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//! Component storage types, implementations for component joins, etc.
pub use self::deref_flagged::{DerefFlaggedStorage, FlaggedAccessMut};
pub use self::{
data::{ReadStorage, WriteStorage},
entry::{Entries, OccupiedEntry, StorageEntry, VacantEntry},
flagged::FlaggedStorage,
generic::{GenericReadStorage, GenericWriteStorage},
restrict::{
PairedStorageRead, PairedStorageWriteExclusive, PairedStorageWriteShared,
RestrictedStorage, SharedGetOnly,
},
storages::{
BTreeStorage, DefaultVecStorage, DenseVecStorage, HashMapStorage, NullStorage, SliceAccess,
VecStorage,
},
track::{ComponentEvent, Tracked},
};
use std::{
self,
marker::PhantomData,
ops::{Deref, DerefMut, Not},
};
use hibitset::{BitSet, BitSetLike, BitSetNot};
use shred::{CastFrom, Fetch};
#[nougat::gat(Type)]
use crate::join::LendJoin;
#[cfg(feature = "parallel")]
use crate::join::ParJoin;
use crate::{
error::{Error, WrongGeneration},
join::{Join, RepeatableLendGet},
world::{Component, EntitiesRes, Entity, Index},
};
use self::drain::Drain;
use self::sync_unsafe_cell::SyncUnsafeCell;
mod data;
mod deref_flagged;
mod drain;
mod entry;
mod flagged;
mod generic;
mod restrict;
mod storages;
mod sync_unsafe_cell;
#[cfg(test)]
mod tests;
mod track;
type AccessMutReturn<'a, T> = <<T as Component>::Storage as UnprotectedStorage<T>>::AccessMut<'a>;
/// An inverted storage type, only useful to iterate entities
/// that do not have a particular component type.
pub struct AntiStorage<'a>(pub &'a BitSet);
// SAFETY: Items are just `()` and it is always safe to retrieve them regardless
// of the mask and value returned by `open`.
#[nougat::gat]
unsafe impl<'a> LendJoin for AntiStorage<'a> {
type Mask = BitSetNot<&'a BitSet>;
type Type<'next> = ();
type Value = ();
unsafe fn open(self) -> (Self::Mask, ()) {
(BitSetNot(self.0), ())
}
unsafe fn get<'next>(_: &'next mut (), _: Index) {}
}
// SAFETY: <AntiStorage as LendJoin>::get does nothing.
unsafe impl RepeatableLendGet for AntiStorage<'_> {}
// SAFETY: Items are just `()` and it is always safe to retrieve them regardless
// of the mask and value returned by `open`.
unsafe impl<'a> Join for AntiStorage<'a> {
type Mask = BitSetNot<&'a BitSet>;
type Type = ();
type Value = ();
unsafe fn open(self) -> (Self::Mask, ()) {
(BitSetNot(self.0), ())
}
unsafe fn get(_: &mut (), _: Index) {}
}
// SAFETY: Since `get` does not do anything it is safe to concurrently call.
// Items are just `()` and it is always safe to retrieve them regardless of the
// mask and value returned by `open`.
#[cfg(feature = "parallel")]
unsafe impl<'a> ParJoin for AntiStorage<'a> {
type Mask = BitSetNot<&'a BitSet>;
type Type = ();
type Value = ();
unsafe fn open(self) -> (Self::Mask, ()) {
(BitSetNot(self.0), ())
}
unsafe fn get(_: &(), _: Index) {}
}
/// A dynamic storage.
pub trait AnyStorage {
/// Drop components of given entities.
fn drop(&mut self, entities: &[Entity]);
}
// SAFETY: Returned pointer has a vtable valid for `T` and retains the same
// address/provenance.
unsafe impl<T> CastFrom<T> for dyn AnyStorage
where
T: AnyStorage + 'static,
{
fn cast(t: *mut T) -> *mut Self {
t
}
}
impl<T> AnyStorage for MaskedStorage<T>
where
T: Component,
{
fn drop(&mut self, entities: &[Entity]) {
for entity in entities {
MaskedStorage::drop(self, entity.id());
}
}
}
/// This is a marker trait which requires you to uphold the following guarantee:
///
/// # Safety
///
/// > Multiple threads may call `SharedGetMutStorage::shared_get_mut()`
/// with distinct indices without causing > undefined behavior.
