bevy/benches
JoJoJet 85a918a8dd
Improve safety for the multi-threaded executor using UnsafeWorldCell (#8292)
# Objective

Fix #7833.

Safety comments in the multi-threaded executor don't really talk about
system world accesses, which makes it unclear if the code is actually
valid.

## Solution

Update the `System` trait to use `UnsafeWorldCell`. This type's API is
written in a way that makes it much easier to cleanly maintain safety
invariants. Use this type throughout the multi-threaded executor, with a
liberal use of safety comments.

---

## Migration Guide

The `System` trait now uses `UnsafeWorldCell` instead of `&World`. This
type provides a robust API for interior mutable world access.
- The method `run_unsafe` uses this type to manage world mutations
across multiple threads.
- The method `update_archetype_component_access` uses this type to
ensure that only world metadata can be used.

```rust
let mut system = IntoSystem::into_system(my_system);
system.initialize(&mut world);

// Before:
system.update_archetype_component_access(&world);
unsafe { system.run_unsafe(&world) }

// After:
system.update_archetype_component_access(world.as_unsafe_world_cell_readonly());
unsafe { system.run_unsafe(world.as_unsafe_world_cell()) }
```

---------

Co-authored-by: James Liu <contact@jamessliu.com>
2023-05-29 15:22:10 +00:00
..
benches Improve safety for the multi-threaded executor using UnsafeWorldCell (#8292) 2023-05-29 15:22:10 +00:00
Cargo.toml update syn, encase, glam and hexasphere (#8573) 2023-05-16 01:24:17 +00:00