# Objective
- We rely on the construction of `EntityRef` to be valid elsewhere in unsafe code. This construction is not checked (for performance reasons), and thus this private method must be unsafe.
- Fixes#7218.
## Solution
- Make the method unsafe.
- Add safety docs.
- Improve safety docs slightly for the sibling `EntityMut::new`.
- Add debug asserts to start to verify these assumptions in debug mode.
## Context for reviewers
I attempted to verify the `EntityLocation` more thoroughly, but this turned out to be more work than expected. I've spun that off into #7221 as a result.
# Objective
The usages of the unsafe function `byte_add` are not properly documented.
Follow-up to #7151.
## Solution
Add safety comments to each call-site.
# Objective
- The function `BlobVec::replace_unchecked` has informal use of safety comments.
- This function does strange things with `OwningPtr` in order to get around the borrow checker.
## Solution
- Put safety comments in front of each unsafe operation. Describe the specific invariants of each operation and how they apply here.
- Added a guard type `OnDrop`, which is used to simplify ownership transfer in case of a panic.
---
## Changelog
+ Added the guard type `bevy_utils::OnDrop`.
+ Added conversions from `Ptr`, `PtrMut`, and `OwningPtr` to `NonNull<u8>`.
# Objective
Fix#5248.
## Solution
Support `In<T>` parameters and allow returning arbitrary types in exclusive systems.
---
## Changelog
- Exclusive systems may now be used with system piping.
## Migration Guide
Exclusive systems (systems that access `&mut World`) now support system piping, so the `ExclusiveSystemParamFunction` trait now has generics for the `In`put and `Out`put types.
```rust
// Before
fn my_generic_system<T, Param>(system_function: T)
where T: ExclusiveSystemParamFunction<Param>
{ ... }
// After
fn my_generic_system<T, In, Out, Param>(system_function: T)
where T: ExclusiveSystemParamFunction<In, Out, Param>
{ ... }
```
# Objective
There are some utility functions for actually working with `Storages` inside `entity_ref.rs` that are used both for `EntityRef/EntityMut` and `World`, with a `// TODO: move to Storages`.
This PR moves them to private methods on `World`, because that's the safest API boundary. On `Storages` you would need to ensure that you pass `Components` from the same world.
## Solution
- move get_component[_with_type], get_ticks[_with_type], get_component_and_ticks[_with_type] to `World` (still pub(crate))
- replace `pub use entity_ref::*;` with `pub use entity_ref::{EntityRef, EntityMut}` and qualified `entity_ref::get_mut[_by_id]` in `world.rs`
- add safety comments to a bunch of methods
# Objective
* `World::init_resource` and `World::get_resource_or_insert_with` are implemented naively, and as such they perform duplicate `TypeId -> ComponentId` lookups.
* `World::get_resource_or_insert_with` contains an additional duplicate `ComponentId -> ResourceData` lookup.
* This function also contains an unnecessary panic branch, which we rely on the optimizer to be able to remove.
## Solution
Implement the functions using engine-internal code, instead of combining high-level functions. This allows computed variables to persist across different branches, instead of being recomputed.
# Objective
Following #6681, both `TableRow` and `TableId` are now part of `EntityLocation`. However, the safety invariant on `EntityLocation` requires that all of the constituent fields are `repr(transprent)` or `repr(C)` and the bit pattern of all 1s must be valid. This is not true for `TableRow` and `TableId` currently.
## Solution
Mark `TableRow` and `TableId` to satisfy the safety requirement. Add safety comments on `ArchetypeId`, `ArchetypeRow`, `TableId` and `TableRow`.
# Objective
Improve safety testing when using `bevy_ptr` types. This is a follow-up to #7113.
## Solution
Add a debug-only assertion that pointers are aligned when casting to a concrete type. This should very quickly catch any unsoundness from unaligned pointers, even without miri. However, this can have a large negative perf impact on debug builds.
---
## Changelog
Added: `Ptr::deref` will now panic in debug builds if the pointer is not aligned.
Added: `PtrMut::deref_mut` will now panic in debug builds if the pointer is not aligned.
Added: `OwningPtr::read` will now panic in debug builds if the pointer is not aligned.
Added: `OwningPtr::drop_as` will now panic in debug builds if the pointer is not aligned.
# Objective
`MutUntyped` is a struct that stores a `PtrMut` alongside change tick metadata. Working with this type is cumbersome, and has few benefits over storing the pointer and change ticks separately.
Related: #6430 (title is out of date)
## Solution
Add a convenience method for transforming an untyped change detection pointer into its typed counterpart.
---
## Changelog
- Added the method `MutUntyped::with_type`.
# Objective
- Fixes#7066
## Solution
- Split the ChangeDetection trait into ChangeDetection and ChangeDetectionMut
- Added Ref as equivalent to &T with change detection
---
## Changelog
- Support for Ref which allow inspecting change detection flags in an immutable way
## Migration Guide
- While bevy prelude includes both ChangeDetection and ChangeDetectionMut any code explicitly referencing ChangeDetection might need to be updated to ChangeDetectionMut or both. Specifically any reading logic requires ChangeDetection while writes requires ChangeDetectionMut.
use bevy_ecs::change_detection::DetectChanges -> use bevy_ecs::change_detection::{DetectChanges, DetectChangesMut}
- Previously Res had methods to access change detection `is_changed` and `is_added` those methods have been moved to the `DetectChanges` trait. If you are including bevy prelude you will have access to these types otherwise you will need to `use bevy_ecs::change_detection::DetectChanges` to continue using them.
`Query`'s fields being `pub(crate)` means that the struct can be constructed via safe code from anywhere in `bevy_ecs` . This is Not Good since it is intended that all construction of this type goes through `Query::new` which is an `unsafe fn` letting various `Query` methods rely on those invariants holding even though they can be trivially bypassed.
This has no user facing impact
# Objective
- Fix#7103.
- The issue is caused because I forgot to add a where clause to a generated struct in #7056.
## Solution
- Add the where clause.
`Query` relies on the `World` it stores being the same as the world used for creating the `QueryState` it stores. If they are not the same then everything is very unsound. This was not actually being checked anywhere, `Query::new` did not have a safety invariant or even an assertion that the `WorldId`'s are the same.
This shouldn't have any user facing impact unless we have really messed up in bevy and have unsoundness elsewhere (in which case we would now get a panic instead of being unsound).
# Objective
- In some cases, you need a `Mut<T>` pointer, but you only have a mutable reference to one. There is no easy way of converting `&'a mut Mut<'_, T>` -> `Mut<'a, T>` outside of the engine.
### Example (Before)
```rust
fn do_with_mut<T>(val: Mut<T>) { ... }
for x: Mut<T> in &mut query {
// The function expects a `Mut<T>`, so `x` gets moved here.
do_with_mut(x);
// Error: use of moved value.
do_a_thing(&x);
}
```
## Solution
- Add the function `reborrow`, which performs the mapping. This is analogous to `PtrMut::reborrow`.
### Example (After)
```rust
fn do_with_mut<T>(val: Mut<T>) { ... }
for x: Mut<T> in &mut query {
// We reborrow `x`, so the original does not get moved.
do_with_mut(x.reborrow());
// Works fine.
do_a_thing(&x);
}
```
---
## Changelog
- Added the method `reborrow` to `Mut`, `ResMut`, `NonSendMut`, and `MutUntyped`.
