Paper/patches/server/0173-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/util/SpawnUtil.java b/src/main/java/net/minecraft/util/SpawnUtil.java
index f4d1a3e861a8727d7f3efd75c0e83cc9418fa9bd..3fb910fadde4875c39523779ad24f381e45b6ab6 100644
--- a/src/main/java/net/minecraft/util/SpawnUtil.java
+++ b/src/main/java/net/minecraft/util/SpawnUtil.java
@@ -19,10 +19,10 @@ public class SpawnUtil {
 
     public static <T extends Mob> Optional<T> trySpawnMob(EntityType<T> entityType, MobSpawnType reason, ServerLevel world, BlockPos pos, int tries, int horizontalRange, int verticalRange, SpawnUtil.Strategy requirements) {
         // CraftBukkit start
-        return SpawnUtil.trySpawnMob(entityType, reason, world, pos, tries, horizontalRange, verticalRange, requirements, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.DEFAULT);
+        return SpawnUtil.trySpawnMob(entityType, reason, world, pos, tries, horizontalRange, verticalRange, requirements, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.DEFAULT, null); // Paper
     }
 
-    public static <T extends Mob> Optional<T> trySpawnMob(EntityType<T> entitytypes, MobSpawnType enummobspawn, ServerLevel worldserver, BlockPos blockposition, int i, int j, int k, SpawnUtil.Strategy spawnutil_a, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason reason) {
+    public static <T extends Mob> Optional<T> trySpawnMob(EntityType<T> entitytypes, MobSpawnType enummobspawn, ServerLevel worldserver, BlockPos blockposition, int i, int j, int k, SpawnUtil.Strategy spawnutil_a, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason reason, @javax.annotation.Nullable Runnable onAbort) { // Paper
         // CraftBukkit end
         BlockPos.MutableBlockPos blockposition_mutableblockposition = blockposition.mutable();
 
@@ -32,6 +32,26 @@ public class SpawnUtil {
 
             blockposition_mutableblockposition.setWithOffset(blockposition, i1, k, j1);
             if (worldserver.getWorldBorder().isWithinBounds((BlockPos) blockposition_mutableblockposition) && SpawnUtil.moveToPossibleSpawnPosition(worldserver, k, blockposition_mutableblockposition, spawnutil_a)) {
+                // Paper start
+                String key = EntityType.getKey(entitytypes).getPath();
+                org.bukkit.entity.EntityType type = org.bukkit.entity.EntityType.fromName(key);
+
+                com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+                event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                    io.papermc.paper.util.MCUtil.toLocation(worldserver, blockposition),
+                    type,
+                    reason
+                );
+                if (!event.callEvent()) {
+                    if (event.shouldAbortSpawn()) {
+                        if (onAbort != null) {
+                            onAbort.run();
+                        }
+                        return Optional.empty();
+                    }
+                    break;
+                }
+                // Paper end
                 T t0 = entitytypes.create(worldserver, (CompoundTag) null, (Component) null, (Player) null, blockposition_mutableblockposition, enummobspawn, false, false); // CraftBukkit - decompile error
 
                 if (t0 != null) {
diff --git a/src/main/java/net/minecraft/world/entity/EntityType.java b/src/main/java/net/minecraft/world/entity/EntityType.java
index 2db27f5e3e3c1bb0502c055f78c4a81eb00fcf1b..fdefccfa07227f315259f636076e36a120c72917 100644
--- a/src/main/java/net/minecraft/world/entity/EntityType.java
+++ b/src/main/java/net/minecraft/world/entity/EntityType.java
@@ -347,6 +347,20 @@ public class EntityType<T extends Entity> implements EntityTypeTest<Entity, T> {
 
     @Nullable
     public T spawn(ServerLevel worldserver, @Nullable CompoundTag nbttagcompound, @Nullable Component ichatbasecomponent, @Nullable Player entityhuman, BlockPos blockposition, MobSpawnType 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(EntityType.getKey(this).getPath());
+        if (type != null) {
+            com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+            event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                io.papermc.paper.util.MCUtil.toLocation(worldserver, blockposition),
+                type,
+                spawnReason
+            );
+            if (!event.callEvent()) {
+                return null;
+            }
+        }
+        // Paper end
         T t0 = this.create(worldserver, nbttagcompound, ichatbasecomponent, entityhuman, blockposition, enummobspawn, flag, flag1);
 
         if (t0 != null) {
diff --git a/src/main/java/net/minecraft/world/entity/npc/Villager.java b/src/main/java/net/minecraft/world/entity/npc/Villager.java
index 25cd8a4101cf44955d95924c9794c238ddde2901..f957c0aca36b7228ac3a33ca04c948b1d10642d1 100644
--- a/src/main/java/net/minecraft/world/entity/npc/Villager.java
+++ b/src/main/java/net/minecraft/world/entity/npc/Villager.java
@@ -947,7 +947,7 @@ public class Villager extends AbstractVillager implements ReputationEventHandler
             }).limit(5L).collect(Collectors.toList());
 
