NonUniqueResource

crates/bevy_ecs/src/component.rs

@@ -1,5 +1,6 @@
 //! Types for declaring and storing [`Component`]s.
 
+use crate::storage::non_unique_resource::NonUniqueResourceEntry;
 use crate::{
     self as bevy_ecs,
     change_detection::MAX_CHANGE_AGE,
@@ -415,6 +416,18 @@ impl ComponentDescriptor {
         }
     }
 
+    fn new_non_unique_resource<T: Any>() -> Self {
+        Self {
+            name: Cow::Borrowed(std::any::type_name::<NonUniqueResourceEntry<T>>()),
+            storage_type: StorageType::Table,
+            is_send_and_sync: true,
+            type_id: Some(TypeId::of::<NonUniqueResourceEntry<T>>()),
+            layout: Layout::new::<NonUniqueResourceEntry<T>>(),
+            drop: needs_drop::<NonUniqueResourceEntry<T>>()
+                .then_some(Self::drop_ptr::<NonUniqueResourceEntry<T>>),
+        }
+    }
+
     /// Returns a value indicating the storage strategy for the current component.
     #[inline]
     pub fn storage_type(&self) -> StorageType {
@@ -647,6 +660,16 @@ impl Components {
         }
     }
 
+    #[inline]
+    pub(crate) fn init_non_unique_resource<T: Any>(&mut self) -> ComponentId {
+        // SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
+        unsafe {
+            self.get_or_insert_resource_with(TypeId::of::<NonUniqueResourceEntry<T>>(), || {
+                ComponentDescriptor::new_non_unique_resource::<T>()
+            })
+        }
+    }
+
     /// # Safety
     ///
     /// The [`ComponentDescriptor`] must match the [`TypeId`]

crates/bevy_ecs/src/lib.rs

@@ -10,6 +10,7 @@ pub mod change_detection;
 pub mod component;
 pub mod entity;
 pub mod event;
+pub mod non_unique_resource;
 pub mod query;
 #[cfg(feature = "bevy_reflect")]
 pub mod reflect;

