Paper/patches/unapplied/server/0884-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 87f8d46cb2032474008811ca11dc7ff1f7859f7e..2e05c953182c27e3571b2c33eceeb379e60b54be 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Bee.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Bee.java
@@ -1028,7 +1028,7 @@ 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));
         }
@@ -1145,7 +1145,7 @@ 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 4c78c04ed031ec2e04642ebe5d79527e848d95f6..fcc5444a1268931a0fd2df1e6bbbc17cfd5a61e0 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 {
     }
 
     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 65f0aa076dbfc4cd72d14ec485d1edf5533d825e..438de71a17d7bfaed8fbb1b4f7aa7f53538603a2 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -35,7 +35,7 @@ public class PrimedTnt extends Entity {
     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);