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Fix Concurrency issue in ShufflingList

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if multiple threads from worldgen sort at same time, it will crash.
So make a copy of the list for sorting purposes.
This commit is contained in:
Aikar 2020-07-06 18:36:41 -04:00
parent c2be5a5354
commit 1d8508b7ac
2 changed files with 55 additions and 0 deletions
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11
paper-server/patches/sources/net/minecraft/world/entity/ai/behavior/GateBehavior.java.patch Normal file
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@ -0,0 +1,11 @@
--- a/net/minecraft/world/entity/ai/behavior/GateBehavior.java
+++ b/net/minecraft/world/entity/ai/behavior/GateBehavior.java
@@ -18,7 +18,7 @@
private final Set<MemoryModuleType<?>> exitErasedMemories;
private final GateBehavior.OrderPolicy orderPolicy;
private final GateBehavior.RunningPolicy runningPolicy;
- private final ShufflingList<BehaviorControl<? super E>> behaviors = new ShufflingList<>();
+ private final ShufflingList<BehaviorControl<? super E>> behaviors = new ShufflingList<>(false); // Paper - Fix Concurrency issue in ShufflingList during worldgen
private Behavior.Status status = Behavior.Status.STOPPED;
public GateBehavior(

44
paper-server/patches/sources/net/minecraft/world/entity/ai/behavior/ShufflingList.java.patch Normal file
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@ -0,0 +1,44 @@
--- a/net/minecraft/world/entity/ai/behavior/ShufflingList.java
+++ b/net/minecraft/world/entity/ai/behavior/ShufflingList.java
@@ -16,12 +16,25 @@
public class ShufflingList<U> implements Iterable<U> {
protected final List<ShufflingList.WeightedEntry<U>> entries;
private final RandomSource random = RandomSource.create();
+ private final boolean isUnsafe; // Paper - Fix Concurrency issue in ShufflingList during worldgen
public ShufflingList() {
+ // Paper start - Fix Concurrency issue in ShufflingList during worldgen
+ this(true);
+ }
+ public ShufflingList(boolean isUnsafe) {
+ this.isUnsafe = isUnsafe;
+ // Paper end - Fix Concurrency issue in ShufflingList during worldgen
this.entries = Lists.newArrayList();
}
private ShufflingList(List<ShufflingList.WeightedEntry<U>> list) {
+ // Paper start - Fix Concurrency issue in ShufflingList during worldgen
+ this(list, true);
+ }
+ private ShufflingList(List<ShufflingList.WeightedEntry<U>> list, boolean isUnsafe) {
+ this.isUnsafe = isUnsafe;
+ // Paper end - Fix Concurrency issue in ShufflingList during worldgen
this.entries = Lists.newArrayList(list);
}
@@ -35,9 +48,12 @@
}
public ShufflingList<U> shuffle() {
- this.entries.forEach(entry -> entry.setRandom(this.random.nextFloat()));
- this.entries.sort(Comparator.comparingDouble(ShufflingList.WeightedEntry::getRandWeight));
- return this;
+ // Paper start - Fix Concurrency issue in ShufflingList during worldgen
+ List<ShufflingList.WeightedEntry<U>> list = this.isUnsafe ? Lists.newArrayList(this.entries) : this.entries;
+ list.forEach(entry -> entry.setRandom(this.random.nextFloat()));
+ list.sort(Comparator.comparingDouble(ShufflingList.WeightedEntry::getRandWeight));
+ return this.isUnsafe ? new ShufflingList<>(list, this.isUnsafe) : this;
+ // Paper end - Fix Concurrency issue in ShufflingList during worldgen
}
public Stream<U> stream() {