Paper/Spigot-Server-Patches/0186-PreCreatureSpawnEvent.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 14 Jan 2018 17:01:31 -0500
Subject: [PATCH] PreCreatureSpawnEvent

Adds an event to fire before an Entity is created, so that plugins that need to cancel
CreatureSpawnEvent can do so from this event instead.

Cancelling CreatureSpawnEvent rapidly causes a lot of garbage collection and CPU waste
as it's done after the Entity object has been fully created.

Mob Limiting plugins and blanket "ban this type of monster" plugins should use this event
instead and save a lot of server resources.

See: https://github.com/PaperMC/Paper/issues/917

diff --git a/src/main/java/net/minecraft/world/entity/EntityTypes.java b/src/main/java/net/minecraft/world/entity/EntityTypes.java
index a707ba365e25ea15e2e9d22110696b6136aa0c6f..8ba75c847efa0633e7b8cb718e3a9b55e0b8ad77 100644
--- a/src/main/java/net/minecraft/world/entity/EntityTypes.java
+++ b/src/main/java/net/minecraft/world/entity/EntityTypes.java
@@ -317,6 +317,20 @@ public class EntityTypes<T extends Entity> {
 
     @Nullable
     public T spawnCreature(WorldServer worldserver, @Nullable NBTTagCompound nbttagcompound, @Nullable IChatBaseComponent ichatbasecomponent, @Nullable EntityHuman entityhuman, BlockPosition blockposition, EnumMobSpawn enummobspawn, boolean flag, boolean flag1, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason) {
+        // Paper start - Call PreCreatureSpawnEvent
+        org.bukkit.entity.EntityType type = org.bukkit.entity.EntityType.fromName(EntityTypes.getName(this).getKey());
+        if (type != null) {
+            com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+            event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                MCUtil.toLocation(worldserver, blockposition),
+                type,
+                spawnReason
+            );
+            if (!event.callEvent()) {
+                return null;
+            }
+        }
+        // Paper end
         T t0 = this.createCreature(worldserver, nbttagcompound, ichatbasecomponent, entityhuman, blockposition, enummobspawn, flag, flag1);
 
         if (t0 != null) {
diff --git a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorGolemLastSeen.java b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorGolemLastSeen.java
index 41f1aecbf6b506231a1b3b525fe0ce23b35c7840..6c01e460d3a1ff7f865ebc34dfd28d55b16aab98 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorGolemLastSeen.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorGolemLastSeen.java
@@ -33,7 +33,7 @@ public class SensorGolemLastSeen extends Sensor<EntityLiving> {
         Optional<List<EntityLiving>> optional = entityliving.getBehaviorController().getMemory(MemoryModuleType.MOBS);
 
         if (optional.isPresent()) {
-            boolean flag = ((List) optional.get()).stream().anyMatch((entityliving1) -> {
+            boolean flag = optional.get().stream().anyMatch((entityliving1) -> { // Paper - decompile fixes
                 return entityliving1.getEntityType().equals(EntityTypes.IRON_GOLEM);
             });
 
@@ -44,6 +44,7 @@ public class SensorGolemLastSeen extends Sensor<EntityLiving> {
         }
     }
 
+    public static void setDetectedRecently(EntityLiving entityLiving) { b(entityLiving); } // Paper - OBFHELPER
     public static void b(EntityLiving entityliving) {
         entityliving.getBehaviorController().a(MemoryModuleType.GOLEM_DETECTED_RECENTLY, true, 600L);
     }
diff --git a/src/main/java/net/minecraft/world/entity/npc/EntityVillager.java b/src/main/java/net/minecraft/world/entity/npc/EntityVillager.java
index adce6f17a5dd33004f8a67cd55d195de029e0263..d1afbfc4458c76a35b9be124f1e09c3b82501798 100644
--- a/src/main/java/net/minecraft/world/entity/npc/EntityVillager.java
+++ b/src/main/java/net/minecraft/world/entity/npc/EntityVillager.java
@@ -936,6 +936,21 @@ public class EntityVillager extends EntityVillagerAbstract implements Reputation
             BlockPosition blockposition1 = this.a(blockposition, d0, d1);
 
             if (blockposition1 != null) {
+                // Paper start - Call PreCreatureSpawnEvent
+                com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+                event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                    MCUtil.toLocation(world, blockposition1),
+                    org.bukkit.entity.EntityType.IRON_GOLEM,
+                    org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.VILLAGE_DEFENSE
+                );
+                if (!event.callEvent()) {
+                    if (event.shouldAbortSpawn()) {
+                        SensorGolemLastSeen.b(this); // Set Golem Last Seen to stop it from spawning another one
+                        return null;
+                    }
+                    break;
+                }
+                // Paper end
                 EntityIronGolem entityirongolem = (EntityIronGolem) EntityTypes.IRON_GOLEM.createCreature(worldserver, (NBTTagCompound) null, (IChatBaseComponent) null, (EntityHuman) null, blockposition1, EnumMobSpawn.MOB_SUMMONED, false, false);
 
