1use crate::{App, AppContext, GpuiBorrow, 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<T>(&mut self, pointer: &Entity<T>) -> Lease<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 id: pointer.entity_id,
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.insert(lease.id, lease.entity.take().unwrap());
128 }
129
130 pub fn read<T: 'static>(&self, entity: &Entity<T>) -> &T {
131 self.assert_valid_context(entity);
132 let mut accessed_entities = self.accessed_entities.borrow_mut();
133 accessed_entities.insert(entity.entity_id);
134
135 self.entities
136 .get(entity.entity_id)
137 .and_then(|entity| entity.downcast_ref())
138 .unwrap_or_else(|| double_lease_panic::<T>("read"))
139 }
140
141 fn assert_valid_context(&self, entity: &AnyEntity) {
142 debug_assert!(
143 Weak::ptr_eq(&entity.entity_map, &Arc::downgrade(&self.ref_counts)),
144 "used a entity with the wrong context"
145 );
146 }
147
148 pub fn extend_accessed(&mut self, entities: &FxHashSet<EntityId>) {
149 self.accessed_entities
150 .borrow_mut()
151 .extend(entities.iter().copied());
152 }
153
154 pub fn clear_accessed(&mut self) {
155 self.accessed_entities.borrow_mut().clear();
156 }
157
158 pub fn take_dropped(&mut self) -> Vec<(EntityId, Box<dyn Any>)> {
159 let mut ref_counts = self.ref_counts.write();
160 let dropped_entity_ids = mem::take(&mut ref_counts.dropped_entity_ids);
161 let mut accessed_entities = self.accessed_entities.borrow_mut();
162
163 dropped_entity_ids
164 .into_iter()
165 .filter_map(|entity_id| {
166 let count = ref_counts.counts.remove(entity_id).unwrap();
167 debug_assert_eq!(
168 count.load(SeqCst),
169 0,
170 "dropped an entity that was referenced"
171 );
172 accessed_entities.remove(&entity_id);
173 // If the EntityId was allocated with `Context::reserve`,
174 // the entity may not have been inserted.
175 Some((entity_id, self.entities.remove(entity_id)?))
176 })
177 .collect()
178 }
179}
180
181#[track_caller]
182fn double_lease_panic<T>(operation: &str) -> ! {
183 panic!(
184 "cannot {operation} {} while it is already being updated",
185 std::any::type_name::<T>()
186 )
187}
188
189pub(crate) struct Lease<T> {
190 entity: Option<Box<dyn Any>>,
191 pub id: EntityId,
192 entity_type: PhantomData<T>,
193}
194
195impl<T: 'static> core::ops::Deref for Lease<T> {
196 type Target = T;
197
198 fn deref(&self) -> &Self::Target {
199 self.entity.as_ref().unwrap().downcast_ref().unwrap()
200 }
201}
202
203impl<T: 'static> core::ops::DerefMut for Lease<T> {
204 fn deref_mut(&mut self) -> &mut Self::Target {
205 self.entity.as_mut().unwrap().downcast_mut().unwrap()
206 }
207}
208
209impl<T> Drop for Lease<T> {
210 fn drop(&mut self) {
211 if self.entity.is_some() && !panicking() {
212 panic!("Leases must be ended with EntityMap::end_lease")
213 }
214 }
215}
216
217#[derive(Deref, DerefMut)]
218pub(crate) struct Slot<T>(Entity<T>);
219
220/// A dynamically typed reference to a entity, which can be downcast into a `Entity<T>`.
221pub struct AnyEntity {
222 pub(crate) entity_id: EntityId,
223 pub(crate) entity_type: TypeId,
224 entity_map: Weak<RwLock<EntityRefCounts>>,
225 #[cfg(any(test, feature = "leak-detection"))]
226 handle_id: HandleId,
227}
228
229impl AnyEntity {
230 fn new(id: EntityId, entity_type: TypeId, entity_map: Weak<RwLock<EntityRefCounts>>) -> Self {
231 Self {
232 entity_id: id,
233 entity_type,
234 #[cfg(any(test, feature = "leak-detection"))]
235 handle_id: entity_map
236 .clone()
237 .upgrade()
238 .unwrap()
239 .write()
240 .leak_detector
241 .handle_created(id),
242 entity_map,
243 }
244 }
245
246 /// Returns the id associated with this entity.
