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[Merged by Bors] - Auto-label function systems with SystemTypeIdLabel #4224

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e8a5c6a
Auto-label function systems
cart Mar 16, 2022
649987b
a.after(b)
cart Mar 16, 2022
76ca7f6
fix ambiguity test
cart Mar 16, 2022
a964e8e
Update crates/bevy_ecs/src/system/function_system.rs
cart Mar 16, 2022
ca7c674
Make SystemTypeIdLabel ZST, remove boxing from AsSystemLabel
cart Mar 23, 2022
c39276e
clippy
cart Mar 23, 2022
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1 change: 1 addition & 0 deletions crates/bevy_ecs/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ pub mod prelude {
system::{
Commands, In, IntoChainSystem, IntoExclusiveSystem, IntoSystem, Local, NonSend,
NonSendMut, Query, QuerySet, RemovedComponents, Res, ResMut, System,
SystemParamFunction,
},
world::{FromWorld, Mut, World},
};
Expand Down
46 changes: 28 additions & 18 deletions crates/bevy_ecs/src/schedule/stage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1583,15 +1583,25 @@ mod tests {
fn ambiguity_detection() {
use super::{find_ambiguities, SystemContainer};

fn find_ambiguities_first_labels(
fn find_ambiguities_first_str_labels(
systems: &[impl SystemContainer],
) -> Vec<(BoxedSystemLabel, BoxedSystemLabel)> {
find_ambiguities(systems)
.drain(..)
.map(|(index_a, index_b, _conflicts)| {
(
systems[index_a].labels()[0].clone(),
systems[index_b].labels()[0].clone(),
systems[index_a]
.labels()
.iter()
.find(|a| (&***a).type_id() == std::any::TypeId::of::<&str>())
.unwrap()
.clone(),
systems[index_b]
.labels()
.iter()
.find(|a| (&***a).type_id() == std::any::TypeId::of::<&str>())
.unwrap()
.clone(),
)
})
.collect()
Expand Down Expand Up @@ -1621,7 +1631,7 @@ mod tests {
.with_system(component.label("4"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("4")))
|| ambiguities.contains(&(Box::new("4"), Box::new("1")))
Expand All @@ -1636,7 +1646,7 @@ mod tests {
.with_system(resource.label("4"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("4")))
|| ambiguities.contains(&(Box::new("4"), Box::new("1")))
Expand All @@ -1661,7 +1671,7 @@ mod tests {
.with_system(resource.label("4"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("0"), Box::new("3")))
|| ambiguities.contains(&(Box::new("3"), Box::new("0")))
Expand All @@ -1680,7 +1690,7 @@ mod tests {
.with_system(resource.label("4").in_ambiguity_set("a"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("0"), Box::new("3")))
|| ambiguities.contains(&(Box::new("3"), Box::new("0")))
Expand All @@ -1693,7 +1703,7 @@ mod tests {
.with_system(component.label("2"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("0"), Box::new("1")))
|| ambiguities.contains(&(Box::new("1"), Box::new("0")))
Expand All @@ -1706,7 +1716,7 @@ mod tests {
.with_system(component.label("2").after("0"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("2")))
|| ambiguities.contains(&(Box::new("2"), Box::new("1")))
Expand All @@ -1720,7 +1730,7 @@ mod tests {
.with_system(component.label("3").after("1").after("2"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("2")))
|| ambiguities.contains(&(Box::new("2"), Box::new("1")))
Expand All @@ -1734,7 +1744,7 @@ mod tests {
.with_system(component.label("3").after("1").after("2"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert_eq!(ambiguities.len(), 0);

let mut stage = SystemStage::parallel()
Expand All @@ -1744,7 +1754,7 @@ mod tests {
.with_system(component.label("3").after("1").after("2"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("2")))
|| ambiguities.contains(&(Box::new("2"), Box::new("1")))
Expand Down Expand Up @@ -1774,7 +1784,7 @@ mod tests {
);
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("2")))
|| ambiguities.contains(&(Box::new("2"), Box::new("1")))
Expand Down Expand Up @@ -1824,7 +1834,7 @@ mod tests {
);
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert_eq!(ambiguities.len(), 0);

