1use crate::{App, AppContext, VisualContext, Window, seal::Sealed};
2use anyhow::{Context as _, Result};
3use collections::FxHashSet;
4use derive_more::{Deref, DerefMut};
5use parking_lot::{RwLock, RwLockUpgradableReadGuard};
6use slotmap::{KeyData, SecondaryMap, SlotMap};
7use std::{
8 any::{Any, TypeId, type_name},
9 cell::RefCell,
10 cmp::Ordering,
11 fmt::{self, Display},
12 hash::{Hash, Hasher},
13 marker::PhantomData,
14 mem,
15 num::NonZeroU64,
16 sync::{
17 Arc, Weak,
18 atomic::{AtomicU64, AtomicUsize, Ordering::SeqCst},
19 },
20 thread::panicking,
21};
22
23use super::Context;
24use crate::util::atomic_incr_if_not_zero;
25#[cfg(any(test, feature = "leak-detection"))]
26use collections::HashMap;
27
28slotmap::new_key_type! {
29 /// A unique identifier for a entity across the application.
30 pub struct EntityId;
31}
32
33impl From<u64> for EntityId {
34 fn from(value: u64) -> Self {
35 Self(KeyData::from_ffi(value))
36 }
37}
38
39impl EntityId {
40 /// Converts this entity id to a [NonZeroU64]
41 pub fn as_non_zero_u64(self) -> NonZeroU64 {
42 NonZeroU64::new(self.0.as_ffi()).unwrap()
43 }
44
45 /// Converts this entity id to a [u64]
46 pub fn as_u64(self) -> u64 {
47 self.0.as_ffi()
48 }
49}
50
51impl Display for EntityId {
52 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
53 write!(f, "{}", self.as_u64())
54 }
55}
56
57pub(crate) struct EntityMap {
58 entities: SecondaryMap<EntityId, Box<dyn Any>>,
59 pub accessed_entities: RefCell<FxHashSet<EntityId>>,
60 ref_counts: Arc<RwLock<EntityRefCounts>>,
61}
62
63struct EntityRefCounts {
64 counts: SlotMap<EntityId, AtomicUsize>,
65 dropped_entity_ids: Vec<EntityId>,
66 #[cfg(any(test, feature = "leak-detection"))]
67 leak_detector: LeakDetector,
68}
69
70impl EntityMap {
71 pub fn new() -> Self {
72 Self {
73 entities: SecondaryMap::new(),
74 accessed_entities: RefCell::new(FxHashSet::default()),
75 ref_counts: Arc::new(RwLock::new(EntityRefCounts {
76 counts: SlotMap::with_key(),
77 dropped_entity_ids: Vec::new(),
78 #[cfg(any(test, feature = "leak-detection"))]
79 leak_detector: LeakDetector {
80 next_handle_id: 0,
81 entity_handles: HashMap::default(),
82 },
83 })),
84 }
85 }
86
87 /// Reserve a slot for an entity, which you can subsequently use with `insert`.
88 pub fn reserve<T: 'static>(&self) -> Slot<T> {
89 let id = self.ref_counts.write().counts.insert(1.into());
90 Slot(Entity::new(id, Arc::downgrade(&self.ref_counts)))
91 }
92
93 /// Insert an entity into a slot obtained by calling `reserve`.
94 pub fn insert<T>(&mut self, slot: Slot<T>, entity: T) -> Entity<T>
95 where
96 T: 'static,
97 {
98 let mut accessed_entities = self.accessed_entities.borrow_mut();
99 accessed_entities.insert(slot.entity_id);
100
101 let handle = slot.0;
102 self.entities.insert(handle.entity_id, Box::new(entity));
103 handle
104 }
105
106 /// Move an entity to the stack.
107 #[track_caller]
108 pub fn lease<'a, T>(&mut self, pointer: &'a Entity<T>) -> Lease<'a, T> {
109 self.assert_valid_context(pointer);
110 let mut accessed_entities = self.accessed_entities.borrow_mut();
111 accessed_entities.insert(pointer.entity_id);
112
113 let entity = Some(
114 self.entities
115 .remove(pointer.entity_id)
116 .unwrap_or_else(|| double_lease_panic::<T>("update")),
117 );
118 Lease {
119 entity,
120 pointer,
121 entity_type: PhantomData,
122 }
123 }
124
125 /// Returns an entity after moving it to the stack.
