# 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
`Res` and `ResMut` perform redundant lookups of the resource storage,
first to initialize the `ArchetypeComponentId` and then to retrieve it.
## Solution
Use the `archetype_component_id` returned from
`initialize_resource_internal` to avoid an extra lookup and `unwrap()`.
# Objective
The code to create `ReflectComponent` and `ReflectResource` instances
manually constructs a `Mut<dyn Reflect>` by copying everything but
`value`. That can be done more concisely and better respecting
encapsulation by calling the `map_unchanged()` method.
## Solution
Use `map_unchanged` instead of creating a `Mut` manually.
---------
Co-authored-by: radiish <cb.setho@gmail.com>
# Objective
As is, calling
[`DeferredWorld::query`](https://docs.rs/bevy/latest/bevy/ecs/world/struct.DeferredWorld.html#method.query)
requires you to first `reborrow()` the world in order to use it at all.
Simple reproduction:
```rust
fn test<'w>(mut world: DeferredWorld<'w>, mut state: QueryState<(), ()>) {
let query = world.query(&mut state);
// let query = world.reborrow().query(&mut state); // << Required
}
```
Error message:
```
error[E0597]: `world` does not live long enough
|
444 | fn test<'w>(mut world: DeferredWorld<'w>, mut state: QueryState<(), ()>) {
| -- --------- binding `world` declared here
| |
| lifetime `'w` defined here
445 | let query = world.query(&mut state);
| ^^^^^------------------
| |
| borrowed value does not live long enough
| argument requires that `world` is borrowed for `'w`
446 | }
| - `world` dropped here while still borrowed
```
## Solution
Fix the world borrow lifetime on the `query` method, which now correctly
allows the above usage.
# 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
- Implements the [Unique Reflect
RFC](https://github.com/nicopap/rfcs/blob/bevy-reflect-api/rfcs/56-better-reflect.md).
## Solution
- Implements the RFC.
- This implementation differs in some ways from the RFC:
- In the RFC, it was suggested `Reflect: Any` but `PartialReflect:
?Any`. During initial implementation I tried this, but we assume the
`PartialReflect: 'static` in a lot of places and the changes required
crept out of the scope of this PR.
- `PartialReflect::try_into_reflect` originally returned `Option<Box<dyn
Reflect>>` but i changed this to `Result<Box<dyn Reflect>, Box<dyn
PartialReflect>>` since the method takes by value and otherwise there
would be no way to recover the type. `as_full` and `as_full_mut` both
still return `Option<&(mut) dyn Reflect>`.
---
## Changelog
- Added `PartialReflect`.
- `Reflect` is now a subtrait of `PartialReflect`.
- Moved most methods on `Reflect` to the new `PartialReflect`.
- Added `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect}`.
- Added `PartialReflect::{try_as_reflect, try_as_reflect_mut,
try_into_reflect}`.
- Added `<dyn PartialReflect>::{try_downcast_ref, try_downcast_mut,
try_downcast, try_take}` supplementing the methods on `dyn Reflect`.
## Migration Guide
- Most instances of `dyn Reflect` should be changed to `dyn
PartialReflect` which is less restrictive, however trait bounds should
generally stay as `T: Reflect`.
- The new `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect, try_as_reflect, try_as_reflect_mut,
try_into_reflect}` methods as well as `Reflect::{as_reflect,
as_reflect_mut, into_reflect}` will need to be implemented for manual
implementors of `Reflect`.
## Future Work
- This PR is designed to be followed up by another "Unique Reflect Phase
2" that addresses the following points:
- Investigate making serialization revolve around `Reflect` instead of
`PartialReflect`.
- [Remove the `try_*` methods on `dyn PartialReflect` since they are
stop
gaps](https://github.com/bevyengine/bevy/pull/7207#discussion_r1083476050).
- Investigate usages like `ReflectComponent`. In the places they
currently use `PartialReflect`, should they be changed to use `Reflect`?