let mut stage = SystemStage::parallel()
Expand Down Expand Up @@ -1855,7 +1865,7 @@ mod tests {
);
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.parallel);
let ambiguities = find_ambiguities_first_str_labels(&stage.parallel);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("4")))
|| ambiguities.contains(&(Box::new("4"), Box::new("1")))
Expand Down Expand Up @@ -1889,7 +1899,7 @@ mod tests {
.with_system(empty.exclusive_system().label("6").after("2").after("5"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.exclusive_at_start);
let ambiguities = find_ambiguities_first_str_labels(&stage.exclusive_at_start);
assert!(
ambiguities.contains(&(Box::new("1"), Box::new("3")))
|| ambiguities.contains(&(Box::new("3"), Box::new("1")))
Expand Down Expand Up @@ -1926,7 +1936,7 @@ mod tests {
.with_system(empty.exclusive_system().label("6").after("2").after("5"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.exclusive_at_start);
let ambiguities = find_ambiguities_first_str_labels(&stage.exclusive_at_start);
assert!(
ambiguities.contains(&(Box::new("2"), Box::new("3")))
|| ambiguities.contains(&(Box::new("3"), Box::new("2")))
Expand All @@ -1952,7 +1962,7 @@ mod tests {
.with_system(empty.exclusive_system().label("3").in_ambiguity_set("a"));
stage.initialize_systems(&mut world);
stage.rebuild_orders_and_dependencies();
let ambiguities = find_ambiguities_first_labels(&stage.exclusive_at_start);
let ambiguities = find_ambiguities_first_str_labels(&stage.exclusive_at_start);
assert_eq!(ambiguities.len(), 0);
}

Expand Down
27 changes: 15 additions & 12 deletions crates/bevy_ecs/src/schedule/system_descriptor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,10 @@ use crate::{
AmbiguitySetLabel, BoxedAmbiguitySetLabel, BoxedSystemLabel, IntoRunCriteria,
RunCriteriaDescriptorOrLabel, SystemLabel,
},
system::{BoxedSystem, ExclusiveSystem, ExclusiveSystemCoerced, ExclusiveSystemFn, IntoSystem},
system::{
AsSystemLabel, BoxedSystem, ExclusiveSystem, ExclusiveSystemCoerced, ExclusiveSystemFn,
IntoSystem,
},
};

/// Encapsulates a system and information on when it run in a `SystemStage`.
Expand Down Expand Up @@ -105,9 +108,9 @@ pub struct ParallelSystemDescriptor {

fn new_parallel_descriptor(system: BoxedSystem<(), ()>) -> ParallelSystemDescriptor {
ParallelSystemDescriptor {
labels: system.default_labels(),
system,
run_criteria: None,
labels: Vec::new(),
before: Vec::new(),
after: Vec::new(),
ambiguity_sets: Vec::new(),
Expand All @@ -126,10 +129,10 @@ pub trait ParallelSystemDescriptorCoercion<Params> {
fn label(self, label: impl SystemLabel) -> ParallelSystemDescriptor;

/// Specifies that the system should run before systems with the given label.
fn before(self, label: impl SystemLabel) -> ParallelSystemDescriptor;
fn before<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor;

/// Specifies that the system should run after systems with the given label.
fn after(self, label: impl SystemLabel) -> ParallelSystemDescriptor;
fn after<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor;

/// Specifies that the system is exempt from execution order ambiguity detection
/// with other systems in this set.
Expand All @@ -150,13 +153,13 @@ impl ParallelSystemDescriptorCoercion<()> for ParallelSystemDescriptor {
self
}

fn before(mut self, label: impl SystemLabel) -> ParallelSystemDescriptor {
self.before.push(Box::new(label));
fn before<Marker>(mut self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
self.before.push(Box::new(label.as_system_label()));
self
}

fn after(mut self, label: impl SystemLabel) -> ParallelSystemDescriptor {
self.after.push(Box::new(label));
fn after<Marker>(mut self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
self.after.push(Box::new(label.as_system_label()));
self
}

Expand All @@ -182,11 +185,11 @@ where
new_parallel_descriptor(Box::new(IntoSystem::into_system(self))).label(label)
}

fn before(self, label: impl SystemLabel) -> ParallelSystemDescriptor {
fn before<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
new_parallel_descriptor(Box::new(IntoSystem::into_system(self))).before(label)
}

fn after(self, label: impl SystemLabel) -> ParallelSystemDescriptor {
fn after<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
new_parallel_descriptor(Box::new(IntoSystem::into_system(self))).after(label)
}

Expand All @@ -207,11 +210,11 @@ impl ParallelSystemDescriptorCoercion<()> for BoxedSystem<(), ()> {
new_parallel_descriptor(self).label(label)
}

fn before(self, label: impl SystemLabel) -> ParallelSystemDescriptor {
fn before<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
new_parallel_descriptor(self).before(label)
}

fn after(self, label: impl SystemLabel) -> ParallelSystemDescriptor {
fn after<Marker>(self, label: impl AsSystemLabel<Marker>) -> ParallelSystemDescriptor {
new_parallel_descriptor(self).after(label)
}

Expand Down
69 changes: 68 additions & 1 deletion crates/bevy_ecs/src/system/function_system.rs
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Expand Up @@ -2,14 +2,15 @@ use crate::{
archetype::{Archetype, ArchetypeComponentId, ArchetypeGeneration, ArchetypeId},
component::ComponentId,
query::{Access, FilteredAccessSet},
schedule::SystemLabel,
system::{
check_system_change_tick, ReadOnlySystemParamFetch, System, SystemParam, SystemParamFetch,
SystemParamState,
},
world::{World, WorldId},
};
use bevy_ecs_macros::all_tuples;
use std::{borrow::Cow, marker::PhantomData};
use std::{borrow::Cow, fmt::Debug, hash::Hash, marker::PhantomData};

