# Objective
Some usecases in the ecosystems are blocked by the inability to stop
bevy internals and third party plugins from touching their entities.
However the specifics of a general purpose entity disabling system are
controversial and further complicated by hierarchies. We can partially
unblock these usecases with an opt-in approach: default query filters.
## Solution
- Introduce DefaultQueryFilters, these filters are automatically applied
to queries that don't otherwise mention the filtered component.
- End users and third party plugins can register default filters and are
responsible for handling entities they have hidden this way.
- Extra features can be left for after user feedback
- The default value could later include official ways to hide entities
---
## Changelog
- Add DefaultQueryFilters
# Objective
- Fix issue identified on the [Discord
server](https://discord.com/channels/691052431525675048/691052431974465548/1328922812530036839)
## Solution
- Implement `Clone` for `QueryIter` using the existing
`QueryIter::remaining` method
## Testing
- CI
---
## Showcase
Users can now explicitly clone a read-only `QueryIter`:
```rust
fn combinations(query: Query<&ComponentA>) {
let mut iter = query.iter();
while let Some(a) = iter.next() {
// Can now clone rather than use remaining
for b in iter.clone() {
// Check every combination (a, b)
}
}
}
```
## Notes
This doesn't add any new functionality outside the context of generic
code (e.g., `T: Iterator<...> + Clone`), it's mostly for
discoverability. Users are more likely to be familiar with
`Clone::clone` than they are with the methods on `QueryIter`.
# Objective
- https://github.com/bevyengine/bevy/issues/17111
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `warn`, and bring
`bevy_ecs` in line with the new restrictions.
## Testing
This PR is a WIP; testing will happen after it's finished.
# Objective
With the `track_location` feature, the error message of trying to
acquire an entity that was despawned pointed to the wrong line if the
entity index has been reused.
## Showcase
```rust
use bevy_ecs::prelude::*;
fn main() {
let mut world = World::new();
let e = world.spawn_empty().id();
world.despawn(e);
world.flush();
let _ = world.spawn_empty();
world.entity(e);
}
```
Old message:
```
Entity 0v1 was despawned by src/main.rs:8:19
```
New message:
```
Entity 0v1 does not exist (its index has been reused)
```
# Objective
Stumbled upon a `from <-> form` transposition while reviewing a PR,
thought it was interesting, and went down a bit of a rabbit hole.
## Solution
Fix em
Related to https://github.com/bevyengine/bevy/pull/16843
Since `WorldQuery::Fetch` is `Clone`, it can't store mutable references
to resources, so it doesn't make sense to mutably access resources. In
that sense, it is hard to find usecases of mutably accessing resources
and to clearly define, what mutably accessing resources would mean, so
it's been decided to disallow write resource access.
Also changed documentation of safety requirements of
`WorldQuery::init_fetch` and `WorldQuery::fetch` to clearly state to the
caller, what safety invariants they need to uphold.
# Objective
- Contributes to #11478
## Solution
- Made `bevy_utils::tracing` `doc(hidden)`
- Re-exported `tracing` from `bevy_log` for end-users
- Added `tracing` directly to crates that need it.
## Testing
- CI
---
## Migration Guide
If you were importing `tracing` via `bevy::utils::tracing`, instead use
`bevy::log::tracing`. Note that many items within `tracing` are also
directly re-exported from `bevy::log` as well, so you may only need
`bevy::log` for the most common items (e.g., `warn!`, `trace!`, etc.).
This also applies to the `log_once!` family of macros.
## Notes
- While this doesn't reduce the line-count in `bevy_utils`, it further
decouples the internal crates from `bevy_utils`, making its eventual
removal more feasible in the future.
- I have just imported `tracing` as we do for all dependencies. However,
a workspace dependency may be more appropriate for version management.
## Objective
The error `EntityFetchError::NoSuchEntity` has an `UnsafeWorldCell`
inside it, which it uses to call
`Entities::entity_does_not_exist_error_details_message` when being
printed. That method returns a `String` that, if the `track_location`
feature is enabled, contains the location of whoever despawned the
relevant entity.
I initially had to modify this error while working on #17043. The
`UnsafeWorldCell` was causing borrow problems when being returned from a
command, so I tried replacing it with the `String` that the method
returns, since that was the world cell's only purpose.
Unfortunately, `String`s are slow, and it significantly impacted
performance (on top of that PR's performance hit):
<details>
<summary>17043 benchmarks</summary>
### With `String`
### No `String`
</details>
For that PR, I just removed the error details entirely, but I figured
I'd try to find a way to keep them around.
## Solution
- Replace the `String` with a helper struct that holds the location, and
only turn it into a string when someone actually wants to print it.
- Replace the `UnsafeWorldCell` with the aforementioned struct.
- Do the same for `QueryEntityError::NoSuchEntity`.
## Benchmarking
This had some interesting performance impact:
<details>
<summary>This PR vs main</summary>
</details>
## Other work
`QueryEntityError::QueryDoesNotMatch` also has an `UnsafeWorldCell`
inside it. This one would be more complicated to rework while keeping
the same functionality.
## Migration Guide
The errors `EntityFetchError::NoSuchEntity` and
`QueryEntityError::NoSuchEntity` now contain an
`EntityDoesNotExistDetails` struct instead of an `UnsafeWorldCell`. If
you were just printing these, they should work identically.
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
# Background
In `no_std` compatible crates, there is often an `std` feature which
will allow access to the standard library. Currently, with the `std`
feature _enabled_, the
[`std::prelude`](https://doc.rust-lang.org/std/prelude/index.html) is
implicitly imported in all modules. With the feature _disabled_, instead
the [`core::prelude`](https://doc.rust-lang.org/core/prelude/index.html)
is implicitly imported. This creates a subtle and pervasive issue where
`alloc` items _may_ be implicitly included (if `std` is enabled), or
must be explicitly included (if `std` is not enabled).
# Objective
- Make the implicit imports for `no_std` crates consistent regardless of
what features are/not enabled.
## Solution
- Replace the `cfg_attr` "double negative" `no_std` attribute with
conditional compilation to _include_ `std` as an external crate.
```rust
// Before
#![cfg_attr(not(feature = "std"), no_std)]
// After
#![no_std]
#[cfg(feature = "std")]
extern crate std;
```
- Fix imports that are currently broken but are only now visible with
the above fix.
## Testing
- CI
## Notes
I had previously used the "double negative" version of `no_std` based on
general consensus that it was "cleaner" within the Rust embedded
community. However, this implicit prelude issue likely was considered
when forming this consensus. I believe the reason why is the items most
affected by this issue are provided by the `alloc` crate, which is
rarely used within embedded but extensively used within Bevy.
# Objective
- As stated in the related issue, this PR is to better align the feature
flag name with what it actually does and the plans for the future.
- Fixes#16852
## Solution
- Simple find / replace
## Testing
- Local run of `cargo run -p ci`
## Migration Guide
The `track_change_detection` feature flag has been renamed to
`track_location` to better reflect its extended capabilities.
# Objective
- Made certain methods public for advanced use cases. Methods that
returns mutable references are marked as unsafe due to the possibility
of violating internal lifetime constraint assumptions.
- Fixes an issue introduced by #15184
# Objective
Fixes#16104
## Solution
I removed all instances of `:?` and put them back one by one where it
caused an error.
I removed some bevy_utils helper functions that were only used in 2
places and don't add value. See: #11478
## Testing
CI should catch the mistakes
## Migration Guide
`bevy::utils::{dbg,info,warn,error}` were removed. Use
`bevy::utils::tracing::{debug,info,warn,error}` instead.
---------
Co-authored-by: SpecificProtagonist <vincentjunge@posteo.net>
# Objective
Some types like `RenderEntity` and `MainEntity` are just wrappers around
`Entity`, so they should be able to implement
`EntityBorrow`/`TrustedEntityBorrow`. This allows using them with
`EntitySet` functionality.
The `EntityRef` family are more than direct wrappers around `Entity`,
but can still benefit from being unique in a collection.
## Solution
Implement `EntityBorrow` and `TrustedEntityBorrow` for simple `Entity`
newtypes and `EntityRef` types.
These impls are an explicit decision to have the `EntityRef` types
compare like just `Entity`.
`EntityWorldMut` is omitted from this impl, because it explicitly
contains a `&mut World` as well, and we do not ever use more than one at
a time.
Add `EntityBorrow` to the `bevy_ecs` prelude.
## Migration Guide
`NormalizedWindowRef::entity` has been replaced with an
`EntityBorrow::entity` impl.
# Objective
In current Bevy, it is very inconvenient to mutably retrieve a
user-provided list of entities more than one element at a time.
If the list contains any duplicate entities, we risk mutable aliasing.
Users of `Query::iter_many_mut` do not have access to `Iterator` trait,
and thus miss out on common functionality, for instance collecting their
`QueryManyIter`.
We can circumvent this issue with validation, however that entails
checking every entity against all others for inequality, or utilizing an
`EntityHashSet`. Even if an entity list remains unchanged, this
validation is/would have to be redone every time we wish to fetch with
the list.
This presents a lot of wasted work, as we often trivially know an entity
list to be unique f.e.: `QueryIter` will fetch every `Entity` once and
only once.
As more things become entities – assets, components, queries – this
issue will become more pronounced.
`get_many`/`many`/`iter_many`/`par_iter_many`-like functionality is all
affected.
## Solution
The solution this PR proposes is to introduce functionality built around
a new trait: `EntitySet`.
The goal is to preserve the property of "uniqueness" in a list wherever
possible, and then rely on it as a bound within new `*_many_unique`
methods to avoid the need for validation.
This is achieved using `Iterator`:
`EntitySet` is blanket implemented for any `T` that implements
`IntoIterator<IntoIter: EntitySetIterator>`.
`EntitySetIterator` is the unsafe trait that actually guarantees an
iterator to be "unique" via its safety contract.
We define an "Iterator over unique entities" as: "No two entities
returned by the iterator may compare equal."
For iterators that cannot return more than 1 element, this is trivially
true.
Whether an iterator can satisfy this is up to the `EntitySetIterator`
implementor to ensure, hence the unsafe.
However, this is not yet a complete solution. Looking at the signature
of `iter_many`, we find that `IntoIterator::Item` is not `Entity`, but
is instead bounded by the `Borrow<Entity>` trait. That is because
iteration without consuming the collection will often yield us
references, not owned items.
`Borrow<Entity>` presents an issue: The `Borrow` docs state that `x = y`
should equal `x.borrow() = y.borrow()`, but unsafe cannot rely on this
for soundness. We run into similar problems with other trait
implementations of any `Borrow<Entity>` type: `PartialEq`, `Eq`,
`PartialOrd`, `Ord`, `Hash`, `Clone`, `Borrow`, and `BorrowMut`.
This PR solves this with the unsafe `TrustedEntityBorrow` trait:
Any implementor promises that the behavior of the aforementioned traits
matches that of the underlying entity.
While `Borrow<Entity>` was the inspiration, we use our own counterpart
trait `EntityBorrow` as the supertrait to `TrustedEntityBorrow`, so we
can circumvent the limitations of the existing `Borrow<T>` blanket
impls.
All together, these traits allow us to implement `*_many_unique`
functionality with a lone `EntitySet` bound.
`EntitySetIterator` is implemented for all the std iterators and
iterator adapters that guarantee or preserve uniqueness, so we can
filter, skip, take, step, reverse, ... our unique entity iterators
without worry!
Sadly, current `HashSet` iterators do not carry the necessary type
information with them to determine whether the source `HashSet` produces
logic errors; A malicious `Hasher` could compromise a `HashSet`.
`HashSet` iteration is generally discouraged in the first place, so we
also exclude the set operation iterators, even though they do carry the
`Hasher` type parameter.
`BTreeSet` implements `EntitySet` without any problems.
If an iterator type cannot guarantee uniqueness at compile time, then a
user can still attach `EntitySetIterator` to an individual instance of
that type via `UniqueEntityIter::from_iterator_unchecked`.
With this, custom types can use `UniqueEntityIter<I>` as their
`IntoIterator::IntoIter` type, if necessary.
This PR is focused on the base concept, and expansions on it are left
for follow-up PRs. See "Potential Future Work" below.