///
/// This is for example valid for `Vec`:
///
/// ```rust
/// vec![1, 2, 3];
/// ```
///
/// We may modify both element 1 and 2 at the same time.
///
/// As a counter example, we may have some kind of cached storage; it caches
/// elements when they're retrieved, so pushes a new element to some
/// cache-vector. This storage is not allowed to implement `DistinctStorage`.
///
/// Implementing this trait marks the storage safe for concurrent mutation (of
/// distinct elements), thus allows `par_join()`.
pub unsafe trait DistinctStorage {}
/// The status of an `insert()`ion into a storage.
/// If the insertion was successful then the Ok value will
/// contain the component that was replaced (if any).
pub type InsertResult<T> = Result<Option<T>, Error>;
/// The `UnprotectedStorage` together with the `BitSet` that knows
/// about which elements are stored, and which are not.
pub struct MaskedStorage<T: Component> {
mask: BitSet,
inner: T::Storage,
}
impl<T: Component> Default for MaskedStorage<T>
where
T::Storage: Default,
{
fn default() -> Self {
Self {
mask: Default::default(),
inner: Default::default(),
}
}
}
impl<T: Component> MaskedStorage<T> {
/// Creates a new `MaskedStorage`. This is called when you register
/// a new component type within the world.
pub fn new(inner: T::Storage) -> MaskedStorage<T> {
MaskedStorage {
mask: BitSet::new(),
inner,
}
}
fn open_mut(&mut self) -> (&BitSet, &mut T::Storage) {
(&self.mask, &mut self.inner)
}
/// Clear the contents of this storage.
pub fn clear(&mut self) {
// NOTE: We replace with default empty mask temporarily to protect against
// unwinding from `Drop` of components.
let mut mask_temp = core::mem::take(&mut self.mask);
// SAFETY: `self.mask` is the correct mask as specified. We swap in a
// temporary empty mask to ensure if this unwinds that the mask will be
// cleared.
unsafe { self.inner.clean(&mask_temp) };
mask_temp.clear();
self.mask = mask_temp;
}
/// Remove an element by a given index.
pub fn remove(&mut self, id: Index) -> Option<T> {
if self.mask.remove(id) {
// SAFETY: We checked the mask (`remove` returned `true`)
Some(unsafe { self.inner.remove(id) })
} else {
None
}
}
/// Drop an element by a given index.
pub fn drop(&mut self, id: Index) {
if self.mask.remove(id) {
// SAFETY: We checked the mask and removed the id before calling
// drop (`remove` returned `true`).
unsafe {
self.inner.drop(id);
}
}
}
}
impl<T: Component> Drop for MaskedStorage<T> {
fn drop(&mut self) {
self.clear();
}
}
/// A wrapper around the masked storage and the generations vector.
/// Can be used for safe lookup of components, insertions and removes.
/// This is what `World::read/write` fetches for the user.
pub struct Storage<'e, T, D> {
data: D,
entities: Fetch<'e, EntitiesRes>,
phantom: PhantomData<T>,
}
impl<'e, T, D> Storage<'e, T, D> {
/// Creates a new `Storage` from a fetched allocator and a immutable or
/// mutable `MaskedStorage`, named `data`.
pub fn new(entities: Fetch<'e, EntitiesRes>, data: D) -> Storage<'e, T, D> {
Storage {
data,
entities,
phantom: PhantomData,
}
}
}
impl<'e, T, D> Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
{
/// Gets the wrapped storage.
pub fn unprotected_storage(&self) -> &T::Storage {
&self.data.inner
}
/// Returns the `EntitiesRes` resource fetched by this storage.
/// **This does not have anything to do with the components inside.**
/// You only want to use this when implementing additional methods
/// for `Storage` via an extension trait.
pub fn fetched_entities(&self) -> &EntitiesRes {
&self.entities
}
/// Tries to read the data associated with an `Entity`.
pub fn get(&self, e: Entity) -> Option<&T> {
if self.data.mask.contains(e.id()) && self.entities.is_alive(e) {
// SAFETY: We checked the mask, so all invariants are met.