# Objective
The type `Local<T>` unnecessarily has the bound `T: Sync` when the local is used in an exclusive system.
## Solution
Lift the bound.
---
## Changelog
Removed the bound `T: Sync` from `Local<T>` when used as an `ExclusiveSystemParam`.
# Objective
Fixes#3310. Fixes#6282. Fixes#6278. Fixes#3666.
## Solution
Split out `!Send` resources into `NonSendResources`. Add a `origin_thread_id` to all `!Send` Resources, check it on dropping `NonSendResourceData`, if there's a mismatch, panic. Moved all of the checks that `MainThreadValidator` would do into `NonSendResources` instead.
All `!Send` resources now individually track which thread they were inserted from. This is validated against for every access, mutation, and drop that could be done against the value.
A regression test using an altered version of the example from #3310 has been added.
This is a stopgap solution for the current status quo. A full solution may involve fully removing `!Send` resources/components from `World`, which will likely require a much more thorough design on how to handle the existing in-engine and ecosystem use cases.
This PR also introduces another breaking change:
```rust
use bevy_ecs::prelude::*;
#[derive(Resource)]
struct Resource(u32);
fn main() {
let mut world = World::new();
world.insert_resource(Resource(1));
world.insert_non_send_resource(Resource(2));
let res = world.get_resource_mut::<Resource>().unwrap();
assert_eq!(res.0, 2);
}
```
This code will run correctly on 0.9.1 but not with this PR, since NonSend resources and normal resources have become actual distinct concepts storage wise.
## Changelog
Changed: Fix soundness bug with `World: Send`. Dropping a `World` that contains a `!Send` resource on the wrong thread will now panic.
## Migration Guide
Normal resources and `NonSend` resources no longer share the same backing storage. If `R: Resource`, then `NonSend<R>` and `Res<R>` will return different instances from each other. If you are using both `Res<T>` and `NonSend<T>` (or their mutable variants), to fetch the same resources, it's strongly advised to use `Res<T>`.
# Objective
- This pulls out some of the changes to Plugin setup and sub apps from #6503 to make that PR easier to review.
- Separate the extract stage from running the sub app's schedule to allow for them to be run on separate threads in the future
- Fixes#6990
## Solution
- add a run method to `SubApp` that runs the schedule
- change the name of `sub_app_runner` to extract to make it clear that this function is only for extracting data between the main app and the sub app
- remove the extract stage from the sub app schedule so it can be run separately. This is done by adding a `setup` method to the `Plugin` trait that runs after all plugin build methods run. This is required to allow the extract stage to be removed from the schedule after all the plugins have added their systems to the stage. We will also need the setup method for pipelined rendering to setup the render thread. See e3267965e1/crates/bevy_render/src/pipelined_rendering.rs (L57-L98)
## Changelog
- Separate SubApp Extract stage from running the sub app schedule.
## Migration Guide
### SubApp `runner` has conceptually been changed to an `extract` function.
The `runner` no longer is in charge of running the sub app schedule. It's only concern is now moving data between the main world and the sub app. The `sub_app.app.schedule` is now run for you after the provided function is called.
```rust
// before
fn main() {
let sub_app = App::empty();
sub_app.add_stage(MyStage, SystemStage::parallel());
App::new().add_sub_app(MySubApp, sub_app, move |main_world, sub_app| {
extract(app_world, render_app);
render_app.app.schedule.run();
});
}
// after
fn main() {
let sub_app = App::empty();
sub_app.add_stage(MyStage, SystemStage::parallel());
App::new().add_sub_app(MySubApp, sub_app, move |main_world, sub_app| {
extract(app_world, render_app);
// schedule is automatically called for you after extract is run
});
}
```
Spiritual successor to #5205.
Actual successor to #6865.
# Objective
Currently, system params are defined using three traits: `SystemParam`, `ReadOnlySystemParam`, `SystemParamState`. The behavior for each param is specified by the `SystemParamState` trait, while `SystemParam` simply defers to the state.
Splitting the traits in this way makes it easier to implement within macros, but it increases the cognitive load. Worst of all, this approach requires each `MySystemParam` to have a public `MySystemParamState` type associated with it.
## Solution
* Merge the trait `SystemParamState` into `SystemParam`.
* Remove all trivial `SystemParam` state types.
* `OptionNonSendMutState<T>`: you will not be missed.
---
- [x] Fix/resolve the remaining test failure.
## Changelog
* Removed the trait `SystemParamState`, merging its functionality into `SystemParam`.
## Migration Guide
**Note**: this should replace the migration guide for #6865.
This is relative to Bevy 0.9, not main.
The traits `SystemParamState` and `SystemParamFetch` have been removed, and their functionality has been transferred to `SystemParam`.
```rust
// Before (0.9)
impl SystemParam for MyParam<'_, '_> {
type State = MyParamState;
}
unsafe impl SystemParamState for MyParamState {
fn init(world: &mut World, system_meta: &mut SystemMeta) -> Self { ... }
}
unsafe impl<'w, 's> SystemParamFetch<'w, 's> for MyParamState {
type Item = MyParam<'w, 's>;
fn get_param(&mut self, ...) -> Self::Item;
}
unsafe impl ReadOnlySystemParamFetch for MyParamState { }
// After (0.10)
unsafe impl SystemParam for MyParam<'_, '_> {
type State = MyParamState;
type Item<'w, 's> = MyParam<'w, 's>;
fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State { ... }
fn get_param<'w, 's>(state: &mut Self::State, ...) -> Self::Item<'w, 's>;
}
unsafe impl ReadOnlySystemParam for MyParam<'_, '_> { }
```
The trait `ReadOnlySystemParamFetch` has been replaced with `ReadOnlySystemParam`.
```rust
// Before
unsafe impl ReadOnlySystemParamFetch for MyParamState {}
// After
unsafe impl ReadOnlySystemParam for MyParam<'_, '_> {}
```
# Objective
- The doctest for `Mut::map_unchanged` uses a fake function `set_if_not_equal` to demonstrate usage.
- Now that #6853 has been merged, we can use `Mut::set_if_neq` directly instead of mocking it.
# Objective
`SystemParam` `Local`s documentation currently leaves out information that should be documented.
- What happens when multiple `SystemParam`s within the same system have the same `Local` type.
- What lifetime parameter is expected by `Local`.
## Solution
- Added sentences to documentation to communicate this information.
- Renamed `Local` lifetimes in code to `'s` where they previously were not. Users can get complicated incorrect suggested fixes if they pass the wrong lifetime. Some instance of the code had `'w` indicating the expected lifetime might not have been known to those that wrote the code either.
Co-authored-by: iiYese <83026177+iiYese@users.noreply.github.com>
# Objective
- Fix#4200
Currently, `#[derive(SystemParam)]` publicly exposes each field type, which makes it impossible to encapsulate private fields.
## Solution
Previously, the fields were leaked because they were used as an input generic type to the macro-generated `SystemParam::State` struct. That type has been changed to store its state in a field with a specific type, instead of a generic type.
---
## Changelog
- Fixed a bug that caused `#[derive(SystemParam)]` to leak the types of private fields.
