I'm adopting this ~~child~~ PR.
# Objective
- Working with exclusive world access is not always easy: in many cases,
a standard system or three is more ergonomic to write, and more
modularly maintainable.
- For small, one-off tasks (commonly handled with scripting), running an
event-reader system incurs a small but flat overhead cost and muddies
the schedule.
- Certain forms of logic (e.g. turn-based games) want very fine-grained
linear and/or branching control over logic.
- SystemState is not automatically cached, and so performance can suffer
and change detection breaks.
- Fixes https://github.com/bevyengine/bevy/issues/2192.
- Partial workaround for https://github.com/bevyengine/bevy/issues/279.
## Solution
- Adds a SystemRegistry resource to the World, which stores initialized
systems keyed by their SystemSet.
- Allows users to call world.run_system(my_system) and
commands.run_system(my_system), without re-initializing or losing state
(essential for change detection).
- Add a Callback type to enable convenient use of dynamic one shot
systems and reduce the mental overhead of working with Box<dyn
SystemSet>.
- Allow users to run systems based on their SystemSet, enabling more
complex user-made abstractions.
## Future work
- Parameterized one-shot systems would improve reusability and bring
them closer to events and commands. The API could be something like
run_system_with_input(my_system, my_input) and use the In SystemParam.
- We should evaluate the unification of commands and one-shot systems
since they are two different ways to run logic on demand over a World.
### Prior attempts
- https://github.com/bevyengine/bevy/pull/2234
- https://github.com/bevyengine/bevy/pull/2417
- https://github.com/bevyengine/bevy/pull/4090
- https://github.com/bevyengine/bevy/pull/7999
This PR continues the work done in
https://github.com/bevyengine/bevy/pull/7999.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Federico Rinaldi <gisquerin@gmail.com>
Co-authored-by: MinerSebas <66798382+MinerSebas@users.noreply.github.com>
Co-authored-by: Aevyrie <aevyrie@gmail.com>
Co-authored-by: Alejandro Pascual Pozo <alejandro.pascual.pozo@gmail.com>
Co-authored-by: Rob Parrett <robparrett@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Dmytro Banin <banind@cs.washington.edu>
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
- Fixes#9244.
## Solution
- Changed the `(Into)SystemSetConfigs` traits and structs be more like
the `(Into)SystemConfigs` traits and structs.
- Replaced uses of `IntoSystemSetConfig` with `IntoSystemSetConfigs`
- Added generic `ItemConfig` and `ItemConfigs` types.
- Changed `SystemConfig(s)` and `SystemSetConfig(s)` to be type aliases
to `ItemConfig(s)`.
- Added generic `process_configs` to `ScheduleGraph`.
- Changed `configure_sets_inner` and `add_systems_inner` to reuse
`process_configs`.
---
## Changelog
- Added `run_if` to `IntoSystemSetConfigs`
- Deprecated `Schedule::configure_set` and `App::configure_set`
- Removed `IntoSystemSetConfig`
## Migration Guide
- Use `App::configure_sets` instead of `App::configure_set`
- Use `Schedule::configure_sets` instead of `Schedule::configure_set`
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Move schedule name into `Schedule` to allow the schedule name to be
used for errors and tracing in Schedule methods
- Fixes#9510
## Solution
- Move label onto `Schedule` and adjust api's on `World` and `Schedule`
to not pass explicit label where it makes sense to.
- add name to errors and tracing.
- `Schedule::new` now takes a label so either add the label or use
`Schedule::default` which uses a default label. `default` is mostly used
in doc examples and tests.
---
## Changelog
- move label onto `Schedule` to improve error message and logging for
schedules.
## Migration Guide
`Schedule::new` and `App::add_schedule`
```rust
// old
let schedule = Schedule::new();
app.add_schedule(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
app.add_schedule(schedule);
```
if you aren't using a label and are using the schedule struct directly
you can use the default constructor.
```rust
// old
let schedule = Schedule::new();
schedule.run(world);
// new
let schedule = Schedule::default();
schedule.run(world);
```
`Schedules:insert`
```rust
// old
let schedule = Schedule::new();
schedules.insert(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
schedules.insert(schedule);
```
`World::add_schedule`
```rust
// old
let schedule = Schedule::new();
world.add_schedule(MyLabel, schedule);
// new
let schedule = Schedule::new(MyLabel);
world.add_schedule(schedule);
```
# Objective
- break up large build_schedule system to make it easier to read
- Clean up related error messages.
- I have a follow up PR that adds the schedule name to the error
messages, but wanted to break this up from that.