126 pub fn end_lease<T>(&mut self, mut lease: Lease<T>) {
127 self.entities
128 .insert(lease.pointer.entity_id, lease.entity.take().unwrap());
129 }
130
131 pub fn read<T: 'static>(&self, entity: &Entity<T>) -> &T {
132 self.assert_valid_context(entity);
133 let mut accessed_entities = self.accessed_entities.borrow_mut();
134 accessed_entities.insert(entity.entity_id);
135
136 self.entities
137 .get(entity.entity_id)
138 .and_then(|entity| entity.downcast_ref())
139 .unwrap_or_else(|| double_lease_panic::<T>("read"))
140 }
141
142 fn assert_valid_context(&self, entity: &AnyEntity) {
143 debug_assert!(
144 Weak::ptr_eq(&entity.entity_map, &Arc::downgrade(&self.ref_counts)),
145 "used a entity with the wrong context"
146 );
147 }
148
149 pub fn extend_accessed(&mut self, entities: &FxHashSet<EntityId>) {
150 self.accessed_entities
151 .borrow_mut()
152 .extend(entities.iter().copied());
153 }
154
155 pub fn clear_accessed(&mut self) {
156 self.accessed_entities.borrow_mut().clear();
157 }
158
159 pub fn take_dropped(&mut self) -> Vec<(EntityId, Box<dyn Any>)> {
160 let mut ref_counts = self.ref_counts.write();
161 let dropped_entity_ids = mem::take(&mut ref_counts.dropped_entity_ids);
162 let mut accessed_entities = self.accessed_entities.borrow_mut();
163
164 dropped_entity_ids
165 .into_iter()
166 .filter_map(|entity_id| {
167 let count = ref_counts.counts.remove(entity_id).unwrap();
168 debug_assert_eq!(
169 count.load(SeqCst),
170 0,
171 "dropped an entity that was referenced"
172 );
173 accessed_entities.remove(&entity_id);
174 // If the EntityId was allocated with `Context::reserve`,
175 // the entity may not have been inserted.
176 Some((entity_id, self.entities.remove(entity_id)?))
177 })
178 .collect()
179 }
180}
181
182#[track_caller]
183fn double_lease_panic<T>(operation: &str) -> ! {
184 panic!(
185 "cannot {operation} {} while it is already being updated",
186 std::any::type_name::<T>()
187 )
188}
189
190pub(crate) struct Lease<'a, T> {
191 entity: Option<Box<dyn Any>>,
192 pub pointer: &'a Entity<T>,
193 entity_type: PhantomData<T>,
194}
195
196impl<T: 'static> core::ops::Deref for Lease<'_, T> {
197 type Target = T;
198
199 fn deref(&self) -> &Self::Target {
200 self.entity.as_ref().unwrap().downcast_ref().unwrap()
201 }
202}
203
204impl<T: 'static> core::ops::DerefMut for Lease<'_, T> {
205 fn deref_mut(&mut self) -> &mut Self::Target {
206 self.entity.as_mut().unwrap().downcast_mut().unwrap()
207 }
208}
209
210impl<T> Drop for Lease<'_, T> {
211 fn drop(&mut self) {
212 if self.entity.is_some() && !panicking() {
213 panic!("Leases must be ended with EntityMap::end_lease")
214 }
215 }
216}
217
218#[derive(Deref, DerefMut)]
219pub(crate) struct Slot<T>(Entity<T>);
220
221/// A dynamically typed reference to a entity, which can be downcast into a `Entity<T>`.
222pub struct AnyEntity {
223 pub(crate) entity_id: EntityId,
224 pub(crate) entity_type: TypeId,
225 entity_map: Weak<RwLock<EntityRefCounts>>,
226 #[cfg(any(test, feature = "leak-detection"))]
227 handle_id: HandleId,
228}
229
230impl AnyEntity {
231 fn new(id: EntityId, entity_type: TypeId, entity_map: Weak<RwLock<EntityRefCounts>>) -> Self {
232 Self {
233 entity_id: id,
234 entity_type,
235 entity_map: entity_map.clone(),
236 #[cfg(any(test, feature = "leak-detection"))]
237 handle_id: entity_map
238 .upgrade()
239 .unwrap()
240 .write()
241 .leak_detector
242 .handle_created(id),
243 }
244 }
245
246 /// Returns the id associated with this entity.