Some(unsafe { self.data.inner.get(e.id()) })
} else {
None
}
}
/// Computes the number of elements this `Storage` contains by counting the
/// bits in the bit set. This operation will never be performed in
/// constant time.
pub fn count(&self) -> usize {
self.mask().iter().count()
}
/// Checks whether this `Storage` is empty. This operation is very cheap.
pub fn is_empty(&self) -> bool {
self.mask().is_empty()
}
/// Returns true if the storage has a component for this entity, and that
/// entity is alive.
pub fn contains(&self, e: Entity) -> bool {
self.data.mask.contains(e.id()) && self.entities.is_alive(e)
}
/// Returns a reference to the bitset of this storage which allows filtering
/// by the component type without actually getting the component.
pub fn mask(&self) -> &BitSet {
&self.data.mask
}
}
impl<'e, T, D> Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
T::Storage: SliceAccess<T>,
{
/// Returns the component data as a slice.
///
/// The indices of this slice may not correspond to anything in particular.
/// Check the underlying storage documentation for details.
pub fn as_slice(&self) -> &[<T::Storage as SliceAccess<T>>::Element] {
self.data.inner.as_slice()
}
}
impl<'e, T, D> Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
T::Storage: SliceAccess<T>,
{
/// Returns the component data as a slice.
///
/// The indices of this slice may not correspond to anything in particular.
/// Check the underlying storage documentation for details.
pub fn as_mut_slice(&mut self) -> &mut [<T::Storage as SliceAccess<T>>::Element] {
self.data.inner.as_mut_slice()
}
}
impl<'e, T, D> Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
{
/// Gets mutable access to the wrapped storage.
///
/// # Safety
///
/// This is unsafe because modifying the wrapped storage without also
/// updating the mask bitset accordingly can result in illegal memory
/// access.
pub unsafe fn unprotected_storage_mut(&mut self) -> &mut T::Storage {
&mut self.data.inner
}
/// Tries to mutate the data associated with an `Entity`.
pub fn get_mut(&mut self, e: Entity) -> Option<AccessMutReturn<'_, T>> {
if self.data.mask.contains(e.id()) && self.entities.is_alive(e) {
// SAFETY: We have exclusive access (which ensures no aliasing or
// concurrent calls from other threads) and we checked the mask,
// thus it's safe to call.
Some(unsafe { self.data.inner.get_mut(e.id()) })
} else {
None
}
}
/// Inserts new data for a given `Entity`.
/// Returns the result of the operation as a `InsertResult<T>`
///
/// If a component already existed for the given `Entity`, then it will
/// be overwritten with the new component. If it did overwrite, then the
/// result will contain `Some(T)` where `T` is the previous component.
pub fn insert(&mut self, e: Entity, mut v: T) -> InsertResult<T> {
if self.entities.is_alive(e) {
let id = e.id();
if self.data.mask.contains(id) {
// SAFETY: `id` is in the mask.
std::mem::swap(&mut v, unsafe { self.data.inner.get_mut(id) }.access_mut());
Ok(Some(v))
} else {
// SAFETY: The mask was previously empty, so this is safe to
// call.
unsafe { self.not_present_insert(id, v) }
Ok(None)
}
} else {
Err(Error::WrongGeneration(WrongGeneration {
action: "insert component for entity",
actual_gen: self.entities.entity(e.id()).gen(),
entity: e,
}))
}
}
/// Insert the provided value at `id` and adds `id` to the mask.
///
/// # Safety
///
/// May only be called if `id` is not present in the mask.
#[inline(always)]
unsafe fn not_present_insert(&mut self, id: Index, value: T) {
// SAFETY: The mask was previously empty, so it is safe to
// insert. We immediately add the value to the mask below and
// unwinding from the `insert` call means that we don't need to
// include the value in the mask. If adding to the mask unwinds we
// remove the value via a drop guard.