# Objective
`Query::get` and other random access methods require looking up `EntityLocation` for every provided entity, then always looking up the `Archetype` to get the table ID and table row. This requires 4 total random fetches from memory: the `Entities` lookup, the `Archetype` lookup, the table row lookup, and the final fetch from table/sparse sets. If `EntityLocation` contains the table ID and table row, only the `Entities` lookup and the final storage fetch are required.
## Solution
Add `TableId` and table row to `EntityLocation`. Ensure it's updated whenever entities are moved around. To ensure `EntityMeta` does not grow bigger, both `TableId` and `ArchetypeId` have been shrunk to u32, and the archetype index and table row are stored as u32s instead of as usizes. This should shrink `EntityMeta` by 4 bytes, from 24 to 20 bytes, as there is no padding anymore due to the change in alignment.
This idea was partially concocted by @BoxyUwU.
## Performance
This should restore the `Query::get` "gains" lost to #6625 that were introduced in #4800 without being unsound, and also incorporates some of the memory usage reductions seen in #3678.
This also removes the same lookups during add/remove/spawn commands, so there may be a bit of a speedup in commands and `Entity{Ref,Mut}`.
---
## Changelog
Added: `EntityLocation::table_id`
Added: `EntityLocation::table_row`.
Changed: `World`s can now only hold a maximum of 2<sup>32</sup>- 1 archetypes.
Changed: `World`s can now only hold a maximum of 2<sup>32</sup> - 1 tables.
## Migration Guide
A `World` can only hold a maximum of 2<sup>32</sup> - 1 archetypes and tables now. If your use case requires more than this, please file an issue explaining your use case.
# Objective
Bevy uses custom `Ptr` types so the rust borrow checker can help ensure lifetimes are correct, even when types aren't known. However, these types don't benefit from the automatic lifetime coercion regular rust references enjoy
## Solution
Add a couple methods to Ptr, PtrMut, and MutUntyped to allow for easy usage of these types in more complex scenarios.
## Changelog
- Added `as_mut` and `as_ref` methods to `MutUntyped`.
- Added `shrink` and `as_ref` methods to `PtrMut`.
## Migration Guide
- `MutUntyped::into_inner` now marks things as changed.
# Objective
Resolve#6156.
The most common type of command is one that runs for a single entity. Built-in commands like this can be ergonomically added to the command queue using the `EntityCommands` struct. However, adding custom entity commands to the queue is quite cumbersome. You must first spawn an entity, store its ID in a local, then construct a command using that ID and add it to the queue. This prevents method chaining, which is the main benefit of using `EntityCommands`.
### Example (before)
```rust
struct MyCustomCommand(Entity);
impl Command for MyCustomCommand { ... }
let id = commands.spawn((...)).id();
commmands.add(MyCustomCommand(id));
```
## Solution
Add the `EntityCommand` trait, which allows directly adding per-entity commands to the `EntityCommands` struct.
### Example (after)
```rust
struct MyCustomCommand;
impl EntityCommand for MyCustomCommand { ... }
commands.spawn((...)).add(MyCustomCommand);
```
---
## Changelog
- Added the trait `EntityCommand`. This is a counterpart of `Command` for types that execute code for a single entity.
## Future Work
If we feel its necessary, we can simplify built-in commands (such as `Despawn`) to use this trait.
# Objective
Any closure with the signature `FnOnce(&mut World)` implicitly implements the trait `Command` due to a blanket implementation. However, this implementation unnecessarily has the `Sync` bound, which limits the types that can be used.
## Solution
Remove the bound.
---
## Changelog
- `Command` closures no longer need to implement the marker trait `std::marker::Sync`.
# Objective
- Be able to name the type that `ManualEventReader::iter/iter_with_id` returns and `EventReader::iter/iter_with_id` by proxy.
Currently for the purpose of https://github.com/bevyengine/bevy/pull/5719
## Solution
- Create a custom `Iterator` type.
# Objective
* Currently, the `SystemParam` derive does not support types with const generic parameters.
* If you try to use const generics, the error message is cryptic and unhelpful.
* Continuation of the work started in #6867 and #6957.
## Solution
Allow const generic parameters to be used with `#[derive(SystemParam)]`.
# Objective
Fixes#4729.
Continuation of #4854.
## Solution
Add documentation to `ParamSet` and its methods. Includes examples suggested by community members in the original PR.
Co-authored-by: Nanox19435 <50684926+Nanox19435@users.noreply.github.com>
Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
# Objective
* The `SystemParam` derive internally uses tuples, which means it is constrained by the 16-field limit on `all_tuples`.
* The error message if you exceed this limit is abysmal.
* Supercedes #5965 -- this does the same thing, but is simpler.
## Solution
If any tuples have more than 16 fields, they are folded into tuples of tuples until they are under the 16-field limit.
# Objective
Currently, only named structs can be used with the `SystemParam` derive macro.
## Solution
Remove the restriction. Tuple structs and unit structs are now supported.
---
## Changelog
+ Added support for tuple structs and unit structs to the `SystemParam` derive macro.
# Objective
There is currently no way to iterate over key/value pairs inside an `EntityMap`, which makes the usage of this struct very awkward. I couldn't think of a good reason why the `iter()` function should not be exposed, considering the interface already exposes `keys()` and `values()`, so I made this PR.
## Solution
Implement `iter()` for `EntityMap` in terms of its inner map type.
# Objective
[Rust 1.66](https://blog.rust-lang.org/inside-rust/2022/12/12/1.66.0-prerelease.html) is coming in a few days, and bevy doesn't build with it.
Fix that.
## Solution
Replace output from a trybuild test, and fix a few new instances of `needless_borrow` and `unnecessary_cast` that are now caught.
## Note
Due to the trybuild test, this can't be merged until 1.66 is released.
# Objective
A separate `tracing` span for running a system's commands is created, even if the system doesn't have commands. This is adding extra measuring overhead (see #4892) where it's not needed.
## Solution
Move the span into `ParallelCommandState` and `CommandQueue`'s `SystemParamState::apply`. To get the right metadata for the span, a additional `&SystemMeta` parameter was added to `SystemParamState::apply`.
---
## Changelog
Added: `SystemMeta::name`
Changed: Systems without `Commands` and `ParallelCommands` will no longer show a "system_commands" span when profiling.
Changed: `SystemParamState::apply` now takes a `&SystemMeta` parameter in addition to the provided `&mut World`.
# Objective
Change detection can be spuriously triggered by setting a field to the same value as before. As a result, a common pattern is to write:
```rust
if *foo != value {
*foo = value;
}
```
This is confusing to read, and heavy on boilerplate.
Adopted from #5373, but untangled and rebased to current `bevy/main`.
## Solution
1. Add a method to the `DetectChanges` trait that implements this boilerplate when the appropriate trait bounds are met.
2. Document this minor footgun, and point users to it.
## Changelog
* added the `set_if_neq` method to avoid triggering change detection when the new and previous values are equal. This will work on both components and resources.
## Migration Guide
If you are manually checking if a component or resource's value is equal to its new value before setting it to avoid triggering change detection, migrate to the clearer and more convenient `set_if_neq` method.
## Context
Related to #2363 as it avoids triggering change detection, but not a complete solution (as it still requires triggering it when real changes are made).
