# Objective
Since #18704 is done, we can track the length of unique entity row
collections with only a `u32` and identify an index within that
collection with only a `NonMaxU32`. This leaves an opportunity for
performance improvements.
## Solution
- Use `EntityRow` in sparse sets.
- Change table, entity, and query lengths to be `u32` instead of
`usize`.
- Keep `batching` module `usize` based since that is reused for events,
which may exceed `u32::MAX`.
- Change according `Range<usize>` to `Range<u32>`. This is more
efficient and helps justify safety.
- Change `ArchetypeRow` and `TableRow` to wrap `NonMaxU32` instead of
`u32`.
Justifying `NonMaxU32::new_unchecked` everywhere is predicated on this
safety comment in `Entities::set`: "`location` must be valid for the
entity at `index` or immediately made valid afterwards before handing
control to unknown code." This ensures no entity is in two table rows
for example. That fact is used to argue uniqueness of the entity rows in
each table, archetype, sparse set, query, etc. So if there's no
duplicates, and a maximum total entities of `u32::MAX` none of the
corresponding row ids / indexes can exceed `NonMaxU32`.
## Testing
CI
---------
Co-authored-by: Christian Hughes <9044780+ItsDoot@users.noreply.github.com>
# Objective
In my own project I was encountering the issue to find out which
entities were spawned after applying commands. I began maintaining a
vector of all entities with generational information before and after
applying the command and diffing it. This was awfully complicated though
and has no constant complexity but grows with the number of entities.
## Solution
Looking at `EntyMeta` it seemed obvious to me that struct can track the
tick just as it does with `MaybeLocation`, updated from the same call.
After that it became almost a given to also introduce query data
`SpawnDetails` which offers methods to get the spawn tick and location,
and query filter `Spawned` that filters entities out that were not
spawned since the last run.
## Testing
I expanded a few tests and added new ones, though maybe I forgot a group
of tests that should be extended too. I basically searched `bevy_ecs`
for mentions of `Changed` and `Added` to see where the tests and docs
are.
Benchmarks of spawn/despawn can be found
[here](https://github.com/bevyengine/bevy/pull/19047#issuecomment-2852181374).
---
## Showcase
From the added docs, systems with equal complexity since the filter is
not archetypal:
```rs
fn system1(q: Query<Entity, Spawned>) {
for entity in &q { /* entity spawned */ }
}
fn system2(query: Query<(Entity, SpawnDetails)>) {
for (entity, spawned) in &query {
if spawned.is_spawned() { /* entity spawned */ }
}
}
```
`SpawnedDetails` has a few more methods:
```rs
fn print_spawn_details(query: Query<(Entity, SpawnDetails)>) {
for (entity, spawn_details) in &query {
if spawn_details.is_spawned() {
print!("new ");
}
println!(
"entity {:?} spawned at {:?} by {:?}",
entity,
spawn_details.spawned_at(),
spawn_details.spawned_by()
);
}
}
```
## Changes
No public api was changed, I only added to it. That is why I added no
migration guide.
- query data `SpawnDetails`
- query filter `Spawned`
- method `Entities::entity_get_spawned_or_despawned_at`
- method `EntityRef::spawned_at`
- method `EntityMut::spawned_at`
- method `EntityWorldMut::spawned_at`
- method `UnsafeEntityCell::spawned_at`
- method `FilteredEntityRef::spawned_at`
- method `FilteredEntityMut::spawned_at`
- method `EntityRefExcept::spawned_at`
- method `EntityMutExcept::spawned_at`
---------
Co-authored-by: Eagster <79881080+ElliottjPierce@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
There are two problems this aims to solve.
First, `Entity::index` is currently a `u32`. That means there are
`u32::MAX + 1` possible entities. Not only is that awkward, but it also
make `Entity` allocation more difficult. I discovered this while working
on remote entity reservation, but even on main, `Entities` doesn't
handle the `u32::MAX + 1` entity very well. It can not be batch reserved
because that iterator uses exclusive ranges, which has a maximum upper
bound of `u32::MAX - 1`. In other words, having `u32::MAX` as a valid
index can be thought of as a bug right now. We either need to make that
invalid (this PR), which makes Entity allocation cleaner and makes
remote reservation easier (because the length only needs to be u32
instead of u64, which, in atomics is a big deal), or we need to take
another pass at `Entities` to make it handle the `u32::MAX` index
properly.
Second, `TableRow`, `ArchetypeRow` and `EntityIndex` (a type alias for
u32) all have `u32` as the underlying type. That means using these as
the index type in a `SparseSet` uses 64 bits for the sparse list because
it stores `Option<IndexType>`. By using `NonMaxU32` here, we cut the
memory of that list in half. To my knowledge, `EntityIndex` is the only
thing that would really benefit from this niche. `TableRow` and
`ArchetypeRow` I think are not stored in an `Option` in bulk. But if
they ever are, this would help. Additionally this ensures
`TableRow::INVALID` and `ArchetypeRow::INVALID` never conflict with an
actual row, which in a nice bonus.
As a related note, if we do components as entities where `ComponentId`
becomes `Entity`, the the `SparseSet<ComponentId>` will see a similar
memory improvement too.
## Solution
Create a new type `EntityRow` that wraps `NonMaxU32`, similar to
`TableRow` and `ArchetypeRow`.
Change `Entity::index` to this type.
## Downsides
`NonMax` is implemented as a `NonZero` with a binary inversion. That
means accessing and storing the value takes one more instruction. I
don't think that's a big deal, but it's worth mentioning.
As a consequence, `to_bits` uses `transmute` to skip the inversion which
keeps it a nop. But that also means that ordering has now flipped. In
other words, higher indices are considered less than lower indices. I
don't think that's a problem, but it's also worth mentioning.
## Alternatives
We could keep the index as a u32 type and just document that `u32::MAX`
is invalid, modifying `Entities` to ensure it never gets handed out.
(But that's not enforced by the type system.) We could still take
advantage of the niche here in `ComponentSparseSet`. We'd just need some
unsafe manual conversions, which is probably fine, but opens up the
possibility for correctness problems later.
We could change `Entities` to fully support the `u32::MAX` index. (But
that makes `Entities` more complex and potentially slightly slower.)
## Testing
- CI
- A few tests were changed because they depend on different ordering and
`to_bits` values.
## Future Work
- It might be worth removing the niche on `Entity::generation` since
there is now a different niche.
- We could move `Entity::generation` into it's own type too for clarity.
- We should change `ComponentSparseSet` to take advantage of the new
niche. (This PR doesn't change that yet.)
- Consider removing or updating `Identifier`. This is only used for
`Entity`, so it might be worth combining since `Entity` is now more
unique.
---------
Co-authored-by: atlv <email@atlasdostal.com>
Co-authored-by: Zachary Harrold <zac@harrold.com.au>
# Objective
- Fixes a subset of https://github.com/bevyengine/bevy/issues/13735 by
making `EntityRef`, `EntityMut` + similar WorldQueries use the system's
change ticks when being created from within a system.
In particular, this means that `entity_ref.get_ref::<T>()` will use the
correct change ticks (the ones from the system), which matches the
behaviour of querying for `Ref<T>` directly in the system parameters.
## Solution
- Implements the solution described by
https://github.com/bevyengine/bevy/issues/13735#issuecomment-2652482918
which is to add change ticks to the `UnsafeEntityCell`
## Testing
- Added a unit test that is close to what users would encounter: before
this PR the `Added`/`Changed` filters on `Ref`s created from `EntityRef`
are incorrect.
# Objective
A fair few items were deprecated in 0.16. Let's delete them now that
we're in the 0.17 development cycle!
## Solution
- Deleted items marked deprecated in 0.16.
## Testing
- CI
---
## Notes
I'm making the assumption that _everything_ deprecated in 0.16 should be
removed in 0.17. That may be a false assumption in certain cases. Please
check the items to be removed to see if there are any exceptions we
should keep around for another cycle!
