Commit graph

441 commits

Author SHA1 Message Date
Brezak
69e78bd03e
Fix Ci failing over dead code in tests (#12623)
# Objective

Fix Pr CI failing over dead code in tests and main branch CI failing
over a missing semicolon. Fixes #12620.

## Solution

Add dead_code annotations and a semicolon.
2024-03-21 18:08:47 +00:00
James Liu
eebf3d61ec
Remove archetype_component_access from QueryState (#12474)
# Objective
`QueryState::archetype_component_access` is only really ever used to
extend `SystemMeta`'s. It can be removed to save some memory for every
`Query` in an app.

## Solution

 * Remove it. 
* Have `new_archetype` pass in a `&mut Access<ArchetypeComponentId>`
instead and pull it from `SystemMeta` directly.
* Split `QueryState::new` from `QueryState::new_with_access` and a
common `QueryState::new_uninitialized`.
* Split `new_archetype` into an internal and public version. Call the
internal version in `update_archetypes`.

This should make it faster to construct new QueryStates, and by proxy
lenses and joins as well.

`matched_tables` also similarly is only used to deduplicate inserting
into `matched_table_ids`. If we can find another efficient way to do so,
it might also be worth removing.

The [generated
assembly](https://github.com/james7132/bevy_asm_tests/compare/main...remove-query-state-archetype-component-access#diff-496530101f0b16e495b7e9b77c0e906ae3068c8adb69ed36c92d5a1be5a9efbe)
reflects this well, with all of the access related updates in
`QueryState` being removed.

---

## Changelog
Removed: `QueryState::archetype_component_access`.
Changed: `QueryState::new_archetype` now takes a `&mut
Access<ArchetypeComponentId>` argument, which will be updated with the
new accesses.
Changed: `QueryState::update_archetype_component_access` now takes a
`&mut Access<ArchetypeComponentId>` argument, which will be updated with
the new accesses.

## Migration Guide
TODO
2024-03-17 19:01:52 +00:00
James Liu
4b64d1d1d7
Make a note about the performance of Query::is_empty (#12466)
# Objective
`Query::is_empty` does not mention the potential performance footgun of
using it with non-archetypal filters.

## Solution
Document it.
2024-03-14 01:36:03 +00:00
Eira Fransham
baaf4c8c2d
SystemId should manually implement Eq (#12436)
# Objective

`System<f32>` currently does not implement `Eq` even though it should

## Solution

Manually implement `Eq` like other traits are manually implemented
2024-03-12 22:11:21 +00:00
Mike
9cd3165105
Query Joins (#11535)
# Objective

- Add a way to combine 2 queries together in a similar way to
`Query::transmute_lens`
- Fixes #1658

## Solution

- Use a similar method to query transmute, but take the intersection of
matched archetypes between the 2 queries and the union of the accesses
to create the new underlying QueryState.

---

## Changelog

- Add query joins

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-03-11 19:07:36 +00:00
James Liu
879b170f28
Mention in docs about the query iteration order and result uniqueness. (#12400)
# Objective
Fix #10876. Improve `Query` and `QueryState`'s docs.

## Solution
Explicitly denote that Query is always guaranteed to return results from
all matching entities once and only once for each entity, and that
iteration order is not guaranteed in any way.
2024-03-11 18:17:46 +00:00
James Liu
ab6a5cac9f
Remove initialize_resource<T> and friends (#12307)
# Objective
`initialize_resource<T>` and it's non-send equivalent is only used in
two locations each. Fix #6285.

## Solution
Remove them, replace their calls with their internals. Cut down on a bit
of generic codegen.

This does mean that `initialize_resource_internal` is now `pub(crate)`,
but that's likely OK given that only one variant will remain once
NonSend resources are removed from the World.
2024-03-05 16:09:13 +00:00
Stepan Koltsov
70b70cd323
Rewrite part of Commands rustdoc (#11141)
- Explain it is flushed in the same schedule run (was not obvious to me)
- Point to `apply_deferred` example
- Remove mentions of `System::apply_deferred` and
`Schedule::apply_deferred` which are probably too low level for the most
users

Co-authored-by: James Liu <contact@jamessliu.com>
2024-03-05 09:52:48 +00:00
Gino Valente
e8583d132c
bevy_ecs: Fix up docs for World::run_system and World::run_system_with_input (#12289)
# Objective

- The doc example for `World::run_system_with_input` mistakenly
indicates that systems share state
- Some of the doc example code is unnecessary and/or could be cleaned up

## Solution

Replace the incorrect result value for the correct one in the doc
example. I also went with an explicit `assert_eq` check as it presents
the same information but can be validated by CI via doc tests.

Also removed some unnecessary code, such as the `Resource` derives on
`Counter`. In fact, I just replaced `Counter` with a `u8` in the
`Local`. I think it makes the example a little cleaner.

---

## Changelog

- Update docs for `World::run_system` and `World::run_system_with_input`
2024-03-04 21:59:24 +00:00
targrub
13cbb9cf10
Move commands module into bevy::ecs::world (#12234)
# Objective

Fixes https://github.com/bevyengine/bevy/issues/11628

## Migration Guide

`Command` and `CommandQueue` have migrated from `bevy_ecs::system` to
`bevy_ecs::world`, so `use bevy_ecs::world::{Command, CommandQueue};`
when necessary.
2024-03-02 23:13:45 +00:00
James O'Brien
94ff123d7f
Component Lifecycle Hooks and a Deferred World (#10756)
# Objective

- Provide a reliable and performant mechanism to allows users to keep
components synchronized with external sources: closing/opening sockets,
updating indexes, debugging etc.
- Implement a generic mechanism to provide mutable access to the world
without allowing structural changes; this will not only be used here but
is a foundational piece for observers, which are key for a performant
implementation of relations.

## Solution

- Implement a new type `DeferredWorld` (naming is not important,
`StaticWorld` is also suitable) that wraps a world pointer and prevents
user code from making any structural changes to the ECS; spawning
entities, creating components, initializing resources etc.
- Add component lifecycle hooks `on_add`, `on_insert` and `on_remove`
that can be assigned callbacks in user code.