Co-authored-by: Zoey <Dessix@Dessix.net>
# Objective
Speed up bundle insertion and spawning from a bundle.
## Solution
Use the same technique used in #6800 to remove the branch on storage type when writing components from a `Bundle` into storage.
- Add a `StorageType` argument to the closure on `Bundle::get_components`.
- Pass `C::Storage::STORAGE_TYPE` into that argument.
- Match on that argument instead of reading from a `Vec<StorageType>` in `BundleInfo`.
- Marked all implementations of `Bundle::get_components` as inline to encourage dead code elimination.
The `Vec<StorageType>` in `BundleInfo` was also removed as it's no longer needed. If users were reliant on this, they can either use the compile time constants or fetch the information from `Components`. Should save a rather negligible amount of memory.
## Performance
Microbenchmarks show a slight improvement to inserting components into existing entities, as well as spawning from a bundle. Ranging about 8-16% faster depending on the benchmark.
```
group main soft-constant-write-components
----- ---- ------------------------------
add_remove/sparse_set 1.08 1019.0±80.10µs ? ?/sec 1.00 944.6±66.86µs ? ?/sec
add_remove/table 1.07 1343.3±20.37µs ? ?/sec 1.00 1257.3±18.13µs ? ?/sec
add_remove_big/sparse_set 1.08 1132.4±263.10µs ? ?/sec 1.00 1050.8±240.74µs ? ?/sec
add_remove_big/table 1.02 2.6±0.05ms ? ?/sec 1.00 2.5±0.08ms ? ?/sec
get_or_spawn/batched 1.15 401.4±17.76µs ? ?/sec 1.00 349.3±11.26µs ? ?/sec
get_or_spawn/individual 1.13 732.1±43.35µs ? ?/sec 1.00 645.6±41.44µs ? ?/sec
insert_commands/insert 1.12 623.9±37.48µs ? ?/sec 1.00 557.4±34.99µs ? ?/sec
insert_commands/insert_batch 1.16 401.4±17.00µs ? ?/sec 1.00 347.4±12.87µs ? ?/sec
insert_simple/base 1.08 416.9±5.60µs ? ?/sec 1.00 385.2±4.14µs ? ?/sec
insert_simple/unbatched 1.06 934.5±44.58µs ? ?/sec 1.00 881.3±47.86µs ? ?/sec
spawn_commands/2000_entities 1.09 190.7±11.41µs ? ?/sec 1.00 174.7±9.15µs ? ?/sec
spawn_commands/4000_entities 1.10 386.5±25.33µs ? ?/sec 1.00 352.3±18.81µs ? ?/sec
spawn_commands/6000_entities 1.10 586.2±34.42µs ? ?/sec 1.00 535.3±27.25µs ? ?/sec
spawn_commands/8000_entities 1.08 778.5±45.15µs ? ?/sec 1.00 718.0±33.66µs ? ?/sec
spawn_world/10000_entities 1.04 1026.4±195.46µs ? ?/sec 1.00 985.8±253.37µs ? ?/sec
spawn_world/1000_entities 1.06 103.8±20.23µs ? ?/sec 1.00 97.6±18.22µs ? ?/sec
spawn_world/100_entities 1.15 11.4±4.25µs ? ?/sec 1.00 9.9±1.87µs ? ?/sec
spawn_world/10_entities 1.05 1030.8±229.78ns ? ?/sec 1.00 986.2±231.12ns ? ?/sec
spawn_world/1_entities 1.01 105.1±23.33ns ? ?/sec 1.00 104.6±31.84ns ? ?/sec
```
---
## Changelog
Changed: `Bundle::get_components` now takes a `FnMut(StorageType, OwningPtr)`. The provided storage type must be correct for the component being fetched.
# Objective
- Fixes https://github.com/bevyengine/bevy/issues/6417
## Solution
- clear_trackers was not being called on the render world. This causes the removed components vecs to continuously grow. This PR adds clear trackers to the end of RenderStage::Cleanup
## Migration Guide
The call to `clear_trackers` in `App` has been moved from the schedule to App::update for the main world and calls to `clear_trackers` have been added for sub_apps in the same function. This was due to needing stronger guarantees. If clear_trackers isn't called on a world it can lead to memory leaks in `RemovedComponents`.
# Objective
* Implementing a custom `SystemParam` by hand requires implementing three traits -- four if it is read-only.
* The trait `SystemParamFetch<'w, 's>` is a workaround from before we had generic associated types, and is no longer necessary.
## Solution
* Combine the trait `SystemParamFetch` with `SystemParamState`.
* I decided to remove the `Fetch` name and keep the `State` name, since the former was consistently conflated with the latter.
* Replace the trait `ReadOnlySystemParamFetch` with `ReadOnlySystemParam`, which simplifies trait bounds in generic code.
---
## Changelog
- Removed the trait `SystemParamFetch`, moving its functionality to `SystemParamState`.
- Replaced the trait `ReadOnlySystemParamFetch` with `ReadOnlySystemParam`.
## Migration Guide
The trait `SystemParamFetch` has been removed, and its functionality has been transferred to `SystemParamState`.
```rust
// Before
impl SystemParamState for MyParamState {
fn init(world: &mut World, system_meta: &mut SystemMeta) -> Self { ... }
}
impl<'w, 's> SystemParamFetch<'w, 's> for MyParamState {
type Item = MyParam<'w, 's>;
fn get_param(...) -> Self::Item;
}
// After
impl SystemParamState for MyParamState {
type Item<'w, 's> = MyParam<'w, 's>; // Generic associated types!
fn init(world: &mut World, system_meta: &mut SystemMeta) -> Self { ... }
fn get_param<'w, 's>(...) -> Self::Item<'w, 's>;
}
```
The trait `ReadOnlySystemParamFetch` has been replaced with `ReadOnlySystemParam`.
```rust
// Before
unsafe impl ReadOnlySystemParamFetch for MyParamState {}
// After
unsafe impl<'w, 's> ReadOnlySystemParam for MyParam<'w, 's> {}
```
# Objective
It's not clear to users how to handle `!Sync` types as components and resources in the absence of engine level support for them.
## Solution
Added a section to `Component`'s and `Resource`'s type level docs on available options for making a type `Sync` when it holds `!Sync` fields, linking `bevy_utils::synccell::SyncCell` and the currently unstable `std::sync::Exclusive`.
Also added a compile_fail doctest that illustrates how to apply `SyncCell`. These will break when/if #6572 gets merged, at which point these docs should be updated.
# Objective
Fixes#6224, add ``dbg``, ``info``, ``warn`` and ``error`` system piping adapter variants to expand #5776, which call the corresponding re-exported [bevy_log macros](https://docs.rs/bevy/latest/bevy/log/macro.info.html) when the result is an error.
## Solution
* Added ``dbg``, ``info``, ``warn`` and ``error`` system piping adapter variants to ``system_piping.rs``.
* Modified and added tests for these under examples in ``system_piping.rs``.
# Objective
#6547 accidentally broke change detection for SparseSet components by using `Ticks::from_tick_cells` with the wrong argument order.
## Solution
Use the right argument order. Add a regression test.
having `doc(hidden)` on the read only version of a generated mutable world query leads to docs on the readonly item having a dead link. It also makes it annoying to have nice docs for libraries attempting to expose derived `WorldQuery` structs as re-exporting the read only item does not cause it to appear in docs even though it would be intended for users to know about the read only world query and use it.