- Merging this opens the door to lots of reflection features we haven't
been able to implement.
- We could re-add [the `Reflectable`
trait](8e3488c880/crates/bevy_reflect/src/reflect.rs (L337-L342))
and make `FromReflect` a requirement to improve [`FromReflect`
ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is
currently not possible because dynamic types cannot sensibly be
`FromReflect`.
- Since this is an alternative to #5772, #5781 would be made cleaner.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
Enables writing queries like `Query<Entity, With<SystemIdMarker>>` to
filter `Entity`s that are, or are not (with `Without`), `SystemId`s.
## Solution
Simple unit struct `SystemIdMarker` added during
`World::register_boxed_system`; `World::remove_system` already despawns
the entity, removing the marker.
## Testing
No tests, but happy to write some with direction.
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
~~Enables writing queries like `Query<Entity, With<ObserverMarker>>` to
filter `Entity`s that are, or are not (with `Without`), `Observer`s.~~
~~`Observer` version of [similar
PR](https://github.com/bevyengine/bevy/pull/14584) for `SystemId`s.~~
just adding a line to the docs :)
## Solution
~~Simple unit struct `ObserverMarker` added in `Observer`'s `.on_add`
component hook.~~
## Testing
No tests, but happy to write some with direction.
# Objective
Support more kinds of system params in buildable systems, such as a
`ParamSet` or `Vec` containing buildable params or tuples of buildable
params.
## Solution
Replace the `BuildableSystemParam` trait with `SystemParamBuilder` to
make it easier to compose builders. Provide implementations for existing
buildable params, plus tuples, `ParamSet`, and `Vec`.
## Examples
```rust
// ParamSet of tuple:
let system = (ParamSetBuilder((
QueryParamBuilder::new(|builder| { builder.with::<B>(); }),
QueryParamBuilder::new(|builder| { builder.with::<C>(); }),
)),)
.build_state(&mut world)
.build_system(|mut params: ParamSet<(Query<&mut A>, Query<&mut A>)>| {
params.p0().iter().count() + params.p1().iter().count()
});
// ParamSet of Vec:
let system = (ParamSetBuilder(vec![
QueryParamBuilder::new_box(|builder| { builder.with::<B>(); }),
QueryParamBuilder::new_box(|builder| { builder.with::<C>(); }),
]),)
.build_state(&mut world)
.build_system(|mut params: ParamSet<Vec<Query<&mut A>>>| {
let mut count = 0;
params.for_each(|mut query| count += query.iter_mut().count());
count
});
```
## Migration Guide
The API for `SystemBuilder` has changed. Instead of constructing a
builder with a world and then adding params, you first create a tuple of
param builders and then supply the world.
```rust
// Before
let system = SystemBuilder::<()>::new(&mut world)
.local::<u64>()
.builder::<Local<u64>>(|x| *x = 10)
.builder::<Query<&A>>(|builder| { builder.with::<B>(); })
.build(system);
// After
let system = (
ParamBuilder,
LocalBuilder(10),
QueryParamBuilder::new(|builder| { builder.with::<B>(); }),
)
.build_state(&mut world)
.build_system(system);
```
## Possible Future Work
Here are a few possible follow-up changes. I coded them up to prove that
this API can support them, but they aren't necessary for this PR.
* chescock/bevy#1
* chescock/bevy#2
* chescock/bevy#3
# 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
- While developing a debug tool I saw the gap where it was not possible
to get all existing states from a World using reflection.
- This PR allows to iterate over all `States` types that exist in a
world, and modify them in case they implement `FreelyMutableState`.
- Two new methods are available on `App` and `SubApp` as helper to
register the data types:
- `register_state_reflect` and `register_mutable_state_reflect`
## Solution
- Two new data types are added:
- `ReflectState`: Allows to extract the current value of a state from
the World.
- `ReflectFreelyMutableState`: Allows to set the next state in a world,
similar to call `NextState::set`.
- There is no distinction between `States`, `SubStates` and
`ComputedStates`:
- `States` can register both `ReflectState` and
`ReflectFreelyMutableState`.
