Mirrors/bevy
2
0
Fork 0
mirror of https://github.com/bevyengine/bevy synced 2025-02-16 22:18:33 +00:00
Code Issues Projects Releases Packages Wiki Activity

Move docs for !Sync resources onto the correct trait (#8066)

Browse source
This commit is contained in:
JoJoJet 2023-03-13 12:16:14 -04:00 • committed by GitHub
parent 0918b30e29
commit ed97c621b8
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 32 additions and 32 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

64
crates/bevy_ecs/src/system/system_param.rs
View file

@ -89,38 +89,6 @@ use std::{
/// This will most commonly occur when working with `SystemParam`s generically, as the requirement
/// has not been proven to the compiler.
///
/// # `!Sync` Resources
/// A `!Sync` type cannot implement `Resource`. However, it is possible to wrap a `Send` but not `Sync`
/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
/// threads.
///
/// This will fail to compile since `RefCell` is `!Sync`.
/// ```compile_fail
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
///
/// #[derive(Resource)]
/// struct NotSync {
/// counter: RefCell<usize>,
/// }
/// ```
///
/// This will compile since the `RefCell` is wrapped with `SyncCell`.
/// ```
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
/// use bevy_utils::synccell::SyncCell;
///
/// #[derive(Resource)]
/// struct ActuallySync {
/// counter: SyncCell<RefCell<usize>>,
/// }
/// ```
///
/// [`SyncCell`]: bevy_utils::synccell::SyncCell
/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
///
/// # Safety
///
/// The implementor must ensure the following is true.
@ -399,6 +367,38 @@ impl_param_set!();
/// # schedule.add_systems((read_resource_system, write_resource_system).chain());
/// # schedule.run(&mut world);
/// ```
///
/// # `!Sync` Resources
/// A `!Sync` type cannot implement `Resource`. However, it is possible to wrap a `Send` but not `Sync`
/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
/// threads.
///
/// This will fail to compile since `RefCell` is `!Sync`.
/// ```compile_fail
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
///
/// #[derive(Resource)]
/// struct NotSync {
/// counter: RefCell<usize>,
/// }
/// ```
///
/// This will compile since the `RefCell` is wrapped with `SyncCell`.
/// ```
/// # use std::cell::RefCell;
/// # use bevy_ecs::system::Resource;
/// use bevy_utils::synccell::SyncCell;
///
/// #[derive(Resource)]
/// struct ActuallySync {
/// counter: SyncCell<RefCell<usize>>,
/// }
/// ```
///
/// [`SyncCell`]: bevy_utils::synccell::SyncCell
/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
pub trait Resource: Send + Sync + 'static {}
// SAFETY: Res only reads a single World resource