# Objective
Prevent future unsoundness that was seen in #6623.
## Solution
Newtype both indexes in `Archetype` and `Table` as `ArchetypeRow` and `TableRow`. This avoids weird numerical manipulation on the indices, and can be stored and treated opaquely. Also enforces the source and destination of where these indices at a type level.
---
## Changelog
Changed: `Archetype` indices and `Table` rows have been newtyped as `ArchetypeRow` and `TableRow`.
# Objective
`EntityRef::get` and friends all type erase calls to fetch the target components by using passing in the `TypeId` instead of using generics. This is forcing a lookup to `Components` to fetch the storage type. This adds an extra memory lookup and forces a runtime branch instead of allowing the compiler to optimize out the unused branch.
## Solution
Leverage `Component::Storage::STORAGE_TYPE` as a constant instead of fetching the metadata from `Components`.
## Performance
This has a near 2x speedup for all calls to `World::get`. Microbenchmark results from my local machine. `Query::get_component`, which uses `EntityRef::get` internally also show a slight speed up. This has closed the gap between `World::get` and `Query::get` for the same use case.
```
group entity-ref-generics main
----- ------------------- ----
query_get_component/50000_entities_sparse 1.00 890.6±40.42µs ? ?/sec 1.10 980.6±28.22µs ? ?/sec
query_get_component/50000_entities_table 1.00 968.5±73.73µs ? ?/sec 1.08 1048.8±31.76µs ? ?/sec
query_get_component_simple/system 1.00 703.2±4.37µs ? ?/sec 1.00 702.1±6.13µs ? ?/sec
query_get_component_simple/unchecked 1.02 855.8±8.98µs ? ?/sec 1.00 843.1±8.19µs ? ?/sec
world_get/50000_entities_sparse 1.00 202.3±3.15µs ? ?/sec 1.85 374.0±20.96µs ? ?/sec
world_get/50000_entities_table 1.00 193.0±1.78µs ? ?/sec 2.02 389.2±26.55µs ? ?/sec
world_query_get/50000_entities_sparse 1.01 162.4±2.23µs ? ?/sec 1.00 161.3±0.95µs ? ?/sec
world_query_get/50000_entities_table 1.00 199.9±0.63µs ? ?/sec 1.00 200.2±0.74µs ? ?/sec
```
This should also, by proxy, speed up the `ReflectComponent` APIs as most of those use `World::get` variants internally.
# Objective
The methods `World::change_tick` and `World::read_change_tick` lack documentation and have confusingly similar behavior.
## Solution
Add documentation and clarify the distinction between the two functions.
The PR fixes the interface of `EventReader::clear`. Currently, the method consumes the reader, which makes it unusable.
## Changelog
- `EventReader::clear` now takes a mutable reference instead of consuming the event reader.
## Migration Guide
`EventReader::clear` now takes a mutable reference instead of consuming the event reader. This means that `clear` now needs explicit mutable access to the reader variable, which previously could have been omitted in some cases:
```rust
// Old (0.9)
fn clear_events(reader: EventReader<SomeEvent>) {
reader.clear();
}
// New (0.10)
fn clear_events(mut reader: EventReader<SomeEvent>) {
reader.clear();
}
```
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Fixes#6812.
## Solution
- Replaced `World::read_change_ticks` with `World::change_ticks` within `bevy_ecs` crate in places where `World` references were mutable.
---
# Objective
Partially addresses #5504. Allow users to get an `Iterator<Item = EntityRef<'a>>` over all entities in the `World`.
## Solution
Change `World::iter_entities` to return an iterator of `EntityRef` instead of `Entity`.
Not sure how to tackle making an `Iterator<Item = EntityMut<'_>>` without being horribly unsound. Might need to wait for `LendingIterator` to stabilize so we can ensure only one of them is valid at a given time.
---
## Changelog
Changed: `World::iter_entities` now returns an iterator of `EntityRef` instead of `Entity`.
# Objective
Currently, the `SystemParam` derive forces you to declare the lifetime parameters `<'w, 's>`, even if you don't use them.
If you don't follow this structure, the error message is quite nasty.
### Example (before):
```rust
#[derive(SystemParam)]
pub struct EventWriter<'w, 's, E: Event> {
events: ResMut<'w, Events<E>>,
// The derive forces us to declare the `'s` lifetime even though we don't use it,
// so we have to add this `PhantomData` to please rustc.
#[system_param(ignore)]
_marker: PhantomData<&'s ()>,
}
```
## Solution
* Allow the user to omit either lifetime.
* Emit a descriptive error if any lifetimes used are invalid.
### Example (after):
```rust
#[derive(SystemParam)]
pub struct EventWriter<'w, E: Event> {
events: ResMut<'w, Events<E>>,
}
```
---
## Changelog
* The `SystemParam` derive is now more flexible, allowing you to omit unused lifetime parameters.
# Objective
The soundness of the ECS `World` partially relies on the correctness of the state of `Entities` stored within it. We're currently allowing users to (unsafely) mutate it, as well as readily construct it without using a `World`. While this is not strictly unsound so long as users (including `bevy_render`) safely use the APIs, it's a fairly easy path to unsoundness without much of a guard rail.
Addresses #3362 for `bevy_ecs::entity`. Incorporates the changes from #3985.
## Solution
Remove `Entities`'s `Default` implementation and force access to the type to only be through a properly constructed `World`.
Additional cleanup for other parts of `bevy_ecs::entity`:
- `Entity::index` and `Entity::generation` are no longer `pub(crate)`, opting to force the rest of bevy_ecs to use the public interface to access these values.
- `EntityMeta` is no longer `pub` and also not `pub(crate)` to attempt to cut down on updating `generation` without going through an `Entities` API. It's currently inaccessible except via the `pub(crate)` Vec on `Entities`, there was no way for an outside user to use it.
- Added `Entities::set`, an unsafe `pub(crate)` API for setting the location of an Entity (parallel to `Entities::get`) that replaces the internal case where we need to set the location of an entity when it's been spawned, moved, or despawned.
- `Entities::alloc_at_without_replacement` is only used in `World::get_or_spawn` within the first party crates, and I cannot find a public use of this API in any ecosystem crate that I've checked (via GitHub search).
- Attempted to document the few remaining undocumented public APIs in the module.
---
## Changelog
Removed: `Entities`'s `Default` implementation.
Removed: `EntityMeta`
Removed: `Entities::alloc_at_without_replacement` and `AllocAtWithoutReplacement`.
Co-authored-by: james7132 <contact@jamessliu.com>
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
Document `bevy_ecs::archetype` and and declutter the public documentation for the module by making types non-`pub`.
Addresses #3362 for `bevy_ecs::archetype`.
## Solution
- Add module level documentation.
- Add type and API level documentation for all public facing types.
- Make `ArchetypeId`, `ArchetypeGeneration`, and `ArchetypeComponentId` truly opaque IDs that are not publicly constructable.
- Make `AddBundle` non-pub, make `Edges::get_add_bundle` return a `Option<ArchetypeId>` and fork the existing function into `Edges::get_add_bundle_internal`.
- Remove `pub(crate)` on fields that have a corresponding pub accessor function.