# Objective
Let `FilteredEntityRef` and `FilteredEntityMut` receive access when
nested inside tuples or `#[derive(QueryData)]` types. Make sure to
exclude any access that would conflict with other subqueries!
Fixes#14349
## Solution
Replace `WorldQuery::set_access(state, access)` with a new method,
`QueryData::provide_extra_access(state, access, available_access)`, that
passes both the total available access and the currently used access.
This is called after `WorldQuery::update_component_access()`, so any
access used by ordinary subqueries will be known. `FilteredEntityRef`
and `FilteredEntityMut` can use the combination to determine how much
access they can safely take, while tuples can safely pass those
parameters directly to their subqueries.
This requires a new `Access::remove_conflicting_access()` method that
can be used to remove any access that would conflict with existing
access. Implementing this method was easier by first factoring some
common set manipulation code out of `Access::extend`. I can extract that
refactoring to a separate PR if desired.
Have `FilteredEntity(Ref|Mut)` store `Access` instead of
`FilteredAccess` because they do not need to keep track of the filter.
This was necessary in an early draft but no longer is. I left it in
because it's small and I'm touching that code anyway, but I can extract
it to a separate PR if desired.
# Objective
Fixes#17803
## Solution
- Add an `Allows<T>` `QueryFilter` that adds archetypal access for `T`
- Fix access merging to include archetypal from both sides
## Testing
- Added a case to the unit test for the application of
`DefaultQueryFilters`
# Objective
Stop using `ArchetypeComponentId` in the executor. These IDs will grow
even more quickly with relations, and the size may start to degrade
performance.
## Solution
Have systems expose their `FilteredAccessSet<ComponentId>`, and have the
executor use that to determine which systems conflict. This can be
determined statically, so determine all conflicts during initialization
and only perform bit tests when running.
## Testing
I ran many_foxes and didn't see any performance changes. It's probably
worth testing this with a wider range of realistic schedules to see
whether the reduced concurrency has a cost in practice, but I don't know
what sort of test cases to use.
## Migration Guide
The schedule will now prevent systems from running in parallel if there
*could* be an archetype that they conflict on, even if there aren't
actually any. For example, these systems will now conflict even if no
entity has both `Player` and `Enemy` components:
```rust
fn player_system(query: Query<(&mut Transform, &Player)>) {}
fn enemy_system(query: Query<(&mut Transform, &Enemy)>) {}
```
To allow them to run in parallel, use `Without` filters, just as you
would to allow both queries in a single system:
```rust
// Either one of these changes alone would be enough
fn player_system(query: Query<(&mut Transform, &Player), Without<Enemy>>) {}
fn enemy_system(query: Query<(&mut Transform, &Enemy), Without<Player>>) {}
```
# Objective
When implementing `SystemParam` for an object which contains a mutable
reference to World, which cannot be derived due to a required lifetime
parameter, it's necessary to check that there aren't any conflicts.
As far as I know, the is_empty method is the only way provided to check
for no conflicts at all
# Objective
The goal of `bevy_platform_support` is to provide a set of platform
agnostic APIs, alongside platform-specific functionality. This is a high
traffic crate (providing things like HashMap and Instant). Especially in
light of https://github.com/bevyengine/bevy/discussions/18799, it
deserves a friendlier / shorter name.
Given that it hasn't had a full release yet, getting this change in
before Bevy 0.16 makes sense.
## Solution
- Rename `bevy_platform_support` to `bevy_platform`.
# Objective
Newest installment of the #16547 series.
In #18319 we introduced `Entity` defaults to accomodate the most common
use case for these types, however that resulted in the switch of the `T`
and `N` generics of `UniqueEntityArray`.
Swapping generics might be somewhat acceptable for `UniqueEntityArray`,
it is not at all acceptable for map and set types, which we would make
generic over `T: EntityEquivalent` in #18408.
Leaving these defaults in place would result in a glaring inconsistency
between these set collections and the others.
Additionally, the current standard in the engine is for "entity" to mean
`Entity`. APIs could be changed to accept `EntityEquivalent`, however
that is a separate and contentious discussion.
## Solution
Name these set collections `UniqueEntityEquivalent*`, and retain the
`UniqueEntity*` name for an alias of the `Entity` case.
While more verbose, this allows for all generics to be in proper order,
full consistency between all set types*, and the "entity" name to be
restricted to `Entity`.
On top of that, `UniqueEntity*` now always have 1 generic less, when
previously this was not enforced for the default case.
*`UniqueEntityIter<I: Iterator<T: EntityEquivalent>>` is the sole
exception to this. Aliases are unable to enforce bounds
(`lazy_type_alias` is needed for this), so for this type, doing this
split would be a mere suggestion, and in no way enforced.
Iterator types are rarely ever named, and this specific one is intended
to be aliased when it sees more use, like we do for the corresponding
set collection iterators.
Furthermore, the `EntityEquivalent` precursor `Borrow<Entity>` was used
exactly because of such iterator bounds!
Because of that, we leave it as is.
While no migration guide for 0.15 users, for those that upgrade from
main:
`UniqueEntityVec<T>` -> `UniqueEntityEquivalentVec<T>`
`UniqueEntitySlice<T>` -> `UniqueEntityEquivalentSlice<T>`
`UniqueEntityArray<N, T>` -> `UniqueEntityEquivalentArray<T, N>`
# Objective
#18173 allows components to be queued without being fully registered.
But much of bevy's debug logging contained
`components.get_name(id).unwrap()`. However, this panics when the id is
queued. This PR fixes this, allowing names to be retrieved for debugging
purposes, etc, even while they're still queued.
## Solution
We change `ComponentInfo::descriptor` to be `Arc<ComponentDescriptor>`
instead of not arc'd. This lets us pass the descriptor around (as a name
or otherwise) as needed. The alternative would require some form of
`MappedRwLockReadGuard`, which is unstable, and would be terribly
blocking. Putting it in an arc also signifies that it doesn't change,
which is a nice signal to users. This does mean there's an extra pointer
dereference, but I don't think that's an issue here, as almost all paths
that use this are for debugging purposes or one-time set ups.
## Testing
Existing tests.
## Migration Guide
`Components::get_name` now returns `Option<Cow<'_, str>` instead of
`Option<&str>`. This is because it now returns results for queued
components. If that behavior is not desired, or you know the component
is not queued, you can use
`components.get_info().map(ComponentInfo::name)` instead.
Similarly, `ScheduleGraph::conflicts_to_string` now returns `impl
Iterator<Item = (String, String, Vec<Cow<str>>)>` instead of `impl
Iterator<Item = (String, String, Vec<&str>)>`. Because `Cow<str>` derefs
to `&str`, most use cases can remain unchanged.
---------
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
# Objective
Fixes#9367.
Yet another follow-up to #16547.
These traits were initially based on `Borrow<Entity>` because that trait
was what they were replacing, and it felt close enough in meaning.
However, they ultimately don't quite match: `borrow` always returns
references, whereas `EntityBorrow` always returns a plain `Entity`.
Additionally, `EntityBorrow` can imply that we are borrowing an `Entity`
from the ECS, which is not what it does.
Due to its safety contract, `TrustedEntityBorrow` is important an
important and widely used trait for `EntitySet` functionality.
In contrast, the safe `EntityBorrow` does not see much use, because even
outside of `EntitySet`-related functionality, it is a better idea to
accept `TrustedEntityBorrow` over `EntityBorrow`.
Furthermore, as #9367 points out, abstracting over returning `Entity`
from pointers/structs that contain it can skip some ergonomic friction.
On top of that, there are aspects of #18319 and #18408 that are relevant
to naming:
We've run into the issue that relying on a type default can switch
generic order. This is livable in some contexts, but unacceptable in
others.
To remedy that, we'd need to switch to a type alias approach:
The "defaulted" `Entity` case becomes a
`UniqueEntity*`/`Entity*Map`/`Entity*Set` alias, and the base type
receives a more general name. `TrustedEntityBorrow` does not mesh
clearly with sensible base type names.