                 if (entityirongolem != null) {
diff --git a/src/main/java/net/minecraft/world/level/MobSpawnerAbstract.java b/src/main/java/net/minecraft/world/level/MobSpawnerAbstract.java
index 883c724fbb86a84ee903b5e7127f14726fe4cf24..79339bcbe15e5b3a409148245c68bbff3a59f59f 100644
--- a/src/main/java/net/minecraft/world/level/MobSpawnerAbstract.java
+++ b/src/main/java/net/minecraft/world/level/MobSpawnerAbstract.java
@@ -125,6 +125,27 @@ public abstract class MobSpawnerAbstract {
                         WorldServer worldserver = (WorldServer) world;
 
                         if (EntityPositionTypes.a((EntityTypes) optional.get(), worldserver, EnumMobSpawn.SPAWNER, new BlockPosition(d3, d4, d5), world.getRandom())) {
+                            // Paper start
+                            EntityTypes<?> entityType = optional.get();
+                            String key = EntityTypes.getName(entityType).getKey();
+
+                            org.bukkit.entity.EntityType type = org.bukkit.entity.EntityType.fromName(key);
+                            if (type != null) {
+                                com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+                                event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                                    MCUtil.toLocation(world, d3, d4, d5),
+                                    type,
+                                    org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER
+                                );
+                                if (!event.callEvent()) {
+                                    flag = true;
+                                    if (event.shouldAbortSpawn()) {
+                                        break;
+                                    }
+                                    continue;
+                                }
+                            }
+                            // Paper end
                             Entity entity = EntityTypes.a(nbttagcompound, world, (entity1) -> {
                                 entity1.setPositionRotation(d3, d4, d5, entity1.yaw, entity1.pitch);
                                 return entity1;
diff --git a/src/main/java/net/minecraft/world/level/SpawnerCreature.java b/src/main/java/net/minecraft/world/level/SpawnerCreature.java
index fd0595fd584046326eccacdf0a6afe40c5e84eed..9a039ce12879baf8088c2ccaf0af61109efb7d74 100644
--- a/src/main/java/net/minecraft/world/level/SpawnerCreature.java
+++ b/src/main/java/net/minecraft/world/level/SpawnerCreature.java
@@ -216,9 +216,16 @@ public final class SpawnerCreature {
                                         j1 = biomesettingsmobs_c.d + worldserver.random.nextInt(1 + biomesettingsmobs_c.e - biomesettingsmobs_c.d);
                                     }
 
-                                    if (a(worldserver, enumcreaturetype, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2) && spawnercreature_c.test(biomesettingsmobs_c.c, blockposition_mutableblockposition, ichunkaccess)) {
+                                    // Paper start
+                                    Boolean doSpawning = a(worldserver, enumcreaturetype, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2);
+                                    if (doSpawning == null) {
+                                        return;
+                                    }
+                                    if (doSpawning && spawnercreature_c.test(biomesettingsmobs_c.c, blockposition_mutableblockposition, ichunkaccess)) {
+                                        // Paper end
                                         EntityInsentient entityinsentient = a(worldserver, biomesettingsmobs_c.c);
 
+
                                         if (entityinsentient == null) {
                                             return;
                                         }
@@ -271,8 +278,24 @@ public final class SpawnerCreature {
         }
     }
 
-    private static boolean a(WorldServer worldserver, EnumCreatureType enumcreaturetype, StructureManager structuremanager, ChunkGenerator chunkgenerator, BiomeSettingsMobs.c biomesettingsmobs_c, BlockPosition.MutableBlockPosition blockposition_mutableblockposition, double d0) {
+    private static Boolean a(WorldServer worldserver, EnumCreatureType enumcreaturetype, StructureManager structuremanager, ChunkGenerator chunkgenerator, BiomeSettingsMobs.c biomesettingsmobs_c, BlockPosition.MutableBlockPosition blockposition_mutableblockposition, double d0) { // Paper
         EntityTypes<?> entitytypes = biomesettingsmobs_c.c;
+        // Paper start
+        com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+        org.bukkit.entity.EntityType type = org.bukkit.entity.EntityType.fromName(EntityTypes.getName(entitytypes).getKey());
+        if (type != null) {
+            event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                MCUtil.toLocation(worldserver, blockposition_mutableblockposition),
+                type, SpawnReason.NATURAL
+            );
+            if (!event.callEvent()) {
+                if (event.shouldAbortSpawn()) {
+                    return null;
+                }
+                return false;
+            }
+        }
+        // Paper end
 
         if (entitytypes.e() == EnumCreatureType.MISC) {
             return false;