## Testing
Doctests on `iter_many_unique`/`iter_many_unique_mut` + 2 tests in
entity_set.rs.
## Showcase
```rust
// Before:
fn system(player_list: Res<SomeUniquePlayerList>, players: Query<&mut Player>) {
let value = 0;
while let Some(player) = players.iter_many_mut(player_list).fetch_next() {
value += mem::take(player.value_mut())
}
}
// After:
fn system(player_list: Res<SomeUniquePlayerList>, players: Query<&mut Player>) {
let value = players
.iter_many_unique_mut(player_list)
.map(|player| mem::take(player.value_mut()))
.sum();
}
```
## Changelog
- added `EntityBorrow`, `TrustedEntityBorrow`, `EntitySet` and
`EntitySetIterator` traits
- added `iter_many_unique`, `iter_many_unique_mut`,
`iter_many_unique_unsafe` methods on `Query`
- added `iter_many_unique`, `iter_many_unique_mut`,
`iter_many_unique_manual` and `iter_many_unique_unchecked_manual`
methods on `QueryState`
- added corresponding `QueryManyUniqueIter`
- added `UniqueEntityIter`
## Migration Guide
Any custom type used as a `Borrow<Entity>` entity list item for an
`iter_many` method now has to implement `EntityBorrow` instead. Any type
that implements `Borrow<Entity>` can trivially implement `EntityBorrow`.
## Potential Future Work
- `ToEntitySet` trait for converting any entity iterator into an
`EntitySetIterator`
- `EntityIndexSet/Map` to tie in hashing with `EntitySet`
- add `EntityIndexSetSlice/MapSlice`
- requires: `EntityIndexSet/Map`
- Implementing `par_iter_many_unique_mut` for parallel mutable iteration
- requires: `par_iter_many`
- allow collecting into `UniqueEntityVec` to store entity sets
- add `UniqueEntitySlice`s
- Doesn't require, but should be done after: `UniqueEntityVec`
- add `UniqueEntityArray`s
- Doesn't require, but should be done after: `UniqueEntitySlice`
- `get_many_unique`/`many_unique` methods
- requires: `UniqueEntityArray`
- `World::entity_unique` to match `World::entity` methods
- Doesn't require, but makes sense after:
`get_many_unique`/`many_unique`
- implement `TrustedEntityBorrow` for the `EntityRef` family
- Doesn't require, but makes sense after: `UniqueEntityVec`
# Objective
- Contributes to #15460
## Solution
- Added the following features:
- `std` (default)
- `async_executor` (default)
- `edge_executor`
- `critical-section`
- `portable-atomic`
- Gated `tracing` in `bevy_utils` to allow compilation on certain
platforms
- Switched from `tracing` to `log` for simple message logging within
`bevy_ecs`. Note that `tracing` supports capturing from `log` so this
should be an uncontroversial change.
- Fixed imports and added feature gates as required
- Made `bevy_tasks` optional within `bevy_ecs`. Turns out it's only
needed for parallel operations which are already gated behind
`multi_threaded` anyway.
## Testing
- Added to `compile-check-no-std` CI command
- `cargo check -p bevy_ecs --no-default-features --features
edge_executor,critical-section,portable-atomic --target
thumbv6m-none-eabi`
- `cargo check -p bevy_ecs --no-default-features --features
edge_executor,critical-section`
- `cargo check -p bevy_ecs --no-default-features`
## Draft Release Notes
Bevy's core ECS now supports `no_std` platforms.
In prior versions of Bevy, it was not possible to work with embedded or
niche platforms due to our reliance on the standard library, `std`. This
has blocked a number of novel use-cases for Bevy, such as an embedded
database for IoT devices, or for creating games on retro consoles.
With this release, `bevy_ecs` no longer requires `std`. To use Bevy on a
`no_std` platform, you must disable default features and enable the new
`edge_executor` and `critical-section` features. You may also need to
enable `portable-atomic` and `critical-section` if your platform does
not natively support all atomic types and operations used by Bevy.
```toml
[dependencies]
bevy_ecs = { version = "0.16", default-features = false, features = [
# Required for platforms with incomplete atomics (e.g., Raspberry Pi Pico)
"portable-atomic",
"critical-section",
# Optional
"bevy_reflect",
"serialize",
"bevy_debug_stepping",
"edge_executor"
] }
```
Currently, this has been tested on bare-metal x86 and the Raspberry Pi
Pico. If you have trouble using `bevy_ecs` on a particular platform,
please reach out either through a GitHub issue or in the `no_std`
working group on the Bevy Discord server.
Keep an eye out for future `no_std` updates as we continue to improve
the parity between `std` and `no_std`. We look forward to seeing what
kinds of applications are now possible with Bevy!
## Notes
- Creating PR in draft to ensure CI is passing before requesting
reviews.
- This implementation has no support for multithreading in `no_std`,
especially due to `NonSend` being unsound if allowed in multithreading.
The reason is we cannot check the `ThreadId` in `no_std`, so we have no
mechanism to at-runtime determine if access is sound.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Vic <59878206+Victoronz@users.noreply.github.com>
# Objective
Expand `track_change_detection` feature to also track entity spawns and
despawns. Use this to create better error messages.
# Solution
Adds `Entities::entity_get_spawned_or_despawned_by` as well as `{all
entity reference types}::spawned_by`.
This also removes the deprecated `get_many_entities_mut` & co (and
therefore can't land in 0.15) because we don't yet have no Polonius.
## Testing
Added a test that checks that the locations get updated and these
updates are ordered correctly vs hooks & observers.
---
## Showcase
Access location:
```rust
let mut world = World::new();
let entity = world.spawn_empty().id();
println!("spawned by: {}", world.entity(entity).spawned_by());
```
```
spawned by: src/main.rs:5:24
```
Error message (with `track_change_detection`):
```rust
world.despawn(entity);
world.entity(entity);
```
```
thread 'main' panicked at src/main.rs:11:11:
Entity 0v1#4294967296 was despawned by src/main.rs:10:11
```
and without:
```
thread 'main' panicked at src/main.rs:11:11:
Entity 0v1#4294967296 does not exist (enable `track_change_detection` feature for more details)
```
Similar error messages now also exists for `Query::get`,
`World::entity_mut`, `EntityCommands` creation and everything that
causes `B0003`, e.g.
```
error[B0003]: Could not insert a bundle (of type `MaterialMeshBundle<StandardMaterial>`) for entity Entity { index: 7, generation: 1 }, which was despawned by src/main.rs:10:11. See: https://bevyengine.org/learn/errors/#b0003
```
---------
Co-authored-by: kurk070ff <108901106+kurk070ff@users.noreply.github.com>
Co-authored-by: Freya Pines <freya@MacBookAir.lan>
Co-authored-by: Freya Pines <freya@Freyas-MacBook-Air.local>
Co-authored-by: Matty Weatherley <weatherleymatthew@gmail.com>
# Objective
When calling any of the `sort` methods on a `QueryManyIter` with mutable
data, `collect_inner()` must be called before fetching items. Remove the
need for that call.
## Solution
Have the `sort` methods `collect()` the entity list into a `Vec` before
returning.
# Objective
Allow resources to be accessed soundly by `QueryData` and `QueryFilter`
implementations.
This mostly works today, and is used in `bevy-trait-query` and will be
used by #16810. The problem is that the access is not made visible to
the executor, so it would be possible for a system with resource access
in a query to run concurrently with a system that accesses the resource
with `ResMut`, resulting in Undefined Behavior.
## Solution
Define calling `add_resource_read` or `add_resource_write` in
`WorldQuery::update_component_access` to be a supported way to declare
resource access in a query.
Modify `QueryState::new_with_access` to check for resource access and
report it in `archetype_component_acccess`.
Modify `FilteredAccess::is_compatible` to consider resource access
conflicting even on queries with disjoint filters.
# Objective
- Remove `derive_more`'s error derivation and replace it with
`thiserror`
## Solution
- Added `derive_more`'s `error` feature to `deny.toml` to prevent it
sneaking back in.
- Reverted to `thiserror` error derivation
## Notes
Merge conflicts were too numerous to revert the individual changes, so
this reversion was done manually. Please scrutinise carefully during
review.
# Objective
- Fixes#16208
## Solution
- Added an associated type to `Component`, `Mutability`, which flags
whether a component is mutable, or immutable. If `Mutability= Mutable`,
the component is mutable. If `Mutability= Immutable`, the component is
immutable.
- Updated `derive_component` to default to mutable unless an
`#[component(immutable)]` attribute is added.
- Updated `ReflectComponent` to check if a component is mutable and, if
not, panic when attempting to mutate.
## Testing
- CI
- `immutable_components` example.
---
## Showcase
Users can now mark a component as `#[component(immutable)]` to prevent
safe mutation of a component while it is attached to an entity:
```rust
#[derive(Component)]
#[component(immutable)]
struct Foo {
// ...
}
```
This prevents creating an exclusive reference to the component while it
is attached to an entity. This is particularly powerful when combined
with component hooks, as you can now fully track a component's value,
ensuring whatever invariants you desire are upheld. Before this would be
done my making a component private, and manually creating a `QueryData`
implementation which only permitted read access.
<details>
<summary>Using immutable components as an index</summary>
```rust
/// This is an example of a component like [`Name`](bevy::prelude::Name), but immutable.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Component)]
#[component(
immutable,
on_insert = on_insert_name,
on_replace = on_replace_name,
)]
pub struct Name(pub &'static str);
/// This index allows for O(1) lookups of an [`Entity`] by its [`Name`].
#[derive(Resource, Default)]
struct NameIndex {
name_to_entity: HashMap<Name, Entity>,
}
impl NameIndex {
fn get_entity(&self, name: &'static str) -> Option<Entity> {
self.name_to_entity.get(&Name(name)).copied()
}
}
fn on_insert_name(mut world: DeferredWorld<'_>, entity: Entity, _component: ComponentId) {
let Some(&name) = world.entity(entity).get::<Name>() else {
unreachable!()
};
let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
return;
};
index.name_to_entity.insert(name, entity);
}
fn on_replace_name(mut world: DeferredWorld<'_>, entity: Entity, _component: ComponentId) {
let Some(&name) = world.entity(entity).get::<Name>() else {
unreachable!()
};
let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
return;
};
index.name_to_entity.remove(&name);
}
// Setup our name index
world.init_resource::<NameIndex>();
// Spawn some entities!
let alyssa = world.spawn(Name("Alyssa")).id();
let javier = world.spawn(Name("Javier")).id();
// Check our index
let index = world.resource::<NameIndex>();
assert_eq!(index.get_entity("Alyssa"), Some(alyssa));
assert_eq!(index.get_entity("Javier"), Some(javier));
// Changing the name of an entity is also fully capture by our index
world.entity_mut(javier).insert(Name("Steven"));
// Javier changed their name to Steven
let steven = javier;
// Check our index
let index = world.resource::<NameIndex>();
assert_eq!(index.get_entity("Javier"), None);
assert_eq!(index.get_entity("Steven"), Some(steven));
```
</details>
Additionally, users can use `Component<Mutability = ...>` in trait
bounds to enforce that a component _is_ mutable or _is_ immutable. When
using `Component` as a trait bound without specifying `Mutability`, any
component is applicable. However, methods which only work on mutable or
immutable components are unavailable, since the compiler must be
pessimistic about the type.
## Migration Guide
- When implementing `Component` manually, you must now provide a type
for `Mutability`. The type `Mutable` provides equivalent behaviour to
earlier versions of `Component`:
```rust
impl Component for Foo {
type Mutability = Mutable;
// ...
}
```
- When working with generic components, you may need to specify that
your generic parameter implements `Component<Mutability = Mutable>`
rather than `Component` if you require mutable access to said component.
- The entity entry API has had to have some changes made to minimise
friction when working with immutable components. Methods which
previously returned a `Mut<T>` will now typically return an
`OccupiedEntry<T>` instead, requiring you to add an `into_mut()` to get
the `Mut<T>` item again.
## Draft Release Notes
Components can now be made immutable while stored within the ECS.