- `SubStates` can register both `ReflectState` and
`ReflectFreelyMutableState`.
- `ComputedStates` can register only `ReflectState` .
## Testing
- Added tests inside the `bevy_state` crate.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: Jan Hohenheim <jan@hohenheim.ch>
# 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
- Fixes#14337
## Solution
- Add a `cfg_attr` that derives `Refect` for this type.
## Testing
- I am going to make sure the tests pass on this PR before requesting
review, If more testing is necessary let me know some good action steps
to take.
# Objective
#13152 added support for reflecting functions. Now, we need a way to
register those functions such that they may be accessed anywhere within
the ECS.
## Solution
Added a `FunctionRegistry` type similar to `TypeRegistry`.
This allows a function to be registered and retrieved by name.
```rust
fn foo() -> i32 {
123
}
let mut registry = FunctionRegistry::default();
registry.register("my_function", foo);
let function = registry.get_mut("my_function").unwrap();
let value = function.call(ArgList::new()).unwrap().unwrap_owned();
assert_eq!(value.downcast_ref::<i32>(), Some(&123));
```
Additionally, I added an `AppFunctionRegistry` resource which wraps a
`FunctionRegistryArc`. Functions can be registered into this resource
using `App::register_function` or by getting a mutable reference to the
resource itself.
### Limitations
#### `Send + Sync`
In order to get this registry to work across threads, it needs to be
`Send + Sync`. This means that `DynamicFunction` needs to be `Send +
Sync`, which means that its internal function also needs to be `Send +
Sync`.
In most cases, this won't be an issue because standard Rust functions
(the type most likely to be registered) are always `Send + Sync`.
Additionally, closures tend to be `Send + Sync` as well, granted they
don't capture any `!Send` or `!Sync` variables.
This PR adds this `Send + Sync` requirement, but as mentioned above, it
hopefully shouldn't be too big of an issue.
#### Closures
Unfortunately, closures can't be registered yet. This will likely be
explored and added in a followup PR.
### Future Work
Besides addressing the limitations listed above, another thing we could
look into is improving the lookup of registered functions. One aspect is
in the performance of hashing strings. The other is in the developer
experience of having to call `std::any::type_name_of_val` to get the
name of their function (assuming they didn't give it a custom name).
## Testing
You can run the tests locally with:
```
cargo test --package bevy_reflect
```
---
## Changelog
- Added `FunctionRegistry`
- Added `AppFunctionRegistry` (a `Resource` available from `bevy_ecs`)
- Added `FunctionRegistryArc`
- Added `FunctionRegistrationError`
- Added `reflect_functions` feature to `bevy_ecs` and `bevy_app`
- `FunctionInfo` is no longer `Default`
- `DynamicFunction` now requires its wrapped function be `Send + Sync`
## Internal Migration Guide
> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.
`DynamicFunction` (both those created manually and those created with
`IntoFunction`), now require `Send + Sync`. All standard Rust functions
should meet that requirement. Closures, on the other hand, may not if
they capture any `!Send` or `!Sync` variables from its environment.
# 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
B0003 indicates that you tried to act upon a nonexistant entity, but
does not mention where the error occured:
```
2024-07-31T15:46:25.954840Z WARN bevy_ecs::world: error[B0003]: Could not despawn entity Entity { index: 4294967295, generation: 1 } because it doesn't exist in this World. See: https://bevyengine.org/learn/errors/b0003
```
## Solution
Include caller location:
```
2024-07-31T15:46:25.954840Z WARN bevy_ecs::world: error[B0003]: src/main.rs:18:11: Could not despawn entity Entity { index: 4294967295, generation: 1 } because it doesn't exist in this World. See: https://bevyengine.org/learn/errors/b0003
```
Open question: What should the exact message format be?
## Testing
None, this doesn't change any logic.
