# Objective
Support the following syntax for adding systems:
```rust
App::new()
.add_system(setup.on_startup())
.add_systems((
show_menu.in_schedule(OnEnter(GameState::Paused)),
menu_ssytem.in_set(OnUpdate(GameState::Paused)),
hide_menu.in_schedule(OnExit(GameState::Paused)),
))
```
## Solution
Add the traits `IntoSystemAppConfig{s}`, which provide the extension methods necessary for configuring which schedule a system belongs to. These extension methods return `IntoSystemAppConfig{s}`, which `App::add_system{s}` uses to choose which schedule to add systems to.
---
## Changelog
+ Added the extension methods `in_schedule(label)` and `on_startup()` for configuring the schedule a system belongs to.
## Future Work
* Replace all uses of `add_startup_system` in the engine.
* Deprecate this method
# Objective
While we use `#[doc(hidden)]` to try and hide marker generics from the user, these types reveal themselves in compiler errors, adding visual noise and confusion.
## Solution
Replace the `AlreadyWasSystem` marker generic with `()`, to reduce visual noise in error messages. This also makes it possible to return `impl Condition<()>` from combinators.
For function systems, use their function signature as the marker type. This should drastically improve the legibility of some error messages.
The `InputMarker` type has been removed, since it is unnecessary.
# Objective
Several places in the ECS use marker generics to avoid overlapping trait implementations, but different places alternately refer to it as `Params` and `Marker`. This is potentially confusing, since it might not be clear that the same pattern is being used. Additionally, users might be misled into thinking that the `Params` type corresponds to the `SystemParam`s of a system.
## Solution
Rename `Params` to `Marker`.
# Objective
Fixes#3980
## Solution
Added examples to show how to run a `Schedule`, one with a unique system, and another with several systems
---
## Changelog
- Added: examples in docs to show how to run a `Schedule`
Co-authored-by: remiCzn <77072160+remiCzn@users.noreply.github.com>
# Objective
The `BoxedCondition` type alias does not require the underlying system to be read-only.
## Solution
Define the type alias using `ReadOnlySystem` instead of `System`.
Graph theory make head hurty. Closes#7367.
Basically, when we topologically sort the dependency graph, we already find its strongly-connected components (a really [neat algorithm][1]). This PR adds an algorithm that can dissect those into simple cycles, giving us more useful error reports.
test: `system_build_errors::dependency_cycle`
```
schedule has 1 before/after cycle(s):
cycle 1: system set 'A' must run before itself
system set 'A'
... which must run before system set 'B'
... which must run before system set 'A'
```
```
schedule has 1 before/after cycle(s):
cycle 1: system 'foo' must run before itself
system 'foo'
... which must run before system 'bar'
... which must run before system 'foo'
```
test: `system_build_errors::hierarchy_cycle`
```
schedule has 1 in_set cycle(s):
cycle 1: system set 'A' contains itself
system set 'A'
... which contains system set 'B'
... which contains system set 'A'
```
[1]: https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
Add some more useful common run conditions.
Some of these existed in `iyes_loopless`. I know people used them, and it would be a regression for those users, when they try to migrate to new Bevy stageless, if they are missing.
I also took the opportunity to add a few more new ones.
---
## Changelog
### Added
- More "common run conditions": on_event, resource change detection, state_changed, any_with_component
# Objective
Fix#5026.
## Solution
Only make a `trace!` log if the event count changed.
---
## Changelog
Changed: `EventWriter::send_batch` will only log a TRACE level log if the batch is non-empty.
# Objective
Fix#7584.
## Solution
Add an abstraction for creating custom system combinators with minimal boilerplate. Use this to implement AND/OR combinators. Use this to simplify the implementation of `PipeSystem`.
## Example
Feel free to bikeshed on the syntax.
I chose the names `and_then`/`or_else` to emphasize the fact that these short-circuit, while I chose method syntax to empasize that the arguments are *not* treated equally.