// NOTE: We rely on any panics in `Bitset::add` leaving the bitset in
// the same state as before `add` was called!
unsafe { self.data.inner.insert(id, value) };
if cfg!(panic = "abort") {
self.data.mask.add(id);
} else {
struct RemoveOnDrop<'a, T: Component>(&'a mut MaskedStorage<T>, Index);
impl<'a, T: Component> Drop for RemoveOnDrop<'a, T> {
fn drop(&mut self) {
// SAFETY: We just inserted a value here above and failed to
// add it to the bitset.
unsafe {
self.0.inner.remove(self.1);
}
}
}
let guard = RemoveOnDrop(&mut self.data, id);
guard.0.mask.add(id);
core::mem::forget(guard);
}
}
/// Removes the data associated with an `Entity`.
pub fn remove(&mut self, e: Entity) -> Option<T> {
if self.entities.is_alive(e) {
self.data.remove(e.id())
} else {
None
}
}
/// Clears the contents of the storage.
pub fn clear(&mut self) {
self.data.clear();
}
/// Creates a draining storage wrapper which can be `.join`ed
/// to get a draining iterator.
pub fn drain(&mut self) -> Drain<T> {
Drain {
data: &mut self.data,
}
}
}
impl<'a, T, D: Clone> Clone for Storage<'a, T, D> {
fn clone(&self) -> Self {
Storage::new(self.entities.clone(), self.data.clone())
}
}
impl<'a, 'e, T, D> Not for &'a Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
{
type Output = AntiStorage<'a>;
fn not(self) -> Self::Output {
AntiStorage(&self.data.mask)
}
}
// SAFETY: The mask and unprotected storage contained in `MaskedStorage`
// correspond and `open` returns references to them from the same
// `MaskedStorage` instance. Iterating the mask does not repeat indices.
#[nougat::gat]
unsafe impl<'a, 'e, T, D> LendJoin for &'a Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
{
type Mask = &'a BitSet;
type Type<'next> = &'a T;
type Value = &'a T::Storage;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
(&self.data.mask, &self.data.inner)
}
unsafe fn get<'next>(v: &'next mut Self::Value, i: Index) -> &'a T {
// SAFETY: Since we require that the mask was checked, an element for
// `i` must have been inserted without being removed.
unsafe { v.get(i) }
}
}
// SAFETY: LendJoin::get impl for this type is safe to call multiple times with
// the same ID.
unsafe impl<'a, 'e, T, D> RepeatableLendGet for &'a Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
{
}
// SAFETY: The mask and unprotected storage contained in `MaskedStorage`
// correspond and `open` returns references to them from the same
// `MaskedStorage` instance. Iterating the mask does not repeat indices.
unsafe impl<'a, 'e, T, D> Join for &'a Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
{
type Mask = &'a BitSet;
type Type = &'a T;
type Value = &'a T::Storage;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
(&self.data.mask, &self.data.inner)
}
unsafe fn get(v: &mut Self::Value, i: Index) -> &'a T {
// SAFETY: Since we require that the mask was checked, an element for
// `i` must have been inserted without being removed.
unsafe { v.get(i) }
}
}
// SAFETY: It is safe to call `<T::Storage as UnprotectedStorage>::get` from
// multiple threads at once since `T::Storage: Sync`.
//
// The mask and unprotected storage contained in `MaskedStorage` correspond and
// `open` returns references to them from the same `MaskedStorage` instance.
// Iterating the mask does not repeat indices.
#[cfg(feature = "parallel")]
unsafe impl<'a, 'e, T, D> ParJoin for &'a Storage<'e, T, D>
where
T: Component,
D: Deref<Target = MaskedStorage<T>>,
T::Storage: Sync,
{
type Mask = &'a BitSet;
type Type = &'a T;
type Value = &'a T::Storage;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
(&self.data.mask, &self.data.inner)
}
unsafe fn get(v: &Self::Value, i: Index) -> &'a T {
// SAFETY: Since we require that the mask was checked, an element for
// `i` must have been inserted without being removed.
unsafe { v.get(i) }
}
}
// SAFETY: The mask and unprotected storage contained in `MaskedStorage`
// correspond and `open` returns references to them from the same
// `MaskedStorage` instance. Iterating the mask does not repeat indices.