## Changelog
- refactor `build_schedule` to be easier to read
## Sample Error Messages
Dependency Cycle
```text
thread 'main' panicked at 'System dependencies contain cycle(s).
schedule has 1 before/after cycle(s):
cycle 1: system set 'A' must run before itself
system set 'A'
... which must run before system set 'B'
... which must run before system set 'A'
', crates\bevy_ecs\src\schedule\schedule.rs:228:13
```
```text
thread 'main' panicked at 'System dependencies contain cycle(s).
schedule has 1 before/after cycle(s):
cycle 1: system 'foo' must run before itself
system 'foo'
... which must run before system 'bar'
... which must run before system 'foo'
', crates\bevy_ecs\src\schedule\schedule.rs:228:13
```
Hierarchy Cycle
```text
thread 'main' panicked at 'System set hierarchy contains cycle(s).
schedule has 1 in_set cycle(s):
cycle 1: set 'A' contains itself
set 'A'
... which contains set 'B'
... which contains set 'A'
', crates\bevy_ecs\src\schedule\schedule.rs:230:13
```
System Type Set
```text
thread 'main' panicked at 'Tried to order against `SystemTypeSet(fn foo())` in a schedule that has more than one `SystemTypeSet(fn foo())` instance. `SystemTypeSet(fn foo())` is a `SystemTypeSet` and cannot be used for ordering if ambiguous. Use a different set without this restriction.', crates\bevy_ecs\src\schedule\schedule.rs:230:13
```
Hierarchy Redundancy
```text
thread 'main' panicked at 'System set hierarchy contains redundant edges.
hierarchy contains redundant edge(s) -- system set 'X' cannot be child of set 'A', longer path exists
', crates\bevy_ecs\src\schedule\schedule.rs:230:13
```
Systems have ordering but interset
```text
thread 'main' panicked at '`A` and `C` have a `before`-`after` relationship (which may be transitive) but share systems.', crates\bevy_ecs\src\schedule\schedule.rs:227:51
```
Cross Dependency
```text
thread 'main' panicked at '`A` and `B` have both `in_set` and `before`-`after` relationships (these might be transitive). This combination is unsolvable as a system cannot run before or after a set it belongs to.', crates\bevy_ecs\src\schedule\schedule.rs:230:13
```
Ambiguity
```text
thread 'main' panicked at 'Systems with conflicting access have indeterminate run order.
1 pairs of systems with conflicting data access have indeterminate execution order. Consider adding `before`, `after`, or `ambiguous_with` relationships between these:
-- res_mut and res_ref
conflict on: ["bevymark::ambiguity::X"]
', crates\bevy_ecs\src\schedule\schedule.rs:230:13
```
# Objective
[Rust 1.72.0](https://blog.rust-lang.org/2023/08/24/Rust-1.72.0.html) is
now stable.
# Notes
- `let-else` formatting has arrived!
- I chose to allow `explicit_iter_loop` due to
https://github.com/rust-lang/rust-clippy/issues/11074.
We didn't hit any of the false positives that prevent compilation, but
fixing this did produce a lot of the "symbol soup" mentioned, e.g. `for
image in &mut *image_events {`.
Happy to undo this if there's consensus the other way.
---------
Co-authored-by: François <mockersf@gmail.com>
# Objective
Title.
---------
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
Methods for interacting with world schedules currently have two
variants: one that takes `impl ScheduleLabel` and one that takes `&dyn
ScheduleLabel`. Operations such as `run_schedule` or `schedule_scope`
only use the label by reference, so there is little reason to have an
owned variant of these functions.
## Solution
Decrease maintenance burden by merging the `ref` variants of these
functions with the owned variants.
---
## Changelog
- Deprecated `World::run_schedule_ref`. It is now redundant, since
`World::run_schedule` can take values by reference.
## Migration Guide
The method `World::run_schedule_ref` has been deprecated, and will be
removed in the next version of Bevy. Use `run_schedule` instead.
# Objective
Label traits such as `ScheduleLabel` currently have a major footgun: the
trait is implemented for `Box<dyn ScheduleLabel>`, but the
implementation does not function as one would expect since `Box<T>` is
considered to be a distinct type from `T`. This is because the behavior
of the `ScheduleLabel` trait is specified mainly through blanket
implementations, which prevents `Box<dyn ScheduleLabel>` from being
properly special-cased.
## Solution
Replace the blanket-implemented behavior with a series of methods
defined on `ScheduleLabel`. This allows us to fully special-case
`Box<dyn ScheduleLabel>` .
---
## Changelog
Fixed a bug where boxed label types (such as `Box<dyn ScheduleLabel>`)
behaved incorrectly when compared with concretely-typed labels.
## Migration Guide
The `ScheduleLabel` trait has been refactored to no longer depend on the
traits `std::any::Any`, `bevy_utils::DynEq`, and `bevy_utils::DynHash`.
Any manual implementations will need to implement new trait methods in
their stead.