crates/bevy_ecs/src/non_unique_resource.rs

@@ -0,0 +1,343 @@
+//! Non-unique resource.
+//!
+//! See [`NonUniqueResourceRef`] for details.
+
+use crate::archetype::ArchetypeComponentId;
+use crate::component::{ComponentId, Tick};
+use crate::prelude::World;
+use crate::query::Access;
+use crate::storage::non_unique_resource::NonUniqueResourceEntry;
+use crate::storage::TableRow;
+use crate::system::{check_system_change_tick, System, SystemMeta};
+use crate::system::{In, IntoSystem};
+use crate::world::unsafe_world_cell::UnsafeWorldCell;
+use bevy_ptr::Ptr;
+use std::any;
+use std::any::TypeId;
+use std::borrow::Cow;
+use std::marker::PhantomData;
+
+/// Non-unique resource (multiple instances of the same type are stored in the world).
+///
+/// Resource is allocated with [`World::new_non_unique_resource()`].
+pub struct NonUniqueResourceRef<T: Sync + Send + 'static> {
+    /// Unique per `NonUniqueResourceRef<T>` instance.
+    component_id: ComponentId,
+    /// Index in table.
+    index: TableRow,
+    /// Allow concurrent access to different instances of `NonUniqueResourceRef<T>`.
+    archetype_component_id: ArchetypeComponentId,
+    /// We secretly store a `T` here.
+    _phantom: PhantomData<T>,
+}
+
+impl<T: Sync + Send + 'static> Clone for NonUniqueResourceRef<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<T: Sync + Send + 'static> Copy for NonUniqueResourceRef<T> {}
+
+struct NonUniqueResourceSystem<T: Sync + Send + 'static, In, Out, F, const WRITE: bool> {
+    non_unique_resource_ref: NonUniqueResourceRef<T>,
+    system_meta: SystemMeta,
+    function: F,
+    _phantom: PhantomData<(In, Out)>,
+}
+
+impl<T, In, Out, F, const WRITE: bool> NonUniqueResourceSystem<T, In, Out, F, WRITE>
+where
+    T: Sync + Send + 'static,
+    In: Send + Sync + 'static,
+    Out: Send + Sync + 'static,
+    F: Fn(In, Ptr) -> Out + Sync + Send + 'static,
+{
+    pub fn new(
+        non_unique_resource_ref: NonUniqueResourceRef<T>,
+        function: F,
+    ) -> NonUniqueResourceSystem<T, In, Out, F, WRITE> {
+        NonUniqueResourceSystem {
+            non_unique_resource_ref,
+            system_meta: SystemMeta::new::<Self>(),
+            function,
+            _phantom: PhantomData,
+        }
+    }
+}
+
+impl<T, In, Out, F, const WRITE: bool> System for NonUniqueResourceSystem<T, In, Out, F, WRITE>
+where
+    T: Sync + Send + 'static,
+    In: Send + Sync + 'static,
+    Out: Send + Sync + 'static,
+    F: Fn(In, Ptr) -> Out + Sync + Send + 'static,
+{
+    type In = In;
+    type Out = Out;
+
+    fn name(&self) -> Cow<'static, str> {
+        self.system_meta.name.clone()
+    }
+
+    fn type_id(&self) -> TypeId {
+        TypeId::of::<Self>()
+    }
+
+    fn component_access(&self) -> &Access<ComponentId> {
+        self.system_meta.component_access_set.combined_access()
+    }
+
+    fn archetype_component_access(&self) -> &Access<ArchetypeComponentId> {
+        &self.system_meta.archetype_component_access
+    }
+
+    fn is_send(&self) -> bool {
+        true
+    }
+
+    fn is_exclusive(&self) -> bool {
+        WRITE
+    }
+
+    unsafe fn run_unsafe(&mut self, input: Self::In, world: UnsafeWorldCell) -> Self::Out {
+        let ptr = world.get_non_unique_resource_by_id(
+            self.non_unique_resource_ref.component_id,
+            self.non_unique_resource_ref.index,
+        );
+        (self.function)(input, ptr)
+    }
+
+    fn apply_deferred(&mut self, _world: &mut World) {}
+
+    fn initialize(&mut self, _world: &mut World) {}
+
+    fn update_archetype_component_access(&mut self, _world: UnsafeWorldCell) {
+        // TODO: is it correct?
+        // TODO: panic somewhere if the same system (this and combined with this)
+        //   accesses the same resource incompatibly.
+        if WRITE {
+            self.system_meta
+                .component_access_set
+                .add_unfiltered_write(self.non_unique_resource_ref.component_id);
+
+            self.system_meta
+                .archetype_component_access
+                .add_write(self.non_unique_resource_ref.archetype_component_id);
+        } else {
+            self.system_meta
+                .component_access_set
+                .add_unfiltered_read(self.non_unique_resource_ref.component_id);
+
+            self.system_meta
+                .archetype_component_access
+                .add_read(self.non_unique_resource_ref.archetype_component_id);
+        }
+    }
+
+    fn check_change_tick(&mut self, change_tick: Tick) {
+        check_system_change_tick(
+            &mut self.system_meta.last_run,
+            change_tick,
+            self.system_meta.name.as_ref(),
+        );
+    }
+
+    fn get_last_run(&self) -> Tick {
+        self.system_meta.last_run
+    }
+
+    fn set_last_run(&mut self, last_run: Tick) {
+        self.system_meta.last_run = last_run;
+    }
+}
+
+impl<T: Sync + Send + 'static> NonUniqueResourceRef<T> {
+    // Technically this function is unsafe because argument must match.
+    pub(crate) fn new(
+        component_id: ComponentId,
+        index: TableRow,
+        archetype_component_id: ArchetypeComponentId,
+    ) -> Self {
+        NonUniqueResourceRef {
+            component_id,
+            index,
+            archetype_component_id,
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Read the value if it is set, return `None` otherwise.
+    pub fn read_opt_system(&self) -> impl System<In = (), Out = Option<T>> {
+        // SAFETY: `NonUniqueResourceSystem` guarantees that the pointer is correct.