#[nougat::gat]
unsafe impl<'a, 'e, T, D> LendJoin for &'a mut Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
{
type Mask = &'a BitSet;
type Type<'next> = AccessMutReturn<'next, T>;
type Value = &'a mut T::Storage;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
self.data.open_mut()
}
unsafe fn get<'next>(value: &'next mut Self::Value, id: Index) -> Self::Type<'next> {
// SAFETY: Since we require that the mask was checked, an element for
// `id` must have been inserted without being removed.
unsafe { value.get_mut(id) }
}
}
// SAFETY: LendJoin::get impl for this type is safe to call multiple times with
// the same ID.
unsafe impl<'a, 'e, T, D> RepeatableLendGet for &'a mut Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
{
}
mod shared_get_mut_only {
use super::{Index, SharedGetMutStorage, UnprotectedStorage};
use core::marker::PhantomData;
/// This type provides a way to ensure only `shared_get_mut` can be called
/// for the lifetime `'a` and that no references previously obtained from
/// the storage exist when it is created. While internally this is a shared
/// reference, constructing it requires an exclusive borrow for the lifetime
/// `'a`.
///
/// This is useful for implementations of [`Join`](super::Join) and
/// [`ParJoin`](super::ParJoin).
pub struct SharedGetMutOnly<'a, T, S>(&'a S, PhantomData<T>);
impl<'a, T, S> SharedGetMutOnly<'a, T, S> {
pub(crate) fn new(storage: &'a mut S) -> Self {
Self(storage, PhantomData)
}
/// # Safety
///
/// May only be called after a call to `insert` with `id` and no
/// following call to `remove` with `id` or to `clean`.
///
/// A mask should keep track of those states, and an `id` being
/// contained in the tracking mask is sufficient to call this method.
///
/// There must be no extant aliasing references to this component (i.e.
/// obtained with the same `id`).
///
/// Unless `S: DistinctStorage`, calling this from multiple threads at
/// once is unsound.
pub(crate) unsafe fn get_mut(
this: &Self,
id: Index,
) -> <S as UnprotectedStorage<T>>::AccessMut<'a>
where
S: SharedGetMutStorage<T>,
{
// SAFETY: `Self::new` takes an exclusive reference to this storage,
// ensuring there are no extant references to its content at the
// time `self` is created and ensuring that only `self` has access
// to the storage for its lifetime and the lifetime of the produced
// `AccessMutReturn`s (the reference we hold to the storage is not
// exposed outside of this module).
//
// This means we only have to worry about aliasing references being
// produced by calling `SharedGetMutStorage::shared_get_mut`.
// Ensuring these don't alias and the remaining safety requirements
// are passed on to the caller.
unsafe { this.0.shared_get_mut(id) }
}
}
}
pub use shared_get_mut_only::SharedGetMutOnly;
// SAFETY: The mask and unprotected storage contained in `MaskedStorage`
// correspond and `open` returns references to them from the same
// `MaskedStorage` instance (the storage is wrapped in `SharedGetMutOnly`).
// Iterating the mask does not repeat indices.
unsafe impl<'a, 'e, T, D> Join for &'a mut Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
T::Storage: SharedGetMutStorage<T>,
{
type Mask = &'a BitSet;
type Type = AccessMutReturn<'a, T>;
type Value = SharedGetMutOnly<'a, T, T::Storage>;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
let (mask, value) = self.data.open_mut();
let value = SharedGetMutOnly::new(value);
(mask, value)
}
unsafe fn get(value: &mut Self::Value, id: Index) -> Self::Type {
// SAFETY:
// * Since we require that the mask was checked, an element for `id` must have
// been inserted without being removed.
// * We also require that there are no subsequent calls with the same `id` for
// this instance of the values from `open`, so there are no extant references
// for the element corresponding to this `id`.
