Paper/patches/server/0768-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/item/ItemEntity.java b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
index 459f793a6603d4f98c84df4e549f069298c54985..8aaca29b115a55bf48306e71432c4c20d2bd21dc 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -66,7 +66,12 @@ 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 level random in entity constructors (to make them thread-safe)
+        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 - Don't use level random in entity constructors
     }
 
     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 3408337b11f04337bb2f62de343e430d94d3a093..cd7b955754b809826048b80723e2e9055b373a4a 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -43,7 +43,7 @@ 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 level random in entity constructors
 
         this.setDeltaMovement(-Math.sin(d3) * 0.02D, 0.20000000298023224D, -Math.cos(d3) * 0.02D);
         this.setFuse(80);