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
hide outer repo
$ hg init
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ mkdir webdir
$ cd webdir
$ hg init a
$ hg --cwd a qinit -c
$ echo a > a/a
$ hg --cwd a ci -A -m a
adding a
$ echo b > a/b
$ hg --cwd a addremove
adding b
$ hg --cwd a qnew -f b.patch
$ hg --cwd a qcommit -m b.patch
$ hg --cwd a log --template "{desc}\n"
[mq]: b.patch
a
$ hg --cwd a/.hg/patches log --template "{desc}\n"
b.patch
$ root=`pwd`
$ cd ..
test with recursive collection
$ cat > collections.conf <<EOF
> [paths]
> /=$root/**
> EOF
$ hg serve -p $HGPORT -d --pid-file=hg.pid --webdir-conf collections.conf \
> -A access-paths.log -E error-paths-1.log
$ cat hg.pid >> $DAEMON_PIDS
$ get-with-headers.py localhost:$HGPORT '?style=raw'
200 Script output follows
/a/
/a/.hg/patches/
$ hg qclone http://localhost:$HGPORT/a b
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:184916345baa
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets 4052ceaa8c4e
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --cwd b log --template "{desc}\n"
a
$ hg --cwd b qpush -a
applying b.patch
now at: b.patch
$ hg --cwd b log --template "{desc}\n"
imported patch b.patch
a
test with normal collection
$ cat > collections1.conf <<EOF
> [paths]
> /=$root/*
> EOF
$ hg serve -p $HGPORT1 -d --pid-file=hg.pid --webdir-conf collections1.conf \
> -A access-paths.log -E error-paths-1.log
$ cat hg.pid >> $DAEMON_PIDS
$ get-with-headers.py localhost:$HGPORT1 '?style=raw'
200 Script output follows
/a/
/a/.hg/patches/
$ hg qclone http://localhost:$HGPORT1/a c
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:184916345baa
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets 4052ceaa8c4e
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --cwd c log --template "{desc}\n"
a
$ hg --cwd c qpush -a
applying b.patch
now at: b.patch
$ hg --cwd c log --template "{desc}\n"
imported patch b.patch
a
test with old-style collection
$ cat > collections2.conf <<EOF
> [collections]
> $root=$root
> EOF
$ hg serve -p $HGPORT2 -d --pid-file=hg.pid --webdir-conf collections2.conf \
> -A access-paths.log -E error-paths-1.log
$ cat hg.pid >> $DAEMON_PIDS
$ get-with-headers.py localhost:$HGPORT2 '?style=raw'
200 Script output follows
/a/
/a/.hg/patches/
$ hg qclone http://localhost:$HGPORT2/a d
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:184916345baa
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets 4052ceaa8c4e
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg --cwd d log --template "{desc}\n"
a
$ hg --cwd d qpush -a
applying b.patch
now at: b.patch
$ hg --cwd d log --template "{desc}\n"
imported patch b.patch
a
test --mq works and uses correct repository config
$ hg --cwd d outgoing --mq
comparing with http://localhost:$HGPORT2/a/.hg/patches
searching for changes
no changes found
[1]
$ hg --cwd d log --mq --template '{rev} {desc|firstline}\n'
0 b.patch
$ killdaemons.py