```rust
app.add_systems((
my_system.run_if(resource_exists::<R>().and_then(resource_equals(R(0)))),
our_system.run_if(resource_exists::<R>().or_else(resource_exists::<S>())),
));
```
---
## Todo
- [ ] Decide on a syntax
- [x] Write docs
- [x] Write tests
## Changelog
+ Added the extension methods `.and_then(...)` and `.or_else(...)` to run conditions, which allows combining run conditions with short-circuiting behavior.
+ Added the trait `Combine`, which can be used with the new `CombinatorSystem` to create system combinators with custom behavior.
# Objective
- Fixes#7442.
## Solution
- Added `report_sets` option to `ScheduleBuildSettings` like described in the linked issue.
The output of the `3d_scene` example when reporting ambiguities with `report_sets` and `use_shortnames` set to `true` (and with #7755 applied) now looks like this:
```
82 pairs of systems with conflicting data access have indeterminate execution order. Consider adding `before`, `after`, or `ambiguous_with` relationships between these:
-- filesystem_watcher_system (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<DynamicScene> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Scene> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Shader> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Mesh> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<SkinnedMeshInverseBindposes> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Image> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<TextureAtlas> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<ColorMaterial> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Font> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<FontAtlasSet> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<StandardMaterial> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<Gltf> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<GltfNode> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<GltfPrimitive> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<GltfMesh> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<AudioSource> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<AudioSink> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- update_asset_storage_system<AnimationClip> (LoadAssets) and apply_system_buffers (FirstFlush)
conflict on: bevy_ecs::world::World
-- scene_spawner_system (Update) and close_when_requested (Update)
conflict on: bevy_ecs::world::World
-- exit_on_all_closed (PostUpdate) and apply_system_buffers (CalculateBoundsFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- exit_on_all_closed (PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<Projection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (CalculateBoundsFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<Projection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<OrthographicProjection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (CalculateBoundsFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<OrthographicProjection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<PerspectiveProjection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (CalculateBoundsFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- camera_system<PerspectiveProjection> (CameraUpdateSystem, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- calculate_bounds (CalculateBounds, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and visibility_propagate_system (PostUpdate, VisibilityPropagate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_text2d_layout (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and ui_stack_system (PostUpdate, Stack)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and text_system (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_image_calculated_size_system (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and flex_node_system (Flex, PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and add_clusters (AddClusters, PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and play_queued_audio_system<AudioSource> (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and animation_player (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and propagate_transforms (PostUpdate, TransformPropagate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and sync_simple_transforms (PostUpdate, TransformPropagate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_directional_light_cascades (PostUpdate, UpdateDirectionalLightCascades)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_clipping_system (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_frusta<Projection> (PostUpdate, UpdateProjectionFrusta)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_frusta<PerspectiveProjection> (PostUpdate, UpdatePerspectiveFrusta)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (CalculateBoundsFlush, PostUpdate) and update_frusta<OrthographicProjection> (PostUpdate, UpdateOrthographicFrusta)
conflict on: bevy_ecs::world::World
-- visibility_propagate_system (PostUpdate, VisibilityPropagate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- update_text2d_layout (PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- ui_stack_system (PostUpdate, Stack) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- text_system (PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- update_image_calculated_size_system (PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- flex_node_system (Flex, PostUpdate) and apply_system_buffers (AddClustersFlush, PostUpdate)
conflict on: bevy_ecs::world::World