247 pub fn entity_id(&self) -> EntityId {
248 self.entity_id
249 }
250
251 /// Returns the [TypeId] associated with this entity.
252 pub fn entity_type(&self) -> TypeId {
253 self.entity_type
254 }
255
256 /// Converts this entity handle into a weak variant, which does not prevent it from being released.
257 pub fn downgrade(&self) -> AnyWeakEntity {
258 AnyWeakEntity {
259 entity_id: self.entity_id,
260 entity_type: self.entity_type,
261 entity_ref_counts: self.entity_map.clone(),
262 }
263 }
264
265 /// Converts this entity handle into a strongly-typed entity handle of the given type.
266 /// If this entity handle is not of the specified type, returns itself as an error variant.
267 pub fn downcast<T: 'static>(self) -> Result<Entity<T>, AnyEntity> {
268 if TypeId::of::<T>() == self.entity_type {
269 Ok(Entity {
270 any_entity: self,
271 entity_type: PhantomData,
272 })
273 } else {
274 Err(self)
275 }
276 }
277}
278
279impl Clone for AnyEntity {
280 fn clone(&self) -> Self {
281 if let Some(entity_map) = self.entity_map.upgrade() {
282 let entity_map = entity_map.read();
283 let count = entity_map
284 .counts
285 .get(self.entity_id)
286 .expect("detected over-release of a entity");
287 let prev_count = count.fetch_add(1, SeqCst);
288 assert_ne!(prev_count, 0, "Detected over-release of a entity.");
289 }
290
291 Self {
292 entity_id: self.entity_id,
293 entity_type: self.entity_type,
294 entity_map: self.entity_map.clone(),
295 #[cfg(any(test, feature = "leak-detection"))]
296 handle_id: self
297 .entity_map
298 .upgrade()
299 .unwrap()
300 .write()
301 .leak_detector
302 .handle_created(self.entity_id),
303 }
304 }
305}
306
307impl Drop for AnyEntity {
308 fn drop(&mut self) {
309 if let Some(entity_map) = self.entity_map.upgrade() {
310 let entity_map = entity_map.upgradable_read();
311 let count = entity_map
312 .counts
313 .get(self.entity_id)
314 .expect("detected over-release of a handle.");
315 let prev_count = count.fetch_sub(1, SeqCst);
316 assert_ne!(prev_count, 0, "Detected over-release of a entity.");
317 if prev_count == 1 {
318 // We were the last reference to this entity, so we can remove it.
319 let mut entity_map = RwLockUpgradableReadGuard::upgrade(entity_map);
320 entity_map.dropped_entity_ids.push(self.entity_id);
321 }
322 }
323
324 #[cfg(any(test, feature = "leak-detection"))]
325 if let Some(entity_map) = self.entity_map.upgrade() {
326 entity_map
327 .write()
328 .leak_detector
329 .handle_released(self.entity_id, self.handle_id)
330 }
331 }
332}
333
334impl<T> From<Entity<T>> for AnyEntity {
335 fn from(entity: Entity<T>) -> Self {
336 entity.any_entity
337 }
338}
339
340impl Hash for AnyEntity {
341 fn hash<H: Hasher>(&self, state: &mut H) {
342 self.entity_id.hash(state);
343 }
344}
345
346impl PartialEq for AnyEntity {
347 fn eq(&self, other: &Self) -> bool {
348 self.entity_id == other.entity_id
349 }
350}
351
352impl Eq for AnyEntity {}
353
354impl Ord for AnyEntity {
355 fn cmp(&self, other: &Self) -> Ordering {
356 self.entity_id.cmp(&other.entity_id)
357 }
358}
359
360impl PartialOrd for AnyEntity {
361 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
362 Some(self.cmp(other))
363 }
364}
365
366impl std::fmt::Debug for AnyEntity {
367 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
368 f.debug_struct("AnyEntity")
369 .field("entity_id", &self.entity_id.as_u64())
370 .finish()
371 }
372}
373
374/// A strong, well typed reference to a struct which is managed
375/// by GPUI
376#[derive(Deref, DerefMut)]
377pub struct Entity<T> {
378 #[deref]
379 #[deref_mut]
380 pub(crate) any_entity: AnyEntity,
381 pub(crate) entity_type: PhantomData<T>,
382}
383
384unsafe impl<T> Send for Entity<T> {}
385unsafe impl<T> Sync for Entity<T> {}
386impl<T> Sealed for Entity<T> {}
387
388impl<T: 'static> Entity<T> {
389 fn new(id: EntityId, entity_map: Weak<RwLock<EntityRefCounts>>) -> Self
390 where
391 T: 'static,
392 {
393 Self {
394 any_entity: AnyEntity::new(id, TypeId::of::<T>(), entity_map),
395 entity_type: PhantomData,
396 }
397 }
398
399 /// Get the entity ID associated with this entity
400 pub fn entity_id(&self) -> EntityId {
401 self.any_entity.entity_id
402 }
403
404 /// Downgrade this entity pointer to a non-retaining weak pointer
405 pub fn downgrade(&self) -> WeakEntity<T> {
406 WeakEntity {
407 any_entity: self.any_entity.downgrade(),
408 entity_type: self.entity_type,
409 }
410 }
411
412 /// Convert this into a dynamically typed entity.
