] > track = command, commandfinish, tagscache > > [experimental] > evolution.createmarkers=True > EOF Create a repo with some tags $ hg init repo $ cd repo $ echo initial > foo $ hg -q commit -A -m initial $ hg tag -m 'test tag' test1 $ echo first > first $ hg -q commit -A -m first $ hg tag -m 'test2 tag' test2 $ hg -q up -r 0 $ echo newhead > newhead $ hg commit -A -m newhead adding newhead created new head $ hg tag -m 'test head 2 tag' head2 $ hg log -G -T '{rev}:{node|short} {tags} {desc}\n' @ 5:2942a772f72a tip test head 2 tag | o 4:042eb6bfcc49 head2 newhead | | o 3:c3cb30f2d2cd test2 tag | | | o 2:d75775ffbc6b test2 first | | | o 1:5f97d42da03f test tag |/ o 0:55482a6fb4b1 test1 initial Trigger tags cache population by doing something that accesses tags info $ hg tags tip 5:2942a772f72a head2 4:042eb6bfcc49 test2 2:d75775ffbc6b test1 0:55482a6fb4b1 $ cat .hg/cache/tags2-visible 5 2942a772f72a444bef4bef13874d515f50fa27b6 042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2 55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1 d75775ffbc6bca1794d300f5571272879bd280da test2 Hiding a non-tip changeset should change filtered hash and cause tags recompute $ hg debugobsolete -d '0 0' c3cb30f2d2cd0aae008cc91a07876e3c5131fd22 -u dummyuser 1 new obsolescence markers obsoleted 1 changesets $ hg tags tip 5:2942a772f72a head2 4:042eb6bfcc49 test1 0:55482a6fb4b1 $ cat .hg/cache/tags2-visible 5 2942a772f72a444bef4bef13874d515f50fa27b6 f34fbc9a9769ba9eff5aff3d008a6b49f85c08b1 042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2 55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1 $ hg blackbox -l 5 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 2/2 cache hits/lookups in * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2-visible with 2 tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags exited 0 after * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5 Hiding another changeset should cause the filtered hash to change $ hg debugobsolete -d '0 0' d75775ffbc6bca1794d300f5571272879bd280da -u dummyuser 1 new obsolescence markers obsoleted 1 changesets $ hg debugobsolete -d '0 0' 5f97d42da03fd56f3b228b03dfe48af5c0adf75b -u dummyuser 1 new obsolescence markers obsoleted 1 changesets $ hg tags tip 5:2942a772f72a head2 4:042eb6bfcc49 $ cat .hg/cache/tags2-visible 5 2942a772f72a444bef4bef13874d515f50fa27b6 2fce1eec33263d08a4d04293960fc73a555230e4 042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2 $ hg blackbox -l 5 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 1/1 cache hits/lookups in * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2-visible with 1 tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> tags exited 0 after * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5 Resolving tags on an unfiltered repo writes a separate tags cache $ hg --hidden tags tip 5:2942a772f72a head2 4:042eb6bfcc49 test2 2:d75775ffbc6b test1 0:55482a6fb4b1 $ cat .hg/cache/tags2 5 2942a772f72a444bef4bef13874d515f50fa27b6 042eb6bfcc4909bad84a1cbf6eb1ddf0ab587d41 head2 55482a6fb4b1881fa8f746fd52cf6f096bb21c89 test1 d75775ffbc6bca1794d300f5571272879bd280da test2 $ hg blackbox -l 5 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> --hidden tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> 2/2 cache hits/lookups in * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> writing .hg/cache/tags2 with 3 tags 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> --hidden tags exited 0 after * seconds (glob) 1970-01-01 00:00:00.000 bob @2942a772f72a444bef4bef13874d515f50fa27b6 (5000)> blackbox -l 5