247 pub const fn entity_id(&self) -> EntityId {
248 self.entity_id
249 }
250
251 /// Returns the [TypeId] associated with this entity.
252 pub const 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<fn(T) -> T>,
382}
383
384impl<T> Sealed for Entity<T> {}
385
386impl<T: 'static> Entity<T> {
387 fn new(id: EntityId, entity_map: Weak<RwLock<EntityRefCounts>>) -> Self
388 where
389 T: 'static,
390 {
391 Self {
392 any_entity: AnyEntity::new(id, TypeId::of::<T>(), entity_map),
393 entity_type: PhantomData,
394 }
395 }
396
397 /// Get the entity ID associated with this entity
398 pub const fn entity_id(&self) -> EntityId {
399 self.any_entity.entity_id
400 }
401
402 /// Downgrade this entity pointer to a non-retaining weak pointer
403 pub fn downgrade(&self) -> WeakEntity<T> {
404 WeakEntity {
405 any_entity: self.any_entity.downgrade(),
406 entity_type: self.entity_type,
407 }
408 }
409
410 /// Convert this into a dynamically typed entity.
411 pub fn into_any(self) -> AnyEntity {
412 self.any_entity
413 }
414
415 /// Grab a reference to this entity from the context.
416 pub fn read<'a>(&self, cx: &'a App) -> &'a T {
417 cx.entities.read(self)
418 }
419
420 /// Read the entity referenced by this handle with the given function.
421 pub fn read_with<R, C: AppContext>(
422 &self,
423 cx: &C,
424 f: impl FnOnce(&T, &App) -> R,
425 ) -> C::Result<R> {
426 cx.read_entity(self, f)
427 }
428
429 /// Updates the entity referenced by this handle with the given function.
430 pub fn update<R, C: AppContext>(
431 &self,
432 cx: &mut C,
433 update: impl FnOnce(&mut T, &mut Context<T>) -> R,
434 ) -> C::Result<R> {
435 cx.update_entity(self, update)
436 }
437
438 /// Updates the entity referenced by this handle with the given function.
439 pub fn as_mut<'a, C: AppContext>(&self, cx: &'a mut C) -> C::Result<GpuiBorrow<'a, T>> {
440 cx.as_mut(self)
441 }
442
443 /// Updates the entity referenced by this handle with the given function.
444 pub fn write<C: AppContext>(&self, cx: &mut C, value: T) -> C::Result<()> {
445 self.update(cx, |entity, cx| {
446 *entity = value;
447 cx.notify();
448 })
449 }
450
451 /// Updates the entity referenced by this handle with the given function if
452 /// the referenced entity still exists, within a visual context that has a window.
453 /// Returns an error if the entity has been released.
454 pub fn update_in<R, C: VisualContext>(
455 &self,
456 cx: &mut C,
457 update: impl FnOnce(&mut T, &mut Window, &mut Context<T>) -> R,
458 ) -> C::Result<R> {
459 cx.update_window_entity(self, update)
460 }
461}
462
463impl<T> Clone for Entity<T> {
464 fn clone(&self) -> Self {
465 Self {
466 any_entity: self.any_entity.clone(),
467 entity_type: self.entity_type,
468 }
469 }
470}
471
472impl<T> std::fmt::Debug for Entity<T> {
473 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
474 f.debug_struct("Entity")
475 .field("entity_id", &self.any_entity.entity_id)
476 .field("entity_type", &type_name::<T>())
477 .finish()
478 }
479}
480
481impl<T> Hash for Entity<T> {
482 fn hash<H: Hasher>(&self, state: &mut H) {
483 self.any_entity.hash(state);
484 }
485}
486
487impl<T> PartialEq for Entity<T> {
488 fn eq(&self, other: &Self) -> bool {
489 self.any_entity == other.any_entity
490 }
491}
492
493impl<T> Eq for Entity<T> {}
494
495impl<T> PartialEq<WeakEntity<T>> for Entity<T> {
496 fn eq(&self, other: &WeakEntity<T>) -> bool {
497 self.any_entity.entity_id() == other.entity_id()
498 }
499}
500
501impl<T: 'static> Ord for Entity<T> {
502 fn cmp(&self, other: &Self) -> std::cmp::Ordering {
503 self.entity_id().cmp(&other.entity_id())
504 }
505}
506
507impl<T: 'static> PartialOrd for Entity<T> {
508 fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
509 Some(self.cmp(other))
510 }
511}
512
513/// A type erased, weak reference to a entity.