Components are the fundamental unit of data within an ECS, and Bevy
provides a number of ways to work with them that align with Rust's rules
around ownership and borrowing. One part of this is hooks, which allow
for defining custom behavior at key points in a component's lifecycle,
such as addition and removal. However, there is currently no way to
respond to _mutation_ of a component using hooks. The reasons for this
are quite technical, but to summarize, their addition poses a
significant challenge to Bevy's core promises around performance.
Without mutation hooks, it's relatively trivial to modify a component in
such a way that breaks invariants it intends to uphold. For example, you
can use `core::mem::swap` to swap the components of two entities,
bypassing the insertion and removal hooks.
This means the only way to react to this modification is via change
detection in a system, which then begs the question of what happens
_between_ that alteration and the next run of that system?
Alternatively, you could make your component private to prevent
mutation, but now you need to provide commands and a custom `QueryData`
implementation to allow users to interact with your component at all.
Immutable components solve this problem by preventing the creation of an
exclusive reference to the component entirely. Without an exclusive
reference, the only way to modify an immutable component is via removal
or replacement, which is fully captured by component hooks. To make a
component immutable, simply add `#[component(immutable)]`:
```rust
#[derive(Component)]
#[component(immutable)]
struct Foo {
// ...
}
```
When implementing `Component` manually, there is an associated type
`Mutability` which controls this behavior:
```rust
impl Component for Foo {
type Mutability = Mutable;
// ...
}
```
Note that this means when working with generic components, you may need
to specify that a component is mutable to gain access to certain
methods:
```rust
// Before
fn bar<C: Component>() {
// ...
}
// After
fn bar<C: Component<Mutability = Mutable>>() {
// ...
}
```
With this new tool, creating index components, or caching data on an
entity should be more user friendly, allowing libraries to provide APIs
relying on components and hooks to uphold their invariants.
## Notes
- ~~I've done my best to implement this feature, but I'm not happy with
how reflection has turned out. If any reflection SMEs know a way to
improve this situation I'd greatly appreciate it.~~ There is an
outstanding issue around the fallibility of mutable methods on
`ReflectComponent`, but the DX is largely unchanged from `main` now.
- I've attempted to prevent all safe mutable access to a component that
does not implement `Component<Mutability = Mutable>`, but there may
still be some methods I have missed. Please indicate so and I will
address them, as they are bugs.
- Unsafe is an escape hatch I am _not_ attempting to prevent. Whatever
you do with unsafe is between you and your compiler.
- I am marking this PR as ready, but I suspect it will undergo fairly
major revisions based on SME feedback.
- I've marked this PR as _Uncontroversial_ based on the feature, not the
implementation.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: Nuutti Kotivuori <naked@iki.fi>
# Objective
Fixes#15941
## Solution
Created https://crates.io/crates/variadics_please and moved the code
there; updating references
`bevy_utils/macros` is deleted.
## Testing
cargo check
## Migration Guide
Use `variadics_please::{all_tuples, all_tuples_with_size}` instead of
`bevy::utils::{all_tuples, all_tuples_with_size}`.
# Objective
~Blocked on #13417~
Motivation is the same as in #13417. If users can sort `QueryIter`, to
only makes sense to also allow them to use this functionality on
`QueryManyIter`.
## Solution
Also implement the sorts on `QueryManyIter`.
The implementation of the sorts themselves are mostly the same as with
`QueryIter` in #13417.
They differ in that they re-use the `entity_iter` passed to the
`iter_many`, and internally call `iter_many_unchecked_manual` on the
lens `QueryState` with it.
These methods also return a different struct, `QuerySortedManyIter`,
because there is no longer a guarantee of unique entities.
`QuerySortedManyIter` implements the various `Iterator` traits for
read-only iteration, as `QueryManyIter` does + `DoubleEndedIterator`.
For mutable iteration, there is both a `fetch_next` and a
`fetch_next_back` method. However, they only become available after the
user calls `collect_inner` on `QuerySortedManyIter` first. This collects
the inner `entity_iter` (this is the sorted one, **not** the original
the user passed) to drop all query lens items to avoid aliasing.
When TAITs are available this `collect_inner` could be hidden away,
until then it is unfortunately not possible to elide this without either
regressing read-only iteration, or introducing a whole new type, mostly
being a copy of `QuerySortedIter`.
As a follow-up we could add a `entities_all_unique` method to check
whether the entity list consists of only unique entities, and then
return a `QuerySortedIter` from it (under opaque impl Trait if need be),
*allowing mutable `Iterator` trait iteration* over what was originally
an `iter_many` call.
Such a method can also be added to `QueryManyIter`, albeit needing a
separate, new return type.
## Testing
I've switched the third example/doc test under `sort` out for one that
shows the collect_inner/fetch_next_back functionality, otherwise the
examples are the same as in #13417, adjusted to use `iter_many` instead
of `iter`.
The `query-iter-many-sorts` test checks for equivalence to the
underlying sorts.
The test after shows that these sorts *do not* panic after
`fetch`/`fetch_next` calls.
## Changelog
Added `sort`, `sort_unstable`, `sort_by`, `sort_unstable_by`,
`sort_by_key`, `sort_by_cached_key` to `QueryManyIter`.
Added `QuerySortedManyIter`.
# Objective
There is currently no way of getting `QueryState` from `&World`, so it
is hard to, for example, iterate over all entities with a component,
only having `&World`.
## Solution
Add `try_new` function to `QueryState` that internally uses
`WorldQuery`'s `get_state`.
## Testing
No testing
# Objective
A new user is likely to try `Query<Component>` instead of
`Query<&Component>`. The error message should guide them to the right
solution.
## Solution
Add a note to the on_unimplemented message for `QueryData` recommending
`&T` and `&mut T`.
The full error message now looks like:
```
error[E0277]: `A` is not valid to request as data in a `Query`
--> crates\bevy_ecs\src\query\world_query.rs:260:18
|
260 | fn system(query: Query<A>) {}
| ^^^^^^^^ invalid `Query` data
|
= help: the trait `fetch::QueryData` is not implemented for `A`
= note: if `A` is a component type, try using `&A` or `&mut A`
= help: the following other types implement trait `fetch::QueryData`:
&'__w mut T
&Archetype
&T
()
(F,)
(F0, F1)
(F0, F1, F2)
(F0, F1, F2, F3)
and 41 others
note: required by a bound in `system::query::Query`
--> crates\bevy_ecs\src\system\query.rs:362:37
|
362 | pub struct Query<'world, 'state, D: QueryData, F: QueryFilter = ()> {
| ^^^^^^^^^ required by this bound in `Query`
```
Use the new `disqualified` crate in `QueryEntityError` to make the error
message more readable.
---
## Showcase
Old:
QueryDoesNotMatch(0v1 with components my_game::main::foo::A,
my_game::main::foo::B, bevy_pbr::light::point_light::PointLight,
bevy_render::primitives::CubemapFrusta,
bevy_pbr::bundle::CubemapVisibleEntities,
bevy_transform::components::transform::Transform,
bevy_transform::components::global_transform::GlobalTransform,
bevy_render::view::visibility::Visibility,
bevy_render::view::visibility::InheritedVisibility,
bevy_render::view::visibility::ViewVisibility,
bevy_render::sync_world::SyncToRenderWorld)
New:
QueryDoesNotMatch(0v1 with components A, B, PointLight, CubemapFrusta,
CubemapVisibleEntities, Transform, GlobalTransform, Visibility,
InheritedVisibility, ViewVisibility, SyncToRenderWorld)
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Continue improving the user experience of our UI Node API in the
direction specified by [Bevy's Next Generation Scene / UI
System](https://github.com/bevyengine/bevy/discussions/14437)
## Solution
As specified in the document above, merge `Style` fields into `Node`,
and move "computed Node fields" into `ComputedNode` (I chose this name
over something like `ComputedNodeLayout` because it currently contains
more than just layout info. If we want to break this up / rename these
concepts, lets do that in a separate PR). `Style` has been removed.
This accomplishes a number of goals:
## Ergonomics wins
Specifying both `Node` and `Style` is now no longer required for
non-default styles
Before:
```rust
commands.spawn((
Node::default(),
Style {
width: Val::Px(100.),
..default()
},
));
```
After:
```rust
commands.spawn(Node {
width: Val::Px(100.),
..default()
});
```
## Conceptual clarity
`Style` was never a comprehensive "style sheet". It only defined "core"
style properties that all `Nodes` shared. Any "styled property" that
couldn't fit that mold had to be in a separate component. A "real" style
system would style properties _across_ components (`Node`, `Button`,
etc). We have plans to build a true style system (see the doc linked
above).
By moving the `Style` fields to `Node`, we fully embrace `Node` as the
driving concept and remove the "style system" confusion.
## Next Steps
* Consider identifying and splitting out "style properties that aren't
core to Node". This should not happen for Bevy 0.15.
---
## Migration Guide
Move any fields set on `Style` into `Node` and replace all `Style`
component usage with `Node`.
Before:
```rust
commands.spawn((
Node::default(),
Style {
width: Val::Px(100.),
..default()
},
));
```
After:
```rust
commands.spawn(Node {
width: Val::Px(100.),
..default()
});
```
For any usage of the "computed node properties" that used to live on
`Node`, use `ComputedNode` instead:
Before:
```rust
fn system(nodes: Query<&Node>) {
for node in &nodes {
let computed_size = node.size();
}
}
```
After:
```rust
fn system(computed_nodes: Query<&ComputedNode>) {
for computed_node in &computed_nodes {
let computed_size = computed_node.size();
}
}
```
# Objective
#15320 is a particularly painful breaking change, and the new
`RenderEntity` in particular is very noisy, with a lot of `let entity =
entity.id()` spam.
## Solution
Implement `WorldQuery`, `QueryData` and `ReadOnlyQueryData` for
`RenderEntity` and `WorldEntity`.
These work the same as the `Entity` impls from a user-facing
perspective: they simply return an owned (copied) `Entity` identifier.
This dramatically reduces noise and eases migration.
Under the hood, these impls defer to the implementations for `&T` for
everything other than the "call .id() for the user" bit, as they involve
read-only access to component data. Doing it this way (as opposed to
implementing a custom fetch, as tried in the first commit) dramatically
reduces the maintenance risk of complex unsafe code outside of
`bevy_ecs`.
To make this easier (and encourage users to do this themselves!), I've
made `ReadFetch` and `WriteFetch` slightly more public: they're no
longer `doc(hidden)`. This is a good change, since trying to vendor the
logic is much worse than just deferring to the existing tested impls.
## Testing
I've run a handful of rendering examples (breakout, alien_cake_addict,
auto_exposure, fog_volumes, box_shadow) and nothing broke.
## Follow-up
We should lint for the uses of `&RenderEntity` and `&MainEntity` in
queries: this is just less nice for no reason.
---------
Co-authored-by: Trashtalk217 <trashtalk217@gmail.com>
# Objective
Support accessing dynamic resources in a dynamic system, including
accessing them by component id. This is similar to how dynamic
components can be queried using `Query<FilteredEntityMut>`.
## Solution
Create `FilteredResources` and `FilteredResourcesMut` types that act
similar to `FilteredEntityRef` and `FilteredEntityMut` and that can be
used as system parameters.
## Example
```rust
// Use `FilteredResourcesParamBuilder` to declare access to resources.
let system = (FilteredResourcesParamBuilder::new(|builder| {
builder.add_read::<B>().add_read::<C>();
}),)
.build_state(&mut world)
.build_system(resource_system);
world.init_resource::<A>();
world.init_resource::<C>();
fn resource_system(res: FilteredResources) {
// The resource exists, but we have no access, so we can't read it.
assert!(res.get::<A>().is_none());
// The resource doesn't exist, so we can't read it.
assert!(res.get::<B>().is_none());
// The resource exists and we have access, so we can read it.
let c = res.get::<C>().unwrap();
// The type parameter can be left out if it can be determined from use.
let c: Res<C> = res.get().unwrap();
}
```
## Future Work
As a follow-up PR, `ReflectResource` can be modified to take `impl
Into<FilteredResources>`, similar to how `ReflectComponent` takes `impl
Into<FilteredEntityRef>`. That will allow dynamic resources to be
accessed using reflection.