             if (list1.size() >= requiredCount) {
-                if (SpawnUtil.trySpawnMob(EntityType.IRON_GOLEM, MobSpawnType.MOB_SUMMONED, world, this.blockPosition(), 10, 8, 6, SpawnUtil.Strategy.LEGACY_IRON_GOLEM, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.VILLAGE_DEFENSE).isPresent()) { // CraftBukkit
+                if (SpawnUtil.trySpawnMob(EntityType.IRON_GOLEM, MobSpawnType.MOB_SUMMONED, world, this.blockPosition(), 10, 8, 6, SpawnUtil.Strategy.LEGACY_IRON_GOLEM, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.VILLAGE_DEFENSE, () -> {GolemSensor.golemDetected(this);}).isPresent()) { // CraftBukkit // Paper - Set Golem Last Seen to stop it from spawning another one
                     list.forEach(GolemSensor::golemDetected);
                 }
             }
diff --git a/src/main/java/net/minecraft/world/level/BaseSpawner.java b/src/main/java/net/minecraft/world/level/BaseSpawner.java
index ac767d107ea0d856f3f8caccfe6f79b14e933005..c41c1fa8085f502363c8273cd9fce1cf1743fe71 100644
--- a/src/main/java/net/minecraft/world/level/BaseSpawner.java
+++ b/src/main/java/net/minecraft/world/level/BaseSpawner.java
@@ -124,6 +124,27 @@ public abstract class BaseSpawner {
                         } else if (!SpawnPlacements.checkSpawnRules((EntityType) optional.get(), world, MobSpawnType.SPAWNER, blockposition1, world.getRandom())) {
                             continue;
                         }
+                        // Paper start
+                        EntityType<?> entityType = optional.get();
+                        String key = EntityType.getKey(entityType).getPath();
+
+                        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(
+                                io.papermc.paper.util.MCUtil.toLocation(world, d0, d1, d2),
+                                type,
+                                org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER
+                            );
+                            if (!event.callEvent()) {
+                                flag = true;
+                                if (event.shouldAbortSpawn()) {
+                                    break;
+                                }
+                                continue;
+                            }
+                        }
+                        // Paper end
 
                         Entity entity = EntityType.loadEntityRecursive(nbttagcompound, world, (entity1) -> {
                             entity1.moveTo(d0, d1, d2, entity1.getYRot(), entity1.getXRot());
diff --git a/src/main/java/net/minecraft/world/level/NaturalSpawner.java b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
index c6ba7427b53398ddc8f0c942a810fad6e24561b4..c41390f5b9260bcfb843460904e1315695a1a972 100644
--- a/src/main/java/net/minecraft/world/level/NaturalSpawner.java
+++ b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
@@ -212,7 +212,13 @@ public final class NaturalSpawner {
                                         j1 = biomesettingsmobs_c.minCount + world.random.nextInt(1 + biomesettingsmobs_c.maxCount - biomesettingsmobs_c.minCount);
                                     }
 
-                                    if (NaturalSpawner.isValidSpawnPostitionForType(world, group, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2) && checker.test(biomesettingsmobs_c.type, blockposition_mutableblockposition, chunk)) {
+                                    // Paper start
+                                    Boolean doSpawning = isValidSpawnPostitionForType(world, group, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2);
+                                    if (doSpawning == null) {
+                                        return;
+                                    }
+                                    if (doSpawning && checker.test(biomesettingsmobs_c.type, blockposition_mutableblockposition, chunk)) {
+                                        // Paper end
                                         Mob entityinsentient = NaturalSpawner.getMobForSpawn(world, biomesettingsmobs_c.type);
 
                                         if (entityinsentient == null) {
@@ -260,9 +266,25 @@ public final class NaturalSpawner {
         return squaredDistance <= 576.0D ? false : (world.getSharedSpawnPos().closerToCenterThan(new Vec3((double) pos.getX() + 0.5D, (double) pos.getY(), (double) pos.getZ() + 0.5D), 24.0D) ? false : Objects.equals(new ChunkPos(pos), chunk.getPos()) || world.isNaturalSpawningAllowed((BlockPos) pos));
     }
 
-    private static boolean isValidSpawnPostitionForType(ServerLevel world, MobCategory group, StructureManager structureAccessor, ChunkGenerator chunkGenerator, MobSpawnSettings.SpawnerData spawnEntry, BlockPos.MutableBlockPos pos, double squaredDistance) {
+    private static Boolean isValidSpawnPostitionForType(ServerLevel world, MobCategory group, StructureManager structureAccessor, ChunkGenerator chunkGenerator, MobSpawnSettings.SpawnerData spawnEntry, BlockPos.MutableBlockPos pos, double squaredDistance) { // Paper
         EntityType<?> entitytypes = spawnEntry.type;
 
+        // Paper start
+        com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event;
+        org.bukkit.entity.EntityType type = org.bukkit.entity.EntityType.fromName(EntityType.getKey(entitytypes).getPath());
+        if (type != null) {
+            event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                io.papermc.paper.util.MCUtil.toLocation(world, pos),
+                type, SpawnReason.NATURAL
+            );
+            if (!event.callEvent()) {
+                if (event.shouldAbortSpawn()) {
+                    return null;
+                }
+                return false;
+            }
+        }
+        // Paper end
         if (entitytypes.getCategory() == MobCategory.MISC) {
             return false;
         } else if (!entitytypes.canSpawnFarFromPlayer() && squaredDistance > (double) (entitytypes.getCategory().getDespawnDistance() * entitytypes.getCategory().getDespawnDistance())) {