---

## Changelog
- Add new `DeferredWorld` type.
- Add new world methods: `register_component::<T>` and
`register_component_with_descriptor`. These differ from `init_component`
in that they provide mutable access to the created `ComponentInfo` but
will panic if the component is already in any archetypes. These
restrictions serve two purposes:
1. Prevent users from defining hooks for components that may already
have associated hooks provided in another plugin. (a use case better
served by observers)
2. Ensure that when an `Archetype` is created it gets the appropriate
flags to early-out when triggering hooks.
- Add methods to `ComponentInfo`: `on_add`, `on_insert` and `on_remove`
to be used to register hooks of the form `fn(DeferredWorld, Entity,
ComponentId)`
- Modify `BundleInserter`, `BundleSpawner` and `EntityWorldMut` to
trigger component hooks when appropriate.
- Add bit flags to `Archetype` indicating whether or not any contained
components have each type of hook, this can be expanded for other flags
as needed.
- Add `component_hooks` example to illustrate usage. Try it out! It's
fun to mash keys.

## Safety
The changes to component insertion, removal and deletion involve a large
amount of unsafe code and it's fair for that to raise some concern. I
have attempted to document it as clearly as possible and have confirmed
that all the hooks examples are accepted by `cargo miri` as not causing
any undefined behavior. The largest issue is in ensuring there are no
outstanding references when passing a `DeferredWorld` to the hooks which
requires some use of raw pointers (as was already happening to some
degree in those places) and I have taken some time to ensure that is the
case but feel free to let me know if I've missed anything.

## Performance
These changes come with a small but measurable performance cost of
between 1-5% on `add_remove` benchmarks and between 1-3% on `insert`
benchmarks. One consideration to be made is the existence of the current
`RemovedComponents` which is on average more costly than the addition of
`on_remove` hooks due to the early-out, however hooks doesn't completely
remove the need for `RemovedComponents` as there is a chance you want to
respond to the removal of a component that already has an `on_remove`
hook defined in another plugin, so I have not removed it here. I do
intend to deprecate it with the introduction of observers in a follow up
PR.

## Discussion Questions
- Currently `DeferredWorld` implements `Deref` to `&World` which makes
sense conceptually, however it does cause some issues with rust-analyzer
providing autocomplete for `&mut World` references which is annoying.
There are alternative implementations that may address this but involve
more code churn so I have attempted them here. The other alternative is
to not implement `Deref` at all but that leads to a large amount of API
duplication.
- `DeferredWorld`, `StaticWorld`, something else?
- In adding support for hooks to `EntityWorldMut` I encountered some
unfortunate difficulties with my desired API. If commands are flushed
after each call i.e. `world.spawn() // flush commands .insert(A) //
flush commands` the entity may be despawned while `EntityWorldMut` still
exists which is invalid. An alternative was then to add
`self.world.flush_commands()` to the drop implementation for
`EntityWorldMut` but that runs into other problems for implementing
functions like `into_unsafe_entity_cell`. For now I have implemented a
`.flush()` which will flush the commands and consume `EntityWorldMut` or
users can manually run `world.flush_commands()` after using
`EntityWorldMut`.
- In order to allowing querying on a deferred world we need
implementations of `WorldQuery` to not break our guarantees of no
structural changes through their `UnsafeWorldCell`. All our
implementations do this, but there isn't currently any safety
documentation specifying what is or isn't allowed for an implementation,
just for the caller, (they also shouldn't be aliasing components they
didn't specify access for etc.) is that something we should start doing?
(see 10752)

Please check out the example `component_hooks` or the tests in
`bundle.rs` for usage examples. I will continue to expand this
description as I go.

See #10839 for a more ergonomic API built on top of this one that isn't
subject to the same restrictions and supports `SystemParam` dependency
injection.
2024-03-01 14:59:22 +00:00
amy universe
cbfeb9438a
include links in error messages (#12165)
# Objective

Fixes #12118

## Solution
did a grip for any "B000" in the crates directory, and added the links

note: ignored the test functions in this file
https://github.com/bevyengine/bevy/blob/main/crates/bevy_ecs/src/system/mod.rs#L537
2024-02-28 00:01:18 +00:00
porkbrain
43b859dfcf
Implements conversion from SystemId to Entity (#11759)
# Objective

Right now when using egui, systems are inserted without any identifier
and to the root. I'd like to name those systems and insert them as
children to a root entity. This helps to keep the editor organized.

## Solution

- Although the `SystemId` is documented as an opaque type, examples
depicted above benefit from tear down of the abstraction.

---

## Changelog

### Added
- Implemented `From<SystemId>` for `Entity`

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-02-26 12:17:30 +00:00
Charles Bournhonesque
5bcc100d10
Update docstrings for some Commands to use the correct type (#12111)
# Objective

- A tiny nit I noticed; I think the type of these function is
`EntityCommand`, not `Command`

Co-authored-by: Charles Bournhonesque <cbournhonesque@snapchat.com>
2024-02-25 19:48:33 +00:00
James Liu
42e61557f8
Immediately apply deferred system params in System::run (#11823)
# Objective
Fixes #11821. 

## Solution
* Run `System::apply_deferred` in `System::run` after executing the
system.
* Switch to using `System::run_unsafe` in `SingleThreadedExecutor` to
preserve the current behavior.
* Remove the `System::apply_deferred` in `SimpleExecutor` as it's now
redundant.
* Remove the `System::apply_deferred` when running one-shot systems, as
it's now redundant.

---

## Changelog
Changed: `System::run` will now immediately apply deferred system params
after running the system.

## Migration Guide
`System::run` will now always run `System::apply_deferred` immediately
after running the system now. If you were running systems and then
applying their deferred buffers at a later point in time, you can
eliminate the latter.

```rust
// in 0.13
system.run(world);
// .. sometime later ...
system.apply_deferred(world);

// in 0.14
system.run(world);
```

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-02-24 14:01:06 +00:00
Ame
9d67edc3a6
fix some typos (#12038)
# Objective

Split - containing only the fixed typos

-
https://github.com/bevyengine/bevy/pull/12036#pullrequestreview-1894738751


# Migration Guide
In `crates/bevy_mikktspace/src/generated.rs` 

```rs
// before
pub struct SGroup {
    pub iVertexRepresentitive: i32,
    ..
}

// after
pub struct SGroup {
    pub iVertexRepresentative: i32,
    ..
}
```

In `crates/bevy_core_pipeline/src/core_2d/mod.rs`

```rs
// before
Node2D::ConstrastAdaptiveSharpening

// after
Node2D::ContrastAdaptiveSharpening
```

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
Co-authored-by: François <mockersf@gmail.com>
2024-02-22 18:55:22 +00:00
Tristan Guichaoua
33c7a2251e
bevy_ecs address trivial cases of unsafe_op_in_unsafe_fn (#11861)
# Objective

- Part of #11590
- Fix `unsafe_op_in_unsafe_fn` for trivial cases in bevy_ecs

## Solution

Fix `unsafe_op_in_unsafe_fn` in bevy_ecs for trivial cases, i.e., add an
`unsafe` block when the safety comment already exists or add a comment
like "The invariants are uphold by the caller".