# Objective
Relevant: #15208
## Solution
I went ahead and added the variadics documentation in all applicable
locations.
## Testing
- I built the documentation and inspected it to see whether the feature
is there.
## Objective
- Adopted #6396
## Solution
Same as #6396, we use a compile-time checked `StorageSwitch` union type
to select the fetch data based on the component's storage type, saving
>= 8 bytes per component fetch in a given query.
Note: We forego the Query iteration change as it exists in a slightly
different form now on main.
## Testing
- All current tests pass locally.
---------
Co-authored-by: james7132 <contact@jamessliu.com>
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
# Objective
- Fixes#6370
- Closes#6581
## Solution
- Added the following lints to the workspace:
- `std_instead_of_core`
- `std_instead_of_alloc`
- `alloc_instead_of_core`
- Used `cargo +nightly fmt` with [item level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Item%5C%3A)
to split all `use` statements into single items.
- Used `cargo clippy --workspace --all-targets --all-features --fix
--allow-dirty` to _attempt_ to resolve the new linting issues, and
intervened where the lint was unable to resolve the issue automatically
(usually due to needing an `extern crate alloc;` statement in a crate
root).
- Manually removed certain uses of `std` where negative feature gating
prevented `--all-features` from finding the offending uses.
- Used `cargo +nightly fmt` with [crate level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Crate%5C%3A)
to re-merge all `use` statements matching Bevy's previous styling.
- Manually fixed cases where the `fmt` tool could not re-merge `use`
statements due to conditional compilation attributes.
## Testing
- Ran CI locally
## Migration Guide
The MSRV is now 1.81. Please update to this version or higher.
## Notes
- This is a _massive_ change to try and push through, which is why I've
outlined the semi-automatic steps I used to create this PR, in case this
fails and someone else tries again in the future.
- Making this change has no impact on user code, but does mean Bevy
contributors will be warned to use `core` and `alloc` instead of `std`
where possible.
- This lint is a critical first step towards investigating `no_std`
options for Bevy.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
- Fixes#15451
## Migration Guide
- `World::init_component` has been renamed to `register_component`.
- `World::init_component_with_descriptor` has been renamed to
`register_component_with_descriptor`.
- `World::init_bundle` has been renamed to `register_bundle`.
- `Components::init_component` has been renamed to `register_component`.
- `Components::init_component_with_descriptor` has been renamed to
`register_component_with_descriptor`.
- `Components::init_resource` has been renamed to `register_resource`.
- `Components::init_non_send` had been renamed to `register_non_send`.
# Objective
Make it easier to debug why an entity doesn't match a query.
## Solution
List the entities components in `QueryEntityError::QueryDoesNotMatch`'s
message, e.g. `The query does not match the entity 0v1, which has
components foo::Bar, foo::Baz`.
This covers most cases as expected components are typically known and
filtering for change detection is rare when assessing a query by entity
id.
## Testing
Added a test confirming the new message matches the entity's components.
## Migration Guide
- `QueryEntityError` now has a lifetime. Convert it to a custom error if
you need to store it.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: poopy <gonesbird@gmail.com>
Enabled `check-private-items` in `clippy.toml` and then fixed the
resulting errors. Most of these were simply misformatted and of the
remaining:
- ~Added `#[allow(clippy::missing_safety_doc)]` to~ Removed unsafe from
a pair of functions in `bevy_utils/futures` which are only unsafe so
that they can be passed to a function which requires `unsafe fn`
- Removed `unsafe` from `UnsafeWorldCell::observers` as from what I can
tell it is always safe like `components`, `bundles` etc. (this should be
checked)
- Added safety docs to:
- `Bundles::get_storage_unchecked`: Based on the function that writes to
`dynamic_component_storages`
- `Bundles::get_storages_unchecked`: Based on the function that writes
to `dynamic_bundle_storages`
- `QueryIterationCursor::init_empty`: Duplicated from `init`
- `QueryIterationCursor::peek_last`: Thanks Giooschi (also added
internal unsafe blocks)
- `tests::drop_ptr`: Moved safety comment out to the doc string
This lint would also apply to `missing_errors_doc`, `missing_panics_doc`
and `unnecessary_safety_doc` if we chose to enable any of those at some
point, although there is an open
[issue](https://github.com/rust-lang/rust-clippy/issues/13074) to
separate these options.
This commit adds two new `WorldQuery` types: `EntityRefExcept` and
`EntityMutExcept`. These types work just like `EntityRef` and
`EntityMut`, but they prevent access to a statically-specified list of
components. For example, `EntityMutExcept<(AnimationPlayer,
Handle<AnimationGraph>)>` provides mutable access to all components
except for `AnimationPlayer` and `Handle<AnimationGraph>`. These types
are useful when you need to be able to process arbitrary queries while
iterating over the results of another `EntityMut` query.
The motivating use case is *generalized animation*, which is an upcoming
feature that allows animation of any component property, not just
rotation, translation, scaling, or morph weights. To implement this, we
must change the current `AnyOf<(&mut Transform, &mut MorphWeights)>` to
instead be `EntityMutExcept<(AnimationPlayer, Handle<AnimationGraph>)>`.
It's possible to use `FilteredEntityMut` in conjunction with a
dynamically-generated system instead, but `FilteredEntityMut` isn't
optimized for the use case of a large number of allowed components
coupled with a small set of disallowed components. No amount of
optimization of `FilteredEntityMut` produced acceptable performance on
the `many_foxes` benchmark. `Query<EntityMut, Without<AnimationPlayer>>`
will not suffice either, as it's legal and idiomatic for an
`AnimationTarget` and an `AnimationPlayer` to coexist on the same
entity.
An alternate proposal was to implement a somewhat-more-general
`Except<Q, CL>` feature, where Q is a `WorldQuery` and CL is a
`ComponentList`. I wasn't able to implement that proposal in a
reasonable way, because of the fact that methods like
`EntityMut::get_mut` and `EntityRef::get` are inherent methods instead
of methods on `WorldQuery`, and therefore there was no way to delegate
methods like `get` and `get_mut` to the inner query in a generic way.
Refactoring those methods into a trait would probably be possible.
However, I didn't see a use case for a hypothetical `Except` with
arbitrary queries: `Query<Except<(&Transform, &Visibility),
Visibility>>` would just be a complicated equivalent to
`Query<&Transform>`, for instance. So, out of a desire for simplicity, I
omitted a generic `Except` mechanism.
I've tested the performance of generalized animation on `many_foxes` and
found that, with this patch, `animate_targets` has a 7.4% slowdown over
`main`. With `FilteredEntityMut` optimized to use `Arc<Access>`, the
slowdown is 75.6%, due to contention on the reference count. Without
`Arc<Access>`, the slowdown is even worse, over 2x.
## Testing
New tests have been added that check that `EntityRefExcept` and
`EntityMutExcept` allow and disallow access to components properly and
that the query engine can correctly reject conflicting queries involving
those types.
A Tracy profile of `many_foxes` with 10,000 foxes showing generalized
animation using `FilteredEntityMut` (red) vs. main (yellow) is as
follows:
A Tracy profile of `many_foxes` with 10,000 foxes showing generalized
animation using this `EntityMutExcept` (yellow) vs. main (red) is as
follows:
# Objective
- Fixes#15236
## Solution
- Use bevy_math::ops instead of std floating point operations.
## Testing
- Did you test these changes? If so, how?
Unit tests and `cargo run -p ci -- test`
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
Execute `cargo run -p ci -- test` on Windows.
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
Windows
## Migration Guide
- Not a breaking change
- Projects should use bevy math where applicable
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
- fix#12853
- Make `Table::allocate` faster
## Solution
The PR consists of multiple steps:
1) For the component data: create a new data-structure that's similar to
`BlobVec` but doesn't store `len` & `capacity` inside of it: "BlobArray"
(name suggestions welcome)
2) For the `Tick` data: create a new data-structure that's similar to
`ThinSlicePtr` but supports dynamic reallocation: "ThinArrayPtr" (name
suggestions welcome)
3) Create a new data-structure that's very similar to `Column` that
doesn't store `len` & `capacity` inside of it: "ThinColumn"
4) Adjust the `Table` implementation to use `ThinColumn` instead of
`Column`
The result is that only one set of `len` & `capacity` is stored in
`Table`, in `Table::entities`
### Notes Regarding Performance
Apart from shaving off some excess memory in `Table`, the changes have
also brought noteworthy performance improvements:
The previous implementation relied on `Vec::reserve` &
`BlobVec::reserve`, but that redundantly repeated the same if statement
(`capacity` == `len`). Now that check could be made at the `Table` level
because the capacity and length of all the columns are synchronized;
saving N branches per allocation. The result is a respectable
performance improvement per every `Table::reserve` (and subsequently
`Table::allocate`) call.
I'm hesitant to give exact numbers because I don't have a lot of
experience in profiling and benchmarking, but these are the results I
got so far:
*`add_remove_big/table` benchmark after the implementation:*
*`add_remove_big/table` benchmark in main branch (measured in comparison
to the implementation):*
*`add_remove_very_big/table` benchmark after the implementation:*
*`add_remove_very_big/table` benchmark in main branch (measured in
comparison to the implementation):*
cc @james7132 to verify
---
## Changelog
- New data-structure that's similar to `BlobVec` but doesn't store `len`
& `capacity` inside of it: `BlobArray`
- New data-structure that's similar to `ThinSlicePtr` but supports
dynamic allocation:`ThinArrayPtr`
- New data-structure that's very similar to `Column` that doesn't store
`len` & `capacity` inside of it: `ThinColumn`
- Adjust the `Table` implementation to use `ThinColumn` instead of
`Column`
- New benchmark: `add_remove_very_big` to benchmark the performance of
spawning a lot of entities with a lot of components (15) each
## Migration Guide
`Table` now uses `ThinColumn` instead of `Column`. That means that
methods that previously returned `Column`, will now return `ThinColumn`
instead.
`ThinColumn` has a much more limited and low-level API, but you can
still achieve the same things in `ThinColumn` as you did in `Column`.
For example, instead of calling `Column::get_added_tick`, you'd call
`ThinColumn::get_added_ticks_slice` and index it to get the specific
added tick.
---------
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
It's possible to create UB using an implementation of `QueryFilter` that
performs mutable access, but that does not violate any documented safety
invariants.
This code:
```rust
#[derive(Component)]
struct Foo(usize);
// This derive is a simple way to get a valid WorldQuery impl. The QueryData impl isn't used.
#[derive(QueryData)]
#[query_data(mutable)]
struct BadFilter<'w> {
foo: &'w mut Foo,
}
impl QueryFilter for BadFilter<'_> {
const IS_ARCHETYPAL: bool = false;
unsafe fn filter_fetch(
fetch: &mut Self::Fetch<'_>,
entity: Entity,
table_row: TableRow,
) -> bool {
// SAFETY: fetch and filter_fetch have the same safety requirements
let f: &mut usize = &mut unsafe { Self::fetch(fetch, entity, table_row) }.foo.0;
println!("Got &mut at {f:p}");
true
}
}
let mut world = World::new();
world.spawn(Foo(0));
world.run_system_once(|query: Query<&Foo, BadFilter>| {
let f: &usize = &query.iter().next().unwrap().0;
println!("Got & at {f:p}");
query.iter().next().unwrap();
println!("Still have & at {f:p}");
});
```
prints:
```
Got &mut at 0x1924b92dfb0
Got & at 0x1924b92dfb0
Got &mut at 0x1924b92dfb0
Still have & at 0x1924b92dfb0
```
Which means it had an `&` and `&mut` alive at the same time.
The only `unsafe` there is around `Self::fetch`, but I believe that call
correctly upholds the safety invariant, and matches what `Added` and
`Changed` do.
## Solution
Make `QueryFilter` an unsafe trait and document the requirement that the
`WorldQuery` implementation be read-only.
## Migration Guide
`QueryFilter` is now an `unsafe trait`. If you were manually
implementing it, you will need to verify that the `WorldQuery`
implementation is read-only and then add the `unsafe` keyword to the
`impl`.
# Objective
- follow of #14049 ,we could use it on our Parallel Iterator,this pr
also unified the used function in both regular iter and parallel
iterations.