## Solution
Replace any `EntityBorrow` bounds with `TrustedEntityBorrow`.
+
Rename them as such:
`EntityBorrow` -> `ContainsEntity`
`TrustedEntityBorrow` -> `EntityEquivalent`
For `EntityBorrow` we produce a change in meaning; We designate it for
types that aren't necessarily strict wrappers around `Entity` or some
pointer to `Entity`, but rather any of the myriad of types that contain
a single associated `Entity`.
This pattern can already be seen in the common `entity`/`id` methods
across the engine.
We do not mean for `ContainsEntity` to be a trait that abstracts input
API (like how `AsRef<T>` is often used, f.e.), because eliding
`entity()` would be too implicit in the general case.
We prefix "Contains" to match the intuition of a struct with an `Entity`
field, like some contain a `length` or `capacity`.
It gives the impression of structure, which avoids the implication of a
relationship to the `ECS`.
`HasEntity` f.e. could be interpreted as "a currently live entity",
As an input trait for APIs like #9367 envisioned, `TrustedEntityBorrow`
is a better fit, because it *does* restrict itself to strict wrappers
and pointers. Which is why we replace any
`EntityBorrow`/`ContainsEntity` bounds with
`TrustedEntityBorrow`/`EntityEquivalent`.
Here, the name `EntityEquivalent` is a lot closer to its actual meaning,
which is "A type that is both equivalent to an `Entity`, and forms the
same total order when compared".
Prior art for this is the
[`Equivalent`](https://docs.rs/hashbrown/latest/hashbrown/trait.Equivalent.html)
trait in `hashbrown`, which utilizes both `Borrow` and `Eq` for its one
blanket impl!
Given that we lose the `Borrow` moniker, and `Equivalent` can carry
various meanings, we expand on the safety comment of `EntityEquivalent`
somewhat. That should help prevent the confusion we saw in
[#18408](https://github.com/bevyengine/bevy/pull/18408#issuecomment-2742094176).
The new name meshes a lot better with the type aliasing approach in
#18408, by aligning with the base name `EntityEquivalentHashMap`.
For a consistent scheme among all set types, we can use this scheme for
the `UniqueEntity*` wrapper types as well!
This allows us to undo the switched generic order that was introduced to
`UniqueEntityArray` by its `Entity` default.
Even without the type aliases, I think these renames are worth doing!
## Migration Guide
Any use of `EntityBorrow` becomes `ContainsEntity`.
Any use of `TrustedEntityBorrow` becomes `EntityEquivalent`.
# Objective
Unlike for their helper typers, the import paths for
`unique_array::UniqueEntityArray`, `unique_slice::UniqueEntitySlice`,
`unique_vec::UniqueEntityVec`, `hash_set::EntityHashSet`,
`hash_map::EntityHashMap`, `index_set::EntityIndexSet`,
`index_map::EntityIndexMap` are quite redundant.
When looking at the structure of `hashbrown`, we can also see that while
both `HashSet` and `HashMap` have their own modules, the main types
themselves are re-exported to the crate level.
## Solution
Re-export the types in their shared `entity` parent module, and simplify
the imports where they're used.
# Objective
Continuation to #16547 and #17954.
The `get_many` family are the last methods on `Query`/`QueryState` for
which we're still missing a `unique` version.
## Solution
Offer `get_many_unique`/`get_many_unique_mut` and
`get_many_unique_inner`!
Their implementation is the same as `get_many`, the difference lies in
their guaranteed-to-be unique inputs, meaning we never do any aliasing
checks.
To reduce confusion, we also rename `get_many_readonly` into
`get_many_inner` and the current `get_many_inner` into
`get_many_mut_inner` to clarify their purposes.
## Testing
Doc examples.
## Migration Guide
`get_many_inner` is now called `get_many_mut_inner`.
`get_many_readonly` is now called `get_many_inner`.
# Objective
Prevents duplicate implementation between IntoSystemConfigs and
IntoSystemSetConfigs using a generic, adds a NodeType trait for more
config flexibility (opening the door to implement
https://github.com/bevyengine/bevy/issues/14195?).
## Solution
Followed writeup by @ItsDoot:
https://hackmd.io/@doot/rJeefFHc1x
Removes IntoSystemConfigs and IntoSystemSetConfigs, instead using
IntoNodeConfigs with generics.
## Testing
Pending
---
## Showcase
N/A
## Migration Guide
SystemSetConfigs -> NodeConfigs<InternedSystemSet>
SystemConfigs -> NodeConfigs<ScheduleSystem>
IntoSystemSetConfigs -> IntoNodeConfigs<InternedSystemSet, M>
IntoSystemConfigs -> IntoNodeConfigs<ScheduleSystem, M>
---------
Co-authored-by: Christian Hughes <9044780+ItsDoot@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Prevent usage of `println!`, `eprintln!` and the like because they
require `std`
- Fixes#17446
## Solution
- Enable the `print_stdout` and `print_stderr` clippy lints
- Replace all `println!` and `eprintln!` occurrences with `log::*` where
applicable or alternatively ignore the warnings
## Testing
- Run `cargo clippy --workspace` to ensure that there are no warnings
relating to printing to `stdout` or `stderr`
# Objective
Part of the #16547 series.
The entity wrapper types often have some associated types an aliases
with them that cannot be re-exported into an outer module together.
Some helper types are best used with part of their path:
`bevy::ecs::entity::index_set::Slice` as `index_set::Slice`.
This has already been done for `entity::hash_set` and
`entity::hash_map`.
## Solution
Publicize the `index_set`, `index_map`, `unique_vec`, `unique_slice`,
and `unique_array` modules.
## Migration Guide
Any mention or import of types in the affected modules have to add the
respective module name to the import path.
F.e.:
`bevy::ecs::entity::EntityIndexSet` ->
`bevy::ecs::entity::index_set::EntityIndexSet`
# Objective
This is an alternative to #17871 and #17701 for tracking issue #18155.
This thanks to @maniwani for help with this design.
The goal is to enable component ids to be reserved from multiple threads
concurrently and with only `&World`. This contributes to assets as
entities, read-only query and system parameter initialization, etc.
## What's wrong with #17871 ?
In #17871, I used my proposed staging utilities to allow *fully*
registering components from any thread concurrently with only
`&Components`. However, if we want to pursue components as entities
(which is desirable for a great many reasons. See
[here](https://discord.com/channels/691052431525675048/692572690833473578/1346499196655505534)
on discord), this staging isn't going to work. After all, if registering
a component requires spawning an entity, and spawning an entity requires
`&mut World`, it is impossible to register a component fully with only
`&World`.
## Solution
But what if we don't have to register it all the way? What if it's
enough to just know the `ComponentId` it will have once it is registered
and to queue it to be registered at a later time? Spoiler alert: That is
all we need for these features.
Here's the basic design:
Queue a registration:
1. Check if it has already been registered.
2. Check if it has already been queued.
3. Reserve a `ComponentId`.
4. Queue the registration at that id.
Direct (normal) registration:
1. Check if this registration has been queued.
2. If it has, use the queued registration instead.
3. Otherwise, proceed like normal.
Appllying the queue:
1. Pop queued items off one by one.
2. Register them directly.
One other change:
The whole point of this design over #17871 is to facilitate coupling
component registration with the World. To ensure that this would fully
work with that, I went ahead and moved the `ComponentId` generator onto
the world itself. That stemmed a couple of minor organizational changes
(see migration guide). As we do components as entities, we will replace
this generator with `Entities`, which lives on `World` too. Doing this
move early let me verify the design and will reduce migration headaches
in the future. If components as entities is as close as I think it is, I
don't think splitting this up into different PRs is worth it. If it is
not as close as it is, it might make sense to still do #17871 in the
meantime (see the risks section). I'll leave it up to y'all what we end
up doing though.