---------

Co-authored-by: James Liu <contact@jamessliu.com>
2024-02-22 00:04:38 +00:00
Jakob Hellermann
a491bce680
Fix SystemTypeSet::system_type being out of sync with System::type_id (#12030)
## Objective

Always have `some_system.into_system().type_id() ==
some_system.into_system_set().system_type().unwrap()`.

System sets have a `fn system_type() -> Option<TypeId>` that is
implemented by `SystemTypeSet` to returning the TypeId of the system's
function type. This was implemented in
https://github.com/bevyengine/bevy/pull/7715 and is used in
`bevy_mod_debugdump` to handle `.after(function)` constraints.

Back then, `System::type_id` always also returned the type id of the
function item, not of `FunctionSystem<M, F>`.

https://github.com/bevyengine/bevy/pull/11728 changes the behaviour of
`System::type_id` so that it returns the id of the
`FunctionSystem`/`ExclusiveFunctionSystem` wrapper, but it did not
change `SystemTypeSet::system_type`, so doing the lookup breaks in
`bevy_mod_debugdump`.

## Solution

Change `IntoSystemSet` for functions to return a
`SystemTypeSet<FunctionSystem>` /
`SystemTypeSet<ExclusiveFunctionSystem>` instead of `SystemTypeSet<F>`.
2024-02-21 23:40:45 +00:00
James Liu
bc82749012
Remove APIs deprecated in 0.13 (#11974)
# Objective
We deprecated quite a few APIs in 0.13. 0.13 has shipped already. It
should be OK to remove them in 0.14's release. Fixes #4059. Fixes #9011.

## Solution
Remove them.
2024-02-19 19:04:47 +00:00
James Liu
e34fb68677
refactor: Extract parallel queue abstraction (#7348)
# Objective
There's a repeating pattern of `ThreadLocal<Cell<Vec<T>>>` which is very
useful for low overhead, low contention multithreaded queues that have
cropped up in a few places in the engine. This pattern is surprisingly
useful when building deferred mutation across multiple threads, as noted
by it's use in `ParallelCommands`.

However, `ThreadLocal<Cell<Vec<T>>>` is not only a mouthful, it's also
hard to ensure the thread-local queue is replaced after it's been
temporarily removed from the `Cell`.

## Solution
Wrap the pattern into `bevy_utils::Parallel<T>` which codifies the
entire pattern and ensures the user follows the contract. Instead of
fetching indivdual cells, removing the value, mutating it, and replacing
it, `Parallel::get` returns a `ParRef<'a, T>` which contains the
temporarily removed value and a reference back to the cell, and will
write the mutated value back to the cell upon being dropped.

I would like to use this to simplify the remaining part of #4899 that
has not been adopted/merged.

---

## Changelog
TODO

---------

Co-authored-by: Joseph <21144246+JoJoJet@users.noreply.github.com>
2024-02-19 16:31:15 +00:00
Joseph
bd25135330
Fix double indirection when applying command queues (#11822)
# Objective

When applying a command, we currently use double indirection for the
world reference `&mut Option<&mut World>`. Since this is used across a
`fn` pointer boundary, this can't get optimized away.

## Solution

Reborrow the world reference and pass `Option<&mut World>` instead.
2024-02-12 15:27:18 +00:00
Joseph
9c2257332a
Add a method for detecting changes within a certain scope (#11687)
# Objective

Bevy's change detection functionality is invaluable for writing robust
apps, but it only works in the context of systems and exclusive systems.
Oftentimes it is necessary to detect changes made in earlier code
without having to place the code in separate systems, but it is not
currently possible to do so since there is no way to set the value of
`World::last_change_tick`.

`World::clear_trackers` allows you to update the change tick, but this
has unintended side effects, since it irreversibly affects the behavior
of change and removal detection for the entire app.

## Solution

Add a method `World::last_change_tick_scope`. This allows you to set
`last_change_tick` to a specific value for a region of code. To ensure
that misuse doesn't break unrelated functions, we restore the world's
original change tick at the end of the provided scope.

### Example

A function that uses this to run an update loop repeatedly, allowing
each iteration of the loop to react to changes made in the previous loop
iteration.

```rust
fn update_loop(
    world: &mut World,
    mut update_fn: impl FnMut(&mut World) -> std::ops::ControlFlow<()>,
) {
    let mut last_change_tick = world.last_change_tick();

    // Repeatedly run the update function until it requests a break.
    loop {
        // Update once.
        let control_flow = world.last_change_tick_scope(last_change_tick, |world| {
            update_fn(world)
        });

        // End the loop when the closure returns `ControlFlow::Break`.
        if control_flow.is_break() {
            break;
        }

        // Increment the change tick so the next update can detect changes from this update.
        last_change_tick = world.change_tick();
        world.increment_change_tick();
    }
}
```

---

## Changelog

+ Added `World::last_change_tick_scope`, which allows you to specify the
reference for change detection within a certain scope.
2024-02-12 15:09:11 +00:00
Zachary Harrold
950bd2284d
System::type_id Consistency (#11728)
# Objective

- Fixes #11679

## Solution

- Added `IntoSystem::system_type_id` which returns the equivalent of
`system.into_system().type_id()` without construction. This allows for
getting the `TypeId` of functions (a function is an unnamed type and
therefore you cannot call `TypeId::of::<apply_deferred::System>()`)
- Added default implementation of `System::type_id` to ensure
consistency between implementations. Some returned `Self`, while others
were returning an inner value instead. This ensures consistency with
`IntoSystem::system_type_id`.

## Migration Guide

If you use `System::type_id()` on function systems (exclusive or not),
ensure you are comparing its value to other `System::type_id()` calls,
or `IntoSystem::system_type_id()`.