413 pub fn into_any(self) -> AnyEntity {
414 self.any_entity
415 }
416
417 /// Grab a reference to this entity from the context.
418 pub fn read<'a>(&self, cx: &'a App) -> &'a T {
419 cx.entities.read(self)
420 }
421
422 /// Read the entity referenced by this handle with the given function.
423 pub fn read_with<R, C: AppContext>(
424 &self,
425 cx: &C,
426 f: impl FnOnce(&T, &App) -> R,
427 ) -> C::Result<R> {
428 cx.read_entity(self, f)
429 }
430
431 /// Updates the entity referenced by this handle with the given function.
432 pub fn update<R, C: AppContext>(
433 &self,
434 cx: &mut C,
435 update: impl FnOnce(&mut T, &mut Context<T>) -> R,
436 ) -> C::Result<R> {
437 cx.update_entity(self, update)
438 }
439
440 /// Updates the entity referenced by this handle with the given function if
441 /// the referenced entity still exists, within a visual context that has a window.
442 /// Returns an error if the entity has been released.
443 pub fn update_in<R, C: VisualContext>(
444 &self,
445 cx: &mut C,
446 update: impl FnOnce(&mut T, &mut Window, &mut Context<T>) -> R,
447 ) -> C::Result<R> {
448 cx.update_window_entity(self, update)
449 }
450}
451
452impl<T> Clone for Entity<T> {
453 fn clone(&self) -> Self {
454 Self {
455 any_entity: self.any_entity.clone(),
456 entity_type: self.entity_type,
457 }
458 }
459}
460
461impl<T> std::fmt::Debug for Entity<T> {
462 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
463 f.debug_struct("Entity")
464 .field("entity_id", &self.any_entity.entity_id)
465 .field("entity_type", &type_name::<T>())
466 .finish()
467 }
468}
469
470impl<T> Hash for Entity<T> {
471 fn hash<H: Hasher>(&self, state: &mut H) {
472 self.any_entity.hash(state);
473 }
474}
475
476impl<T> PartialEq for Entity<T> {
477 fn eq(&self, other: &Self) -> bool {
478 self.any_entity == other.any_entity
479 }
480}
481
482impl<T> Eq for Entity<T> {}
483
484impl<T> PartialEq<WeakEntity<T>> for Entity<T> {
485 fn eq(&self, other: &WeakEntity<T>) -> bool {
486 self.any_entity.entity_id() == other.entity_id()
487 }
488}
489
490impl<T: 'static> Ord for Entity<T> {
491 fn cmp(&self, other: &Self) -> std::cmp::Ordering {
492 self.entity_id().cmp(&other.entity_id())
493 }
494}
495
496impl<T: 'static> PartialOrd for Entity<T> {
497 fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
498 Some(self.cmp(other))
499 }
500}
501
502/// A type erased, weak reference to a entity.
503#[derive(Clone)]
504pub struct AnyWeakEntity {
505 pub(crate) entity_id: EntityId,
506 entity_type: TypeId,
507 entity_ref_counts: Weak<RwLock<EntityRefCounts>>,
508}
509
510impl AnyWeakEntity {
511 /// Get the entity ID associated with this weak reference.
