PaperMC/patches/server/0833-Don-t-use-level-random-in-entity-constructors.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sun, 10 Jul 2022 14:13:22 -0700
Subject: [PATCH] Don't use level random in entity constructors

Paper makes the entity random thread-safe
and constructing an entity off the main thread
should be supported. Some entities (for whatever
reason) use the level's random in some places.

diff --git a/src/main/java/net/minecraft/world/entity/animal/Bee.java b/src/main/java/net/minecraft/world/entity/animal/Bee.java
index e06d5eea4bc81be264a1f5d5fad2d4548c4ae8d2..55026e1731e41b4e3e4c6a8fef5d96a32051a556 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Bee.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Bee.java
@@ -1029,7 +1029,7 @@ public class Bee extends Animal implements NeutralMob, FlyingAnimal {
 
         BeeGoToHiveGoal() {
             super();
-            this.travellingTicks = Bee.this.level().random.nextInt(10);
+            this.travellingTicks = Bee.this./* level(). */random.nextInt(10); // Paper - use entity random
             this.blacklistedTargets = Lists.newArrayList();
             this.setFlags(EnumSet.of(Goal.Flag.MOVE));
         }
@@ -1146,7 +1146,7 @@ public class Bee extends Animal implements NeutralMob, FlyingAnimal {
 
         BeeGoToKnownFlowerGoal() {
             super();
-            this.travellingTicks = Bee.this.level().random.nextInt(10);
+            this.travellingTicks = Bee.this./* level(). */random.nextInt(10); // Paper - use entity random
             this.setFlags(EnumSet.of(Goal.Flag.MOVE));
         }
 
diff --git a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
index 6b3a17e6717b8c03c5bd674771b29e4becd42c71..22d29a2e58c5615dcee04ba68752fb76489c8a28 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -64,7 +64,12 @@ public class ItemEntity extends Entity implements TraceableEntity {
     }
 
     public ItemEntity(Level world, double x, double y, double z, ItemStack stack) {
-        this(world, x, y, z, stack, world.random.nextDouble() * 0.2D - 0.1D, 0.2D, world.random.nextDouble() * 0.2D - 0.1D);
+        // Paper start - don't use world random in entity constructor
+        this(EntityType.ITEM, world);
+        this.setPos(x, y, z);
+        this.setDeltaMovement(this.random.nextDouble() * 0.2D - 0.1D, 0.2D, this.random.nextDouble() * 0.2D - 0.1D);
+        this.setItem(stack);
+        // Paper end
     }
 
     public ItemEntity(Level world, double x, double y, double z, ItemStack stack, double velocityX, double velocityY, double velocityZ) {
diff --git a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
index 57f9bf73ee14bc8811d0192543caf2b02e890ee0..4ce3e69970dd9eb251d0538a2d233ca30e9e5e47 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -36,7 +36,7 @@ public class PrimedTnt extends Entity implements TraceableEntity {
     public PrimedTnt(Level world, double x, double y, double z, @Nullable LivingEntity igniter) {
         this(EntityType.TNT, world);
         this.setPos(x, y, z);
-        double d3 = world.random.nextDouble() * 6.2831854820251465D;
+        double d3 = this.random.nextDouble() * 6.2831854820251465D; // Paper - don't use world random in entity constructor
 
         this.setDeltaMovement(-Math.sin(d3) * 0.02D, 0.20000000298023224D, -Math.cos(d3) * 0.02D);
         this.setFuse(80);