This code wont require any changes, because `IntoSystem`'s are directly
compared to each other.

```rust
fn test_system() {}

let type_id = test_system.type_id();

// ...

// No change required
assert_eq!(test_system.type_id(), type_id);
```

Likewise, this code wont, because `System`'s are directly compared.

```rust
fn test_system() {}

let type_id = IntoSystem::into_system(test_system).type_id();

// ...

// No change required
assert_eq!(IntoSystem::into_system(test_system).type_id(), type_id);
```

The below _does_ require a change, since you're comparing a `System`
type to a `IntoSystem` type.

```rust
fn test_system() {}

// Before
assert_eq!(test_system.type_id(), IntoSystem::into_system(test_system).type_id());

// After
assert_eq!(test_system.system_type_id(), IntoSystem::into_system(test_system).type_id());
```
2024-02-06 14:43:33 +00:00
Zachary Harrold
1974723a63
Deprecated Various Component Methods from Query and QueryState (#9920)
# Objective

- (Partially) Fixes #9904
- Acts on #9910

## Solution

- Deprecated the relevant methods from `Query`, cascading changes as
required across Bevy.

---

## Changelog

- Deprecated `QueryState::get_component_unchecked_mut` method
- Deprecated `Query::get_component` method
- Deprecated `Query::get_component_mut` method
- Deprecated `Query::component` method
- Deprecated `Query::component_mut` method
- Deprecated `Query::get_component_unchecked_mut` method

## Migration Guide

### `QueryState::get_component_unchecked_mut`

Use `QueryState::get_unchecked_manual` and select for the exact
component based on the structure of the exact query as required.

### `Query::(get_)component(_unchecked)(_mut)`

Use `Query::get` and select for the exact component based on the
structure of the exact query as required.

- For mutable access (`_mut`), use `Query::get_mut`
- For unchecked access (`_unchecked`), use `Query::get_unchecked`
- For panic variants (non-`get_`), add `.unwrap()`

## Notes

- `QueryComponentError` can be removed once these deprecated methods are
also removed. Due to an interaction with `thiserror`'s derive macro, it
is not marked as deprecated.
2024-02-04 01:01:59 +00:00
Lane Kolbly
9fcf862114
bevy_ecs: Add doc example for par_iter_mut (#11311) (#11499)
# Objective

Fixes #11311 

## Solution

Adds an example to the documentation for `par_iter_mut`. I didn't add
any examples to `par_iter`, because I couldn't think of a good example
and I figure users can infer that `par_iter` and `par_iter_mut` are
similar.
2024-01-28 02:13:03 +00:00
Trashtalk217
a955d65ffa
Exclusive systems can now be used for one-shot systems (#11560)
Joy notified me that exclusive systems should now work (they may have
always worked, I don't know), so here's a quick change to the
documentation.
2024-01-27 16:10:39 +00:00
Pixelstorm
df063ab1ef
Implement Debug for CommandQueue (#11444)
# Objective

Allow users to impl Debug on types containing `CommandQueue`s

## Solution

Derive Debug on `CommandQueue`

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-22 15:45:17 +00:00
Joseph
7d69d3195f
refactor: Simplify lifetimes for Commands and related types (#11445)
# Objective

It would be convenient to be able to call functions with `Commands` as a
parameter without having to move your own instance of `Commands`. Since
this struct is composed entirely of references, we can easily get an
owned instance of `Commands` by shortening the lifetime.

## Solution

Add `Commands::reborrow`, `EntiyCommands::reborrow`, and
`Deferred::reborrow`, which returns an owned version of themselves with
a shorter lifetime.

Remove unnecessary lifetimes from `EntityCommands`. The `'w` and `'s`
lifetimes only have to be separate for `Commands` because it's used as a
`SystemParam` -- this is not the case for `EntityCommands`.

---

## Changelog

Added `Commands::reborrow`. This is useful if you have `&mut Commands`
but need `Commands`. Also added `EntityCommands::reborrow` and
`Deferred:reborrow` which serve the same purpose.

## Migration Guide

The lifetimes for `EntityCommands` have been simplified.

```rust
// Before (Bevy 0.12)
struct MyStruct<'w, 's, 'a> {
     commands: EntityCommands<'w, 's, 'a>,
}

// After (Bevy 0.13)
struct MyStruct<'a> {
    commands: EntityCommands<'a>,
}
```

The method `EntityCommands::commands` now returns `Commands` rather than
`&mut Commands`.

```rust
// Before (Bevy 0.12)
let commands = entity_commands.commands();
commands.spawn(...);

// After (Bevy 0.13)
let mut commands = entity_commands.commands();
commands.spawn(...);
```
2024-01-22 15:35:42 +00:00
laund
e2e4e8eb9a
document which lifetime is needed for systemparam derive (#11321)
# Objective

Document a few common cases of which lifetime is required when using
SystemParam Derive

## Solution

Added a table in the doc comment

---------

Co-authored-by: laund <me@laund.moe>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-22 15:32:42 +00:00
James O'Brien
ea42d14344
Dynamic queries and builder API (#9774)
# Objective
Expand the existing `Query` API to support more dynamic use cases i.e.
scripting.

## Prior Art
 - #6390 
 - #8308 
- #10037

## Solution
- Create a `QueryBuilder` with runtime methods to define the set of
component accesses for a built query.
- Create new `WorldQueryData` implementations `FilteredEntityMut` and
`FilteredEntityRef` as variants of `EntityMut` and `EntityRef` that
provide run time checked access to the components included in a given
query.
- Add new methods to `Query` to create "query lens" with a subset of the
access of the initial query.