-- flex_node_system (Flex, PostUpdate) and animation_player (PostUpdate)
conflict on: ["bevy_transform::components::transform::Transform"]
-- apply_system_buffers (AddClustersFlush, PostUpdate) and play_queued_audio_system<AudioSource> (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and animation_player (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and propagate_transforms (PostUpdate, TransformPropagate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and sync_simple_transforms (PostUpdate, TransformPropagate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_directional_light_cascades (PostUpdate, UpdateDirectionalLightCascades)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_clipping_system (PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_frusta<Projection> (PostUpdate, UpdateProjectionFrusta)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_frusta<PerspectiveProjection> (PostUpdate, UpdatePerspectiveFrusta)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_frusta<OrthographicProjection> (PostUpdate, UpdateOrthographicFrusta)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and check_visibility (CheckVisibility, PostUpdate)
conflict on: bevy_ecs::world::World
-- apply_system_buffers (AddClustersFlush, PostUpdate) and update_directional_light_frusta (PostUpdate, UpdateLightFrusta)
conflict on: bevy_ecs::world::World
-- Assets<Scene>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<Shader>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<Mesh>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<SkinnedMeshInverseBindposes>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<Image>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<TextureAtlas>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<ColorMaterial>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<Font>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<FontAtlasSet>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<StandardMaterial>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<Gltf>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<GltfNode>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<GltfPrimitive>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<GltfMesh>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<AudioSource>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<AudioSink>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<AnimationClip>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
-- Assets<DynamicScene>::asset_event_system (AssetEvents) and apply_system_buffers (PostUpdateFlush)
conflict on: bevy_ecs::world::World
```
Co-authored-by: Edgar Geier <geieredgar@gmail.com>
# Objective
Allow using `Local<WorldId>` in systems.
## Solution
- Describe the solution used to achieve the objective above.
---
## Changelog
+ `WorldId` now implements the `FromWorld` trait.
…top sort. reduce mem alloc
# Objective
- Reduce alloc count.
- Improve code quality.
## Solution
- use `TarjanScc::run` directly, which calls a closure with each scc, in closure, we can detect cycles and flatten nodes
# Objective
`ChangeTrackers<>` is a `WorldQuery` type that lets you access the change ticks for a component. #7097 has added `Ref<>`, which gives access to a component's value in addition to its change ticks. Since bevy's access model does not separate a component's value from its change ticks, there is no benefit to using `ChangeTrackers<T>` over `Ref<T>`.
## Solution
Deprecate `ChangeTrackers<>`.
---
## Changelog
* `ChangeTrackers<T>` has been deprecated. It will be removed in Bevy 0.11.
## Migration Guide
`ChangeTrackers<T>` has been deprecated, and will be removed in the next release. Any usage should be replaced with `Ref<T>`.
```rust
// Before (0.9)
fn my_system(q: Query<(&MyComponent, ChangeTrackers<MyComponent>)>) {
for (value, trackers) in &q {
if trackers.is_changed() {
// Do something with `value`.
}
}
}
// After (0.10)
fn my_system(q: Query<Ref<MyComponent>>) {
for value in &q {
if value.is_changed() {
// Do something with `value`.
}
}
}
```
# Objective
Fixes#7736
## Solution
Implement the `SystemParam` trait for `WorldId`
## Changelog
- `WorldId` can now be taken as a system parameter and will return the id of the world the system is running in
# Objective
- Fixes#7659.
## Solution
- This PR extracted the `distributive_run_if` part of #7676, because it does not require the controversial introduction of anonymous system sets.
- The distinctive name should make the user aware about the differences between `IntoSystemConfig::run_if` and `IntoSystemConfigs::distributive_run_if`.
- The documentation explains in detail the consequences of using the API and possible pit falls when using it.
- A test demonstrates the possibility of changing the condition result, resulting in some of the systems not being run.
---
## Changelog
### Added
- Add `distributive_run_if` to `IntoSystemConfigs` to enable adding a run condition to each system when using `add_systems`.
follow-up to https://github.com/bevyengine/bevy/pull/7716
# Objective
System access is only populated in `System::initialize`, so without calling `initialize` it's actually impossible to see most ambiguities.
## Solution
- make `initialize` public. The method is idempotent, so calling it multiple times doesn't hurt
# Objective
Continuation of https://github.com/bevyengine/bevy/pull/5719
Now that we have a definable type for the iterator.
---
## Changelog
- Implemented IntoIterator for EventReader so you can now do `&mut reader` instead of `reader.iter()` for events.