512 pub fn entity_id(&self) -> EntityId {
513 self.entity_id
514 }
515
516 /// Check if this weak handle can be upgraded, or if the entity has already been dropped
517 pub fn is_upgradable(&self) -> bool {
518 let ref_count = self
519 .entity_ref_counts
520 .upgrade()
521 .and_then(|ref_counts| Some(ref_counts.read().counts.get(self.entity_id)?.load(SeqCst)))
522 .unwrap_or(0);
523 ref_count > 0
524 }
525
526 /// Upgrade this weak entity reference to a strong reference.
527 pub fn upgrade(&self) -> Option<AnyEntity> {
528 let ref_counts = &self.entity_ref_counts.upgrade()?;
529 let ref_counts = ref_counts.read();
530 let ref_count = ref_counts.counts.get(self.entity_id)?;
531
532 if atomic_incr_if_not_zero(ref_count) == 0 {
533 // entity_id is in dropped_entity_ids
534 return None;
535 }
536 drop(ref_counts);
537
538 Some(AnyEntity {
539 entity_id: self.entity_id,
540 entity_type: self.entity_type,
541 entity_map: self.entity_ref_counts.clone(),
542 #[cfg(any(test, feature = "leak-detection"))]
543 handle_id: self
544 .entity_ref_counts
545 .upgrade()
546 .unwrap()
547 .write()
548 .leak_detector
549 .handle_created(self.entity_id),
550 })
551 }
552
553 /// Assert that entity referenced by this weak handle has been released.
554 #[cfg(any(test, feature = "leak-detection"))]
555 pub fn assert_released(&self) {
556 self.entity_ref_counts
557 .upgrade()
558 .unwrap()
559 .write()
560 .leak_detector
561 .assert_released(self.entity_id);
562
563 if self
564 .entity_ref_counts
565 .upgrade()
566 .and_then(|ref_counts| Some(ref_counts.read().counts.get(self.entity_id)?.load(SeqCst)))
567 .is_some()
568 {
569 panic!(
570 "entity was recently dropped but resources are retained until the end of the effect cycle."
571 )
572 }
573 }
574
575 /// Creates a weak entity that can never be upgraded.
576 pub fn new_invalid() -> Self {
577 /// To hold the invariant that all ids are unique, and considering that slotmap
578 /// increases their IDs from `0`, we can decrease ours from `u64::MAX` so these
579 /// two will never conflict (u64 is way too large).
580 static UNIQUE_NON_CONFLICTING_ID_GENERATOR: AtomicU64 = AtomicU64::new(u64::MAX);
581 let entity_id = UNIQUE_NON_CONFLICTING_ID_GENERATOR.fetch_sub(1, SeqCst);
582
583 Self {
584 // Safety:
585 // Docs say this is safe but can be unspecified if slotmap changes the representation
586 // after `1.0.7`, that said, providing a valid entity_id here is not necessary as long
587 // as we guarantee that `entity_id` is never used if `entity_ref_counts` equals
588 // to `Weak::new()` (that is, it's unable to upgrade), that is the invariant that
589 // actually needs to be hold true.
590 //
591 // And there is no sane reason to read an entity slot if `entity_ref_counts` can't be
592 // read in the first place, so we're good!
593 entity_id: entity_id.into(),
594 entity_type: TypeId::of::<()>(),
595 entity_ref_counts: Weak::new(),
596 }
597 }
598}
599
600impl std::fmt::Debug for AnyWeakEntity {
601 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
602 f.debug_struct(type_name::<Self>())
603 .field("entity_id", &self.entity_id)
604 .field("entity_type", &self.entity_type)
605 .finish()
606 }
607}
608
609impl<T> From<WeakEntity<T>> for AnyWeakEntity {
610 fn from(entity: WeakEntity<T>) -> Self {
611 entity.any_entity
612 }
613}
614
615impl Hash for AnyWeakEntity {
616 fn hash<H: Hasher>(&self, state: &mut H) {
617 self.entity_id.hash(state);
618 }
619}
620
621impl PartialEq for AnyWeakEntity {
622 fn eq(&self, other: &Self) -> bool {
623 self.entity_id == other.entity_id
624 }
625}
626
627impl Eq for AnyWeakEntity {}
628
629impl Ord for AnyWeakEntity {
630 fn cmp(&self, other: &Self) -> Ordering {
631 self.entity_id.cmp(&other.entity_id)
632 }
633}
634
635impl PartialOrd for AnyWeakEntity {
636 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
637 Some(self.cmp(other))
638 }
639}
640
641/// A weak reference to a entity of the given type.