514#[derive(Clone)]
515pub struct AnyWeakEntity {
516 pub(crate) entity_id: EntityId,
517 entity_type: TypeId,
518 entity_ref_counts: Weak<RwLock<EntityRefCounts>>,
519}
520
521impl AnyWeakEntity {
522 /// Get the entity ID associated with this weak reference.
523 pub const fn entity_id(&self) -> EntityId {
524 self.entity_id
525 }
526
527 /// Check if this weak handle can be upgraded, or if the entity has already been dropped
528 pub fn is_upgradable(&self) -> bool {
529 let ref_count = self
530 .entity_ref_counts
531 .upgrade()
532 .and_then(|ref_counts| Some(ref_counts.read().counts.get(self.entity_id)?.load(SeqCst)))
533 .unwrap_or(0);
534 ref_count > 0
535 }
536
537 /// Upgrade this weak entity reference to a strong reference.
538 pub fn upgrade(&self) -> Option<AnyEntity> {
539 let ref_counts = &self.entity_ref_counts.upgrade()?;
540 let ref_counts = ref_counts.read();
541 let ref_count = ref_counts.counts.get(self.entity_id)?;
542
543 if atomic_incr_if_not_zero(ref_count) == 0 {
544 // entity_id is in dropped_entity_ids
545 return None;
546 }
547 drop(ref_counts);
548
549 Some(AnyEntity {
550 entity_id: self.entity_id,
551 entity_type: self.entity_type,
552 entity_map: self.entity_ref_counts.clone(),
553 #[cfg(any(test, feature = "leak-detection"))]
554 handle_id: self
555 .entity_ref_counts
556 .upgrade()
557 .unwrap()
558 .write()
559 .leak_detector
560 .handle_created(self.entity_id),
561 })
562 }
563
564 /// Assert that entity referenced by this weak handle has been released.
565 #[cfg(any(test, feature = "leak-detection"))]
566 pub fn assert_released(&self) {
567 self.entity_ref_counts
568 .upgrade()
569 .unwrap()
570 .write()
571 .leak_detector
572 .assert_released(self.entity_id);
573
574 if self
575 .entity_ref_counts
576 .upgrade()
577 .and_then(|ref_counts| Some(ref_counts.read().counts.get(self.entity_id)?.load(SeqCst)))
578 .is_some()
579 {
580 panic!(
581 "entity was recently dropped but resources are retained until the end of the effect cycle."
582 )
583 }
584 }
585
586 /// Creates a weak entity that can never be upgraded.
587 pub fn new_invalid() -> Self {
588 /// To hold the invariant that all ids are unique, and considering that slotmap
589 /// increases their IDs from `0`, we can decrease ours from `u64::MAX` so these
590 /// two will never conflict (u64 is way too large).
591 static UNIQUE_NON_CONFLICTING_ID_GENERATOR: AtomicU64 = AtomicU64::new(u64::MAX);
592 let entity_id = UNIQUE_NON_CONFLICTING_ID_GENERATOR.fetch_sub(1, SeqCst);
593
594 Self {
595 // Safety:
596 // Docs say this is safe but can be unspecified if slotmap changes the representation
597 // after `1.0.7`, that said, providing a valid entity_id here is not necessary as long
598 // as we guarantee that `entity_id` is never used if `entity_ref_counts` equals
599 // to `Weak::new()` (that is, it's unable to upgrade), that is the invariant that
600 // actually needs to be hold true.
601 //
602 // And there is no sane reason to read an entity slot if `entity_ref_counts` can't be
603 // read in the first place, so we're good!
604 entity_id: entity_id.into(),
605 entity_type: TypeId::of::<()>(),
606 entity_ref_counts: Weak::new(),
607 }
608 }
609}
610
611impl std::fmt::Debug for AnyWeakEntity {
612 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
613 f.debug_struct(type_name::<Self>())
614 .field("entity_id", &self.entity_id)
615 .field("entity_type", &self.entity_type)
616 .finish()
617 }
618}
619
620impl<T> From<WeakEntity<T>> for AnyWeakEntity {
621 fn from(entity: WeakEntity<T>) -> Self {
622 entity.any_entity
623 }
624}
625
626impl Hash for AnyWeakEntity {
627 fn hash<H: Hasher>(&self, state: &mut H) {
628 self.entity_id.hash(state);
629 }
630}
631
632impl PartialEq for AnyWeakEntity {
633 fn eq(&self, other: &Self) -> bool {
634 self.entity_id == other.entity_id
635 }
636}
637
638impl Eq for AnyWeakEntity {}
639
640impl Ord for AnyWeakEntity {
641 fn cmp(&self, other: &Self) -> Ordering {
642 self.entity_id.cmp(&other.entity_id)
643 }
644}
645
646impl PartialOrd for AnyWeakEntity {
647 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
648 Some(self.cmp(other))
649 }
650}
651
652/// A weak reference to a entity of the given type.