# Objective
Fix#7440. Fix#7441.
## Solution
* Remove builder functions on `ScheduleBuildSettings` in favor of public fields, move docs to the fields.
* Add `use_shortnames` and use it in `get_node_name` to feed it through `bevy_utils::get_short_name`.
# Objective
Web builds do not support running on multiple threads right now. Defaulting to the multi-threaded executor has significant overhead without any benefit.
## Solution
Default to the single threaded executor on wasm32 builds.
# Objective
- other tools (bevy_mod_debugdump) would like to have access to the ambiguities so that they can do their own reporting/visualization
## Solution
- store `conflicting_systems` in `ScheduleGraph` after calling `build_schedule`
The solution isn't very pretty and as pointed out it https://github.com/bevyengine/bevy/pull/7522, there may be a better way of exposing this, but this is the quick and dirty way if we want to have this functionality exposed in 0.10.
# Objective
- RemovedComponents is just a thin wrapper around Events/ManualEventReader which is the same as an EventReader, so most usecases that of an EventReader will probably be useful for RemovedComponents too.
I was thinking of making a trait for this but I don't think it is worth the overhead currently.
## Solution
- Mirror the api surface of EventReader
# Objective
Motivated by #7469.
`EventReader` iterators use the default implementations for `.nth()` and `.last()`, which includes iterating over and throwing out all events before the desired one.
## Solution
Add specialized implementations for these methods that directly updates the unread event counter and returns a reference to the desired event.
TODO:
- [x] Add a unit test.
- [x] ~~Add a benchmark, to see if the compiler was doing this automatically already.~~ *On second thought, this doesn't feel like a very useful thing to include in the benchmark suite.*
# Objective
- it would be nice to be able to associate a `NodeId` of a system type set to the `NodeId` of the actual system (used in bevy_mod_debugdump)
## Solution
- make `system_type` return the type id of the system
- that way you can check if a `dyn SystemSet` is the system type set of a `dyn System`
- I don't know if this information is already present somewhere else in the scheduler or if there is a better way to expose it
# Objective
Fixes#7702.
## Solution
- Added an test that ensures that no error is returned if a system or set is inside two different sets that share the same base set.
- Added an check to only return an error if the two base sets are not equal.
# Objective
The `ScheduleGraph` should be expose so that crates like [bevy_mod_debugdump](https://github.com/jakobhellermann/bevy_mod_debugdump/blob/stageless/docs/README.md) can access useful information.
## Solution
- expose `ScheduleGraph`, `NodeId`, `BaseSetMembership`, `Dag`
- add accessor functions for sets and systems
## Changelog
- expose `ScheduleGraph` for use in third party tools
This does expose our use of `petgraph` as a graph library, so we can only change that as a breaking change.
# Objective
- Fixes#5432
- Fixes#6680
## Solution
- move code responsible for generating the `impl TypeUuid` from `type_uuid_derive` into a new function, `gen_impl_type_uuid`.
- this allows the new proc macro, `impl_type_uuid`, to call the code for generation.
- added struct `TypeUuidDef` and implemented `syn::Parse` to allow parsing of the input for the new macro.
- finally, used the new macro `impl_type_uuid` to implement `TypeUuid` for the standard library (in `crates/bevy_reflect/src/type_uuid_impl.rs`).
- fixes#6680 by doing a wrapping add of the param's index to its `TYPE_UUID`
Co-authored-by: dis-da-moe <84386186+dis-da-moe@users.noreply.github.com>
# Objective
The trait `Condition<>` is implemented for any type that can be converted into a `ReadOnlySystem` which takes no inputs and returns a bool. However, due to the current implementation, consumers of the trait cannot rely on the fact that `<T as Condition>::System` implements `ReadOnlySystem`. In cases such as the `not` combinator (added in #7559), we are required to add redundant `T::System: ReadOnlySystem` trait bounds, even though this should be implied by the `Condition<>` trait.