- Removed the `Archetypes: Default` impl, opting for a `pub(crate) fn new` alternative instead.
---
## Changelog
Added: `ArchetypeGeneration` now implements `Ord` and `PartialOrd`.
Removed: `Archetypes`'s `Default` implementation.
Removed: `Archetype::new` and `Archetype::is_empty`.
Removed: `ArchetypeId::new` and `ArchetypeId::value`.
Removed: `ArchetypeGeneration::value`
Removed: `ArchetypeIdentity`.
Removed: `ArchetypeComponentId::new` and `ArchetypeComponentId::value`.
Removed: `AddBundle`. `Edges::get_add_bundle` now returns `Option<ArchetypeId>`
# Objective
- The documentation describing different ways to spawn an Entity is missing reference to "method" for "Spawn an entity with components".
## Solution
- Update the documentation to add the reference to `World::spawn`.
# Objective
One of the use-cases for the function `Entity::from_raw` is creating placeholder entity ids, which are meant to be overwritten later. If we use a constant for this instead of `from_raw`, it is more ergonomic and self-documenting.
## Solution
Add a constant that returns an entity ID with an index of `u32::MAX` and a generation of zero. Users are instructed to overwrite this value before using it.
# Objective
- Reverts #5730.
- Fixes#6173, fixes#6596.
## Solution
Remove the warning entirely.
## Changelog
You will no longer be spammed about
> Missed 31 `bevy_input:🐭:MouseMotion` events. Consider
reading from the `EventReader` more often (generally the best
solution) or calling Events::update() less frequently
(normally this is called once per frame). This problem is most
likely due to run criteria/fixed timesteps or consuming events
conditionally. See the Events documentation for
more information.
when you miss events. These warnings were often (but not always) a false positive. You can still check this manually by using `ManualEventReader::missed_events`
# Objective
Consider the test
```rust
let cell = world.cell();
let _value_a = cell.resource_mut::<A>();
let _value_b = cell.resource_mut::<A>();
```
Currently, this will roughly execute
```rust
// first call
let value = unsafe {
self.world
.get_non_send_unchecked_mut_with_id(component_id)?
};
return Some(WorldBorrowMut::new(value, archetype_component_id, self.access)))
// second call
let value = unsafe {
self.world
.get_non_send_unchecked_mut_with_id(component_id)?
};
return Some(WorldBorrowMut::new(value, archetype_component_id, self.access)))
```
where `WorldBorrowMut::new` will panic if the resource is already borrowed.
This means, that `_value_a` will be created, the access checked (OK), then `value_b` will be created, and the access checked (`panic`).
For a moment, both `_value_a` and `_value_b` existed as `&mut T` to the same location, which is insta-UB as far as I understand it.
## Solution
Flip the order so that `WorldBorrowMut::new` first checks the access, _then_ fetches creates the value. To do that, we pass a `impl FnOnce() -> Mut<T>` instead of the `Mut<T>` directly:
```rust
let get_value = || unsafe {
self.world
.get_non_send_unchecked_mut_with_id(component_id)?
};
return Some(WorldBorrowMut::new(get_value, archetype_component_id, self.access)))
```
Without this fix, piped systems containing exclusive systems fail to run, giving a runtime panic.
With this PR, running piped systems that contain exclusive systems now works.
## Explanation of the bug
This is because, unless overridden, the default implementation of `run` from the `System` trait simply calls `run_unsafe`. That is not valid for exclusive systems. They must always be called via `run`, as `run_unsafe` takes `&World` instead of `&mut World`.
Trivial reproduction example:
```rust
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_system(exclusive.pipe(another))
.run();
}
fn exclusive(_world: &mut World) {}
fn another() {}
```
If you run this, you will get a panic 'Cannot run exclusive systems with a shared World reference' and the backtrace shows how bevy (correctly) tries to call the `run` method (because the system is exclusive), but it is the implementation from the `System` trait (because `PipeSystem` does not have its own), which calls `run_unsafe` (incorrect):
- 3: <bevy_ecs::system::system_piping::PipeSystem<SystemA,SystemB> as bevy_ecs::system::system::System>::run_unsafe
- 4: bevy_ecs::system::system::System::run
# Objective
Fixes#4884. `ComponentTicks` stores both added and changed ticks contiguously in the same 8 bytes. This is convenient when passing around both together, but causes half the bytes fetched from memory for the purposes of change detection to effectively go unused. This is inefficient when most queries (no filter, mutating *something*) only write out to the changed ticks.
## Solution
Split the storage for change detection ticks into two separate `Vec`s inside `Column`. Fetch only what is needed during iteration.
This also potentially also removes one blocker from autovectorization of dense queries.
EDIT: This is confirmed to enable autovectorization of dense queries in `for_each` and `par_for_each` where possible. Unfortunately `iter` has other blockers that prevent it.
### TODO
- [x] Microbenchmark
- [x] Check if this allows query iteration to autovectorize simple loops.
- [x] Clean up all of the spurious tuples now littered throughout the API
### Open Questions
- ~~Is `Mut::is_added` absolutely necessary? Can we not just use `Added` or `ChangeTrackers`?~~ It's optimized out if unused.
- ~~Does the fetch of the added ticks get optimized out if not used?~~ Yes it is.
---
## Changelog
Added: `Tick`, a wrapper around a single change detection tick.
Added: `Column::get_added_ticks`
Added: `Column::get_column_ticks`
Added: `SparseSet::get_added_ticks`
Added: `SparseSet::get_column_ticks`
Changed: `Column` now stores added and changed ticks separately internally.
Changed: Most APIs returning `&UnsafeCell<ComponentTicks>` now returns `TickCells` instead, which contains two separate `&UnsafeCell<Tick>` for either component ticks.
Changed: `Query::for_each(_mut)`, `Query::par_for_each(_mut)` will now leverage autovectorization to speed up query iteration where possible.
## Migration Guide
TODO
# Objective
Fix#5149
## Solution
Instead of returning the **total count** of elements in the `QueryIter` in
`size_hint`, we return the **count of remaining elements**. This
Fixes#5149 even when #5148 gets merged.
- https://github.com/bevyengine/bevy/issues/5149
- https://github.com/bevyengine/bevy/pull/5148
---
## Changelog
- Fix partially consumed `QueryIter` and `QueryCombinationIter` having invalid `size_hint`
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
# Objective
BlobVec currently relies on a scratch piece of memory allocated at initialization to make a temporary copy of a component when using `swap_remove_and_{forget/drop}`. This is potentially suboptimal as it writes to a, well-known, but random part of memory instead of using the stack.
## Solution
As the `FIXME` in the file states, replace `swap_scratch` with a call to `swap_nonoverlapping::<u8>`. The swapped last entry is returned as a `OwnedPtr`.
In theory, this should be faster as the temporary swap is allocated on the stack, `swap_nonoverlapping` allows for easier vectorization for bigger types, and the same memory is used between the swap and the returned `OwnedPtr`.
# Objective
* Enable `Res` and `Query` parameter mutual exclusion
* Required for https://github.com/bevyengine/bevy/pull/5080
The `FilteredAccessSet::get_conflicts` methods didn't work properly with
`Res` and `ResMut` parameters. Because those added their access by using
the `combined_access_mut` method and directly modifying the global
access state of the FilteredAccessSet. This caused an inconsistency,
because get_conflicts assumes that ALL added access have a corresponding
`FilteredAccess` added to the `filtered_accesses` field.