653#[derive(Deref, DerefMut)]
654pub struct WeakEntity<T> {
655 #[deref]
656 #[deref_mut]
657 any_entity: AnyWeakEntity,
658 entity_type: PhantomData<fn(T) -> T>,
659}
660
661impl<T> std::fmt::Debug for WeakEntity<T> {
662 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
663 f.debug_struct(type_name::<Self>())
664 .field("entity_id", &self.any_entity.entity_id)
665 .field("entity_type", &type_name::<T>())
666 .finish()
667 }
668}
669
670impl<T> Clone for WeakEntity<T> {
671 fn clone(&self) -> Self {
672 Self {
673 any_entity: self.any_entity.clone(),
674 entity_type: self.entity_type,
675 }
676 }
677}
678
679impl<T: 'static> WeakEntity<T> {
680 /// Upgrade this weak entity reference into a strong entity reference
681 pub fn upgrade(&self) -> Option<Entity<T>> {
682 Some(Entity {
683 any_entity: self.any_entity.upgrade()?,
684 entity_type: self.entity_type,
685 })
686 }
687
688 /// Updates the entity referenced by this handle with the given function if
689 /// the referenced entity still exists. Returns an error if the entity has
690 /// been released.
691 pub fn update<C, R>(
692 &self,
693 cx: &mut C,
694 update: impl FnOnce(&mut T, &mut Context<T>) -> R,
695 ) -> Result<R>
696 where
697 C: AppContext,
698 Result<C::Result<R>>: crate::Flatten<R>,
699 {
700 crate::Flatten::flatten(
701 self.upgrade()
702 .context("entity released")
703 .map(|this| cx.update_entity(&this, update)),
704 )
705 }
706
707 /// Updates the entity referenced by this handle with the given function if
708 /// the referenced entity still exists, within a visual context that has a window.
709 /// Returns an error if the entity has been released.
710 pub fn update_in<C, R>(
711 &self,
712 cx: &mut C,
713 update: impl FnOnce(&mut T, &mut Window, &mut Context<T>) -> R,
714 ) -> Result<R>
715 where
716 C: VisualContext,
717 Result<C::Result<R>>: crate::Flatten<R>,
718 {
719 let window = cx.window_handle();
720 let this = self.upgrade().context("entity released")?;
721
722 crate::Flatten::flatten(window.update(cx, |_, window, cx| {
723 this.update(cx, |entity, cx| update(entity, window, cx))
724 }))
725 }
726
727 /// Reads the entity referenced by this handle with the given function if
728 /// the referenced entity still exists. Returns an error if the entity has
729 /// been released.
730 pub fn read_with<C, R>(&self, cx: &C, read: impl FnOnce(&T, &App) -> R) -> Result<R>
731 where
732 C: AppContext,
733 Result<C::Result<R>>: crate::Flatten<R>,
734 {
735 crate::Flatten::flatten(
736 self.upgrade()
737 .context("entity released")
738 .map(|this| cx.read_entity(&this, read)),
739 )
740 }
741
742 /// Create a new weak entity that can never be upgraded.