# Objective
Fixes#12139
## Solution
See this comment on original issue for my proposal:
https://github.com/bevyengine/bevy/issues/12139#issuecomment-2241915791
This PR is an implementation of this proposal.
I modified the implementation of `fmt::Debug` to instead display
`0v0#12345` to ensure entity index, generation, and raw bits are all
present in the output for debug purposes while still keeping log message
concise.
`fmt::Display` remains as is (`0v0`) to offer an even shorter output.
To me, this is the most non-intrusive fix for this issue.
## Testing
Add `fn entity_debug` test
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
- Fixes#14517.
## Solution
- Replace two instances of `map()` with `inspect()`.
- `#[allow(dead_code)]` on `Bundle` derive macro tests.
## Testing
You need to install the beta toolchain, since these lints are not stable
yet.
```bash
cargo +beta clippy --workspace
cargo +beta test --workspace
```
# 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
- Fix issue #2611
## Solution
- Add `--generate-link-to-definition` to all the `rustdoc-args` arrays
in the `Cargo.toml`s (for docs.rs)
- Add `--generate-link-to-definition` to the `RUSTDOCFLAGS` environment
variable in the docs workflow (for dev-docs.bevyengine.org)
- Document all the workspace crates in the docs workflow (needed because
otherwise only the source code of the `bevy` package will be included,
making the argument useless)
- I think this also fixes#3662, since it fixes the bug on
dev-docs.bevyengine.org, while on docs.rs it has been fixed for a while
on their side.
---
## Changelog
- The source code viewer on docs.rs now includes links to the
definitions.
# Objective
- `SystemId`'s `Debug` implementation includes its `entity` field twice.
- This was likely an oversight in #11019, since before that PR the
second field was the `PhantomData` one.
## Solution
- Only include it once
Alternatively, this could be changed to match the struct representation
of `SystemId`, thus instructing the formatter to print a named struct
and including the `PhantomData` field.
# Objective
When using observers you might want to know what the difference is
between `OnAdd` vs `OnReplace` vs `OnInsert` etc. It's not obvious where
to look (`component_hooks.rs`). Added intradoc links for easier
disambiguation.
# Objective
The method `World::increment_change_tick` currently takes `&self` as the
method receiver, which is semantically strange. Even though the interior
mutability is sound, the existence of this method is strange since we
tend to think of `&World` as being a read-only snapshot of a world, not
an aliasable reference to a world with mutability. For those purposes,
we have `UnsafeWorldCell`.
## Solution
Change the method signature to take `&mut self`. Use exclusive access to
remove the need for atomic adds, which makes the method slightly more
efficient. Redirect users to [`UnsafeWorldCell::increment_change_tick`]
if they need to increment the world's change tick from an aliased
context.
In practice I don't think there will be many breakages, if any. In cases
where you need to call `increment_change_tick`, you usually already have
either `&mut World` or `UnsafeWorldCell`.
---
## Migration Guide
The method `World::increment_change_tick` now requires `&mut self`
instead of `&self`. If you need to call this method but do not have
mutable access to the world, consider using
`world.as_unsafe_world_cell_readonly().increment_change_tick()`, which
does the same thing, but is less efficient than the method on `World`
due to requiring atomic synchronization.
```rust
fn my_system(world: &World) {
// Before
world.increment_change_tick();
// After
world.as_unsafe_world_cell_readonly().increment_change_tick();
}
```
# Objective
Sometimes one wants to retrieve a `&dyn Reflect` for an entity's
component, which so far required multiple, non-obvious steps and
`unsafe`-code.
The docs for
[`MutUntyped`](https://docs.rs/bevy/latest/bevy/ecs/change_detection/struct.MutUntyped.html#method.map_unchanged)
contain an example of the unsafe part.
## Solution
This PR adds the two methods:
```rust
// immutable variant
World::get_reflect(&self, entity: Entity, type_id: TypeId) -> Result<&dyn Reflect, GetComponentReflectError>
// mutable variant
World::get_reflect_mut(&mut self, entity: Entity, type_id: TypeId) -> Result<Mut<'_, dyn Reflect>, GetComponentReflectError>
```
which take care of the necessary steps, check required invariants etc.,
and contain the unsafety so the caller doesn't have to deal with it.