+        NonUniqueResourceSystem::<_, _, _, _, true>::new(*self, |(), ptr| unsafe {
+            ptr.assert_unique()
+                .deref_mut::<NonUniqueResourceEntry<T>>()
+                .value
+                .take()
+        })
+    }
+
+    /// Read the value if it is set, panic otherwise.
+    pub fn read_system(&self) -> impl System<In = (), Out = T> {
+        // Slightly inefficient: we store index twice in the resulting system.
+        let index = self.index.index();
+        self.read_opt_system().map(move |opt| match opt {
+            Some(v) => v,
+            None => panic!(
+                "Non-unique resource {}.{} is not set",
+                any::type_name::<T>(),
+                index
+            ),
+        })
+    }
+
+    /// Read the value if it is set, return `None` otherwise.
+    ///
+    /// Keeps the value in the resource.
+    pub fn read_opt_clone_system(&self) -> impl System<In = (), Out = Option<T>>
+    where
+        T: Clone,
+    {
+        // SAFETY: `NonUniqueResourceSystem` guarantees that the pointer is correct.
+        NonUniqueResourceSystem::<_, _, _, _, false>::new(*self, |(), ptr| unsafe {
+            ptr.deref::<NonUniqueResourceEntry<T>>().value.clone()
+        })
+    }
+
+    /// Read the value if it is set, panic otherwise.
+    ///
+    /// Keeps the value in the resource.
+    pub fn read_clone_system(&self) -> impl System<In = (), Out = T>
+    where
+        T: Clone,
+    {
+        // Slightly inefficient: we store index twice in the resulting system.
+        let index = self.index.index();
+        self.read_opt_clone_system().map(move |opt| match opt {
+            Some(v) => v,
+            None => panic!(
+                "Non-unique resource {}.{} is not set",
+                any::type_name::<T>(),
+                index
+            ),
+        })
+    }
+
+    /// Write the value overwriting the previous one.
+    pub fn write_opt_system(&self) -> impl System<In = Option<T>, Out = ()> {
+        // SAFETY: `NonUniqueResourceSystem` guarantees that the pointer is correct.
+        NonUniqueResourceSystem::<_, _, _, _, true>::new(*self, |value, ptr| unsafe {
+            ptr.assert_unique()
+                .deref_mut::<NonUniqueResourceEntry<T>>()
+                .value = value;
+        })
+    }
+
+    /// Write the value overwriting the previous one.
+    pub fn write_system(&self) -> impl System<In = T, Out = ()> {
+        (|In(value)| Some(value)).pipe(self.write_opt_system())
+    }
+
+    /// Write the given value into the resource.
+    pub fn write_value_system(&self, value: T) -> impl System<In = (), Out = ()>
+    where
+        T: Clone,
+    {
+        (move || value.clone()).pipe(self.write_system())
+    }
+
+    /// Unset the resource.
+    pub fn remove_system(&self) -> impl System<In = (), Out = ()> {
+        (|| None).pipe(self.write_opt_system())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate as bevy_ecs;
+    use crate::schedule::IntoSystemConfigs;
+    use crate::schedule::Schedule;
+    use crate::schedule::SystemSet;
+    use crate::system::Resource;
+    use crate::system::{In, IntoSystem, ResMut};
+    use crate::world::World;
+
+    #[test]
+    fn test_write_read() {
+        let mut world = World::default();
+
+        let res = world.new_non_unique_resource::<String>();
+
+        #[derive(Resource, Default)]
+        struct TestState(bool);
+
+        world.init_resource::<TestState>();
+
+        let a = res.write_value_system("a".to_owned());
+
+        let b = res
+            .read_system()
+            .pipe(|In(v), mut result: ResMut<TestState>| {
+                assert_eq!("a", v);
+                assert!(!result.0);
+                result.0 = true;
+            });
+
+        #[derive(SystemSet, Clone, Debug, Eq, PartialEq, Hash)]
+        struct Between;
+
+        let mut schedule = Schedule::default();
+        schedule.add_systems(a.before(Between));
+        schedule.add_systems(b.after(Between));
+
+        schedule.run(&mut world);
+
+        assert!(world.get_resource::<TestState>().unwrap().0);
+    }
+
+    #[test]
+    fn test_write_read_clone() {
+        let mut world = World::default();
+
+        let res = world.new_non_unique_resource::<String>();
+
+        #[derive(Resource, Default)]
+        struct TestState {
+            b_read: bool,
+            c_read: bool,
+        }
+
+        world.init_resource::<TestState>();
+
+        let a = res.write_value_system("a".to_owned());
+
+        let b = res
+            .read_clone_system()
+            .pipe(|In(v): In<String>, mut result: ResMut<TestState>| {
+                assert_eq!("a", v);
+                assert!(!result.b_read);
+                result.b_read = true;
+            });
+        let c = res
+            .read_clone_system()
+            .pipe(|In(v): In<String>, mut result: ResMut<TestState>| {
+                assert_eq!("a", v);
+                assert!(!result.c_read);
+                result.c_read = true;
+            });
+
+        #[derive(SystemSet, Clone, Debug, Eq, PartialEq, Hash)]
+        struct Between;
+
+        let mut schedule = Schedule::default();
+        schedule.add_systems(a.before(Between));
+        schedule.add_systems(b.after(Between));
+        schedule.add_systems(c.after(Between));
+
+        schedule.run(&mut world);
+
+        assert!(world.get_resource::<TestState>().unwrap().b_read);
+        assert!(world.get_resource::<TestState>().unwrap().c_read);
+    }
+}