```rust
impl ScheduleLabel for MyType {
// Before:
fn dyn_clone(&self) -> Box<dyn ScheduleLabel> { ... }
// After:
fn dyn_clone(&self) -> Box<dyn ScheduleLabel> { ... }
fn as_dyn_eq(&self) -> &dyn DynEq {
self
}
// No, `mut state: &mut` is not a typo.
fn dyn_hash(&self, mut state: &mut dyn Hasher) {
self.hash(&mut state);
// Hashing the TypeId isn't strictly necessary, but it prevents collisions.
TypeId::of::<Self>().hash(&mut state);
}
}
```
# Objective
- Fixes#7659
## Solution
The idea of anonymous system sets or "implicit hidden organizational
sets" was briefly mentioned by @cart here:
https://github.com/bevyengine/bevy/pull/7634#issuecomment-1428619449.
- `Schedule::add_systems` creates an implicit, anonymous system set of
all systems in `SystemConfigs`.
- All dependencies and conditions from the `SystemConfigs` are now
applied to the implicit system set, instead of being applied to each
individual system. This should not change the behavior, AFAIU, because
`before`, `after`, `run_if` and `ambiguous_with` are transitive
properties from a set to its members.
- The newly added `AnonymousSystemSet` stores the names of its members
to provide better error messages.
- The names are stored in a reference counted slice, allowing fast
clones of the `AnonymousSystemSet`.
- However, only the pointer of the slice is used for hash and equality
operations
- This ensures that two `AnonymousSystemSet` are not equal, even if they
have the same members / member names.
- So two identical `add_systems` calls will produce two different
`AnonymousSystemSet`s.
- Clones of the same `AnonymousSystemSet` will be equal.
## Drawbacks
If my assumptions are correct, the observed behavior should stay the
same. But the number of system sets in the `Schedule` will increase with
each `add_systems` call. If this has negative performance implications,
`add_systems` could be changed to only create the implicit system set if
necessary / when a run condition was added.
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
#7863 introduced a potential footgun. When trying to incorrectly add a user-defined type using `in_base_set`, the compiler will suggest that the user implement `BaseSystemSet` for their type. This is a reasonable-sounding suggestion, however this is not the correct way to make a base set, and will lead to a confusing panic message when a marker trait is implemented for the wrong type.
## Solution
Rewrite the documentation for these traits, making it more clear that `BaseSystemSet` is a marker for types that are already base sets, and not a way to define a base set.
# Objective
Base sets, added in #7466 are a special type of system set. Systems can only be added to base sets via `in_base_set`, while non-base sets can only be added via `in_set`. Unfortunately this is currently guarded by a runtime panic, which presents an unfortunate toe-stub when the wrong method is used. The delayed response between writing code and encountering the error (possibly hours) makes the distinction between base sets and other sets much more difficult to learn.
## Solution
Add the marker traits `BaseSystemSet` and `FreeSystemSet`. `in_base_set` and `in_set` now respectively accept these traits, which moves the runtime panic to a compile time error.
---
## Changelog
+ Added the marker trait `BaseSystemSet`, which is distinguished from a `FreeSystemSet`. These are both subtraits of `SystemSet`.
## Migration Guide
None if merged with 0.10
# Objective
- it would be nice to be able to associate a `NodeId` of a system type set to the `NodeId` of the actual system (used in bevy_mod_debugdump)
## Solution
- make `system_type` return the type id of the system
- that way you can check if a `dyn SystemSet` is the system type set of a `dyn System`
- I don't know if this information is already present somewhere else in the scheduler or if there is a better way to expose it
# Objective
The `SystemParamFunction` (and `ExclusiveSystemParamFunction`) trait is very cumbersome to use, due to it requiring four generic type parameters. These are currently all used as marker parameters to satisfy rust's trait coherence rules.
### Example (before)
```rust
pub fn pipe<AIn, Shared, BOut, A, AParam, AMarker, B, BParam, BMarker>(
mut system_a: A,
mut system_b: B,
) -> impl FnMut(In<AIn>, ParamSet<(AParam, BParam)>) -> BOut
where
A: SystemParamFunction<AIn, Shared, AParam, AMarker>,
B: SystemParamFunction<Shared, BOut, BParam, BMarker>,
AParam: SystemParam,
BParam: SystemParam,
```
## Solution
Turn the `In`, `Out`, and `Param` generics into associated types. Merge the marker types together to retain coherence.
### Example (after)
```rust
pub fn pipe<A, B, AMarker, BMarker>(
mut system_a: A,
mut system_b: B,
) -> impl FnMut(In<A::In>, ParamSet<(A::Param, B::Param)>) -> B::Out
where
A: SystemParamFunction<AMarker>,
B: SystemParamFunction<BMarker, In = A::Out>,
```
---
## Changelog
+ Simplified the `SystemParamFunction` and `ExclusiveSystemParamFunction` traits.
## Migration Guide
For users of the `SystemParamFunction` trait, the generic type parameters `In`, `Out`, and `Param` have been turned into associated types. The same has been done with the `ExclusiveSystemParamFunction` trait.