## Testing
- Did you test these changes? If so, how?
- Added tests and a doc test, also (successfully) ran `cargo run -p ci`.
- Are there any parts that need more testing?
- Could add tests for each individual error variant, but it's not
required imo.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- Run `cargo test --doc --package bevy_ecs --all-features --
world::World::get_reflect --show-output` for the doctest
- Run `cargo test --package bevy_ecs --lib --all-features --
world::tests::reflect_tests --show-output` for the unittests
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
- Don't think it's relevant, but tested on 64bit linux (only).
---
## Showcase
Copy of the doctest example which gives a good overview of what this
enables:
```rust
use bevy_ecs::prelude::*;
use bevy_reflect::Reflect;
use std::any::TypeId;
// define a `Component` and derive `Reflect` for it
#[derive(Component, Reflect)]
struct MyComponent;
// create a `World` for this example
let mut world = World::new();
// Note: This is usually handled by `App::register_type()`, but this example can not use `App`.
world.init_resource::<AppTypeRegistry>();
world.get_resource_mut::<AppTypeRegistry>().unwrap().write().register::<MyComponent>();
// spawn an entity with a `MyComponent`
let entity = world.spawn(MyComponent).id();
// retrieve a reflected reference to the entity's `MyComponent`
let comp_reflected: &dyn Reflect = world.get_reflect(entity, TypeId::of::<MyComponent>()).unwrap();
// make sure we got the expected type
assert!(comp_reflected.is::<MyComponent>());
```
## Migration Guide
No breaking changes, but users can use the new methods if they did it
manually before.
---------
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
Simplify Bevy-provided functions that return a condition-satisfying
closure instead of just being the condition.
## Solution
Become the condition.
## Testing
I did not test. Game jamming. Hopefully CI passes.
---
## Migration Guide
Some run conditions have been simplified.
```rust
// Before:
app.add_systems(Update, (
system_0.run_if(run_once()),
system_1.run_if(resource_changed_or_removed::<T>()),
system_2.run_if(resource_removed::<T>()),
system_3.run_if(on_event::<T>()),
system_4.run_if(any_component_removed::<T>()),
));
// After:
app.add_systems(Update, (
system_0.run_if(run_once),
system_1.run_if(resource_changed_or_removed::<T>),
system_2.run_if(resource_removed::<T>),
system_3.run_if(on_event::<T>),
system_4.run_if(any_component_removed::<T>),
));
```
# Objective
- Some types are missing reflection attributes, which means we can't use
them in scene serialization etc.
- Effected types
- `BorderRadius`
- `AnimationTransitions`
- `OnAdd`
- `OnInsert`
- `OnRemove`
- My use-case for `OnAdd` etc to derive reflect is 'Serializable
Observer Components'. Add the component, save the scene, then the
observer is re-added on scene load.
```rust
#[derive(Reflect)]
struct MySerializeableObserver<T: Event>(#[reflect(ignore)]PhantomData<T>);
impl<T: Event> Component for MySerializeableObserver<T> {
const STORAGE_TYPE: StorageType = StorageType::Table;
fn register_component_hooks(hooks: &mut ComponentHooks) {
hooks.on_add(|mut world, entity, _| {
world
.commands()
.entity(entity)
.observe(|_trigger: Trigger<T>| {
println!("it triggered etc.");
});
});
}
}
```
## Solution
- Add the missing traits
---
# 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 event propagation benchmark is largely derived from
bevy_eventlistener. However, it doesn't accurately reflect performance
of bevy side, as our event bubble propagation is based on observer.
## Solution
- added several new benchmarks that focuse on observer itself rather
than event bubble
# Objective
When using tracing or
[`bevy_mod_debugdump`](https://github.com/jakobhellermann/bevy_mod_debugdump),
the names of function systems produced by closures are either ambiguous
(like `game::mainapp::{closure}` when tracing) or too long
(`bevy_mod_debugdump` includes full type signature if no name given),
which makes debugging with tracing difficult.
