Messages in this thread | | | Date | Tue, 23 May 2023 13:31:12 -0300 | Subject | Re: [PATCH v2 3/4] rust: specify when `ARef` is thread safe | From | Martin Rodriguez Reboredo <> |
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On 5/23/23 11:44, Alice Ryhl wrote: > An `ARef` behaves just like the `Arc` when it comes to thread safety, so > we can reuse the thread safety comments from `Arc` here. > > This is necessary because without this change, the Rust compiler will > assume that things are not thread safe even though they are. > > Signed-off-by: Alice Ryhl <aliceryhl@google.com> > Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> > Reviewed-by: Boqun Feng <boqun.feng@gmail.com> > --- > [...] > > +// SAFETY: It is safe to send `ARef<T>` to another thread when the underlying `T` is `Sync` because > +// it effectively means sharing `&T` (which is safe because `T` is `Sync`); additionally, it needs > +// `T` to be `Send` because any thread that has an `ARef<T>` may ultimately access `T` using a > +// mutable reference, for example, when the reference count reaches zero and `T` is dropped. > +unsafe impl<T: AlwaysRefCounted + Sync + Send> Send for ARef<T> {} > + > +// SAFETY: It is safe to send `&ARef<T>` to another thread when the underlying `T` is `Sync` > +// because it effectively means sharing `&T` (which is safe because `T` is `Sync`); additionally, > +// it needs `T` to be `Send` because any thread that has a `&ARef<T>` may clone it and get an > +// `ARef<T>` on that thread, so the thread may ultimately access `T` using a mutable reference, for > +// example, when the reference count reaches zero and `T` is dropped. > +unsafe impl<T: AlwaysRefCounted + Sync + Send> Sync for ARef<T> {} > + > impl<T: AlwaysRefCounted> ARef<T> { > /// Creates a new instance of [`ARef`]. > ///
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
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