Paper/patches/server/0669-Fix-swamp-hut-cat-generation-deadlock.patch
Spottedleaf 8c5b837e05 Rework async chunk api implementation
Firstly, the old methods all routed to the CompletableFuture method.
However, the CF method could not guarantee that if the caller
was off-main that the future would be "completed" on-main. Since
the callback methods used the CF one, this meant that the callback
methods did not guarantee that the callbacks were to be called on
the main thread.

Now, all methods route to getChunkAtAsync(x, z, gen, urgent, cb)
so that the methods with the callback are guaranteed to invoke
the callback on the main thread. The CF behavior remains unchanged;
it may still appear to complete on main if invoked off-main.

Secondly, remove the scheduleOnMain invocation in the async
chunk completion. This unnecessarily delays the callback
by 1 tick.

Thirdly, add getChunksAtAsync(minX, minZ, maxX, maxZ, ...) which
will load chunks within an area. This method is provided as a helper
as keeping all chunks loaded within an area can be complicated to
implement for plugins (due to the lacking ticket API), and is
already implemented internally anyways.

Fourthly, remove the ticket addition that occured with getChunkAt
and getChunkAtAsync. The ticket addition may delay the unloading
of the chunk unnecessarily. It also fixes a very rare timing bug
where the future/callback would be completed after the chunk
unloads.
2024-11-18 23:00:59 -08:00

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4.2 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sat, 12 Mar 2022 06:31:13 -0800
Subject: [PATCH] Fix swamp hut cat generation deadlock
The worldgen thread will attempt to get structure references
via the world's getChunkAt method, which is fine if the gen is
not cancelled - but if the chunk was unloaded, the call will block
indefinitely. Instead of using the world state, we use the already
supplied ServerLevelAccessor which will always have the chunk available.
diff --git a/src/main/java/net/minecraft/world/entity/animal/Cat.java b/src/main/java/net/minecraft/world/entity/animal/Cat.java
index f3a991aa878f3b29fdc525ecdde6766efb5e129c..5a86530c65d7d83e4608600a04ffd931bf59dc4a 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Cat.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Cat.java
@@ -366,7 +366,7 @@ public class Cat extends TamableAnimal implements VariantHolder<Holder<CatVarian
BuiltInRegistries.CAT_VARIANT.getRandomElementOf(tagkey, world.getRandom()).ifPresent(this::setVariant);
ServerLevel worldserver = world.getLevel();
- if (worldserver.structureManager().getStructureWithPieceAt(this.blockPosition(), StructureTags.CATS_SPAWN_AS_BLACK).isValid()) {
+ if (worldserver.structureManager().getStructureWithPieceAt(this.blockPosition(), StructureTags.CATS_SPAWN_AS_BLACK, world).isValid()) { // Paper - Fix swamp hut cat generation deadlock
this.setVariant((Holder) BuiltInRegistries.CAT_VARIANT.getOrThrow(CatVariant.ALL_BLACK));
this.setPersistenceRequired();
}
diff --git a/src/main/java/net/minecraft/world/level/StructureManager.java b/src/main/java/net/minecraft/world/level/StructureManager.java
index 3d607ac74de4bc051ab68269dbab0bbd3a52dc54..03adb02297911e5a5051edac14453d7e3eeac29c 100644
--- a/src/main/java/net/minecraft/world/level/StructureManager.java
+++ b/src/main/java/net/minecraft/world/level/StructureManager.java
@@ -48,7 +48,12 @@ public class StructureManager {
}
public List<StructureStart> startsForStructure(ChunkPos pos, Predicate<Structure> predicate) {
- Map<Structure, LongSet> map = this.level.getChunk(pos.x, pos.z, ChunkStatus.STRUCTURE_REFERENCES).getAllReferences();
+ // Paper start - Fix swamp hut cat generation deadlock
+ return this.startsForStructure(pos, predicate, null);
+ }
+ public List<StructureStart> startsForStructure(ChunkPos pos, Predicate<Structure> predicate, @Nullable ServerLevelAccessor levelAccessor) {
+ Map<Structure, LongSet> map = (levelAccessor == null ? this.level : levelAccessor).getChunk(pos.x, pos.z, ChunkStatus.STRUCTURE_REFERENCES).getAllReferences();
+ // Paper end - Fix swamp hut cat generation deadlock
Builder<StructureStart> builder = ImmutableList.builder();
for (Entry<Structure, LongSet> entry : map.entrySet()) {
@@ -116,10 +121,20 @@ public class StructureManager {
}
public StructureStart getStructureWithPieceAt(BlockPos pos, Predicate<Holder<Structure>> predicate) {
+ // Paper start - Fix swamp hut cat generation deadlock
+ return this.getStructureWithPieceAt(pos, predicate, null);
+ }
+
+ public StructureStart getStructureWithPieceAt(BlockPos pos, TagKey<Structure> tag, @Nullable ServerLevelAccessor levelAccessor) {
+ return this.getStructureWithPieceAt(pos, structure -> structure.is(tag), levelAccessor);
+ }
+
+ public StructureStart getStructureWithPieceAt(BlockPos pos, Predicate<Holder<Structure>> predicate, @Nullable ServerLevelAccessor levelAccessor) {
+ // Paper end - Fix swamp hut cat generation deadlock
Registry<Structure> registry = this.registryAccess().lookupOrThrow(Registries.STRUCTURE);
for (StructureStart structureStart : this.startsForStructure(
- new ChunkPos(pos), structure -> registry.get(registry.getId(structure)).map(predicate::test).orElse(false)
+ new ChunkPos(pos), structure -> registry.get(registry.getId(structure)).map(predicate::test).orElse(false), levelAccessor // Paper - Fix swamp hut cat generation deadlock
)) {
if (this.structureHasPieceAt(pos, structureStart)) {
return structureStart;