## Performance
no performance regression for regular itertaion
3.5X faster in hybrid parallel iteraion,this number is far greater than
the benefits obtained in regular iteration(~1.81) because mutable
iterations on continuous memory can effectively reduce the cost of
mataining core cache coherence
# Objective
- Fixes#14348
- Fixes#14528
- Less complex (but also likely less performant) alternative to #14611
## Solution
- Add a `is_dense` field flag to `QueryIter` indicating whether it is
dense or not, that is whether it can perform dense iteration or not;
- Check this flag any time iteration over a query is performed.
---
It would be nice if someone could try benching this change to see if it
actually matters.
~Note that this not 100% ready for mergin, since there are a bunch of
safety comments on the use of the various `IS_DENSE` for checks that
still need to be updated.~ This is ready modulo benchmarks
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Fixes#14782
## Solution
Enable the lint and fix all upcoming hints (`--fix`). Also tried to
figure out the false-positive (see review comment). Maybe split this PR
up into multiple parts where only the last one enables the lint, so some
can already be merged resulting in less many files touched / less
potential for merge conflicts?
Currently, there are some cases where it might be easier to read the
code with the qualifier, so perhaps remove the import of it and adapt
its cases? In the current stage it's just a plain adoption of the
suggestions in order to have a base to discuss.
## Testing
`cargo clippy` and `cargo run -p ci` are happy.
# Objective
- Sometimes some method or function takes an owned `Query`, but we don't
want to give up ours;
- transmuting it technically a solution, but it more costly than
necessary.
- Make query iterators more flexible
- this would allow the equivalent of
`slice::split_first`/`slice::split_first_mut` for query iterators
- helps with requests like #14685
## Solution
- Add a way for reborrowing queries, that is going from a `&'a mut
Query<'w, 's, D, F>` to a `Query<'a, 's, D, F>`:
- this is safe because the original query will be borrowed while the new
query exists and thus no aliased access can happen;
- it's basically the equivalent of going from `&'short mut &'long mut T`
to `&'short mut T` the the compiler automatically implements.
- Add a way for getting the remainder of a query iterator:
- this is interesting also because the original iterator keeps its
position, which was not possible before;
- this in turn requires a way to reborrow query fetches, which I had to
add to `WorldQuery`.
## Showcase
- You can now reborrow a `Query`, getting an equivalent `Query` with a
shorter lifetime. Previously this was possible for read-only queries by
using `Query::to_readonly`, now it's possible for mutable queries too;
- You can now separately iterate over the remainder of `QueryIter`.
## Migration Guide
- `WorldQuery` now has an additional `shrink_fetch` method you have to
implement if you were implementing `WorldQuery` manually.
# Objective
- Fixes#14697
## Solution
This PR modifies the existing `all_tuples!` macro to optionally accept a
`#[doc(fake_variadic)]` attribute in its input. If the attribute is
present, each invocation of the impl macro gets the correct attributes
(i.e. the first impl receives `#[doc(fake_variadic)]` while the other
impls are hidden using `#[doc(hidden)]`.
Impls for the empty tuple (unit type) are left untouched (that's what
the [standard
library](https://doc.rust-lang.org/std/cmp/trait.PartialEq.html#impl-PartialEq-for-())
and
[serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-())
do).
To work around https://github.com/rust-lang/cargo/issues/8811 and to get
impls on re-exports to correctly show up as variadic, `--cfg docsrs_dep`
is passed when building the docs for the toplevel `bevy` crate.
`#[doc(fake_variadic)]` only works on tuples and fn pointers, so impls
for structs like `AnyOf<(T1, T2, ..., Tn)>` are unchanged.
## Testing
I built the docs locally using `RUSTDOCFLAGS='--cfg docsrs'
RUSTFLAGS='--cfg docsrs_dep' cargo +nightly doc --no-deps --workspace`
and checked the documentation page of a trait both in its original crate
and the re-exported version in `bevy`.
The description should correctly mention for how many tuple items the
trait is implemented.
I added `rustc-args` for docs.rs to the `bevy` crate, I hope there
aren't any other notable crates that re-export `#[doc(fake_variadic)]`
traits.
---
## Showcase
`bevy_ecs::query::QueryData`:
<img width="1015" alt="Screenshot 2024-08-12 at 16 41 28"
src="https://github.com/user-attachments/assets/d40136ed-6731-475f-91a0-9df255cd24e3">
`bevy::ecs::query::QueryData` (re-export):
<img width="1005" alt="Screenshot 2024-08-12 at 16 42 57"
src="https://github.com/user-attachments/assets/71d44cf0-0ab0-48b0-9a51-5ce332594e12">
## Original Description
<details>
Resolves#14697
Submitting as a draft for now, very WIP.
Unfortunately, the docs don't show the variadics nicely when looking at
reexported items.
For example:
`bevy_ecs::bundle::Bundle` correctly shows the variadic impl:
while `bevy::ecs::bundle::Bundle` (the reexport) shows all the impls
(not good):
Built using `RUSTDOCFLAGS='--cfg docsrs' cargo +nightly doc --workspace
--no-deps` (`--no-deps` because of wgpu-core).
Maybe I missed something or this is a limitation in the *totally not
private* `#[doc(fake_variadic)]` thingy. In any case I desperately need
some sleep now :))
</details>
# Objective
- fix#14679
- bevy's performance highly depends on compiler optimization,inline hot
function could greatly help compiler to optimize our program
# Objective
- after #14502 ,explicit using clone_from should has better performance
because it could reuse the resources to avoid unnecessary allocations.
# Objective
- I made a mistake when fixing the merge conflicts here:
https://github.com/bevyengine/bevy/pull/14579#discussion_r1705377452
It wasn't caught because there's no easy way to trigger access conflicts
with resources without triggering them with components first.
# Objective
- Fixes https://github.com/bevyengine/bevy/issues/14575
- There is a soundness issue because we use `conflicts()` to check for
system ambiguities + soundness issues. However since the current
conflicts is a `Vec<T>`, we cannot express conflicts where there is no
specific `ComponentId` at fault. For example `q1: Query<EntityMut>, q2:
Query<EntityMut>`
There was a TODO to handle the `write_all` case but it was never
resolved
## Solution
- Introduce an `AccessConflict` enum that is either a list of specific
ids that are conflicting or `All` if all component ids are conflicting
## Testing
- Introduced a new unit test to check for the `EntityMut` case
## Migration guide
The `get_conflicts` method of `Access` now returns an `AccessConflict`
enum instead of simply a `Vec` of `ComponentId`s that are causing the
access conflict. This can be useful in cases where there are no
particular `ComponentId`s conflicting, but instead **all** of them are;
for example `fn system(q1: Query<EntityMut>, q2: Query<EntityRef>)`
# Objective
To implement relations we will need to add a `ComponentIndex`, which is
a map from a Component to the list of archetypes that contain this
component.
One of the reasons is that with fragmenting relations the number of
archetypes will explode, so it will become inefficient to create and
update the query caches by iterating through the list of all archetypes.
In this PR, we introduce the `ComponentIndex`, and we update the
`QueryState` to make use of it:
- if a query has at least 1 required component (i.e. something other
than `()`, `Entity` or `Option<>`, etc.): for each of the required
components we find the list of archetypes that contain it (using the
ComponentIndex). Then, we select the smallest list among these. This
gives a small subset of archetypes to iterate through compared with
iterating through all new archetypes
- if it doesn't, then we keep using the current approach of iterating
through all new archetypes
# Implementation
- This breaks query iteration order, in the sense that we are not
guaranteed anymore to return results in the order in which the
archetypes were created. I think this should be fine because this wasn't
an explicit bevy guarantee so users should not be relying on this. I
updated a bunch of unit tests that were failing because of this.
- I had an issue with the borrow checker because iterating the list of
potential archetypes requires access to `&state.component_access`, which
was conflicting with the calls to
```
if state.new_archetype_internal(archetype) {
state.update_archetype_component_access(archetype, access);
}
```
which need a mutable access to the state.
The solution I chose was to introduce a `QueryStateView` which is a
temporary view into the `QueryState` which enables a "split-borrows"
kind of approach. It is described in detail in this blog post:
https://smallcultfollowing.com/babysteps/blog/2018/11/01/after-nll-interprocedural-conflicts/
# Test
The unit tests pass.
Benchmark results:
```
❯ critcmp main pr
group main pr
----- ---- --
iter_fragmented/base 1.00 342.2±25.45ns ? ?/sec 1.02 347.5±16.24ns ? ?/sec
iter_fragmented/foreach 1.04 165.4±11.29ns ? ?/sec 1.00 159.5±4.27ns ? ?/sec
iter_fragmented/foreach_wide 1.03 3.3±0.04µs ? ?/sec 1.00 3.2±0.06µs ? ?/sec
iter_fragmented/wide 1.03 3.1±0.06µs ? ?/sec 1.00 3.0±0.08µs ? ?/sec
iter_fragmented_sparse/base 1.00 6.5±0.14ns ? ?/sec 1.02 6.6±0.08ns ? ?/sec
iter_fragmented_sparse/foreach 1.00 6.3±0.08ns ? ?/sec 1.04 6.6±0.08ns ? ?/sec
iter_fragmented_sparse/foreach_wide 1.00 43.8±0.15ns ? ?/sec 1.02 44.6±0.53ns ? ?/sec
iter_fragmented_sparse/wide 1.00 29.8±0.44ns ? ?/sec 1.00 29.8±0.26ns ? ?/sec
iter_simple/base 1.00 8.2±0.10µs ? ?/sec 1.00 8.2±0.09µs ? ?/sec
iter_simple/foreach 1.00 3.8±0.02µs ? ?/sec 1.02 3.9±0.03µs ? ?/sec
iter_simple/foreach_sparse_set 1.00 19.0±0.26µs ? ?/sec 1.01 19.3±0.16µs ? ?/sec
iter_simple/foreach_wide 1.00 17.8±0.24µs ? ?/sec 1.00 17.9±0.31µs ? ?/sec
iter_simple/foreach_wide_sparse_set 1.06 95.6±6.23µs ? ?/sec 1.00 90.6±0.59µs ? ?/sec
iter_simple/sparse_set 1.00 19.3±1.63µs ? ?/sec 1.01 19.5±0.29µs ? ?/sec
iter_simple/system 1.00 8.1±0.10µs ? ?/sec 1.00 8.1±0.09µs ? ?/sec
iter_simple/wide 1.05 37.7±2.53µs ? ?/sec 1.00 35.8±0.57µs ? ?/sec
iter_simple/wide_sparse_set 1.00 95.7±1.62µs ? ?/sec 1.00 95.9±0.76µs ? ?/sec
par_iter_simple/with_0_fragment 1.04 35.0±2.51µs ? ?/sec 1.00 33.7±0.49µs ? ?/sec
par_iter_simple/with_1000_fragment 1.00 50.4±2.52µs ? ?/sec 1.01 51.0±3.84µs ? ?/sec
par_iter_simple/with_100_fragment 1.02 40.3±2.23µs ? ?/sec 1.00 39.5±1.32µs ? ?/sec
par_iter_simple/with_10_fragment 1.14 38.8±7.79µs ? ?/sec 1.00 34.0±0.78µs ? ?/sec
```
# Objective
- Fix#14629
## Solution
- Make `QueryState::transmute`, `QueryState::transmute_filtered`,
`QueryState::join` and `QueryState::join_filtered` take a `impl
Into<UnsafeWorldCell>` instead of a `&Components` and validate their
`WorldId`
## Migration Guide
- `QueryState::transmute`, `QueryState::transmute_filtered`,
`QueryState::join` and `QueryState::join_filtered` now take a `impl
Into<UnsafeWorldCell>` instead of a `&Components`
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- currently, bevy employs sparse iteration if any of the target
components in the query are stored in a sparse set. it may lead to
increased cache misses in some cases, potentially impacting performance.
- partial fixes#12381
## Solution
- use dense iteration when an archetype and its table have the same
entity count.
- to avoid introducing complicate unsafe noise, this pr only implement
for `for_each ` style iteration.
- added a benchmark to test performance for hybrid iteration.