## Solution
Add a hidden associated type which allows the compiler to figure out that the `System` associated type implements `ReadOnlySystem`.
…able like Table. Rename clear to clear_entities to clarify that metadata keeps, only value cleared
# Objective
- Provide some inspectability for SparseSets.
## Solution
- `Tables` has these three methods, len, is_empty and iter too. Add these methods to `SparseSets`, so user can print the shape of storage.
---
## Changelog
> This section is optional. If this was a trivial fix, or has no externally-visible impact, you can delete this section.
- Add `len`, `is_empty`, `iter` methods on SparseSets.
- Rename `clear` to `clear_entities` to clarify its purpose.
- Add `new_for_test` on `ComponentInfo` to make test code easy.
- Add test case covering new methods.
## Migration Guide
> This section is optional. If there are no breaking changes, you can delete this section.
- Simply adding new functionality is not a breaking change.
# Objective
This PR improves message that caused by duplicate components in bundle.
## Solution
Show names of duplicate components.
The solution is not very elegant, in my opinion, I will be happy to listen to suggestions for improving it
Co-authored-by: Саня Череп <41489405+SDesya74@users.noreply.github.com>
# Objective
While porting my crate `bevy_trait_query` to bevy 0.10, I ran into an issue with the `DetectChangesMut` trait. Due to the way that the `set_if_neq` method (added in #6853) is implemented, you are forced to write a nonsense implementation of it for dynamically sized types. This edge case shows up when implementing trait queries, since `DetectChangesMut` is implemented for `Mut<dyn Trait>`.
## Solution
Simplify the generics for `set_if_neq` and add the `where Self::Target: Sized` trait bound to it. Add a default implementation so implementers don't need to implement a method with nonsensical trait bounds.
# Objective
The `SystemParamFunction` (and `ExclusiveSystemParamFunction`) trait is very cumbersome to use, due to it requiring four generic type parameters. These are currently all used as marker parameters to satisfy rust's trait coherence rules.
### Example (before)
```rust
pub fn pipe<AIn, Shared, BOut, A, AParam, AMarker, B, BParam, BMarker>(
mut system_a: A,
mut system_b: B,
) -> impl FnMut(In<AIn>, ParamSet<(AParam, BParam)>) -> BOut
where
A: SystemParamFunction<AIn, Shared, AParam, AMarker>,
B: SystemParamFunction<Shared, BOut, BParam, BMarker>,
AParam: SystemParam,
BParam: SystemParam,
```
## Solution
Turn the `In`, `Out`, and `Param` generics into associated types. Merge the marker types together to retain coherence.
### Example (after)
```rust
pub fn pipe<A, B, AMarker, BMarker>(
mut system_a: A,
mut system_b: B,
) -> impl FnMut(In<A::In>, ParamSet<(A::Param, B::Param)>) -> B::Out
where
A: SystemParamFunction<AMarker>,
B: SystemParamFunction<BMarker, In = A::Out>,
```
---
## Changelog
+ Simplified the `SystemParamFunction` and `ExclusiveSystemParamFunction` traits.
## Migration Guide
For users of the `SystemParamFunction` trait, the generic type parameters `In`, `Out`, and `Param` have been turned into associated types. The same has been done with the `ExclusiveSystemParamFunction` trait.
# Objective
- #6402 changed `World::fetch_table` (now `UnsafeWorldCell::fetch_table`) to access the archetype in order to get the `table_id` and `table_row` of the entity involved. However this is useless since those were already present in the `EntityLocation`
- Moreover it's useless for `UnsafeWorldCell::fetch_table` to return the `TableRow` too, since the caller must already have access to the `EntityLocation` which contains the `TableRow`.
- The result is that `UnsafeWorldCell::fetch_table` now only does 2 memory fetches instead of 4.
## Solution
- Revert the changes to the implementation of `UnsafeWorldCell::fetch_table` made in #6402
…u64, so hash safety is not a concern
# Objective
- While reading the code, just noticed the BundleInfo's HashMap is std::collections::HashMap, which uses a slow but safe hasher.