## Risks and Testing
The biggest downside of this compared to #17871 is that now we have to
deal with correct but invalid `ComponentId`s. They are invalid because
the component still isn't registered, but they are correct because, once
registered, the component will have exactly that id.
However, the only time this becomes a problem is if some code violates
safety rules by queuing a registration and using the returned id as if
it was valid. As this is a new feature though, nothing in Bevy does
this, so no new tests were added for it. When we do use it, I left
detailed docs to help mitigate issues here, and we can test those
usages. Ex: we will want some tests on using queries initialized from
queued registrations.
## Migration Guide
Component registration can now be queued with only `&World`. To
facilitate this, a few APIs needed to be moved around.
The following functions have moved from `Components` to
`ComponentsRegistrator`:
- `register_component`
- `register_component_with_descriptor`
- `register_resource_with_descriptor`
- `register_non_send`
- `register_resource`
- `register_required_components_manual`
Accordingly, functions in `Bundle` and `Component` now take
`ComponentsRegistrator` instead of `Components`.
You can obtain `ComponentsRegistrator` from the new
`World::components_registrator`.
You can obtain `ComponentsQueuedRegistrator` from the new
`World::components_queue`, and use it to stage component registration if
desired.
# Open Question
Can we verify that it is enough to queue registration with `&World`? I
don't think it would be too difficult to package this up into a
`Arc<MyComponentsManager>` type thing if we need to, but keeping this on
`&World` certainly simplifies things. If we do need the `Arc`, we'll
need to look into partitioning `Entities` for components as entities, so
we can keep most of the allocation fast on `World` and only keep a
smaller partition in the `Arc`. I'd love an SME on assets as entities to
shed some light on this.
---------
Co-authored-by: andriyDev <andriydzikh@gmail.com>
# Objective
- Allow `Query` methods such as `Query::get` to have their error
short-circuited using `?` in systems using Bevy's `Error` type
## Solution
- Removed `UnsafeWorldCell<'w>` from `QueryEntityError` and instead
store `ArchetypeId` (the information the error formatter was extracting
anyway).
- Replaced trait implementations with derives now that the type is
plain-old-data.
## Testing
- CI
---
## Migration Guide
- `QueryEntityError::QueryDoesNotMatch.1` is of type `ArchetypeId`
instead of `UnsafeWorldCell`. It is up to the caller to obtain an
`UnsafeWorldCell` now.
- `QueryEntityError` no longer has a lifetime parameter, remove it from
type signatures where required.
## Notes
This was discussed on Discord and accepted by Cart as the desirable path
forward in [this
message](https://discord.com/channels/691052431525675048/749335865876021248/1346611950527713310).
Scroll up from this point for context.
---------
Co-authored-by: SpecificProtagonist <30270112+SpecificProtagonist@users.noreply.github.com>
# Objective
Alternative to and closes#18120.
Sibling to #18082, see that PR for broader reasoning.
Folks weren't sold on the name `many` (get_many is clearer, and this is
rare), and that PR is much more complex.
## Solution
- Simply deprecate `Query::many` and `Query::many_mut`
- Clean up internal usages
Mentions of this in the docs can wait until it's fully removed in the
0.17 cycle IMO: it's much easier to catch the problems when doing that.
## Testing
CI!
## Migration Guide
`Query::many` and `Query::many_mut` have been deprecated to reduce
panics and API duplication. Use `Query::get_many` and
`Query::get_many_mut` instead, and handle the `Result`.
---------
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
## Objective
Fixes#18092
Bevy's current error type is a simple type alias for `Box<dyn Error +
Send + Sync + 'static>`. This largely works as a catch-all error, but it
is missing a critical feature: the ability to capture a backtrace at the
point that the error occurs. The best way to do this is `anyhow`-style
error handling: a new error type that takes advantage of the fact that
the `?` `From` conversion happens "inline" to capture the backtrace at
the point of the error.
## Solution
This PR adds a new `BevyError` type (replacing our old
`std::error::Error` type alias), which uses the "from conversion
backtrace capture" approach:
```rust
fn oh_no() -> Result<(), BevyError> {
// this fails with Rust's built in ParseIntError, which
// is converted into the catch-all BevyError type
let number: usize = "hi".parse()?;
println!("parsed {number}");
Ok(())
}
```
This also updates our exported `Result` type alias to default to
`BevyError`, meaning you can write this instead:
```rust
fn oh_no() -> Result {
let number: usize = "hi".parse()?;
println!("parsed {number}");
Ok(())
}
```
When a BevyError is encountered in a system, it will use Bevy's default
system error handler (which panics by default). BevyError does custom
"backtrace filtering" by default, meaning we can cut out the _massive_
amount of "rust internals", "async executor internals", and "bevy system
scheduler internals" that show up in backtraces. It also trims out the
first generally-unnecssary `From` conversion backtrace lines that make
it harder to locate the real error location. The result is a blissfully
simple backtrace by default:
The full backtrace can be shown by setting the `BEVY_BACKTRACE=full`
environment variable. Non-BevyError panics still use the default Rust
backtrace behavior.
One issue that prevented the truly noise-free backtrace during panics
that you see above is that Rust's default panic handler will print the
unfiltered (and largely unhelpful real-panic-point) backtrace by
default, in _addition_ to our filtered BevyError backtrace (with the
helpful backtrace origin) that we capture and print. To resolve this, I
have extended Bevy's existing PanicHandlerPlugin to wrap the default
panic handler. If we panic from the result of a BevyError, we will skip
the default "print full backtrace" panic handler. This behavior can be
enabled and disabled using the new `error_panic_hook` cargo feature in
`bevy_app` (which is enabled by default).
One downside to _not_ using `Box<dyn Error>` directly is that we can no
longer take advantage of the built-in `Into` impl for strings to errors.
To resolve this, I have added the following:
```rust
// Before
Err("some error")?
// After
Err(BevyError::message("some error"))?
```
We can discuss adding shorthand methods or macros for this (similar to
anyhow's `anyhow!("some error")` macro), but I'd prefer to discuss that
later.
I have also added the following extension method:
```rust
// Before
some_option.ok_or("some error")?;
// After
some_option.ok_or_message("some error")?;
```
I've also moved all of our existing error infrastructure from
`bevy_ecs::result` to `bevy_ecs::error`, as I think that is the better
home for it
## Why not anyhow (or eyre)?
The biggest reason is that `anyhow` needs to be a "generically useful
error type", whereas Bevy is a much narrower scope. By using our own
error, we can be significantly more opinionated. For example, anyhow
doesn't do the extensive (and invasive) backtrace filtering that
BevyError does because it can't operate on Bevy-specific context, and
needs to be generically useful.
Bevy also has a lot of operational context (ex: system info) that could
be useful to attach to errors. If we have control over the error type,
we can add whatever context we want to in a structured way. This could
be increasingly useful as we add more visual / interactive error
handling tools and editor integrations.
Additionally, the core approach used is simple and requires almost no
code. anyhow clocks in at ~2500 lines of code, but the impl here uses
160. We are able to boil this down to exactly what we need, and by doing
so we improve our compile times and the understandability of our code.
# Objective
Fix unsound query transmutes on queries obtained from
`Query::as_readonly()`.
The following compiles, and the call to `transmute_lens()` should panic,
but does not:
```rust
fn bad_system(query: Query<&mut A>) {
let mut readonly = query.as_readonly();
let mut lens: QueryLens<&mut A> = readonly.transmute_lens();
let other_readonly: Query<&A> = query.as_readonly();
// `lens` and `other_readonly` alias, and are both alive here!
}
```
To make `Query::as_readonly()` zero-cost, we pointer-cast
`&QueryState<D, F>` to `&QueryState<D::ReadOnly, F>`. This means that
the `component_access` for a read-only query's state may include
accesses for the original mutable version, but the `Query` does not have
exclusive access to those components! `transmute` and `join` use that
access to ensure that a join is valid, and will incorrectly allow a
transmute that includes mutable access.