In practice, that means that SystemParam that adds their access through
the `Access` returned by `combined_access_mut` and the ones that add
their access using the `add` method lived in two different universes. As
a result, they could never be mutually exclusive.
## Solution
This commit fixes it by removing the `combined_access_mut` method. This
ensures that the `combined_access` field of FilteredAccessSet is always
updated consistently with the addition of a filter. When checking for
filtered access, it is now possible to account for `Res` and `ResMut`
invalid access. This is currently not needed, but might be in the
future.
We add the `add_unfiltered_{read,write}` methods to replace previous
usages of `combined_access_mut`.
We also add improved Debug implementations on FixedBitSet so that their
meaning is much clearer in debug output.
---
## Changelog
* Fix `Res` and `Query` parameter never being mutually exclusive.
## Migration Guide
Note: this mostly changes ECS internals, but since the API is public, it is technically breaking:
* Removed `FilteredAccessSet::combined_access_mut`
* Replace _immutable_ usage of those by `combined_access`
* For _mutable_ usages, use the new `add_unfiltered_{read,write}` methods instead of `combined_access_mut` followed by `add_{read,write}`
# Objective
Make core types in ECS smaller. The column sparse set in Tables is never updated after creation.
## Solution
Create `ImmutableSparseSet` which removes the capacity fields in the backing vec's and the APIs for inserting or removing elements. Drops the size of the sparse set by 3 usizes (24 bytes on 64-bit systems)
## Followup
~~After #4809, Archetype's component SparseSet should be replaced with it.~~ This has been done.
---
## Changelog
Removed: `Table::component_capacity`
## Migration Guide
`Table::component_capacity()` has been removed as Tables do not support adding/removing columns after construction.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Archetype is a deceptively large type in memory. It stores metadata about which components are in which storage in multiple locations, which is only used when creating new Archetypes while moving entities.
## Solution
Remove the redundant `Box<[ComponentId]>`s and iterate over the sparse set of component metadata instead. Reduces Archetype's size by 4 usizes (32 bytes on 64-bit systems), as well as the additional allocations for holding these slices.
It'd seem like there's a downside that the origin archetype has it's component metadata iterated over twice when creating a new archetype, but this change also removes the extra `Vec<ArchetypeComponentId>` allocations when creating a new archetype which may amortize out to a net gain here. This change likely negatively impacts creating new archetypes with a large number of components, but that's a cost mitigated by the fact that these archetypal relationships are cached in Edges and is incurred only once for each edge created.
## Additional Context
There are several other in-flight PRs that shrink Archetype:
- #4800 merges the entities and rows Vecs together (shaves off 24 bytes per archetype)
- #4809 removes unique_components and moves it to it's own dedicated storage (shaves off 72 bytes per archetype)
---
## Changelog
Changed: `Archetype::table_components` and `Archetype::sparse_set_components` return iterators instead of slices. `Archetype::new` requires iterators instead of parallel slices/vecs.
## Migration Guide
Do I still need to do this? I really hope people were not relying on the public facing APIs changed here.
# Objective
In bevy 0.8 you could list all resources using `world.archetypes().resource().components()`. As far as I can tell the resource archetype has been replaced with the `Resources` storage, and it would be nice if it could be used to iterate over all resource component IDs as well.
## Solution
- add `fn Resources::iter(&self) -> impl Iterator<Item = (ComponentId, &ResourceData)>`
# Objective
Fixes#6615.
`BlobVec` does not respect alignment for zero-sized types, which results in UB whenever a ZST with alignment other than 1 is used in the world.
## Solution
Add the fn `bevy_ptr::dangling_with_align`.
---
## Changelog
+ Added the function `dangling_with_align` to `bevy_ptr`, which creates a well-aligned dangling pointer to a type whose alignment is not known at compile time.
# Objective
Fix#6548. Most of these methods were already made `const` in #5688. `Entity::to_bits` is the only one that remained.
## Solution
Make it const.
# Objective
Copy `send_event` and friends from `World` to `WorldCell`.
Clean up `bevy_winit` using `WorldCell::send_event`.
## Changelog
Added `send_event`, `send_event_default`, and `send_event_batch` to `WorldCell`.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
* Move the despawn debug log from `World::despawn` to `EntityMut::despawn`.
* Move the despawn non-existent warning log from `Commands::despawn` to `World::despawn`.
This should make logging consistent regardless of which of the three `despawn` methods is used.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
When an error causes `debug_checked_unreachable` to be called, the panic message unhelpfully points to the function definition instead of the place that caused the error.
## Solution
Add the `#[track_caller]` attribute in debug mode.
`EntityMut::remove_children` does not call `self.update_location()` which is unsound.
Verified by adding the following assertion, which fails when running the tests.
```rust
let before = self.location();
self.update_location();
assert_eq!(before, self.location());
```
I also removed incorrect messages like "parent entity is not modified" and the unhelpful "Inserting a bundle in the children entities may change the parent entity's location if they were of the same archetype" which might lead people to think that's the *only* thing that can change the entity's location.
# Changelog
Added `EntityMut::world_scope`.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
Alternative to #6424Fixes#6226
Fixes spawning empty bundles
## Solution
Add `BundleComponentStatus` trait and implement it for `AddBundle` and a new `SpawnBundleStatus` type (which always returns an Added status). `write_components` is now generic on `BundleComponentStatus` instead of taking `AddBundle` directly. This means BundleSpawner can now avoid needing AddBundle from the Empty archetype, which means BundleSpawner no longer needs a reference to the original archetype.
In theory this cuts down on the work done in `write_components` when spawning, but I'm seeing no change in the spawn benchmarks.
# Objective
Replace `WorldQueryGats` trait with actual gats
## Solution
Replace `WorldQueryGats` trait with actual gats
---
## Changelog
- Replaced `WorldQueryGats` trait with actual gats
## Migration Guide
- Replace usage of `WorldQueryGats` assoc types with the actual gats on `WorldQuery` trait
# Objective
Right now, the `TaskPool` implementation allows panics to permanently kill worker threads upon panicking. This is currently non-recoverable without using a `std::panic::catch_unwind` in every scheduled task. This is poor ergonomics and even poorer developer experience. This is exacerbated by #2250 as these threads are global and cannot be replaced after initialization.
Removes the need for temporary fixes like #4998. Fixes#4996. Fixes#6081. Fixes#5285. Fixes#5054. Supersedes #2307.
## Solution
The current solution is to wrap `Executor::run` in `TaskPool` with a `catch_unwind`, and discarding the potential panic. This was taken straight from [smol](404c7bcc0a/src/spawn.rs (L44))'s current implementation. ~~However, this is not entirely ideal as:~~
- ~~the signaled to the awaiting task. We would need to change `Task<T>` to use `async_task::FallibleTask` internally, and even then it doesn't signal *why* it panicked, just that it did.~~ (See below).
- ~~no error is logged of any kind~~ (See below)
- ~~it's unclear if it drops other tasks in the executor~~ (it does not)
- ~~This allows the ECS parallel executor to keep chugging even though a system's task has been dropped. This inevitably leads to deadlock in the executor.~~ Assuming we don't catch the unwind in ParallelExecutor, this will naturally kill the main thread.