### Query Builder
The `QueryBuilder` API allows you to define a query at runtime. At it's
most basic use it will simply create a query with the corresponding type
signature:
```rust
let query = QueryBuilder::<Entity, With<A>>::new(&mut world).build();
// is equivalent to
let query = QueryState::<Entity, With<A>>::new(&mut world);
```
Before calling `.build()` you also have the opportunity to add
additional accesses and filters. Here is a simple example where we add
additional filter terms:
```rust
let entity_a = world.spawn((A(0), B(0))).id();
let entity_b = world.spawn((A(0), C(0))).id();

let mut query_a = QueryBuilder::<Entity>::new(&mut world)
    .with::<A>()
    .without::<C>()
    .build();
            
assert_eq!(entity_a, query_a.single(&world));
```
This alone is useful in that allows you to decide which archetypes your
query will match at runtime. However it is also very limited, consider a
case like the following:
```rust
let query_a = QueryBuilder::<&A>::new(&mut world)
// Add an additional access
    .data::<&B>()
    .build();
```
This will grant the query an additional read access to component B
however we have no way of accessing the data while iterating as the type
signature still only includes &A. For an even more concrete example of
this consider dynamic components:
```rust
let query_a = QueryBuilder::<Entity>::new(&mut world)
// Adding a filter is easy since it doesn't need be read later
    .with_id(component_id_a)
// How do I access the data of this component?
    .ref_id(component_id_b)
    .build();
```
With this in mind the `QueryBuilder` API seems somewhat incomplete by
itself, we need some way method of accessing the components dynamically.
So here's one:
### Query Transmutation
If the problem is not having the component in the type signature why not
just add it? This PR also adds transmute methods to `QueryBuilder` and
`QueryState`. Here's a simple example:
```rust
world.spawn(A(0));
world.spawn((A(1), B(0)));
let mut query = QueryBuilder::<()>::new(&mut world)
    .with::<B>()
    .transmute::<&A>()
    .build();

query.iter(&world).for_each(|a| assert_eq!(a.0, 1));
```
The `QueryState` and `QueryBuilder` transmute methods look quite similar
but are different in one respect. Transmuting a builder will always
succeed as it will just add the additional accesses needed for the new
terms if they weren't already included. Transmuting a `QueryState` will
panic in the case that the new type signature would give it access it
didn't already have, for example:
```rust
let query = QueryState::<&A, Option<&B>>::new(&mut world);
/// This is fine, the access for Option<&A> is less restrictive than &A
query.transmute::<Option<&A>>(&world);
/// Oh no, this would allow access to &B on entities that might not have it, so it panics
query.transmute::<&B>(&world);
/// This is right out
query.transmute::<&C>(&world);
```
This is quite an appealing API to also have available on `Query` however
it does pose one additional wrinkle: In order to to change the iterator
we need to create a new `QueryState` to back it. `Query` doesn't own
it's own state though, it just borrows it, so we need a place to borrow
it from. This is why `QueryLens` exists, it is a place to store the new
state so it can be borrowed when you call `.query()` leaving you with an
API like this:
```rust
fn function_that_takes_a_query(query: &Query<&A>) {
    // ...
}

fn system(query: Query<(&A, &B)>) {
    let lens = query.transmute_lens::<&A>();
    let q = lens.query();
    function_that_takes_a_query(&q);
}
```
Now you may be thinking: Hey, wait a second, you introduced the problem
with dynamic components and then described a solution that only works
for static components! Ok, you got me, I guess we need a bit more:
### Filtered Entity References
Currently the only way you can access dynamic components on entities
through a query is with either `EntityMut` or `EntityRef`, however these
can access all components and so conflict with all other accesses. This
PR introduces `FilteredEntityMut` and `FilteredEntityRef` as
alternatives that have additional runtime checking to prevent accessing
components that you shouldn't. This way you can build a query with a
`QueryBuilder` and actually access the components you asked for:
```rust
let mut query = QueryBuilder::<FilteredEntityRef>::new(&mut world)
    .ref_id(component_id_a)
    .with(component_id_b)
    .build();

let entity_ref = query.single(&world);

// Returns Some(Ptr) as we have that component and are allowed to read it
let a = entity_ref.get_by_id(component_id_a);
// Will return None even though the entity does have the component, as we are not allowed to read it
let b = entity_ref.get_by_id(component_id_b);
```
For the most part these new structs have the exact same methods as their
non-filtered equivalents.

Putting all of this together we can do some truly dynamic ECS queries,
check out the `dynamic` example to see it in action:
```
Commands:
    comp, c   Create new components
    spawn, s  Spawn entities
    query, q  Query for entities
Enter a command with no parameters for usage.

> c A, B, C, Data 4  
Component A created with id: 0
Component B created with id: 1
Component C created with id: 2
Component Data created with id: 3

> s A, B, Data 1
Entity spawned with id: 0v0

> s A, C, Data 0
Entity spawned with id: 1v0

> q &Data
0v0: Data: [1, 0, 0, 0]
1v0: Data: [0, 0, 0, 0]

> q B, &mut Data                                                                                     
0v0: Data: [2, 1, 1, 1]

> q B || C, &Data 
0v0: Data: [2, 1, 1, 1]
1v0: Data: [0, 0, 0, 0]
```
## Changelog
 - Add new `transmute_lens` methods to `Query`.
- Add new types `QueryBuilder`, `FilteredEntityMut`, `FilteredEntityRef`
and `QueryLens`
- `update_archetype_component_access` has been removed, archetype
component accesses are now determined by the accesses set in
`update_component_access`
- Added method `set_access` to `WorldQuery`, this is called before
`update_component_access` for queries that have a restricted set of
accesses, such as those built by `QueryBuilder` or `QueryLens`. This is
primarily used by the `FilteredEntity*` variants and has an empty trait
implementation.
- Added method `get_state` to `WorldQuery` as a fallible version of
`init_state` when you don't have `&mut World` access.

## Future Work
Improve performance of `FilteredEntityMut` and `FilteredEntityRef`,
currently they have to determine the accesses a query has in a given
archetype during iteration which is far from ideal, especially since we
already did the work when matching the archetype in the first place. To
avoid making more internal API changes I have left it out of this PR.

---------

Co-authored-by: Mike Hsu <mike.hsu@gmail.com>
2024-01-16 19:16:49 +00:00
Ixentus
e2fd63104d
Simplify conditions (#11316)
# Objective

- Conditions don't have to be closures unless they have state or mutate.

## Solution

- Simplify conditions when possible.

---

## Changelog

The following run conditions are now regular systems:
- resource_exists<T>
- resource_added<T>
- resource_changed<T>
- resource_exists_and_changed<T>
- state_exists<S: States>
- state_changed<S: States>
- any_with_component<T: Component>

## Migration Guide

- resource_exists<T>() -> resource_exists<T>
- resource_added<T>() -> resource_added<T>
- resource_changed<T>() -> resource_changed<T>
- resource_exists_and_changed<T>() -> resource_exists_and_changed<T>
- state_exists<S: States>() -> state_exists<S: States>
- state_changed<S: States>() -> state_changed<S: States>
- any_with_component<T: Component>() -> any_with_component<T: Component>
2024-01-13 13:22:17 +00:00
Joseph
df2ba09989
Restore support for running fn EntityCommands on entities that might be despawned (#11107)
# Objective

In #9604 we removed the ability to define an `EntityCommand` as
`fn(Entity, &mut World)`. However I have since realized that `fn(Entity,
&mut World)` is an incredibly expressive and powerful way to define a
command for an entity that may or may not exist (`fn(EntityWorldMut)`
only works on entities that are alive).

## Solution

Support `EntityCommand`s in the style of `fn(Entity, &mut World)`, as
well as `fn(EntityWorldMut)`. Use a marker generic on the
`EntityCommand` trait to allow multiple impls.