## Solution
Add a function `with_name` to rename a system. The proposed API can be
used in the following way:
```rust
app
.add_systems(Startup, IntoSystem::into_system(|name: SystemName| {
println!("System name: {}", name.name().to_owned());
}).with_name("print_test_system"));
```
## Testing
- There is a test in
`bevy_ecs::system:system_name::test_closure_system_name_regular_param`
# Objective
- Fixes#14333
## Solution
- Updated `trigger_observers` signature to operate over a slice instead
of an `Iterator`.
- Updated calls to `trigger_observers` to match the new signature.
---
## Migration Guide
- TBD
# Objective
- Allow queuing insertion of dynamic components to an existing entity
## Solution
- Add `insert_by_id<T: Send + 'static>(commands: &mut EntityCommands,
component_id: ComponentId, value: T)` and the `try_insert_by_id`
counterpart
## Testing
TODO
- Did you test these changes? If so, how?
- Are there any parts that need more testing?
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
## Alternatives
This PR is not feature-complete for dynamic components. In particular,
it
- only supports one component
- only supports adding components with a known, sized type
These were not implemented because doing so would require enhancing
`CommandQueue` to support pushing unsized commands (or equivalently,
pushing commands with a buffer of data). Even so, the cost would not be
transparent compared to the implementation in this PR, which simply
captures the `ComponentId` and `value: T` into the command closure and
can be easily memcpy'ed to the stack during execution. For example, to
efficiently pass `&[ComponentId]` from the caller to the world, we would
need to:
1. Update `CommandQueue.bytes` from `Vec<MaybeUninit<u8>>` to
`Vec<MaybeUninit<usize>>` so that it has the same alignment as
`ComponentId` (which probably needs to be made `#[repr(transparent)]`
too)
2. After pushing the Command metadata, push padding bytes until the vec
len is a multiple of `size_of::<usize>()`
3. Store `components.len()` in the data
4. memcpy the user-provided `&[ComponentId]` to `CommandQueue.bytes`
5. During execution, round up the data pointer behind the `Command` to
skip padding, then cast the pointer and consume it as a `&[ComponentId]`
The effort here seems unnecessarily high, unless someone else has such a
requirement. At least for the use case I am working with, I only need a
single known type, and if we need multiple components, we could always
enhance this function to accept a `[ComponentId; N]`.
I recommend enhancing the `Bundle` API in the long term to achieve this
goal more elegantly.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Felix Rath <felixm.rath@gmail.com>
# Objective
The github action summary titles every compile test group as
`compile_fail_utils`.
## Solution
Manually specify group names for compile fail tests.
## Testing
- Wait for compile fail tests to run.
- Observe the generated summary.
# Objective
`TriggerTargets` can not be borrowed for use in `World::trigger_targets`
## Solution
Drop `'static` bound on `TriggerEvent`, keep it for `Command` impl.
## Testing
n/a
# Objective
`Commands::spawn_empty` docs say that it queues a command to spawn an
entity, but it doesn't. It immediately reserves an `Entity` to be
spawned at the next flush point, which is possible because
`Entities::reserve_entity()` takes `&self` and no components are added
yet.
## Solution
Fix docs.
# Objective
Fixes#14202
## Solution
Add `on_replaced` component hook and `OnReplaced` observer trigger
## Testing
- Did you test these changes? If so, how?
- Updated & added unit tests
---
## Changelog
- Added new `on_replaced` component hook and `OnReplaced` observer
trigger for performing cleanup on component values when they are
overwritten with `.insert()`
# Objective
Fixes https://github.com/bevyengine/bevy/issues/14157
## Solution
- Update the ObserverSystem traits to accept an `Out` parameter
## Testing
- Added a test where an observer system has a non-empty output which is
piped into another system
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