// * Since we have an exclusive reference to `Self::Value`, we know this isn't
// being called from multiple threads at once.
unsafe { SharedGetMutOnly::get_mut(value, id) }
}
}
// SAFETY: It is safe to call `SharedGetMutOnly<'a, T>::get_mut` from multiple
// threads at once since `T::Storage: DistinctStorage`.
//
// The mask and unprotected storage contained in `MaskedStorage` correspond and
// `open` returns references to them from the same `MaskedStorage` instance (the
// storage is wrapped in `SharedGetMutOnly`). Iterating the mask does not repeat
// indices.
#[cfg(feature = "parallel")]
unsafe impl<'a, 'e, T, D> ParJoin for &'a mut Storage<'e, T, D>
where
T: Component,
D: DerefMut<Target = MaskedStorage<T>>,
T::Storage: Sync + SharedGetMutStorage<T> + DistinctStorage,
{
type Mask = &'a BitSet;
type Type = AccessMutReturn<'a, T>;
type Value = SharedGetMutOnly<'a, T, T::Storage>;
unsafe fn open(self) -> (Self::Mask, Self::Value) {
let (mask, value) = self.data.open_mut();
let value = SharedGetMutOnly::new(value);
(mask, value)
}
unsafe fn get(value: &Self::Value, id: Index) -> Self::Type {
// SAFETY:
// * Since we require that the mask was checked, an element for `id` must have
// been inserted without being removed.
// * We also require that the returned value is no longer alive before
// subsequent calls with the same `id`, so there are no extant references that
// were obtained with the same `id`.
// * `T::Storage` implements the unsafe trait `DistinctStorage` so it is safe to
// call this from multiple threads at once.
unsafe { SharedGetMutOnly::get_mut(value, id) }
}
}
/// Tries to create a default value, returns an `Err` with the name of the
/// storage and/or component if there's no default.
pub trait TryDefault: Sized {
/// Tries to create the default.
fn try_default() -> Result<Self, String>;
/// Calls `try_default` and panics on an error case.
fn unwrap_default() -> Self {
match Self::try_default() {
Ok(x) => x,
Err(e) => panic!("Failed to create a default value for storage ({:?})", e),
}
}
}
impl<T> TryDefault for T
where
T: Default,
{
fn try_default() -> Result<Self, String> {
Ok(T::default())
}
}
/// DerefMut without autoderefing.
///
/// Allows forcing mutable access to be explicit. Useful to implement a flagged
/// storage where it is easier to discover sites where components are marked as
/// mutated. Of course, individual storages can use an associated `AccessMut`
/// type that also implements `DerefMut`, but this provides the common
/// denominator.
pub trait AccessMut: core::ops::Deref {
/// This may generate a mutation event for certain flagged storages.
fn access_mut(&mut self) -> &mut Self::Target;
}
impl<T: ?Sized> AccessMut for T
where
T: core::ops::DerefMut,
{
fn access_mut(&mut self) -> &mut Self::Target {
&mut *self
}
}
/// Used by the framework to quickly join components.
pub trait UnprotectedStorage<T>: TryDefault {
/// The wrapper through with mutable access of a component is performed.
type AccessMut<'a>: AccessMut<Target = T>
where
Self: 'a;
/// Clean the storage given a bitset with bits set for valid indices
/// dropping all existing components.
///
/// Allows us to drop the storage without leaking components.
///
/// # Safety
///
/// May only be called with the mask which keeps track of the elements
/// existing in this storage.
///
/// If this unwinds (e.g. due to a drop impl panicing), the mask should
/// still be cleared.
unsafe fn clean<B>(&mut self, has: B)
where
B: BitSetLike;
/// Gets a shared reference to the data associated with an `Index`.
///
/// This is unsafe because the external set used to protect this storage is
/// absent.
///
/// # Safety
///
/// May only be called after a call to `insert` with `id` and
/// no following call to `remove` with `id` or to `clean`.
///
/// A mask should keep track of those states, and an `id` being contained
/// in the tracking mask is sufficient to call this method.
unsafe fn get(&self, id: Index) -> &T;
/// Gets mutable access to the the data associated with an `Index`.
///
/// This doesn't necessarily directly return a `&mut` reference. This
/// allows storages more flexibility. For example, some flagged storages
/// utilize this to defer generation of mutation events until the user
/// obtains an `&mut` reference out of the returned wrapper type.