The second commit in this PR replaces all of the internal command
definitions with ones using `fn` definitions. This is mostly just to
show off how expressive this style of command is -- we can revert this
commit if we'd rather avoid breaking changes.

---

## Changelog

Re-added support for expressively defining an `EntityCommand` as a
function that takes `Entity, &mut World`.

## Migration Guide

All `Command` types in `bevy_ecs`, such as `Spawn`, `SpawnBatch`,
`Insert`, etc., have been made private. Use the equivalent methods on
`Commands` or `EntityCommands` instead.
2024-01-08 22:32:28 +00:00
Chia-Hsiang Cheng
b6da40cfe6
Print a warning for un-applied commands being dropped from a CommandQueue (#11146)
# Objective

- Fixes #11125 
## Solution

Add a warning for un-applied commands to the `drop` function.
2024-01-03 15:32:57 +00:00
Stepan Koltsov
6bc2686a7a
impl ExclusiveSystemParam for SystemName (#11163)
# Objective

`SystemName` might be useful in systems which accept `&mut World`.

## Solution

- `impl ExclusiveSystemParam for SystemName`
- move `SystemName` into a separate file, because it no longer belongs
to a file which defines `SystemParam`
- add a test for new impl, and for existing impl

## Changelog

- `impl ExclusiveSystemParam for SystemName`
2024-01-01 17:08:29 +00:00
Adam
8baefa1570
Implement Deref and DerefMut for In (#11104)
# Objective

Implement Deref and DerefMut for In<T>

makes it so the user doesn't have to add ".0" in most cases
2024-01-01 16:55:07 +00:00
Doonv
189ceaf0d3
Replace or document ignored doctests (#11040)
# Objective

There are a lot of doctests that are `ignore`d for no documented reason.
And that should be fixed.

## Solution

I searched the bevy repo with the regex ` ```[a-z,]*ignore ` in order to
find all `ignore`d doctests. For each one of the `ignore`d doctests, I
did the following steps:
1. Attempt to remove the `ignored` attribute while still passing the
test. I did this by adding hidden dummy structs and imports.
2. If step 1 doesn't work, attempt to replace the `ignored` attribute
with the `no_run` attribute while still passing the test.
3. If step 2 doesn't work, keep the `ignored` attribute but add
documentation for why the `ignored` attribute was added.

---------

Co-authored-by: François <mockersf@gmail.com>
2024-01-01 16:50:56 +00:00
Stepan Koltsov
4fba03b529
impl ExclusiveSystemParam for PhantomData (#11153)
# Objective

Implement `ExclusiveSystemParam` for `PhantomData`.

For the same reason `SystemParam` impl exists: to simplify writing
generic code.


786abbf3f5/crates/bevy_ecs/src/system/system_param.rs (L1557)

Also for consistency.

## Solution

`impl ExclusiveSystemParam for PhantomData`.

## Changelog
Added: PhantomData<T> now implements ExclusiveSystemParam.
2024-01-01 16:02:21 +00:00
Stepan Koltsov
ac58a5fe57
Better doc for SystemName (#11084)
Compared to [current
documentation](https://docs.rs/bevy/latest/bevy/ecs/system/struct.SystemName.html)
it is now immediately clear that it is `SystemParam` readily available
to user, and not just some accidentally exposed internal data type.
2023-12-25 05:09:15 +00:00
Tygyh
7b8305e5b4
Remove unnecessary parens (#11075)
# Objective

- Increase readability.

## Solution

- Remove unnecessary parens.
2023-12-24 17:43:01 +00:00
Tygyh
63d17e8494
Simplify equality assertions (#10988)
# Objective

- Shorten assertions.

## Solution

- Replace '==' assertions with 'assert_eq()' and '!=' assertions with
'assert_ne()' .
2023-12-16 23:58:41 +00:00
Mike
6b84ba97a3
Auto insert sync points (#9822)
# Objective

- Users are often confused when their command effects are not visible in
the next system. This PR auto inserts sync points if there are deferred
buffers on a system and there are dependents on that system (systems
with after relationships).
- Manual sync points can lead to users adding more than needed and it's
hard for the user to have a global understanding of their system graph
to know which sync points can be merged. However we can easily calculate
which sync points can be merged automatically.

## Solution

1. Add new edge types to allow opting out of new behavior
2. Insert an sync point for each edge whose initial node has deferred
system params.
3. Reuse nodes if they're at the number of sync points away.

* add opt outs for specific edges with `after_ignore_deferred`,
`before_ignore_deferred` and `chain_ignore_deferred`. The
`auto_insert_apply_deferred` boolean on `ScheduleBuildSettings` can be
set to false to opt out for the whole schedule.

## Perf
This has a small negative effect on schedule build times.
```text
group                                           auto-sync                              main-for-auto-sync
-----                                           -----------                            ------------------
build_schedule/1000_schedule                    1.06       2.8±0.15s        ? ?/sec    1.00       2.7±0.06s        ? ?/sec
build_schedule/1000_schedule_noconstraints      1.01     26.2±0.88ms        ? ?/sec    1.00     25.8±0.36ms        ? ?/sec
build_schedule/100_schedule                     1.02     13.1±0.33ms        ? ?/sec    1.00     12.9±0.28ms        ? ?/sec
build_schedule/100_schedule_noconstraints       1.08   505.3±29.30µs        ? ?/sec    1.00   469.4±12.48µs        ? ?/sec
build_schedule/500_schedule                     1.00    485.5±6.29ms        ? ?/sec    1.00    485.5±9.80ms        ? ?/sec
build_schedule/500_schedule_noconstraints       1.00      6.8±0.10ms        ? ?/sec    1.02      6.9±0.16ms        ? ?/sec
```
---

## Changelog

- Auto insert sync points and added `after_ignore_deferred`,
`before_ignore_deferred`, `chain_no_deferred` and
`auto_insert_apply_deferred` APIs to opt out of this behavior

## Migration Guide

- `apply_deferred` points are added automatically when there is ordering
relationship with a system that has deferred parameters like `Commands`.
If you want to opt out of this you can switch from `after`, `before`,
and `chain` to the corresponding `ignore_deferred` API,
`after_ignore_deferred`, `before_ignore_deferred` or
`chain_ignore_deferred` for your system/set ordering.
- You can also set `ScheduleBuildSettings::auto_insert_sync_points` to
`false` if you want to do it for the whole schedule. Note that in this
mode you can still add `apply_deferred` points manually.
- For most manual insertions of `apply_deferred` you should remove them
as they cannot be merged with the automatically inserted points and
might reduce parallelizability of the system graph.