/// The metadata of a [`System`].
pub struct SystemMeta {
Expand Down Expand Up @@ -421,6 +422,47 @@ where
self.system_meta.name.as_ref(),
);
}
fn default_labels(&self) -> Vec<Box<dyn SystemLabel>> {
vec![Box::new(self.func.as_system_label())]
}
}

/// A [`SystemLabel`] that was automatically generated for a system on the basis of its `TypeId`.
pub struct SystemTypeIdLabel<T: 'static>(PhantomData<fn() -> T>);
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This couldn't be derive(Default) because of the type parameter bounds, but should it still be Default?

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Interesting. This would enable people to construct these labels without an instance to a system type. Maybe thats good. Is there a use case?

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Interesting. This would enable people to construct these labels without an instance to a system type. Maybe thats good. Is there a use case?

This could be useful if you wanted to initialize an array of these things, especially if we also impl'd Copy. I'm not immediately sure why you'd want to do that though.

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Haha I'm impatient, so I'm just going to merge this now. I'm happy to add this if we decide its needed.


impl<T> Debug for SystemTypeIdLabel<T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_tuple("SystemTypeIdLabel")
.field(&std::any::type_name::<T>())
.finish()
}
}
impl<T> Hash for SystemTypeIdLabel<T> {
fn hash<H: std::hash::Hasher>(&self, _state: &mut H) {
// All SystemTypeIds of a given type are the same.
}
}
impl<T> Clone for SystemTypeIdLabel<T> {
fn clone(&self) -> Self {
Self(PhantomData)
}
}

impl<T> Copy for SystemTypeIdLabel<T> {}

impl<T> PartialEq for SystemTypeIdLabel<T> {
#[inline]
fn eq(&self, _other: &Self) -> bool {
// All labels of a given type are equal, as they will all have the same type id
true
}
}
impl<T> Eq for SystemTypeIdLabel<T> {}

impl<T> SystemLabel for SystemTypeIdLabel<T> {
fn dyn_clone(&self) -> Box<dyn SystemLabel> {
Box::new(*self)
}
}

/// A trait implemented for all functions that can be used as [`System`]s.
Expand Down Expand Up @@ -489,3 +531,28 @@ macro_rules! impl_system_function {
}

all_tuples!(impl_system_function, 0, 16, F);

/// Used to implicitly convert systems to their default labels. For example, it will convert
/// "system functions" to their [`SystemTypeIdLabel`].
pub trait AsSystemLabel<Marker> {
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Please add a short doc comment stating this is used for system -> SystemLabel coercion plus a pointer to SystemLabel which illustrates the ergonomics.

It'd also stave off the perpetually missing #[forbid(missing_docs)] for the crate.

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Good call!

type SystemLabel: SystemLabel;
fn as_system_label(&self) -> Self::SystemLabel;
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I'll record that I'm still not super happy with this being a method, but I don't think that's changing.

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@cart cart Mar 23, 2022 •
edited
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Yeah I'm not (yet) convinced. I think there are good reasons to make "manually retrieving the label from a system instance" a part of our api. We don't abstract out "other" labels and we let those instances float around. Why abstract out these?
I'm down to continue discussing, but I dont want to block on this.

}

impl<In, Out, Param: SystemParam, Marker, T: SystemParamFunction<In, Out, Param, Marker>>
AsSystemLabel<(In, Out, Param, Marker)> for T
{
type SystemLabel = SystemTypeIdLabel<Self>;

fn as_system_label(&self) -> Self::SystemLabel {
SystemTypeIdLabel(PhantomData::<fn() -> Self>)
}
}

impl<T: SystemLabel + Clone> AsSystemLabel<()> for T {
type SystemLabel = T;

fn as_system_label(&self) -> Self::SystemLabel {
self.clone()
}
}
5 changes: 5 additions & 0 deletions crates/bevy_ecs/src/system/system.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ use crate::{
archetype::{Archetype, ArchetypeComponentId},
component::ComponentId,
query::Access,
schedule::SystemLabel,
world::World,
};
use std::borrow::Cow;
Expand Down Expand Up @@ -56,6 +57,10 @@ pub trait System: Send + Sync + 'static {
/// Initialize the system.
fn initialize(&mut self, _world: &mut World);
fn check_change_tick(&mut self, change_tick: u32);
/// The default labels for the system
fn default_labels(&self) -> Vec<Box<dyn SystemLabel>> {
Vec::new()
}
}

/// A convenience type alias for a boxed [`System`] trait object.
Expand Down
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