///
/// This is unsafe because the external set used to protect this storage is
/// absent.
///
/// # Safety
///
/// May only be called after a call to `insert` with `id` and no following
/// call to `remove` with `id` or to `clean`.
///
/// A mask should keep track of those states, and an `id` being contained in
/// the tracking mask is sufficient to call this method.
unsafe fn get_mut(&mut self, id: Index) -> Self::AccessMut<'_>;
/// Inserts new data for a given `Index`.
///
/// # Safety
///
/// May only be called if `insert` was not called with `id` before, or
/// was reverted by a call to `remove` with `id` or a call to `clean`.
///
/// A mask should keep track of those states, and an `id` missing from the
/// mask is sufficient to call `insert`.
///
/// If this call unwinds the insertion should be considered to have failed
/// and not be included in the mask or count as having called `insert` for
/// the safety requirements of other methods here.
unsafe fn insert(&mut self, id: Index, value: T);
/// Removes the data associated with an `Index`.
///
/// # Safety
///
/// May only be called if an element with `id` was `insert`ed and not yet
/// removed / dropped.
unsafe fn remove(&mut self, id: Index) -> T;
/// Drops the data associated with an `Index`.
/// This could be used when a more efficient implementation for it exists
/// than `remove` when the data is no longer needed.
/// Defaults to simply calling `remove`.
///
/// # Safety
///
/// May only be called if an element with `id` was `insert`ed and not yet
/// removed / dropped.
///
/// Caller must ensure this is cleared from the mask even if the drop impl
/// of the component panics and this unwinds. Usually, this can be
/// accomplished by removing the id from the mask just before calling this.
unsafe fn drop(&mut self, id: Index) {
// SAFETY: Requirements passed to the caller.
unsafe { self.remove(id) };
}
}
/// Used by the framework to mutably access components in contexts where
/// exclusive access to the storage is not possible.
pub trait SharedGetMutStorage<T>: UnprotectedStorage<T> {
/// Gets mutable access to the the data associated with an `Index`.
///
/// This is unsafe because the external set used to protect this storage is
/// absent and because it doesn't protect against concurrent calls from
/// multiple threads and aliasing must manually be managed.
///
/// # Safety
///
/// May only be called after a call to `insert` with `id` and no following
/// call to `remove` with `id` or to `clean`.
///
/// A mask should keep track of those states, and an `id` being contained in
/// the tracking mask is sufficient to call this method.
///
/// There must be no extant aliasing references to this component (i.e.
/// obtained with the same `id`). Additionally, references obtained from
/// methods on this type that take `&self` (e.g. [`SliceAccess::as_slice`],
/// [`Tracked::channel`]) must no longer be alive when
/// `shared_get_mut` is called and these methods must not be
/// called while the references returned here are alive. An exception is
/// made for [`UnprotectedStorage::get`] as long as the live references it
/// has returned do not alias with live references returned here.
///
/// Essentially, the `unsafe` code calling this must hold exclusive access
/// of the storage at some level to ensure only known code is calling
/// `&self` methods during the usage of this method and the references it
/// produces.
///
/// Unless this type implements `DistinctStorage`, calling this from
/// multiple threads at once is unsound.
unsafe fn shared_get_mut(&self, id: Index) -> <Self as UnprotectedStorage<T>>::AccessMut<'_>;
}
#[cfg(test)]
#[cfg(feature = "parallel")]
mod tests_inline {
use crate::{
Builder, Component, DenseVecStorage, Entities, ParJoin, ReadStorage, World, WorldExt,
};
use rayon::iter::ParallelIterator;
struct Pos;
impl Component for Pos {
type Storage = DenseVecStorage<Self>;
}
#[test]
fn test_anti_par_join() {
let mut world = World::new();
world.create_entity().build();
world.exec(|(entities, pos): (Entities, ReadStorage<Pos>)| {
(&entities, !&pos).par_join().for_each(|(ent, ())| {
println!("Processing entity: {:?}", ent);
});
});
}
}