642#[derive(Deref, DerefMut)]
643pub struct WeakEntity<T> {
644 #[deref]
645 #[deref_mut]
646 any_entity: AnyWeakEntity,
647 entity_type: PhantomData<T>,
648}
649
650impl<T> std::fmt::Debug for WeakEntity<T> {
651 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
652 f.debug_struct(&type_name::<Self>())
653 .field("entity_id", &self.any_entity.entity_id)
654 .field("entity_type", &type_name::<T>())
655 .finish()
656 }
657}
658
659unsafe impl<T> Send for WeakEntity<T> {}
660unsafe impl<T> Sync for WeakEntity<T> {}
661
662impl<T> Clone for WeakEntity<T> {
663 fn clone(&self) -> Self {
664 Self {
665 any_entity: self.any_entity.clone(),
666 entity_type: self.entity_type,
667 }
668 }
669}
670
671impl<T: 'static> WeakEntity<T> {
672 /// Upgrade this weak entity reference into a strong entity reference
673 pub fn upgrade(&self) -> Option<Entity<T>> {
674 Some(Entity {
675 any_entity: self.any_entity.upgrade()?,
676 entity_type: self.entity_type,
677 })
678 }
679
680 /// Updates the entity referenced by this handle with the given function if
681 /// the referenced entity still exists. Returns an error if the entity has
682 /// been released.
683 pub fn update<C, R>(
684 &self,
685 cx: &mut C,
686 update: impl FnOnce(&mut T, &mut Context<T>) -> R,
687 ) -> Result<R>
688 where
689 C: AppContext,
690 Result<C::Result<R>>: crate::Flatten<R>,
691 {
692 crate::Flatten::flatten(
693 self.upgrade()
694 .context("entity released")
695 .map(|this| cx.update_entity(&this, update)),
696 )
697 }
698
699 /// Updates the entity referenced by this handle with the given function if
700 /// the referenced entity still exists, within a visual context that has a window.
701 /// Returns an error if the entity has been released.
702 pub fn update_in<C, R>(
703 &self,
704 cx: &mut C,
705 update: impl FnOnce(&mut T, &mut Window, &mut Context<T>) -> R,
706 ) -> Result<R>
707 where
708 C: VisualContext,
709 Result<C::Result<R>>: crate::Flatten<R>,
710 {
711 let window = cx.window_handle();
712 let this = self.upgrade().context("entity released")?;
713
714 crate::Flatten::flatten(window.update(cx, |_, window, cx| {
715 this.update(cx, |entity, cx| update(entity, window, cx))
716 }))
717 }
718
719 /// Reads the entity referenced by this handle with the given function if
720 /// the referenced entity still exists. Returns an error if the entity has
721 /// been released.
722 pub fn read_with<C, R>(&self, cx: &C, read: impl FnOnce(&T, &App) -> R) -> Result<R>
723 where
724 C: AppContext,
725 Result<C::Result<R>>: crate::Flatten<R>,
726 {
727 crate::Flatten::flatten(
728 self.upgrade()
729 .context("entity released")
730 .map(|this| cx.read_entity(&this, read)),
731 )
732 }
733
734 /// Create a new weak entity that can never be upgraded.