## Performance
nearly 2x win in specific scenarios, and no performance degradation in
other test cases.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Christian Hughes <9044780+ItsDoot@users.noreply.github.com>
# Objective
- Make it possible to know *what* changed your component or resource.
- Common need when debugging, when you want to know the last code
location that mutated a value in the ECS.
- This feature would be very useful for the editor alongside system
stepping.
## Solution
- Adds the caller location to column data.
- Mutations now `track_caller` all the way up to the public API.
- Commands that invoke these functions immediately call
`Location::caller`, and pass this into the functions, instead of the
functions themselves attempting to get the caller. This would not work
for commands which are deferred, as the commands are executed by the
scheduler, not the user's code.
## Testing
- The `component_change_detection` example now shows where the component
was mutated:
```
2024-07-28T06:57:48.946022Z INFO component_change_detection: Entity { index: 1, generation: 1 }: New value: MyComponent(0.0)
2024-07-28T06:57:49.004371Z INFO component_change_detection: Entity { index: 1, generation: 1 }: New value: MyComponent(1.0)
2024-07-28T06:57:49.012738Z WARN component_change_detection: Change detected!
-> value: Ref(MyComponent(1.0))
-> added: false
-> changed: true
-> changed by: examples/ecs/component_change_detection.rs:36:23
```
- It's also possible to inspect change location from a debugger:
<img width="608" alt="image"
src="https://github.com/user-attachments/assets/c90ecc7a-0462-457a-80ae-42e7f5d346b4">
---
## Changelog
- Added source locations to ECS change detection behind the
`track_change_detection` flag.
## Migration Guide
- Added `changed_by` field to many internal ECS functions used with
change detection when the `track_change_detection` feature flag is
enabled. Use Location::caller() to provide the source of the function
call.
---------
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
Optimize the cloning process for Access-related structs in the ECS
system, specifically targeting the `clone_from` method.
Previously, profiling showed that 1% of CPU time was spent in
`FixedBitSet`'s `drop_in_place`, due to the default `clone_from`
implementation:
```rust
fn clone_from(&mut self, source: &Self) {
*self = source.clone()
}
```
This implementation causes unnecessary allocations and deallocations.
However, [FixedBitSet provides a more optimized clone_from
method](https://github.com/petgraph/fixedbitset/blob/master/src/lib.rs#L1445-L1465)
that avoids these allocations and utilizes SIMD instructions for better
performance.
This PR aims to leverage the optimized clone_from method of FixedBitSet
and implement custom clone_from methods for Access-related structs to
take full advantage of this optimization. By doing so, we expect to
significantly reduce CPU time spent on cloning operations and improve
overall system performance.
## Solution
- Implemented custom `clone` and `clone_from` methods for `Access`,
`FilteredAccess`, `AccessFilters`, and `FilteredAccessSet` structs.
- Removed `#[derive(Clone)]` and manually implemented `Clone` trait to
use optimized `clone_from` method from `FixedBitSet`.
- Added unit tests for cloning and `clone_from` methods to ensure
correctness.
## Testing
- Conducted performance testing comparing the original and optimized
versions.
- Measured CPU time consumption for the `clone_from` method:
- Original version: 1.34% of CPU time
- Optimized version: 0.338% of CPU time
- Compared FPS before and after the changes (results may vary depending
on the run):
Before optimization:
```
2024-07-28T12:49:11.864019Z INFO bevy diagnostic: fps : 213.489463 (avg 214.502488)
2024-07-28T12:49:11.864037Z INFO bevy diagnostic: frame_time : 4.704746ms (avg 4.682251ms)
2024-07-28T12:49:11.864042Z INFO bevy diagnostic: frame_count: 7947.000000 (avg 7887.500000)
```
After optimization:
```
2024-07-28T12:29:42.705738Z INFO bevy diagnostic: fps : 220.273721 (avg 220.912227)
2024-07-28T12:29:42.705762Z INFO bevy diagnostic: frame_time : 4.559127ms (avg 4.544905ms)
2024-07-28T12:29:42.705769Z INFO bevy diagnostic: frame_count: 7596.000000 (avg 7536.500000)
```
---
Reviewers can test these changes by running `cargo run --release
--example ssr`
# Objective
- The implementation of `update_component_access` for `AnyOf`/`Or` is
kinda weird due to special casing the first filter, let's simplify it;
- Fundamentally we want to fold/reduce the various filters using an OR
operation, however in order to do a proper fold we need a neutral
element for the initial accumulator, which for OR is FALSE. However we
didn't have a way to create a `FilteredAccess` value corresponding to
FALSE and thus the only option was reducing, which special cases the
first element as being the initial accumulator.
This is an alternative to https://github.com/bevyengine/bevy/pull/14026
## Solution
- Introduce `FilteredAccess::empty` as a way to create a
`FilteredAccess` corresponding to the logical proposition FALSE;
- Use it as the initial accumulator for the above operations, allowing
to handle all the elements to fold in the same way.
---
## Migration Guide
- The behaviour of `AnyOf<()>` and `Or<()>` has been changed to match no
archetypes rather than all archetypes to naturally match the
corresponding logical operation. Consider replacing them with `()`
instead.
# Objective
We currently cannot iterate from the back of `QueryManyIter`.
## Solution
Implement `DoubleEndedIterator` for `QueryManyIter` and add a
`fetch_next_back` method. These impls are bounded on the underlying
`entity_iter` implementing `DoubleEndedIterator`.
## Changelog
Added `DoubleEndedIterator` implementation for `QueryManyIter`.
Added the `fetch_next_back` method to `QueryManyIter`.
# Objective
The bounds for query iterators are quite intimidating.
## Solution
With Rust 1.79, [associated type
bounds](https://github.com/rust-lang/rust/pull/122055/) stabilized,
which can simplify the bounds slightly.
# Objective
- Fixes a correctness error introduced in
https://github.com/bevyengine/bevy/pull/14013 ...
## Solution
I've been playing around a lot of with the access code and I realized
that I introduced a soundness error when trying to simplify the code.
When we have a `Or<(With<A>, With<B>)>` filter, we cannot call
```
let mut intermediate = FilteredAccess::default();
$name::update_component_access($name, &mut intermediate);
_new_access.append_or(&intermediate);
```
because that's just equivalent to adding the new components as `Or`
clauses.
For example if the existing `filter_sets` was `vec![With<C>]`, we would
then get `vec![With<C>, With<A>, With<B>]` which translates to `A or B
or C`.
Instead what we want is `(A and B) or (A and C)`, so we need to have
each new OR clause compose with the existing access like so:
```
let mut intermediate = _access.clone();
// if we previously had a With<C> in the filter_set, this will become `With<C> AND With<A>`
$name::update_component_access($name, &mut intermediate);
_new_access.append_or(&intermediate);
```
## Testing
- Added a unit test that is broken in main, but passes in this PR
# Objective
Fixes https://github.com/bevyengine/bevy/issues/13993
PR inspired by https://github.com/bevyengine/bevy/pull/14007 to
accomplish the same thing, but maybe in a clearer fashion.
@Gingeh feel free to take my changes and add them to your PR, I don't
want to steal any credit
---------
Co-authored-by: Gingeh <39150378+Gingeh@users.noreply.github.com>
Co-authored-by: Bob Gardner <rgardner@inworld.ai>
Co-authored-by: Martín Maita <47983254+mnmaita@users.noreply.github.com>
# Objective
- Provide an expressive way to register dynamic behavior in response to
ECS changes that is consistent with existing bevy types and traits as to
provide a smooth user experience.
- Provide a mechanism for immediate changes in response to events during
command application in order to facilitate improved query caching on the
path to relations.
## Solution
- A new fundamental ECS construct, the `Observer`; inspired by flec's
observers but adapted to better fit bevy's access patterns and rust's
type system.
---
## Examples
There are 3 main ways to register observers. The first is a "component
observer" that looks like this:
```rust
world.observe(|trigger: Trigger<OnAdd, Transform>, query: Query<&Transform>| {
let transform = query.get(trigger.entity()).unwrap();
});
```
The above code will spawn a new entity representing the observer that
will run it's callback whenever the `Transform` component is added to an
entity. This is a system-like function that supports dependency
injection for all the standard bevy types: `Query`, `Res`, `Commands`
etc. It also has a `Trigger` parameter that provides information about
the trigger such as the target entity, and the event being triggered.
Importantly these systems run during command application which is key
for their future use to keep ECS internals up to date. There are similar
events for `OnInsert` and `OnRemove`, and this will be expanded with
things such as `ArchetypeCreated`, `TableEmpty` etc. in follow up PRs.
Another way to register an observer is an "entity observer" that looks
like this:
```rust
world.entity_mut(entity).observe(|trigger: Trigger<Resize>| {
// ...
});
```
Entity observers run whenever an event of their type is triggered
targeting that specific entity. This type of observer will de-spawn
itself if the entity (or entities) it is observing is ever de-spawned so
as to not leave dangling observers.
Entity observers can also be spawned from deferred contexts such as
other observers, systems, or hooks using commands:
```rust
commands.entity(entity).observe(|trigger: Trigger<Resize>| {
// ...
});
```
Observers are not limited to in built event types, they can be used with
any type that implements `Event` (which has been extended to implement
Component). This means events can also carry data:
```rust
#[derive(Event)]
struct Resize { x: u32, y: u32 }
commands.entity(entity).observe(|trigger: Trigger<Resize>, query: Query<&mut Size>| {
let event = trigger.event();
// ...
});
// Will trigger the observer when commands are applied.
commands.trigger_targets(Resize { x: 10, y: 10 }, entity);
```
You can also trigger events that target more than one entity at a time:
```rust
commands.trigger_targets(Resize { x: 10, y: 10 }, [e1, e2]);
```
Additionally, Observers don't _need_ entity targets:
```rust
app.observe(|trigger: Trigger<Quit>| {
})
commands.trigger(Quit);
```
In these cases, `trigger.entity()` will be a placeholder.
Observers are actually just normal entities with an `ObserverState` and
`Observer` component! The `observe()` functions above are just shorthand
for:
```rust
world.spawn(Observer::new(|trigger: Trigger<Resize>| {});
```
This will spawn the `Observer` system and use an `on_add` hook to add
the `ObserverState` component.
Dynamic components and trigger types are also fully supported allowing
for runtime defined trigger types.
## Possible Follow-ups
1. Deprecate `RemovedComponents`, observers should fulfill all use cases
while being more flexible and performant.
2. Queries as entities: Swap queries to entities and begin using
observers listening to archetype creation triggers to keep their caches
in sync, this allows unification of `ObserverState` and `QueryState` as
well as unlocking several API improvements for `Query` and the
management of `QueryState`.
3. Trigger bubbling: For some UI use cases in particular users are
likely to want some form of bubbling for entity observers, this is
trivial to implement naively but ideally this includes an acceleration
structure to cache hierarchy traversals.
4. All kinds of other in-built trigger types.
5. Optimization; in order to not bloat the complexity of the PR I have
kept the implementation straightforward, there are several areas where
performance can be improved. The focus for this PR is to get the
behavior implemented and not incur a performance cost for users who
don't use observers.
I am leaving each of these to follow up PR's in order to keep each of
them reviewable as this already includes significant changes.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: MiniaczQ <xnetroidpl@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
…izer (#13442)"
This reverts commit 5cfb063d4a.
- This PR broke bevy-trait-query, which needs to be able to write a
resource in init_state. See #13798 for more details.
- Note this doesn't fix everything as transmutes for bevy-trait-query
will still be broken,. But the current usage in that crate is UB, so we
need to find another solution.
# Objective
In #13343, `WorldQuery::get_state` was constrained from `&World` as the
argument to `&Components`, but `WorldQuery::init_state` hasn't yet been
changed from `&mut World` to match.
Fixes#13358
## Solution
Create a wrapper around `&mut Components` and `&mut Storages` that can
be obtained from `&mut World` with a `component_initializer` method.
This new `ComponentInitializer` re-exposes the API on `&mut Components`
minus the `&mut Storages` parameter where it was present. For the
`&Components` API, it simply derefs to its `components` field.
## Changelog
### Added
The `World::component_initializer` method.
