Don't use level random in entity constructors (#8122)

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

@@ -0,0 +1,63 @@
+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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/entity/animal/Bee.java
++++ b/src/main/java/net/minecraft/world/entity/animal/Bee.java
+@@ -0,0 +0,0 @@ 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));
+         }
+@@ -0,0 +0,0 @@ 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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
++++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+@@ -0,0 +0,0 @@ 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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
++++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+@@ -0,0 +0,0 @@ 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);