743 pub fn new_invalid() -> Self {
744 Self {
745 any_entity: AnyWeakEntity::new_invalid(),
746 entity_type: PhantomData,
747 }
748 }
749}
750
751impl<T> Hash for WeakEntity<T> {
752 fn hash<H: Hasher>(&self, state: &mut H) {
753 self.any_entity.hash(state);
754 }
755}
756
757impl<T> PartialEq for WeakEntity<T> {
758 fn eq(&self, other: &Self) -> bool {
759 self.any_entity == other.any_entity
760 }
761}
762
763impl<T> Eq for WeakEntity<T> {}
764
765impl<T> PartialEq<Entity<T>> for WeakEntity<T> {
766 fn eq(&self, other: &Entity<T>) -> bool {
767 self.entity_id() == other.any_entity.entity_id()
768 }
769}
770
771impl<T: 'static> Ord for WeakEntity<T> {
772 fn cmp(&self, other: &Self) -> Ordering {
773 self.entity_id().cmp(&other.entity_id())
774 }
775}
776
777impl<T: 'static> PartialOrd for WeakEntity<T> {
778 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
779 Some(self.cmp(other))
780 }
781}
782
783#[cfg(any(test, feature = "leak-detection"))]
784static LEAK_BACKTRACE: std::sync::LazyLock<bool> =
785 std::sync::LazyLock::new(|| std::env::var("LEAK_BACKTRACE").is_ok_and(|b| !b.is_empty()));
786
787#[cfg(any(test, feature = "leak-detection"))]
788#[derive(Clone, Copy, Debug, Default, Hash, PartialEq, Eq)]
789pub(crate) struct HandleId {
790 id: u64, // id of the handle itself, not the pointed at object
791}
792
793#[cfg(any(test, feature = "leak-detection"))]
794pub(crate) struct LeakDetector {
795 next_handle_id: u64,
796 entity_handles: HashMap<EntityId, HashMap<HandleId, Option<backtrace::Backtrace>>>,
797}
798
799#[cfg(any(test, feature = "leak-detection"))]
800impl LeakDetector {
801 #[track_caller]
802 pub fn handle_created(&mut self, entity_id: EntityId) -> HandleId {
803 let id = util::post_inc(&mut self.next_handle_id);
804 let handle_id = HandleId { id };
805 let handles = self.entity_handles.entry(entity_id).or_default();
806 handles.insert(
807 handle_id,
808 LEAK_BACKTRACE.then(backtrace::Backtrace::new_unresolved),
809 );
810 handle_id
811 }
812
813 pub fn handle_released(&mut self, entity_id: EntityId, handle_id: HandleId) {
814 let handles = self.entity_handles.entry(entity_id).or_default();
815 handles.remove(&handle_id);
816 }
817
818 pub fn assert_released(&mut self, entity_id: EntityId) {
819 let handles = self.entity_handles.entry(entity_id).or_default();
820 if !handles.is_empty() {
821 for backtrace in handles.values_mut() {
822 if let Some(mut backtrace) = backtrace.take() {
823 backtrace.resolve();
824 eprintln!("Leaked handle: {:#?}", backtrace);
825 } else {
826 eprintln!("Leaked handle: export LEAK_BACKTRACE to find allocation site");
827 }
828 }
829 panic!();
830 }
831 }
832}
833
834#[cfg(test)]
835mod test {
836 use crate::EntityMap;
837
838 struct TestEntity {
839 pub i: i32,
840 }
841
842 #[test]
843 fn test_entity_map_slot_assignment_before_cleanup() {
844 // Tests that slots are not re-used before take_dropped.
845 let mut entity_map = EntityMap::new();
846
847 let slot = entity_map.reserve::<TestEntity>();
848 entity_map.insert(slot, TestEntity { i: 1 });
849
850 let slot = entity_map.reserve::<TestEntity>();
851 entity_map.insert(slot, TestEntity { i: 2 });
852
853 let dropped = entity_map.take_dropped();
854 assert_eq!(dropped.len(), 2);
855
856 assert_eq!(
857 dropped
858 .into_iter()
859 .map(|(_, entity)| entity.downcast::<TestEntity>().unwrap().i)
860 .collect::<Vec<i32>>(),
861 vec![1, 2],
862 );
863 }
864
865 #[test]
866 fn test_entity_map_weak_upgrade_before_cleanup() {
867 // Tests that weak handles are not upgraded before take_dropped
868 let mut entity_map = EntityMap::new();
869
870 let slot = entity_map.reserve::<TestEntity>();
871 let handle = entity_map.insert(slot, TestEntity { i: 1 });
872 let weak = handle.downgrade();
873 drop(handle);
874
875 let strong = weak.upgrade();
876 assert_eq!(strong, None);
877
878 let dropped = entity_map.take_dropped();
879 assert_eq!(dropped.len(), 1);
880
881 assert_eq!(
882 dropped
883 .into_iter()
884 .map(|(_, entity)| entity.downcast::<TestEntity>().unwrap().i)
885 .collect::<Vec<i32>>(),
886 vec![1],
887 );
888 }
889}