The `ComponentInitializer` struct that re-exposes `Components` API.
### Changed
`WorldQuery::init_state` now takes `&mut ComponentInitializer` instead
of `&mut World`.
## Migration Guide
Instead of passing `&mut World` to `WorldQuery::init_state` directly,
pass in a mutable reference to the struct returned from
`World::component_initializer`.
# Objective
The current query iterators cannot be used in positions with a `Debug`
bound.
F.e. when they are packaged in `Result` in the error position, `expect`
cannot be called on them.
Required for `QueryManyIter::entities_all_unique` in #13477.
## Solution
Add simple `Debug` impls that print the query iterator names.
## Changelog
`QueryIter`, `QueryManyIter`, `QueryCombinationIter`, and
`QuerySortedIter` now implement `Debug`.
# Objective
Currently, a query iterator can be collected into a `Vec` and sorted,
but this can be quite unwieldy, especially when many `Component`s are
involved. The `itertools` crate helps somewhat, but the need to write a
closure over all of `QueryData`
can sometimes hurt ergonomics, anywhere from slightly to strongly. A key
extraction function only partially helps, as `sort_by_key` does not
allow returning non-`Copy` data. `sort_by` does not suffer from the
`Copy` restriction, but now the user has to write out a `cmp` function
over two `QueryData::Item`s when it could have just been handled by the
`Ord` impl for the key.
`sort` requires the entire `Iterator` Item to be `Ord`, which is rarely
usable without manual helper functionality. If the user wants to hide
away unused components with a `..` range, they need to track item tuple
order across their function. Mutable `QueryData` can also introduce
further complexity.
Additionally, sometimes users solely include `Component`s /`Entity` to
guarantee iteration order.
For a user to write a function to abstract away repeated sorts over
various `QueryData` types they use would require reaching for the
`all_tuples!` macro, and continue tracking tuple order afterwards.
Fixes https://github.com/bevyengine/bevy/issues/1470.
## Solution
Custom sort methods on `QueryIter`, which take a query lens as a generic
argument, like `transmute_lens` in `Query`.
This allows users to choose what part of their queries they pass to
their sort function calls, serving as a kind of "key extraction
function" before the sort call. F.e. allowing users to implement `Ord`
for a Component, then call `query.iter().sort::<OrdComponent>()`
This works independent of mutability in `QueryData`, `QueryData` tuple
order, or the underlying `iter/iter_mut` call.
Non-`Copy` components could also be used this way, an internal
`Arc<usize>` being an example.
If `Ord` impls on components do not suffice, other sort methods can be
used. Notably useful when combined with `EntityRef` or `EntityMut`.
Another boon from using underlying `transmute` functionality, is that
with the [allowed
transmutes](http://dev-docs.bevyengine.org/bevy/ecs/prelude/struct.Query.html#allowed-transmutes),
it is possible to sort a `Query` with `Entity` even if it wasn't
included in the original `Query`.
The additional generic parameter on the methods other than `sort` and
`sort_unstable` currently cannot be removed due to Rust limitations,
however their types can be inferred.
The new methods do not conflict with the `itertools` sort methods, as
those use the "sorted" prefix.
This is implemented barely touching existing code. That change to
existing code being that `QueryIter` now holds on to the reference to
`UnsafeWorldCell` that is used to initialize it.
A lens query is constructed with `Entity` attached at the end, sorted,
and turned into an iterator. The iterator maps away the lens query,
leaving only an iterator of `Entity`, which is used by `QuerySortedIter`
to retrieve the actual items.
`QuerySortedIter` resembles a combination of `QueryManyIter` and
`QueryIter`, but it uses an entity list that is guaranteed to contain
unique entities, and implements `ExactSizeIterator`,
`DoubleEndedIterator`, `FusedIterator` regardless of mutability or
filter kind (archetypal/non-archetypal).
The sort methods are not allowed to be called after `next`, and will
panic otherwise. This is checked using `QueryIterationCursor` state,
which is unique on initialization. Empty queries are an exception to
this, as they do not return any item in the first place.
That is because tracking how many iterations have already passed would
require regressing either normal query iteration a slight bit, or sorted
iteration by a lot. Besides, that would not be the intended use of these
methods.
## Testing
To ensure that `next` being called before `sort` results in a panic, I
added some tests. I also test that empty `QueryIter`s do not exhibit
this restriction.
The query sorts test checks for equivalence to the underlying sorts.
This change requires that `Query<(Entity, Entity)>` remains legal, if
that is not already guaranteed, which is also ensured by the
aforementioned test.
## Next Steps
Implement the set of sort methods for `QueryManyIter` as well.
- This will mostly work the same, other than needing to return a new
`QuerySortedManyIter` to account for iteration
over lists of entities that are not guaranteed to be unique. This new
query iterator will need a bit of internal restructuring
to allow for double-ended mutable iteration, while not regressing
read-only iteration.
The implementations for each pair of
- `sort`, `sort_unstable`,
- `sort_by`, sort_unstable_by,
- `sort_by_key,` `sort_by_cached_key`
are the same aside from the panic message and the sort call, so they
could be merged with an inner function.
That would require the use of higher-ranked trait bounds on
`WorldQuery::Item<'1>`, and is unclear to me whether it is currently
doable.
Iteration in QuerySortedIter might have space for improvement.
When sorting by `Entity`, an `(Entity, Entity)` lens `QueryData` is
constructed, is that worth remedying?
When table sorts are implemented, a fast path could be introduced to
these sort methods.
## Future Possibilities
Implementing `Ord` for EntityLocation might be useful.
Some papercuts in ergonomics can be improved by future Rust features:
- The additional generic parameter aside from the query lens can be
removed once this feature is stable:
`Fn -> impl Trait` (`impl Trait` in `Fn` trait return position)
- With type parameter defaults, the query lens generic can be defaulted
to `QueryData::Item`, allowing the sort methods
to look and behave like `slice::sort` when no query lens is specified.
- With TAIT, the iterator generic on `QuerySortedIter` and thus the huge
visible `impl Iterator` type in the sort function
signatures can be removed.
- With specialization, the bound on `L` could be relaxed to `QueryData`
when the underlying iterator is mutable.
## Changelog
Added `sort`, `sort_unstable`, `sort_by`, `sort_unstable_by`,
`sort_by_key`, `sort_by_cached_key` to `QueryIter`.
# Objective
- Fixes#12377
## Solution
Added simple `#[diagnostic::on_unimplemented(...)]` attributes to some
critical public traits providing a more approachable initial error
message. Where appropriate, a `note` is added indicating that a `derive`
macro is available.
## Examples
<details>
<summary>Examples hidden for brevity</summary>
Below is a collection of examples showing the new error messages
produced by this change. In general, messages will start with a more
Bevy-centric error message (e.g., _`MyComponent` is not a `Component`_),
and a note directing the user to an available derive macro where
appropriate.
### Missing `#[derive(Resource)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct MyResource;
fn main() {
App::new()
.insert_resource(MyResource)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `MyResource` is not a `Resource`
--> examples/app/empty.rs:7:26
|
7 | .insert_resource(MyResource)
| --------------- ^^^^^^^^^^ invalid `Resource`
| |
| required by a bound introduced by this call
|
= help: the trait `Resource` is not implemented for `MyResource`
= note: consider annotating `MyResource` with `#[derive(Resource)]`
= help: the following other types implement trait `Resource`:
AccessibilityRequested
ManageAccessibilityUpdates
bevy::bevy_a11y::Focus
DiagnosticsStore
FrameCount
bevy::prelude::State<S>
SystemInfo
bevy::prelude::Axis<T>
and 141 others
note: required by a bound in `bevy::prelude::App::insert_resource`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:419:31
|
419 | pub fn insert_resource<R: Resource>(&mut self, resource: R) -> &mut Self {
| ^^^^^^^^ required by this bound in `App::insert_resource`
```
</details>
### Putting A `QueryData` in a `QueryFilter` Slot
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Component)]
struct A;
#[derive(Component)]
struct B;
fn my_system(_query: Query<&A, &B>) {}
fn main() {
App::new()
.add_systems(Update, my_system)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `&B` is not a valid `Query` filter
--> examples/app/empty.rs:9:22
|
9 | fn my_system(_query: Query<&A, &B>) {}
| ^^^^^^^^^^^^^ invalid `Query` filter
|
= help: the trait `QueryFilter` is not implemented for `&B`
= help: the following other types implement trait `QueryFilter`:
With<T>
Without<T>
bevy::prelude::Or<()>
bevy::prelude::Or<(F0,)>
bevy::prelude::Or<(F0, F1)>
bevy::prelude::Or<(F0, F1, F2)>
bevy::prelude::Or<(F0, F1, F2, F3)>
bevy::prelude::Or<(F0, F1, F2, F3, F4)>
and 28 others
note: required by a bound in `bevy::prelude::Query`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\query.rs:349:51
|
349 | pub struct Query<'world, 'state, D: QueryData, F: QueryFilter = ()> {
| ^^^^^^^^^^^ required by this bound in `Query`
```
</details>
### Missing `#[derive(Component)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct A;
fn my_system(mut commands: Commands) {
commands.spawn(A);
}
fn main() {
App::new()
.add_systems(Startup, my_system)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `A` is not a `Bundle`
--> examples/app/empty.rs:6:20
|
6 | commands.spawn(A);
| ----- ^ invalid `Bundle`
| |
| required by a bound introduced by this call
|
= help: the trait `bevy::prelude::Component` is not implemented for `A`, which is required by `A: Bundle`
= note: consider annotating `A` with `#[derive(Component)]` or `#[derive(Bundle)]`
= help: the following other types implement trait `Bundle`:
TransformBundle
SceneBundle
DynamicSceneBundle
AudioSourceBundle<Source>
SpriteBundle
SpriteSheetBundle
Text2dBundle
MaterialMesh2dBundle<M>
and 34 others
= note: required for `A` to implement `Bundle`
note: required by a bound in `bevy::prelude::Commands::<'w, 's>::spawn`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\commands\mod.rs:243:21
|
243 | pub fn spawn<T: Bundle>(&mut self, bundle: T) -> EntityCommands {
| ^^^^^^ required by this bound in `Commands::<'w, 's>::spawn`
```
</details>
### Missing `#[derive(Asset)]`
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
struct A;
fn main() {
App::new()
.init_asset::<A>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `A` is not an `Asset`
--> examples/app/empty.rs:7:23
|
7 | .init_asset::<A>()
| ---------- ^ invalid `Asset`
| |
| required by a bound introduced by this call
|
= help: the trait `Asset` is not implemented for `A`
= note: consider annotating `A` with `#[derive(Asset)]`
= help: the following other types implement trait `Asset`:
Font
AnimationGraph
DynamicScene
Scene
AudioSource
Pitch
bevy::bevy_gltf::Gltf
GltfNode
and 17 others
note: required by a bound in `init_asset`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_asset\src\lib.rs:307:22
|
307 | fn init_asset<A: Asset>(&mut self) -> &mut Self;
| ^^^^^ required by this bound in `AssetApp::init_asset`
```
</details>
### Mismatched Input and Output on System Piping
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
fn producer() -> u32 {
123
}
fn consumer(_: In<u16>) {}
fn main() {
App::new()
.add_systems(Update, producer.pipe(consumer))
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `fn(bevy::prelude::In<u16>) {consumer}` is not a valid system with input `u32` and output `_`
--> examples/app/empty.rs:11:44
|
11 | .add_systems(Update, producer.pipe(consumer))
| ---- ^^^^^^^^ invalid system
| |
| required by a bound introduced by this call
|
= help: the trait `bevy::prelude::IntoSystem<u32, _, _>` is not implemented for fn item `fn(bevy::prelude::In<u16>) {consumer}`
= note: expecting a system which consumes `u32` and produces `_`
note: required by a bound in `pipe`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_ecs\src\system\mod.rs:168:12
|
166 | fn pipe<B, Final, MarkerB>(self, system: B) -> PipeSystem<Self::System, B::System>
| ---- required by a bound in this associated function
167 | where
168 | B: IntoSystem<Out, Final, MarkerB>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `IntoSystem::pipe`
```
</details>
### Missing Reflection
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Component)]
struct MyComponent;
fn main() {
App::new()
.register_type::<MyComponent>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `MyComponent` does not provide type registration information
--> examples/app/empty.rs:8:26
|
8 | .register_type::<MyComponent>()
| ------------- ^^^^^^^^^^^ the trait `GetTypeRegistration` is not implemented for `MyComponent`
| |
| required by a bound introduced by this call
|
= note: consider annotating `MyComponent` with `#[derive(Reflect)]`
= help: the following other types implement trait `GetTypeRegistration`:
bool
char
isize
i8
i16
i32
i64
i128
and 443 others
note: required by a bound in `bevy::prelude::App::register_type`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:619:29
|
619 | pub fn register_type<T: bevy_reflect::GetTypeRegistration>(&mut self) -> &mut Self {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::register_type`
```
</details>
### Missing `#[derive(States)]` Implementation
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, Hash)]
enum AppState {
#[default]
Menu,
InGame {
paused: bool,
turbo: bool,
},
}
fn main() {
App::new()
.init_state::<AppState>()
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: the trait bound `AppState: FreelyMutableState` is not satisfied
--> examples/app/empty.rs:15:23
|
15 | .init_state::<AppState>()
| ---------- ^^^^^^^^ the trait `FreelyMutableState` is not implemented for `AppState`
| |
| required by a bound introduced by this call
|
= note: consider annotating `AppState` with `#[derive(States)]`
note: required by a bound in `bevy::prelude::App::init_state`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:282:26
|
282 | pub fn init_state<S: FreelyMutableState + FromWorld>(&mut self) -> &mut Self {
| ^^^^^^^^^^^^^^^^^^ required by this bound in `App::init_state`
```
</details>
### Adding a `System` with Unhandled Output
<details>
<summary>Example Code</summary>
```rust
use bevy::prelude::*;
fn producer() -> u32 {
123
}
fn main() {
App::new()
.add_systems(Update, consumer)
.run();
}
```
</details>
<details>
<summary>Error Generated</summary>
```error
error[E0277]: `fn() -> u32 {producer}` does not describe a valid system configuration
--> examples/app/empty.rs:9:30
|
9 | .add_systems(Update, producer)
| ----------- ^^^^^^^^ invalid system configuration
| |
| required by a bound introduced by this call
|
= help: the trait `IntoSystem<(), (), _>` is not implemented for fn item `fn() -> u32 {producer}`, which is required by `fn() -> u32 {producer}: IntoSystemConfigs<_>`
= help: the following other types implement trait `IntoSystemConfigs<Marker>`:
<Box<(dyn bevy::prelude::System<In = (), Out = ()> + 'static)> as IntoSystemConfigs<()>>
<NodeConfigs<Box<(dyn bevy::prelude::System<In = (), Out = ()> + 'static)>> as IntoSystemConfigs<()>>
<(S0,) as IntoSystemConfigs<(SystemConfigTupleMarker, P0)>>
<(S0, S1) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1)>>
<(S0, S1, S2) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2)>>
<(S0, S1, S2, S3) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3)>>
<(S0, S1, S2, S3, S4) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3, P4)>>
<(S0, S1, S2, S3, S4, S5) as IntoSystemConfigs<(SystemConfigTupleMarker, P0, P1, P2, P3, P4, P5)>>
and 14 others
= note: required for `fn() -> u32 {producer}` to implement `IntoSystemConfigs<_>`
note: required by a bound in `bevy::prelude::App::add_systems`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:342:23
|
339 | pub fn add_systems<M>(
| ----------- required by a bound in this associated function
...