735 pub fn new_invalid() -> Self {
736 Self {
737 any_entity: AnyWeakEntity::new_invalid(),
738 entity_type: PhantomData,
739 }
740 }
741}
742
743impl<T> Hash for WeakEntity<T> {
744 fn hash<H: Hasher>(&self, state: &mut H) {
745 self.any_entity.hash(state);
746 }
747}
748
749impl<T> PartialEq for WeakEntity<T> {
750 fn eq(&self, other: &Self) -> bool {
751 self.any_entity == other.any_entity
752 }
753}
754
755impl<T> Eq for WeakEntity<T> {}
756
757impl<T> PartialEq<Entity<T>> for WeakEntity<T> {
758 fn eq(&self, other: &Entity<T>) -> bool {
759 self.entity_id() == other.any_entity.entity_id()
760 }
761}
762
763impl<T: 'static> Ord for WeakEntity<T> {
764 fn cmp(&self, other: &Self) -> Ordering {
765 self.entity_id().cmp(&other.entity_id())
766 }
767}
768
769impl<T: 'static> PartialOrd for WeakEntity<T> {
770 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
771 Some(self.cmp(other))
772 }
773}
774
775#[cfg(any(test, feature = "leak-detection"))]
776static LEAK_BACKTRACE: std::sync::LazyLock<bool> =
777 std::sync::LazyLock::new(|| std::env::var("LEAK_BACKTRACE").map_or(false, |b| !b.is_empty()));
778
779#[cfg(any(test, feature = "leak-detection"))]
780#[derive(Clone, Copy, Debug, Default, Hash, PartialEq, Eq)]
781pub(crate) struct HandleId {
782 id: u64, // id of the handle itself, not the pointed at object
783}
784
785#[cfg(any(test, feature = "leak-detection"))]
786pub(crate) struct LeakDetector {
787 next_handle_id: u64,
788 entity_handles: HashMap<EntityId, HashMap<HandleId, Option<backtrace::Backtrace>>>,
789}
790
791#[cfg(any(test, feature = "leak-detection"))]
792impl LeakDetector {
793 #[track_caller]
794 pub fn handle_created(&mut self, entity_id: EntityId) -> HandleId {
795 let id = util::post_inc(&mut self.next_handle_id);
796 let handle_id = HandleId { id };
797 let handles = self.entity_handles.entry(entity_id).or_default();
798 handles.insert(
799 handle_id,
800 LEAK_BACKTRACE.then(backtrace::Backtrace::new_unresolved),
801 );
802 handle_id
803 }
804
805 pub fn handle_released(&mut self, entity_id: EntityId, handle_id: HandleId) {
806 let handles = self.entity_handles.entry(entity_id).or_default();
807 handles.remove(&handle_id);
808 }
809
810 pub fn assert_released(&mut self, entity_id: EntityId) {
811 let handles = self.entity_handles.entry(entity_id).or_default();
812 if !handles.is_empty() {
813 for backtrace in handles.values_mut() {
814 if let Some(mut backtrace) = backtrace.take() {
815 backtrace.resolve();
816 eprintln!("Leaked handle: {:#?}", backtrace);
817 } else {
818 eprintln!("Leaked handle: export LEAK_BACKTRACE to find allocation site");
819 }
820 }
821 panic!();
822 }
823 }
824}
825
826#[cfg(test)]
827mod test {
828 use crate::EntityMap;
829
830 struct TestEntity {
831 pub i: i32,
832 }
833
834 #[test]
835 fn test_entity_map_slot_assignment_before_cleanup() {
836 // Tests that slots are not re-used before take_dropped.
837 let mut entity_map = EntityMap::new();
838
839 let slot = entity_map.reserve::<TestEntity>();
840 entity_map.insert(slot, TestEntity { i: 1 });
841
842 let slot = entity_map.reserve::<TestEntity>();
843 entity_map.insert(slot, TestEntity { i: 2 });
844
845 let dropped = entity_map.take_dropped();
846 assert_eq!(dropped.len(), 2);
847
848 assert_eq!(
849 dropped
850 .into_iter()
851 .map(|(_, entity)| entity.downcast::<TestEntity>().unwrap().i)
852 .collect::<Vec<i32>>(),
853 vec![1, 2],
854 );
855 }
856
857 #[test]
858 fn test_entity_map_weak_upgrade_before_cleanup() {
859 // Tests that weak handles are not upgraded before take_dropped
860 let mut entity_map = EntityMap::new();
861
862 let slot = entity_map.reserve::<TestEntity>();
863 let handle = entity_map.insert(slot, TestEntity { i: 1 });
864 let weak = handle.downgrade();
865 drop(handle);
866
867 let strong = weak.upgrade();
868 assert_eq!(strong, None);
869
870 let dropped = entity_map.take_dropped();
871 assert_eq!(dropped.len(), 1);
872
873 assert_eq!(
874 dropped
875 .into_iter()
876 .map(|(_, entity)| entity.downcast::<TestEntity>().unwrap().i)
877 .collect::<Vec<i32>>(),
878 vec![1],
879 );
880 }
881}