## TODO
- [x] remove any apply_deferred used in the engine
- [x] ~~decide if we should deprecate manually using apply_deferred.~~
We'll still allow inserting manual sync points for now for whatever edge
cases users might have.
- [x] Update migration guide
- [x] rerun schedule build benchmarks

---------

Co-authored-by: Joseph <21144246+JoJoJet@users.noreply.github.com>
2023-12-14 16:34:01 +00:00
Tygyh
b2661ea73d
Reorder impl to be the same as the trait (#10964)
# Objective

- Make the implementation order consistent between all sources to fit
the order in the trait.

## Solution

- Change the implementation order.
2023-12-13 21:19:49 +00:00
Federico Rinaldi
9c78128e8f
Rename Q type parameter to D when referring to WorldQueryData (#10782)
# Objective

Since #10776 split `WorldQuery` to `WorldQueryData` and
`WorldQueryFilter`, it should be clear that the query is actually
composed of two parts. It is not factually correct to call "query" only
the data part. Therefore I suggest to rename the `Q` parameter to `D` in
`Query` and related items.

As far as I know, there shouldn't be breaking changes from renaming
generic type parameters.

## Solution

I used a combination of rust-analyzer go to reference and `Ctrl-F`ing
various patterns to catch as many cases as possible. Hopefully I got
them all. Feel free to check if you're concerned of me having missed
some.

## Notes

This and #10779 have many lines in common, so merging one will cause a
lot of merge conflicts to the other.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2023-12-13 18:50:46 +00:00
Mantas
5af2f022d8
Rename WorldQueryData & WorldQueryFilter to QueryData & QueryFilter (#10779)
# Rename `WorldQueryData` & `WorldQueryFilter` to `QueryData` &
`QueryFilter`

Fixes #10776 

## Solution

Traits `WorldQueryData` & `WorldQueryFilter` were renamed to `QueryData`
and `QueryFilter`, respectively. Related Trait types were also renamed.

---

## Changelog

- Trait `WorldQueryData` has been renamed to `QueryData`. Derive macro's
`QueryData` attribute `world_query_data` has been renamed to
`query_data`.
- Trait `WorldQueryFilter` has been renamed to `QueryFilter`. Derive
macro's `QueryFilter` attribute `world_query_filter` has been renamed to
`query_filter`.
- Trait's `ExtractComponent` type `Query` has been renamed to `Data`.
- Trait's `GetBatchData` types `Query` & `QueryFilter` has been renamed
to `Data` & `Filter`, respectively.
- Trait's `ExtractInstance` type `Query` has been renamed to `Data`.
- Trait's `ViewNode` type `ViewQuery` has been renamed to `ViewData`.
- Trait's `RenderCommand` types `ViewWorldQuery` & `ItemWorldQuery` has
been renamed to `ViewData` & `ItemData`, respectively.

## Migration Guide

Note: if merged before 0.13 is released, this should instead modify the
migration guide of #10776 with the updated names.

- Rename `WorldQueryData` & `WorldQueryFilter` trait usages to
`QueryData` & `QueryFilter` and their respective derive macro attributes
`world_query_data` & `world_query_filter` to `query_data` &
`query_filter`.
- Rename the following trait type usages:
  - Trait's `ExtractComponent` type `Query` to `Data`.
  - Trait's `GetBatchData` type `Query` to `Data`.
  - Trait's `ExtractInstance` type `Query` to `Data`.
  - Trait's `ViewNode` type `ViewQuery` to `ViewData`'
- Trait's `RenderCommand` types `ViewWolrdQuery` & `ItemWorldQuery` to
`ViewData` & `ItemData`, respectively.

```rust
// Before
#[derive(WorldQueryData)]
#[world_query_data(derive(Debug))]
struct EmptyQuery {
    empty: (),
}

// After
#[derive(QueryData)]
#[query_data(derive(Debug))]
struct EmptyQuery {
    empty: (),
}

// Before
#[derive(WorldQueryFilter)]
struct CustomQueryFilter<T: Component, P: Component> {
    _c: With<ComponentC>,
    _d: With<ComponentD>,
    _or: Or<(Added<ComponentC>, Changed<ComponentD>, Without<ComponentZ>)>,
    _generic_tuple: (With<T>, With<P>),
}

// After
#[derive(QueryFilter)]
struct CustomQueryFilter<T: Component, P: Component> {
    _c: With<ComponentC>,
    _d: With<ComponentD>,
    _or: Or<(Added<ComponentC>, Changed<ComponentD>, Without<ComponentZ>)>,
    _generic_tuple: (With<T>, With<P>),
}

// Before
impl ExtractComponent for ContrastAdaptiveSharpeningSettings {
    type Query = &'static Self;
    type Filter = With<Camera>;
    type Out = (DenoiseCAS, CASUniform);

    fn extract_component(item: QueryItem<Self::Query>) -> Option<Self::Out> {
        //...
    }
}

// After
impl ExtractComponent for ContrastAdaptiveSharpeningSettings {
    type Data = &'static Self;
    type Filter = With<Camera>;
    type Out = (DenoiseCAS, CASUniform);

    fn extract_component(item: QueryItem<Self::Data>) -> Option<Self::Out> {
        //...
    }
}

// Before
impl GetBatchData for MeshPipeline {
    type Param = SRes<RenderMeshInstances>;
    type Query = Entity;
    type QueryFilter = With<Mesh3d>;
    type CompareData = (MaterialBindGroupId, AssetId<Mesh>);
    type BufferData = MeshUniform;

    fn get_batch_data(
        mesh_instances: &SystemParamItem<Self::Param>,
        entity: &QueryItem<Self::Query>,
    ) -> (Self::BufferData, Option<Self::CompareData>) {
        // ....
    }
}

// After
impl GetBatchData for MeshPipeline {
    type Param = SRes<RenderMeshInstances>;
    type Data = Entity;
    type Filter = With<Mesh3d>;
    type CompareData = (MaterialBindGroupId, AssetId<Mesh>);
    type BufferData = MeshUniform;

    fn get_batch_data(
        mesh_instances: &SystemParamItem<Self::Param>,
        entity: &QueryItem<Self::Data>,
    ) -> (Self::BufferData, Option<Self::CompareData>) {
        // ....
    }
}

// Before
impl<A> ExtractInstance for AssetId<A>
where
    A: Asset,
{
    type Query = Read<Handle<A>>;
    type Filter = ();

    fn extract(item: QueryItem<'_, Self::Query>) -> Option<Self> {
        Some(item.id())
    }
}

// After
impl<A> ExtractInstance for AssetId<A>
where
    A: Asset,
{
    type Data = Read<Handle<A>>;
    type Filter = ();

    fn extract(item: QueryItem<'_, Self::Data>) -> Option<Self> {
        Some(item.id())
    }
}

// Before
impl ViewNode for PostProcessNode {
    type ViewQuery = (
        &'static ViewTarget,
        &'static PostProcessSettings,
    );

    fn run(
        &self,
        _graph: &mut RenderGraphContext,
        render_context: &mut RenderContext,
        (view_target, _post_process_settings): QueryItem<Self::ViewQuery>,
        world: &World,
    ) -> Result<(), NodeRunError> {
        // ...
    }
}

// After
impl ViewNode for PostProcessNode {
    type ViewData = (
        &'static ViewTarget,
        &'static PostProcessSettings,
    );

    fn run(
        &self,
        _graph: &mut RenderGraphContext,
        render_context: &mut RenderContext,
        (view_target, _post_process_settings): QueryItem<Self::ViewData>,
        world: &World,
    ) -> Result<(), NodeRunError> {
        // ...
    }
}

// Before
impl<P: CachedRenderPipelinePhaseItem> RenderCommand<P> for SetItemPipeline {
    type Param = SRes<PipelineCache>;
    type ViewWorldQuery = ();
    type ItemWorldQuery = ();
    #[inline]
    fn render<'w>(
        item: &P,
        _view: (),
        _entity: (),
        pipeline_cache: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        // ...
    }
}

// After
impl<P: CachedRenderPipelinePhaseItem> RenderCommand<P> for SetItemPipeline {
    type Param = SRes<PipelineCache>;
    type ViewData = ();
    type ItemData = ();
    #[inline]
    fn render<'w>(
        item: &P,
        _view: (),
        _entity: (),
        pipeline_cache: SystemParamItem<'w, '_, Self::Param>,
        pass: &mut TrackedRenderPass<'w>,
    ) -> RenderCommandResult {
        // ...
    }
}
```
2023-12-12 19:45:50 +00:00
Ben Frankel
9c8576996f
Add a doc note about despawn footgun (#10889)
# Objective