## Solution
- Use bevy_utils::HashMap instead
benchmark diff (I run several times in a linux box, the perf improvement is consistent, though numbers varies from time to time, I paste my last run result here):
``` bash
cargo bench -- spawn
Compiling bevy_ecs v0.9.0 (/home/lishuo/developer/pr/bevy/crates/bevy_ecs)
Compiling bevy_app v0.9.0 (/home/lishuo/developer/pr/bevy/crates/bevy_app)
Compiling benches v0.1.0 (/home/lishuo/developer/pr/bevy/benches)
Finished bench [optimized] target(s) in 1m 17s
Running benches/bevy_ecs/change_detection.rs (/home/lishuo/developer/pr/bevy/benches/target/release/deps/change_detection-86c5445d0dc34529)
Gnuplot not found, using plotters backend
Running benches/bevy_ecs/benches.rs (/home/lishuo/developer/pr/bevy/benches/target/release/deps/ecs-e49b3abe80bfd8c0)
Gnuplot not found, using plotters backend
spawn_commands/2000_entities
time: [153.94 µs 159.19 µs 164.37 µs]
change: [-14.706% -11.050% -6.9633%] (p = 0.00 < 0.05)
Performance has improved.
spawn_commands/4000_entities
time: [328.77 µs 339.11 µs 349.11 µs]
change: [-7.6331% -3.9932% +0.0487%] (p = 0.06 > 0.05)
No change in performance detected.
spawn_commands/6000_entities
time: [445.01 µs 461.29 µs 477.36 µs]
change: [-16.639% -13.358% -10.006%] (p = 0.00 < 0.05)
Performance has improved.
spawn_commands/8000_entities
time: [657.94 µs 677.71 µs 696.95 µs]
change: [-8.8708% -5.2591% -1.6847%] (p = 0.01 < 0.05)
Performance has improved.
get_or_spawn/individual time: [452.02 µs 466.70 µs 482.07 µs]
change: [-17.218% -14.041% -10.728%] (p = 0.00 < 0.05)
Performance has improved.
get_or_spawn/batched time: [291.12 µs 301.12 µs 311.31 µs]
change: [-12.281% -8.9163% -5.3660%] (p = 0.00 < 0.05)
Performance has improved.
spawn_world/1_entities time: [81.668 ns 84.284 ns 86.860 ns]
change: [-12.251% -6.7872% -1.5402%] (p = 0.02 < 0.05)
Performance has improved.
spawn_world/10_entities time: [789.78 ns 821.96 ns 851.95 ns]
change: [-19.738% -14.186% -8.0733%] (p = 0.00 < 0.05)
Performance has improved.
spawn_world/100_entities
time: [7.9906 µs 8.2449 µs 8.5013 µs]
change: [-12.417% -6.6837% -0.8766%] (p = 0.02 < 0.05)
Change within noise threshold.
spawn_world/1000_entities
time: [81.602 µs 84.161 µs 86.833 µs]
change: [-13.656% -8.6520% -3.0491%] (p = 0.00 < 0.05)
Performance has improved.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high mild
Benchmarking spawn_world/10000_entities: Warming up for 500.00 ms
Warning: Unable to complete 100 samples in 4.0s. You may wish to increase target time to 4.0s, enable flat sampling, or reduce sample count to 70.
spawn_world/10000_entities
time: [813.02 µs 839.76 µs 865.41 µs]
change: [-12.133% -6.1970% -0.2302%] (p = 0.05 < 0.05)
Change within noise threshold.
```
---
## Changelog
> This section is optional. If this was a trivial fix, or has no externally-visible impact, you can delete this section.
- use bevy_utils::HashMap for Bundles::bundle_ids
## Migration Guide
> This section is optional. If there are no breaking changes, you can delete this section.
- Not a breaking change, hashmap is internal impl.