As a bonus, allow `Query::join`s that output `FilteredEntityRef` or
`FilteredEntityMut` to receive access from the `other` query. Currently
they only receive access from `self`.
## Solution
When transmuting or joining from a read-only query, remove any writes
before performing checking that the transmute is valid. For joins, be
sure to handle the case where one input query was the result of
`as_readonly()` but the other has valid mutable access.
This requires identifying read-only queries, so add a
`QueryData::IS_READ_ONLY` associated constant. Note that we only call
`QueryState::as_transmuted_state()` with `NewD: ReadOnlyQueryData`, so
checking for read-only queries is sufficient to check for
`as_transmuted_state()`.
Removing writes requires allocating a new `FilteredAccess`, so only do
so if the query is read-only and the state has writes. Otherwise, the
existing access is correct and we can continue using a reference to it.
Use the new read-only state to call `NewD::set_access`, so that
transmuting to a `FilteredAccessMut` results in a read-only
`FilteredAccessMut`. Otherwise, it would take the original write access,
and then the transmute would panic because it had too much access.
Note that `join` was previously passing `self.component_access` to
`NewD::set_access`. Switching it to `joined_component_access` also
allows a join that outputs `FilteredEntity(Ref|Mut)` to receive access
from `other`. The fact that it didn't do that before seems like an
oversight, so I didn't try to prevent that change.
## Testing
Added unit tests with the unsound transmute and join.
# Objective
- Fixes#16339
## Solution
- Replaced `component_reads_and_writes` and `component_writes` with
`try_iter_component_access`.
## Testing
- Ran `dynamic` example to confirm behaviour is unchanged.
- CI
---
## Migration Guide
The following methods (some removed in previous PRs) are now replaced by
`Access::try_iter_component_access`:
* `Access::component_reads_and_writes`
* `Access::component_reads`
* `Access::component_writes`
As `try_iter_component_access` returns a `Result`, you'll now need to
handle the failing case (e.g., `unwrap()`). There is currently a single
failure mode, `UnboundedAccess`, which occurs when the `Access` is for
all `Components` _except_ certain exclusions. Since this list is
infinite, there is no meaningful way for `Access` to provide an
iterator. Instead, get a list of components (e.g., from the `Components`
structure) and iterate over that instead, filtering using
`Access::has_component_read`, `Access::has_component_write`, etc.
Additionally, you'll need to `filter_map` the accesses based on which
method you're attempting to replace:
* `Access::component_reads_and_writes` -> `Exclusive(_) | Shared(_)`
* `Access::component_reads` -> `Shared(_)`
* `Access::component_writes` -> `Exclusive(_)`
To ease migration, please consider the below extension trait which you
can include in your project:
```rust
pub trait AccessCompatibilityExt {
/// Returns the indices of the components this has access to.
fn component_reads_and_writes(&self) -> impl Iterator<Item = T> + '_;
/// Returns the indices of the components this has non-exclusive access to.
fn component_reads(&self) -> impl Iterator<Item = T> + '_;
/// Returns the indices of the components this has exclusive access to.
fn component_writes(&self) -> impl Iterator<Item = T> + '_;
}
impl<T: SparseSetIndex> AccessCompatibilityExt for Access<T> {
fn component_reads_and_writes(&self) -> impl Iterator<Item = T> + '_ {
self
.try_iter_component_access()
.expect("Access is unbounded. Please refactor the usage of this method to directly use try_iter_component_access")
.filter_map(|component_access| {
let index = component_access.index().sparse_set_index();
match component_access {
ComponentAccessKind::Archetypal(_) => None,
ComponentAccessKind::Shared(_) => Some(index),
ComponentAccessKind::Exclusive(_) => Some(index),
}
})
}
fn component_reads(&self) -> impl Iterator<Item = T> + '_ {
self
.try_iter_component_access()
.expect("Access is unbounded. Please refactor the usage of this method to directly use try_iter_component_access")
.filter_map(|component_access| {
let index = component_access.index().sparse_set_index();
match component_access {
ComponentAccessKind::Archetypal(_) => None,
ComponentAccessKind::Shared(_) => Some(index),
ComponentAccessKind::Exclusive(_) => None,
}
})
}
fn component_writes(&self) -> impl Iterator<Item = T> + '_ {
self
.try_iter_component_access()
.expect("Access is unbounded. Please refactor the usage of this method to directly use try_iter_component_access")
.filter_map(|component_access| {
let index = component_access.index().sparse_set_index();
match component_access {
ComponentAccessKind::Archetypal(_) => None,
ComponentAccessKind::Shared(_) => None,
ComponentAccessKind::Exclusive(_) => Some(index),
}
})
}
}
```
Please take note of the use of `expect(...)` in these methods. You
should consider using these as a starting point for a more appropriate
migration based on your specific needs.
## Notes
- This new method is fallible based on whether the `Access` is bounded
or unbounded (unbounded occurring with inverted component sets). If
bounded, will return an iterator of every item and its access level. I
believe this makes sense without exposing implementation details around
`Access`.
- The access level is defined by an `enum` `ComponentAccessKind<T>`,
either `Archetypical`, `Shared`, or `Exclusive`. As a convenience, this
`enum` has a method `index` to get the inner `T` value without a match
statement. It does add more code, but the API is clearer.
- Within `QueryBuilder` this new method simplifies several pieces of
logic without changing behaviour.
- Within `QueryState` the logic is simplified and the amount of
iteration is reduced, potentially improving performance.
- Within the `dynamic` example it has identical behaviour, with the
inversion footgun explicitly highlighted by an `unwrap`.
---------
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
Co-authored-by: Mike <2180432+hymm@users.noreply.github.com>
The test case `query_iter_sorts` was doing lots of comparisons to ensure
that various query arrays were sorted, but the arrays were all empty.
This PR spawns some entities so that the entity lists to compare not
empty, and sorting can actually be tested for correctness.
# Objective
As discussed in #14275, Bevy is currently too prone to panic, and makes
the easy / beginner-friendly way to do a large number of operations just
to panic on failure.
This is seriously frustrating in library code, but also slows down
development, as many of the `Query::single` panics can actually safely
be an early return (these panics are often due to a small ordering issue
or a change in game state.
More critically, in most "finished" products, panics are unacceptable:
any unexpected failures should be handled elsewhere. That's where the
new
With the advent of good system error handling, we can now remove this.
Note: I was instrumental in a) introducing this idea in the first place
and b) pushing to make the panicking variant the default. The
introduction of both `let else` statements in Rust and the fancy system
error handling work in 0.16 have changed my mind on the right balance
here.
## Solution
1. Make `Query::single` and `Query::single_mut` (and other random
related methods) return a `Result`.
2. Handle all of Bevy's internal usage of these APIs.
3. Deprecate `Query::get_single` and friends, since we've moved their
functionality to the nice names.
4. Add detailed advice on how to best handle these errors.
Generally I like the diff here, although `get_single().unwrap()` in
tests is a bit of a downgrade.
## Testing
I've done a global search for `.single` to track down any missed
deprecated usages.
As to whether or not all the migrations were successful, that's what CI
is for :)
## Future work
~~Rename `Query::get_single` and friends to `Query::single`!~~
~~I've opted not to do this in this PR, and smear it across two releases
in order to ease the migration. Successive deprecations are much easier
to manage than the semantics and types shifting under your feet.~~
Cart has convinced me to change my mind on this; see
https://github.com/bevyengine/bevy/pull/18082#discussion_r1974536085.
## Migration guide
`Query::single`, `Query::single_mut` and their `QueryState` equivalents
now return a `Result`. Generally, you'll want to:
1. Use Bevy 0.16's system error handling to return a `Result` using the
`?` operator.
2. Use a `let else Ok(data)` block to early return if it's an expected
failure.
3. Use `unwrap()` or `Ok` destructuring inside of tests.
The old `Query::get_single` (etc) methods which did this have been
deprecated.
# Objective
`QueryIter::sort_by()` is unsound. It passes the lens items with the
full `'w` lifetime, and a malicious user could smuggle them out of the
closure where they could alias with the query results.