### Alternatives
A final solution likely will incorporate elements of any or all of the following.
#### ~~Log and Ignore~~
~~Log the panic, drop the task, keep chugging. This only addresses the discoverability of the panic. The process will continue to run, probably deadlocking the executor. tokio's detatched tasks operate in this fashion.~~
Panics already do this by default, even when caught by `catch_unwind`.
#### ~~`catch_unwind` in `ParallelExecutor`~~
~~Add another layer catching system-level panics into the `ParallelExecutor`. How the executor continues when a core dependency of many systems fails to run is up for debate.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### ~~Emulate/Copy `tokio::JoinHandle` with `Task<T>`~~
~~`tokio::JoinHandle<T>` bubbles up the panic from the underlying task when awaited. This can be transitively applied across other APIs that also use `Task<T>` like `Query::par_for_each` and `TaskPool::scope`, bubbling up the panic until it's either caught or it reaches the main thread.~~
`async_task::Task` bubbles up panics already, this will transitively push panics all the way to the main thread.
#### Abort on Panic
The nuclear option. Log the error, abort the entire process on any thread in the task pool panicking. Definitely avoids any additional infrastructure for passing the panic around, and might actually lead to more efficient code as any unwinding is optimized out. However gives the developer zero options for dealing with the issue, a seemingly poor choice for debuggability, and prevents graceful shutdown of the process. Potentially an option for handling very low-level task management (a la #4740). Roughly takes the shape of:
```rust
struct AbortOnPanic;
impl Drop for AbortOnPanic {
fn drop(&mut self) {
abort!();
}
}
let guard = AbortOnPanic;
// Run task
std::mem::forget(AbortOnPanic);
```
---
## Changelog
Changed: `bevy_tasks::TaskPool`'s threads will no longer terminate permanently when a task scheduled onto them panics.
Changed: `bevy_tasks::Task` and`bevy_tasks::Scope` will propagate panics in the spawned tasks/scopes to the parent thread.
This reverts commit 53d387f340.
# Objective
Reverts #6448. This didn't have the intended effect: we're now getting bevy::prelude shown in the docs again.
Co-authored-by: Alejandro Pascual <alejandro.pascual.pozo@gmail.com>
# Objective
- Right now re-exports are completely hidden in prelude docs.
- Fixes#6433
## Solution
- We could show the re-exports without inlining their documentation.
# Objective
Fixes#6059, changing all incorrect occurrences of ``id`` in the ``entity`` module to ``index``:
* struct level documentation,
* ``id`` struct field,
* ``id`` method and its documentation.
## Solution
Renaming and verifying using CI.
Co-authored-by: Edvin Kjell <43633999+Edwox@users.noreply.github.com>
For `derive(WorldQuery)`, there are three structs generated, `Item`, `Fetch` and `State`.
These inherit the visibility of the derived structure, thus `#![warn(missing_docs)]` would
warn about missing documentation for these structures.
- [ ] I'd like some advice on what to write here, as I personally don't really understand `Fetch` nor `State`.
# Objective
* Add benchmarks for `Query::get_many`.
* Speed up `Query::get_many`.
## Solution
Previously, `get_many` and `get_many_mut` used the method `array::map`, which tends to optimize very poorly. This PR replaces uses of that method with loops.
## Benchmarks
| Benchmark name | Execution time | Change from this PR |
|--------------------------------------|----------------|---------------------|
| query_get_many_2/50000_calls_table | 1.3732 ms | -24.967% |
| query_get_many_2/50000_calls_sparse | 1.3826 ms | -24.572% |
| query_get_many_5/50000_calls_table | 2.6833 ms | -30.681% |
| query_get_many_5/50000_calls_sparse | 2.9936 ms | -30.672% |
| query_get_many_10/50000_calls_table | 5.7771 ms | -36.950% |
| query_get_many_10/50000_calls_sparse | 7.4345 ms | -36.987% |
# Objective
Add documentation `#[world_query(ignore)]`. Fixes#6283.
---
I've only described it's behavior so far (which appears to be the same as with `system_param`). Is there another use-case for this besides with `PhantomData`? I could only find a single usage of this construct on GitHub, which is [here](ffcb816927/bevy/examples/ecs/custom_query_param.rs (L102)).
I was also wondering if it would make sense to add a usage example to the `custom_query_example`? 🤔 That's why it's currently still in there.
Co-authored-by: Lucas Jenß <243719+x3ro@users.noreply.github.com>
# Objective
Bevy still has many instances of using single-tuples `(T,)` to create a bundle. Due to #2975, this is no longer necessary.
## Solution
Search for regex `\(.+\s*,\)`. This should have found every instance.
# Objective
Fix the soundness issue outlined in #5866. In short the problem is that `query.to_readonly().get_component_mut::<T>()` can provide unsound mutable access to the component. This PR is an alternative to just removing the offending api. Given that `to_readonly` is a useful tool, I think this approach is a preferable short term solution. Long term I think theres a better solution out there, but we can find that on its own time.
## Solution
Add what amounts to a "dirty flag" that marks Queries that have been converted to their read-only variant via `to_readonly` as dirty. When this flag is set to true, `get_component_mut` will fail with an error, preventing the unsound access.
# Objective
Currently for entities we serialize only `id`. But this is not very expected behavior. For example, in networking, when the server sends its state, it contains entities and components. On the client, I create new objects and map them (using `EntityMap`) to those received from the server (to know which one matches which). And if `generation` field is missing, this mapping can be broken. Example:
1. Server sends an entity `Entity{ id: 2, generation: 1}` with components.
2. Client puts the received entity in a map and create a new entity that maps to this received entity. The new entity have different `id` and `generation`. Let's call it `Entity{ id: 12, generation: 4}`.
3. Client sends a command for `Entity{ id: 12, generation: 4}`. To do so, it maps local entity to the one from server. But `generation` field is 0 because it was omitted for serialization on the server. So it maps to `Entity{ id: 2, generation: 0}`.
4. Server receives `Entity{ id: 2, generation: 0}` which is invalid.
In my game I worked around it by [writing custom serialization](https://github.com/dollisgame/dollis/blob/master/src/core/network/entity_serde.rs) and using `serde(with = "...")`. But it feels like a bad default to me.
Using `Entity` over a custom `NetworkId` also have the following advantages:
1. Re-use `MapEntities` trait to map `Entity`s in replicated components.
2. Instead of server `Entity <-> NetworkId ` and `Entity <-> NetworkId`, we map entities only on client.
3. No need to handling uniqueness. It's a rare case, but makes things simpler. For example, I don't need to query for a resource to create an unique ID.
Closes#6143.
## Solution
Use default serde impls. If anyone want to avoid wasting memory on `generation`, they can create a new type that holds `u32`. This is what Bevy do for [DynamicEntity](https://docs.rs/bevy/latest/bevy/scene/struct.DynamicEntity.html) to serialize scenes. And I don't see any use case to serialize an entity id expect this one.
---
## Changelog
### Changed
- Entity now serializes / deserializes `generation` field.
## Migration Guide
- Entity now fully serialized. If you want to serialze only `id`, as it was before, you can create a new type that wraps `u32`.