# Objective
We have a few old system labels that are now system sets but are still named or documented as labels. Documentation also generally mentioned system labels in some places.
## Solution
- Clean up naming and documentation regarding system sets
## Migration Guide
`PrepareAssetLabel` is now called `PrepareAssetSet`
# Objective
- Improve readability of the run condition for systems only running in a certain state
## Solution
- Rename `state_equals` to `in_state` (see [comment by cart](https://github.com/bevyengine/bevy/pull/7634#issuecomment-1428740311) in #7634 )
- `.run_if(state_equals(variant))` now is `.run_if(in_state(variant))`
This breaks the naming pattern a bit with the related conditions `state_exists` and `state_exists_and_equals` but I could not think of better names for those and think the improved readability of `in_state` is worth it.
# Objective
Fixes#7632.
As discussed in #7634, it can be quite challenging for users to intuit the mental model of how states now work.
## Solution
Rather than change the behavior of the `OnUpdate` system set, instead work on making sure it's easy to understand what's going on.
Two things have been done:
1. Remove the `.on_update` method from our bevy of system building traits. This was special-cased and made states feel much more magical than they need to.
2. Improve the docs for the `OnUpdate` system set.
# Objective
- Fixes: #7187
Since avoiding the `SRes::into_inner` call does not seem to be possible, this PR tries to at least document its usage.
I am not sure if I explained the lifetime issue correctly, please let me know if something is incorrect.
## Solution
- Add information about the `SRes::into_inner` usage on both `RenderCommand` and `Res`
# Objective
Related to #7530.
`EventReader` iterators currently use the default impl for `.count()`, which unnecessarily loops over all unread events.
# Solution
Add specialized impls that mark the `EventReader` as consumed and return the number of unread events.
# Objective
Make the name less verbose without sacrificing clarity.
---
## Migration Guide
*Note for maintainers:* This PR has no breaking changes relative to bevy 0.9. Instead of this PR having its own migration guide, we should just edit the changelog for #6404.
The type `UnsafeWorldCellEntityRef` has been renamed to `UnsafeEntityCell`.
# Objective
Continuation of #7560.
`MutUntyped::last_changed` and `set_last_changed` do not behave as described in their docs.
## Solution
Fix them using the same approach that was used for `Mut<>` in #7560.
# Objective
Make `last_changed` behave as described in its docs.
## Solution
- Return `changed` instead of `last_change_tick`. `last_change_tick` is the system's previous tick and is just used for comparison.
- Update the docs of the similarly named `set_last_changed` (which does correctly interact with `last_change_tick`) to clarify that the two functions touch different data. (I advocate for renaming one or the other if anyone has any good suggestions).
It also might make sense to return a cloned `Tick` instead of `u32`.
---
## Changelog
- Fixed `DetectChanges::last_changed` returning the wrong value.
- Fixed `DetectChangesMut::set_last_changed` not actually updating the `changed` tick.
## Migration Guide
- The incorrect value that was being returned by `DetectChanges::last_changed` was the previous run tick of the system checking for changed values. If you depended on this value, you can get it from the `SystemChangeTick` `SystemParam` instead.
# Objective
Clarify what the function is actually calculating.
The `Tick::is_older_than` function is actually calculating whether the tick is newer than the system's `last_change_tick`, not older. As far as I can tell, the engine was using it correctly everywhere already.
## Solution
- Rename the function.
---
## Changelog
- `Tick::is_older_than` was renamed to `Tick::is_newer_than`. This is not a functional change, since that was what was always being calculated, despite the wrong name.
## Migration Guide
- Replace usages of `Tick::is_older_than` with `Tick::is_newer_than`.
# Objective
Closes#7202
## Solution
~~Introduce a `not` helper to pipe conditions. Opened mostly for discussion. Maybe create an extension trait with `not` method? Please, advice.~~
Introduce `not(condition)` condition that inverses the result of the passed.
---
## Changelog
### Added
- `not` condition.