## Solution
Make the sort closures generic in the lifetime parameter of the lens
item. This ensures the lens items cannot outlive the call to the
closure.
## Testing
Added a compile-fail test that demonstrates the unsound pattern.
## Migration Guide
The `sort` family of methods on `QueryIter` unsoundly gave access
`L::Item<'w>` with the full `'w` lifetime. It has been shortened to
`L::Item<'w>` so that items cannot escape the comparer. If you get
lifetime errors using these methods, you will need to make the comparer
generic in the new lifetime. Often this can be done by replacing named
`'w` with `'_`, or by replacing the use of a function item with a
closure.
```rust
// Before: Now fails with "error: implementation of `FnMut` is not general enough"
query.iter().sort_by::<&C>(Ord::cmp);
// After: Wrap in a closure
query.iter().sort_by::<&C>(|l, r| Ord::cmp(l, r));
query.iter().sort_by::<&C>(comparer);
// Before: Uses specific `'w` lifetime from some outer scope
// now fails with "error: implementation of `FnMut` is not general enough"
fn comparer(left: &&'w C, right: &&'w C) -> Ordering { /* ... */ }
// After: Accepts any lifetime using inferred lifetime parameter
fn comparer(left: &&C, right: &&C) -> Ordering { /* ... */ }
# Objective
- Fixes#17960
## Solution
- Followed the [edition upgrade
guide](https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)
## Testing
- CI
---
## Summary of Changes
### Documentation Indentation
When using lists in documentation, proper indentation is now linted for.
This means subsequent lines within the same list item must start at the
same indentation level as the item.
```rust
/* Valid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
/* Invalid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
```
### Implicit `!` to `()` Conversion
`!` (the never return type, returned by `panic!`, etc.) no longer
implicitly converts to `()`. This is particularly painful for systems
with `todo!` or `panic!` statements, as they will no longer be functions
returning `()` (or `Result<()>`), making them invalid systems for
functions like `add_systems`. The ideal fix would be to accept functions
returning `!` (or rather, _not_ returning), but this is blocked on the
[stabilisation of the `!` type
itself](https://doc.rust-lang.org/std/primitive.never.html), which is
not done.
The "simple" fix would be to add an explicit `-> ()` to system
signatures (e.g., `|| { todo!() }` becomes `|| -> () { todo!() }`).
However, this is _also_ banned, as there is an existing lint which (IMO,
incorrectly) marks this as an unnecessary annotation.
So, the "fix" (read: workaround) is to put these kinds of `|| -> ! { ...
}` closuers into variables and give the variable an explicit type (e.g.,
`fn()`).
```rust
// Valid
let system: fn() = || todo!("Not implemented yet!");
app.add_systems(..., system);
// Invalid
app.add_systems(..., || todo!("Not implemented yet!"));
```
### Temporary Variable Lifetimes
The order in which temporary variables are dropped has changed. The
simple fix here is _usually_ to just assign temporaries to a named
variable before use.
### `gen` is a keyword
We can no longer use the name `gen` as it is reserved for a future
generator syntax. This involved replacing uses of the name `gen` with
`r#gen` (the raw-identifier syntax).
### Formatting has changed
Use statements have had the order of imports changed, causing a
substantial +/-3,000 diff when applied. For now, I have opted-out of
this change by amending `rustfmt.toml`
```toml
style_edition = "2021"
```
This preserves the original formatting for now, reducing the size of
this PR. It would be a simple followup to update this to 2024 and run
`cargo fmt`.
### New `use<>` Opt-Out Syntax
Lifetimes are now implicitly included in RPIT types. There was a handful
of instances where it needed to be added to satisfy the borrow checker,
but there may be more cases where it _should_ be added to avoid
breakages in user code.
### `MyUnitStruct { .. }` is an invalid pattern
Previously, you could match against unit structs (and unit enum
variants) with a `{ .. }` destructuring. This is no longer valid.
### Pretty much every use of `ref` and `mut` are gone
Pattern binding has changed to the point where these terms are largely
unused now. They still serve a purpose, but it is far more niche now.
### `iter::repeat(...).take(...)` is bad
New lint recommends using the more explicit `iter::repeat_n(..., ...)`
instead.
## Migration Guide
The lifetimes of functions using return-position impl-trait (RPIT) are
likely _more_ conservative than they had been previously. If you
encounter lifetime issues with such a function, please create an issue
to investigate the addition of `+ use<...>`.
## Notes
- Check the individual commits for a clearer breakdown for what
_actually_ changed.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
## Objective
There's no general error for when an entity doesn't exist, and some
methods are going to need one when they get Resultified. The closest
thing is `EntityFetchError`, but that error has a slightly more specific
purpose.
## Solution
- Added `EntityDoesNotExistError`.
- Contains `Entity` and `EntityDoesNotExistDetails`.
- Changed `EntityFetchError` and `QueryEntityError`:
- Changed `NoSuchEntity` variant to wrap `EntityDoesNotExistError` and
renamed the variant to `EntityDoesNotExist`.
- Renamed `EntityFetchError` to `EntityMutableFetchError` to make its
purpose clearer.
- Renamed `TryDespawnError` to `EntityDespawnError` to make it more
general.
- Changed `World::inspect_entity` to return `Result<[ok],
EntityDoesNotExistError>` instead of panicking.
- Changed `World::get_entity` and `WorldEntityFetch::fetch_ref` to
return `Result<[ok], EntityDoesNotExistError>` instead of `Result<[ok],
Entity>`.
- Changed `UnsafeWorldCell::get_entity` to return
`Result<UnsafeEntityCell, EntityDoesNotExistError>` instead of
`Option<UnsafeEntityCell>`.
## Migration Guide
- `World::inspect_entity` now returns `Result<impl Iterator<Item =
&ComponentInfo>, EntityDoesNotExistError>` instead of `impl
Iterator<Item = &ComponentInfo>`.
- `World::get_entity` now returns `EntityDoesNotExistError` as an error
instead of `Entity`. You can still access the entity's ID through the
error's `entity` field.
- `UnsafeWorldCell::get_entity` now returns `Result<UnsafeEntityCell,
EntityDoesNotExistError>` instead of `Option<UnsafeEntityCell>`.
# Objective
Simplify the API surface by removing duplicated functionality between
`Query` and `QueryState`.
Reduce the amount of `unsafe` code required in `QueryState`.
This is a follow-up to #15858.
## Solution
Move implementations of `Query` methods from `QueryState` to `Query`.
Instead of the original methods being on `QueryState`, with `Query`
methods calling them by passing the individual parameters, the original
methods are now on `Query`, with `QueryState` methods calling them by
constructing a `Query`.
This also adds two `_inner` methods that were missed in #15858:
`iter_many_unique_inner` and `single_inner`.
One goal here is to be able to deprecate and eventually remove many of
the methods on `QueryState`, reducing the overall API surface. (I
expected to do that in this PR, but this change was large enough on its
own!) Now that the `QueryState` methods each consist of a simple
expression like `self.query(world).get_inner(entity)`, a future PR can
deprecate some or all of them with simple migration instructions.
The other goal is to reduce the amount of `unsafe` code. The current
implementation of a read-only method like `QueryState::get` directly
calls the `unsafe fn get_unchecked_manual` and needs to repeat the proof
that `&World` has enough access. With this change, `QueryState::get` is
entirely safe code, with the proof that `&World` has enough access done
by the `query()` method and shared across all read-only operations.
## Future Work
The next step will be to mark the `QueryState` methods as
`#[deprecated]` and migrate callers to the methods on `Query`.
# Objective
Continuation of #16547.
We do not yet have parallel versions of `par_iter_many` and
`par_iter_many_unique`. It is currently very painful to try and use
parallel iteration over entity lists. Even if a list is not long, each
operation might still be very expensive, and worth parallelizing.
Plus, it has been requested several times!
## Solution
Once again, we implement what we lack!