342 | systems: impl IntoSystemConfigs<M>,
| ^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::add_systems`
```
</details>
</details>
## Testing
CI passed locally.
## Migration Guide
Upgrade to version 1.78 (or higher) of Rust.
## Future Work
- Currently, hints are not supported in this diagnostic. Ideally,
suggestions like _"consider using ..."_ would be in a hint rather than a
note, but that is the best option for now.
- System chaining and other `all_tuples!(...)`-based traits have bad
error messages due to the slightly different error message format.
---------
Co-authored-by: Jamie Ridding <Themayu@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
# Objective
Provides a `WorldQuery` implementation on `Mut<T>` that forwards to the
implementation on `&mut T`, and give users a way to opt-in to change
detection in auto-generated `QueryData::ReadOnly` types.
Fixes#13329.
## Solution
I implemented `WorldQuery` on `Mut<'w, T>` as a forwarding
implementation to `&mut T`, setting the `QueryData::ReadOnly` associated
type to `Ref<'w, T>`. This provides users the ability to explicitly
opt-in to change detection in the read-only forms of queries.
## Testing
A documentation test was added to `Mut` showcasing the new
functionality.
---
## Changelog
### Added
- Added an implementation of `WorldQuery` and `QueryData` on
`bevy_ecs::change_detection::Mut`.
# Objective
Passing `&World` in the `WorldQuery::get_state` method is unnecessary,
as all implementations of this method in the engine either only access
`Components` in `&World`, or do nothing with it.
It can introduce UB by necessitating the creation of a `&World` from a
`UnsafeWorldCell`.
This currently happens in `Query::transmute_lens`, which obtains a
`&World` from the internal `UnsafeWorldCell` solely to pass to
`get_state`. `Query::join` suffers from the same issue.
Other cases of UB come from allowing implementors of `WorldQuery` to
freely access `&World`, like in the `bevy-trait-query` crate, where a
[reference to a resource is
obtained](0c0e7dd646/src/lib.rs (L445))
inside of
[`get_state`](0c0e7dd646/src/one.rs (L245)),
potentially aliasing with a `ResMut` parameter in the same system.
`WorldQuery::init_state` currently requires `&mut World`, which doesn't
suffer from these issues.
But that too can be changed to receive a wrapper around `&mut
Components` and `&mut Storages` for consistency in a follow-up PR.
## Solution
Replace the `&World` parameter in `get_state` with `&Components`.
## Changelog
`WorldQuery::get_state` now takes `&Components` instead of `&World`.
The `transmute`, `transmute_filtered`, `join` and `join_filtered`
methods on `QueryState` now similarly take `&Components` instead of
`&World`.
## Migration Guide
Users of `WorldQuery::get_state` or `transmute`, `transmute_filtered`,
`join` and `join_filtered` methods on `QueryState` now need to pass
`&Components` instead of `&World`.
`&Components` can be trivially obtained from either `components` method
on `&World` or `UnsafeWorldCell`.
For implementors of `WorldQuery::get_state` that were accessing more
than the `Components` inside `&World` and its methods, this is no longer
allowed.
# Objective
Fixes#12966
## Solution
Renaming multi_threaded feature to match snake case
## Migration Guide
Bevy feature multi-threaded should be refered to multi_threaded from now
on.
# Objective
- bevy usually use `Parallel::scope` to collect items from `par_iter`,
but `scope` will be called with every satifified items. it will cause a
lot of unnecessary lookup.
## Solution
- similar to Rayon ,we introduce `for_each_init` for `par_iter` which
only be invoked when spawn a task for a group of items.
---
## Changelog
- added `for_each_init`
## Performance
`check_visibility ` in `many_foxes `
~40% performance gain in `check_visibility`.
---------
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
Allow parallel iteration over events, resolve#10766
## Solution
- Add `EventParIter` which works similarly to `QueryParIter`,
implementing a `for_each{_with_id}` operator.
I chose to not mirror `EventIteratorWithId` and instead implement both
operations on a single struct.
- Reuse `BatchingStrategy` from `QueryParIter`
## Changelog
- `EventReader` now supports parallel event iteration using
`par_read().for_each(|event| ...)`.
---------
Co-authored-by: James Liu <contact@jamessliu.com>
Co-authored-by: Pablo Reinhardt <126117294+pablo-lua@users.noreply.github.com>
# Objective
Fix#2128. Both `Query::new_archetype` and `SystemParam::new_archetype`
do not check if the `Archetype` comes from the same World the state is
initialized from. This could result in unsoundness via invalid accesses
if called incorrectly.
## Solution
Make them `unsafe` functions and lift the invariant to the caller. This
also caught one instance of us not validating the World in
`SystemState::update_archetypes_unsafe_world_cell`'s implementation.
---
## Changelog
Changed: `QueryState::new_archetype` is now an unsafe function.
Changed: `SystemParam::new_archetype` is now an unsafe function.
## Migration Guide
`QueryState::new_archetype` and `SystemParam::new_archetype` are now an
unsafe functions that must be sure that the provided `Archetype` is from
the same `World` that the state was initialized from. Callers may need
to add additional assertions or propagate the safety invariant upwards
through the callstack to ensure safety.
# Objective
- I daily drive nightly Rust when developing Bevy, so I notice when new
warnings are raised by `cargo check` and Clippy.
- `cargo +nightly clippy` raises a few of these new warnings.
## Solution
- Fix most warnings from `cargo +nightly clippy`
- I skipped the docs-related warnings because some were covered by
#12692.
- Use `Clone::clone_from` in applicable scenarios, which can sometimes
avoid an extra allocation.
- Implement `Default` for structs that have a `pub const fn new() ->
Self` method.
- Fix an occurrence where generic constraints were defined in both `<C:
Trait>` and `where C: Trait`.
- Removed generic constraints that were implied by the `Bundle` trait.
---
## Changelog
- `BatchingStrategy`, `NonGenericTypeCell`, and `GenericTypeCell` now
implement `Default`.
# Objective
- Fix#7303
- bevy would spawn a lot of tasks in parallel iteration when it matchs a
large storage and many small storage ,it significantly increase the
overhead of schedule.
## Solution
- collect small storage into one task
# Objective
- There are several redundant imports in the tests and examples that are
not caught by CI because additional flags need to be passed.
## Solution
- Run `cargo check --workspace --tests` and `cargo check --workspace
--examples`, then fix all warnings.
- Add `test-check` to CI, which will be run in the check-compiles job.
This should catch future warnings for tests. Examples are already
checked, but I'm not yet sure why they weren't caught.
## Discussion
- Should the `--tests` and `--examples` flags be added to CI, so this is
caught in the future?
- If so, #12818 will need to be merged first. It was also a warning
raised by checking the examples, but I chose to split off into a
separate PR.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
Other than the exposed functions for reading matched tables and
archetypes, a `QueryState` does not actually need both internal Vecs for
storing matched archetypes and tables. In practice, it will only use one
of the two depending on if it uses dense or archetypal iteration.
Same vein as #12474. The goal is to reduce the memory overhead of using
queries, which Bevy itself, ecosystem plugins, and end users are already
fairly liberally using.
## Solution
Add `StorageId`, which is a union over `TableId` and `ArchetypeId`, and
store only one of the two at runtime. Read the slice as if it was one ID
depending on whether the query is dense or not.
This follows in the same vein as #5085; however, this one directly
impacts heap memory usage at runtime, while #5085 primarily targeted
transient pointers that might not actually exist at runtime.
---
## Changelog
Changed: `QueryState::matched_tables` now returns an iterator instead of
a reference to a slice.
Changed: `QueryState::matched_archetypes` now returns an iterator
instead of a reference to a slice.
## Migration Guide
`QueryState::matched_tables` and `QueryState::matched_archetypes` does
not return a reference to a slice, but an iterator instead. You may need
to use iterator combinators or collect them into a Vec to use it as a
slice.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Fixes#12752. Fixes#12750. Document the runtime complexity of all of
the `O(1)` operations on the individual APIs.
## Solution
* Mirror `Query::contains` onto `QueryState::contains`
* Make `QueryState::as_nop` pub(crate)
* Make `NopWorldQuery` pub(crate)
* Document all of the O(1) operations on Query and QueryState.
# Objective
Fixes#12392, fixes#12393, and fixes#11387. Implement QueryData for
Archetype and EntityLocation.
## Solution
Add impls for both of the types.
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## Changelog
Added: `&Archetype` now implements `QueryData`
Added: `EntityLocation` now implements `QueryData`
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Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
I'm reading through the ecs query code for the first time, and updating
the docs:
- fixed some typos
- added some docs about things I was confused about (in particular what
the difference between `matches_component_set` and
`update_component_access` was)