The `Despawn` command breaks the hierarchy whenever you use it if the
despawned entity has a parent or any children. This is a serious footgun
because the `Despawn` command has the shortest name, the behavior is
unexpected and not likely to be what you want, and the crash that it
causes can be very difficult to track down.

## Solution

Until this can be fixed by relations, add a note mentioning the footgun
in the documentation.
2023-12-12 19:44:05 +00:00
TheBigCheese
6a15ed564d
Improve EntityWorldMut.remove, retain and despawn docs by linking to more detail (#10943)
## Solution

`Commands.remove` and `.retain` (because I copied `remove`s doc)
referenced `EntityWorldMut.remove` and `retain` for more detail but the
`Commands` docs are much more detailed (which makes sense because it is
the most common api), so I have instead inverted this so that
`EntityWorldMut` docs link to `Commands`.

I also made `EntityWorldMut.despawn` reference `World.despawn` for more
details, like `Commands.despawn` does.
2023-12-12 19:27:11 +00:00
Nicola Papale
d2614f2d80
Add a couple assertions for system types (#10893)
# Objective

Test more complex function signatures for exclusive systems, and test
that `StaticSystemParam` is indeed a `SystemParam`.

I mean, it currently works, but might as well add a test for it.
2023-12-06 20:35:46 +00:00
TheBigCheese
9da65b10b4
Add EntityCommands.retain and EntityWorldMut.retain (#10873)
# Objective
Adds `EntityCommands.retain` and `EntityWorldMut.retain` to remove all
components except the given bundle from the entity.
Fixes #10865.

## Solution

I added a private unsafe function in `EntityWorldMut` called
`remove_bundle_info` which performs the shared behaviour of `remove` and
`retain`, namely taking a `BundleInfo` of components to remove, and
removing them from the given entity. Then `retain` simply gets all the
components on the entity and filters them by whether they are in the
bundle it was passed, before passing this `BundleInfo` into
`remove_bundle_info`.

`EntityCommands.retain` just creates a new type `Retain` which runs
`EntityWorldMut.retain` when run.

---

## Changelog

Added `EntityCommands.retain` and `EntityWorldMut.retain`, which remove
all components except the given bundle from the entity, they can also be
used to remove all components by passing `()` as the bundle.
2023-12-05 15:37:33 +00:00
Nathan
24c6a7df05
Clarifying Commands' purpose (#10837)
# Objective
As described in [Issue
#10805](https://github.com/bevyengine/bevy/issues/10805) I have changed
"impactful changes" to "structural changes"

## Solution
Updated the text "impactful" to "structural"
2023-12-02 10:07:19 +00:00
James Liu
2148518758
Override QueryIter::fold to port Query::for_each perf gains to select Iterator combinators (#6773)
# Objective
After #6547, `Query::for_each` has been capable of automatic
vectorization on certain queries, which is seeing a notable (>50% CPU
time improvements) for iteration. However, `Query::for_each` isn't
idiomatic Rust, and lacks the flexibility of iterator combinators.

Ideally, `Query::iter` and friends should be able to achieve the same
results. However, this does seem to blocked upstream
(rust-lang/rust#104914) by Rust's loop optimizations.

## Solution
This is an intermediate solution and refactor. This moves the
`Query::for_each` implementation onto the `Iterator::fold`
implementation for `QueryIter` instead. This should result in the same
automatic vectorization optimization on all `Iterator` functions that
internally use fold, including `Iterator::for_each`, `Iterator::count`,
etc.

With this, it should close the gap between the two completely.
Internally, this PR changes `Query::for_each` to use
`query.iter().for_each(..)` instead of the duplicated implementation.

Separately, the duplicate implementations of internal iteration (i.e.
`Query::par_for_each`) now use portions of the current `Query::for_each`
implementation factored out into their own functions.

This also massively cleans up our internal fragmentation of internal
iteration options, deduplicating the iteration code used in `for_each`
and `par_iter().for_each()`.

---

## Changelog
Changed: `Query::for_each`, `Query::for_each_mut`, `Query::for_each`,
and `Query::for_each_mut` have been moved to `QueryIter`'s
`Iterator::for_each` implementation, and still retains their performance
improvements over normal iteration. These APIs are deprecated in 0.13
and will be removed in 0.14.

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Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2023-12-01 09:09:55 +00:00