These parallel iterators collect their input entity list into a
`Vec`/`UniqueEntityVec`, then chunk that over the available threads,
inspired by the original `par_iter`.
Since no order guarantee is given to the caller, we could sort the input
list according to `EntityLocation`, but that would likely only be worth
it for very large entity lists.
There is some duplication which could likely be improved, but I'd like
to leave that for a follow-up.
## Testing
The doc tests on `for_each_init` of `QueryParManyIter` and
`QueryParManyUniqueIter`.
# Objective
Currently, default query filters, as added in #13120 / #17514 are
hardcoded to only use a single query filter.
This is limiting, as multiple distinct disabling components can serve
important distinct roles. I ran into this limitation when experimenting
with a workflow for prefabs, which don't represent the same state as "an
entity which is temporarily nonfunctional".
## Solution
1. Change `DefaultQueryFilters` to store a SmallVec of ComponentId,
rather than an Option.
2. Expose methods on `DefaultQueryFilters`, `World` and `App` to
actually configure this.
3. While we're here, improve the docs, write some tests, make use of
FromWorld and make some method names more descriptive.
## Follow-up
I'm not convinced that supporting sparse set disabling components is
useful, given the hit to iteration performance and runtime checks
incurred. That's disjoint from this PR though, so I'm not doing it here.
The existing warnings are fine for now.
## Testing
I've added both a doc test and an mid-level unit test to verify that
this works!
# Objective
Restore the behavior of `Query::get_many` prior to #15858.
When passed duplicate `Entity`s, `get_many` is supposed to return
results for all of them, since read-only queries don't alias. However,
#15858 merged the implementation with `get_many_mut` and caused it to
return `QueryEntityError::AliasedMutability`.
## Solution
Introduce a new `Query::get_many_readonly` method that consumes the
`Query` like `get_many_inner`, but that is constrained to `D:
ReadOnlyQueryData` so that it can skip the aliasing check. Implement
`Query::get_many` in terms of that new method. Add a test, and a comment
explaining why it doesn't match the pattern of the other `&self`
methods.
# Objective
Eliminate the need to write `cfg(feature = "track_location")` every time
one uses an API that may use location tracking. It's verbose, and a
little intimidating. And it requires code outside of `bevy_ecs` that
wants to use location tracking needs to either unconditionally enable
the feature, or include conditional compilation of its own. It would be
good for users to be able to log locations when they are available
without needing to add feature flags to their own crates.
Reduce the number of cases where code compiles with the `track_location`
feature enabled, but not with it disabled, or vice versa. It can be hard
to remember to test it both ways!
Remove the need to store a `None` in `HookContext` when the
`track_location` feature is disabled.
## Solution
Create an `MaybeLocation<T>` type that contains a `T` if the
`track_location` feature is enabled, and is a ZST if it is not. The
overall API is similar to `Option`, but whether the value is `Some` or
`None` is set at compile time and is the same for all values.
Default `T` to `&'static Location<'static>`, since that is the most
common case.
Remove all `cfg(feature = "track_location")` blocks outside of the
implementation of that type, and instead call methods on it.
When `track_location` is disabled, `MaybeLocation` is a ZST and all
methods are `#[inline]` and empty, so they should be entirely removed by
the compiler. But the code will still be visible to the compiler and
checked, so if it compiles with the feature disabled then it should also
compile with it enabled, and vice versa.
## Open Questions
Where should these types live? I put them in `change_detection` because
that's where the existing `MaybeLocation` types were, but we now use
these outside of change detection.
While I believe that the compiler should be able to remove all of these
calls, I have not actually tested anything. If we want to take this
approach, what testing is required to ensure it doesn't impact
performance?
## Migration Guide
Methods like `Ref::changed_by()` that return a `&'static
Location<'static>` will now be available even when the `track_location`
feature is disabled, but they will return a new `MaybeLocation` type.
`MaybeLocation` wraps a `&'static Location<'static>` when the feature is
enabled, and is a ZST when the feature is disabled.
Existing code that needs a `&Location` can call `into_option().unwrap()`
to recover it. Many trait impls are forwarded, so if you only need
`Display` then no changes will be necessary.
If that code was conditionally compiled, you may instead want to use the
methods on `MaybeLocation` to remove the need for conditional
compilation.
Code that constructs a `Ref`, `Mut`, `Res`, or `ResMut` will now need to
provide location information unconditionally. If you are creating them
from existing Bevy types, you can obtain a `MaybeLocation` from methods
like `Table::get_changed_by_slice_for()` or
`ComponentSparseSet::get_with_ticks`. Otherwise, you will need to store
a `MaybeLocation` next to your data and use methods like `as_ref()` or
`as_mut()` to obtain wrapped references.
This pr uses the `extern crate self as` trick to make proc macros behave
the same way inside and outside bevy.
# Objective
- Removes noise introduced by `crate as` in the whole bevy repo.
- Fixes#17004.
- Hardens proc macro path resolution.
## TODO
- [x] `BevyManifest` needs cleanup.
- [x] Cleanup remaining `crate as`.
- [x] Add proper integration tests to the ci.
## Notes
- `cargo-manifest-proc-macros` is written by me and based/inspired by
the old `BevyManifest` implementation and
[`bkchr/proc-macro-crate`](https://github.com/bkchr/proc-macro-crate).
- What do you think about the new integration test machinery I added to
the `ci`?
More and better integration tests can be added at a later stage.
The goal of these integration tests is to simulate an actual separate
crate that uses bevy. Ideally they would lightly touch all bevy crates.
## Testing
- Needs RA test
- Needs testing from other users
- Others need to run at least `cargo run -p ci integration-test` and
verify that they work.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Progresses #17569. The end goal here is to synchronize component
registration. See the other PR for details for the motivation behind
that.
For this PR specifically, the objective is to decouple `Components` from
`Storages`. What components are registered etc should have nothing to do
with what Storages looks like. Storages should only care about what
entity archetypes have been spawned.
## Solution
Previously, this was used to create sparse sets for relevant components
when those components were registered. Now, we do that when the
component is inserted/spawned.
This PR proposes doing that in `BundleInfo::new`, but there may be a
better place.
## Testing
In theory, this shouldn't have changed any functionality, so no new
tests were created. I'm not aware of any examples that make heavy use of
sparse set components either.
## Migration Guide
- Remove storages from functions where it is no longer needed.
- Note that SparseSets are no longer present for all registered sparse
set components, only those that have been spawned.
---------
Co-authored-by: SpecificProtagonist <vincentjunge@posteo.net>
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
# Objective
Fixes#17662
## Solution
Moved `Item` and `fetch` from `WorldQuery` to `QueryData`, and adjusted
their implementations accordingly.
Currently, documentation related to `fetch` is written under
`WorldQuery`. It would be more appropriate to move it to the `QueryData`
documentation for clarity.
I am not very experienced with making contributions. If there are any
mistakes or areas for improvement, I would appreciate any suggestions
you may have.
## Migration Guide
The `WorldQuery::Item` type and `WorldQuery::fetch` method have been
moved to `QueryData`, as they were not useful for `QueryFilter` types.
---------
Co-authored-by: Chris Russell <8494645+chescock@users.noreply.github.com>
# Objective
Simplify and expand the API for `QueryState`.
`QueryState` has a lot of methods that mirror those on `Query`. These
are then multiplied by variants that take `&World`, `&mut World`, and
`UnsafeWorldCell`. In addition, many of them have `_manual` variants
that take `&QueryState` and avoid calling `update_archetypes()`. Not all
of the combinations exist, however, so some operations are not possible.
## Solution
Introduce methods to get a `Query` from a `QueryState`. That will reduce
duplication between the types, and ensure that the full `Query` API is
always available for `QueryState`.
Introduce methods on `Query` that consume the query to return types with
the full `'w` lifetime. This avoids issues with borrowing where things
like `query_state.query(&world).get(entity)` don't work because they
borrow from the temporary `Query`.
Finally, implement `Copy` for read-only `Query`s. `get_inner` and
`iter_inner` currently take `&self`, so changing them to consume `self`
would be a breaking change. By making `Query: Copy`, they can consume a
copy of `self` and continue to work.
The consuming methods also let us simplify the implementation of methods
on `Query`, by doing `fn foo(&self) { self.as_readonly().foo_inner() }`
and `fn foo_mut(&mut self) { self.reborrow().foo_inner() }`. That
structure makes it more difficult to accidentally extend lifetimes,
since the safe `as_readonly()` and `reborrow()` methods shrink them
appropriately. The optimizer is able to see that they are both identity
functions and inline them, so there should be no performance cost.
Note that this change would conflict with #15848. If `QueryState` is
stored as a `Cow`, then the consuming methods cannot be implemented, and
`Copy` cannot be implemented.
## Future Work
The next step is to mark the methods on `QueryState` as `#[deprecated]`,
and move the implementations into `Query`.
## Migration Guide
`Query::to_readonly` has been renamed to `Query::as_readonly`.
# Objective
While working on #17649, I found the docs for `WorldQuery` and the
related traits frustratingly vague.
## Solution
Clarify them and add some more tangible advice.
Also fix a copy-pasted typo in related comments.
---------
Co-authored-by: James O'Brien <james.obrien@drafly.net>
# Objective
Prevent unsound uses of `DeferredWorld` as a `SystemParam`. It is
currently unsound because it does not check for existing access, and
because it incorrectly registers filtered access.
## Solution
Have `DeferredWorld` panic if a previous parameter has conflicting
access.
Have `DeferredWorld` update `archetype_component_access` so that the
multi-threaded executor sees the access.
Fix `FilteredAccessSet::read_all()` and `write_all()` to correctly add a
`FilteredAccess` with no filter so that `Query` is able to detect the
conflicts.
Remove redundant `read_all()` call, since `write_all()` already declares
read access.
Remove unnecessary `set_has_deferred()` call, since `<DeferredWorld as
SystemParam>::apply_deferred()` does nothing. Previously we were
inserting unnecessary `apply_deferred` systems in the schedule.
## Testing
Added unit tests for systems where `DeferredWorld` conflicts with a
`Query` in the same system.
# Objective
The various `Query::sort()` methods have a lot of duplicated code
between them, including some unsafe code. Reduce the duplication to make
the code easier to read and maintain.
## Solution
Extract the duplicated code to a private method, and pass in the sorting
strategy as a closure.
## Testing
I used `cargo-show-asm` to verify that the closures were inlined, but I
didn't run anything through a profiler. The `sort()` method itself even
had identical assembly before and after this change, although the others
did not.
# Objective
Some usecases in the ecosystems are blocked by the inability to stop
bevy internals and third party plugins from touching their entities.
However the specifics of a general purpose entity disabling system are
controversial and further complicated by hierarchies. We can partially
unblock these usecases with an opt-in approach: default query filters.
## Solution
- Introduce DefaultQueryFilters, these filters are automatically applied
to queries that don't otherwise mention the filtered component.
- End users and third party plugins can register default filters and are
responsible for handling entities they have hidden this way.
- Extra features can be left for after user feedback
- The default value could later include official ways to hide entities
---
## Changelog
- Add DefaultQueryFilters
# Objective
- Fix issue identified on the [Discord
server](https://discord.com/channels/691052431525675048/691052431974465548/1328922812530036839)
## Solution
- Implement `Clone` for `QueryIter` using the existing
`QueryIter::remaining` method
## Testing
- CI
---
## Showcase
Users can now explicitly clone a read-only `QueryIter`:
```rust
fn combinations(query: Query<&ComponentA>) {
let mut iter = query.iter();
while let Some(a) = iter.next() {
// Can now clone rather than use remaining
for b in iter.clone() {
// Check every combination (a, b)
}
}
}
```
## Notes
This doesn't add any new functionality outside the context of generic
code (e.g., `T: Iterator<...> + Clone`), it's mostly for
discoverability. Users are more likely to be familiar with
`Clone::clone` than they are with the methods on `QueryIter`.
# Objective
- https://github.com/bevyengine/bevy/issues/17111
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `warn`, and bring
`bevy_ecs` in line with the new restrictions.
## Testing
This PR is a WIP; testing will happen after it's finished.
# Objective
With the `track_location` feature, the error message of trying to
acquire an entity that was despawned pointed to the wrong line if the
entity index has been reused.
## Showcase
```rust
use bevy_ecs::prelude::*;
fn main() {
let mut world = World::new();
let e = world.spawn_empty().id();
world.despawn(e);
world.flush();
let _ = world.spawn_empty();
world.entity(e);
}
```
Old message:
```
Entity 0v1 was despawned by src/main.rs:8:19
```
New message:
```
Entity 0v1 does not exist (its index has been reused)
```
# Objective
Stumbled upon a `from <-> form` transposition while reviewing a PR,
thought it was interesting, and went down a bit of a rabbit hole.
## Solution
Fix em
Related to https://github.com/bevyengine/bevy/pull/16843
Since `WorldQuery::Fetch` is `Clone`, it can't store mutable references
to resources, so it doesn't make sense to mutably access resources. In
that sense, it is hard to find usecases of mutably accessing resources
and to clearly define, what mutably accessing resources would mean, so
it's been decided to disallow write resource access.
Also changed documentation of safety requirements of
`WorldQuery::init_fetch` and `WorldQuery::fetch` to clearly state to the
caller, what safety invariants they need to uphold.
# Objective
- Contributes to #11478
## Solution
- Made `bevy_utils::tracing` `doc(hidden)`
- Re-exported `tracing` from `bevy_log` for end-users
- Added `tracing` directly to crates that need it.
## Testing
- CI
---
## Migration Guide
If you were importing `tracing` via `bevy::utils::tracing`, instead use
`bevy::log::tracing`. Note that many items within `tracing` are also
directly re-exported from `bevy::log` as well, so you may only need
`bevy::log` for the most common items (e.g., `warn!`, `trace!`, etc.).
This also applies to the `log_once!` family of macros.
## Notes
- While this doesn't reduce the line-count in `bevy_utils`, it further
decouples the internal crates from `bevy_utils`, making its eventual
removal more feasible in the future.
- I have just imported `tracing` as we do for all dependencies. However,
a workspace dependency may be more appropriate for version management.
## Objective
The error `EntityFetchError::NoSuchEntity` has an `UnsafeWorldCell`
inside it, which it uses to call
`Entities::entity_does_not_exist_error_details_message` when being
printed. That method returns a `String` that, if the `track_location`
feature is enabled, contains the location of whoever despawned the
relevant entity.
I initially had to modify this error while working on #17043. The
`UnsafeWorldCell` was causing borrow problems when being returned from a
command, so I tried replacing it with the `String` that the method
returns, since that was the world cell's only purpose.
Unfortunately, `String`s are slow, and it significantly impacted
performance (on top of that PR's performance hit):
<details>
<summary>17043 benchmarks</summary>
### With `String`
### No `String`
</details>
For that PR, I just removed the error details entirely, but I figured
I'd try to find a way to keep them around.
## Solution
- Replace the `String` with a helper struct that holds the location, and
only turn it into a string when someone actually wants to print it.
- Replace the `UnsafeWorldCell` with the aforementioned struct.
- Do the same for `QueryEntityError::NoSuchEntity`.
## Benchmarking
This had some interesting performance impact:
<details>
<summary>This PR vs main</summary>
</details>
## Other work
`QueryEntityError::QueryDoesNotMatch` also has an `UnsafeWorldCell`
inside it. This one would be more complicated to rework while keeping
the same functionality.
## Migration Guide
The errors `EntityFetchError::NoSuchEntity` and
`QueryEntityError::NoSuchEntity` now contain an
`EntityDoesNotExistDetails` struct instead of an `UnsafeWorldCell`. If
you were just printing these, they should work identically.
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
