PaperMC/patches/server/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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/util/SpawnUtil.java
+++ b/src/main/java/net/minecraft/util/SpawnUtil.java
@@ -0,0 +0,0 @@ public class SpawnUtil {
 
     public static <T extends Mob> Optional<T> trySpawnMob(EntityType<T> entityType, EntitySpawnReason 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, EntitySpawnReason entityspawnreason, 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, EntitySpawnReason entityspawnreason, 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 - pre creature spawn event
         // CraftBukkit end
         BlockPos.MutableBlockPos blockposition_mutableblockposition = blockposition.mutable();
 
@@ -0,0 +0,0 @@ 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 - PreCreatureSpawnEvent
+                com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                    io.papermc.paper.util.MCUtil.toLocation(worldserver, blockposition),
+                    org.bukkit.craftbukkit.entity.CraftEntityType.minecraftToBukkit(entitytypes),
+                    reason
+                );
+                if (!event.callEvent()) {
+                    if (event.shouldAbortSpawn()) {
+                        if (onAbort != null) {
+                            onAbort.run();
+                        }
+                        return Optional.empty();
+                    }
+                    break;
+                }
+                // Paper end - PreCreatureSpawnEvent
                 T t0 = entitytypes.create(worldserver, (Consumer<T>) null, blockposition_mutableblockposition, entityspawnreason, 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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/entity/EntityType.java
+++ b/src/main/java/net/minecraft/world/entity/EntityType.java
@@ -0,0 +0,0 @@ public class EntityType<T extends Entity> implements FeatureElement, EntityTypeT
     @Nullable
     public T spawn(ServerLevel worldserver, @Nullable Consumer<T> consumer, BlockPos blockposition, EntitySpawnReason entityspawnreason, boolean flag, boolean flag1, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason) {
         // CraftBukkit end
+        // Paper start - PreCreatureSpawnEvent
+        com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+            io.papermc.paper.util.MCUtil.toLocation(worldserver, blockposition),
+            org.bukkit.craftbukkit.entity.CraftEntityType.minecraftToBukkit(this),
+            spawnReason
+        );
+        if (!event.callEvent()) {
+            return null;
+        }
+        // Paper end - PreCreatureSpawnEvent
         T t0 = this.create(worldserver, consumer, blockposition, entityspawnreason, 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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/entity/npc/Villager.java
+++ b/src/main/java/net/minecraft/world/entity/npc/Villager.java
@@ -0,0 +0,0 @@ public class Villager extends AbstractVillager implements ReputationEventHandler
             }).limit(5L).toList();
 
             if (list1.size() >= requiredCount) {
-                if (!SpawnUtil.trySpawnMob(EntityType.IRON_GOLEM, EntitySpawnReason.MOB_SUMMONED, world, this.blockPosition(), 10, 8, 6, SpawnUtil.Strategy.LEGACY_IRON_GOLEM, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.VILLAGE_DEFENSE).isEmpty()) { // CraftBukkit
+                if (SpawnUtil.trySpawnMob(EntityType.IRON_GOLEM, EntitySpawnReason.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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/BaseSpawner.java
+++ b/src/main/java/net/minecraft/world/level/BaseSpawner.java
@@ -0,0 +0,0 @@ public abstract class BaseSpawner {
                         } else if (!SpawnPlacements.checkSpawnRules((EntityType) optional.get(), world, EntitySpawnReason.SPAWNER, blockposition1, world.getRandom())) {
                             continue;
                         }
+                        // Paper start - PreCreatureSpawnEvent
+                        com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+                            io.papermc.paper.util.MCUtil.toLocation(world, d0, d1, d2),
+                            org.bukkit.craftbukkit.entity.CraftEntityType.minecraftToBukkit(optional.get()),
+                            org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER
+                        );
+                        if (!event.callEvent()) {
+                            flag = true;
+                            if (event.shouldAbortSpawn()) {
+                                break;
+                            }
+                            continue;
+                        }
+                        // Paper end - PreCreatureSpawnEvent
 
                         Entity entity = EntityType.loadEntityRecursive(nbttagcompound, world, EntitySpawnReason.SPAWNER, (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 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/NaturalSpawner.java
+++ b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
@@ -0,0 +0,0 @@ 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 - PreCreatureSpawnEvent
+                                    PreSpawnStatus doSpawning = isValidSpawnPostitionForType(world, group, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2);
+                                    if (doSpawning == PreSpawnStatus.ABORT) {
+                                        return;
+                                    }
+                                    if (doSpawning == PreSpawnStatus.SUCCESS && checker.test(biomesettingsmobs_c.type, blockposition_mutableblockposition, chunk)) {
+                                        // Paper end - PreCreatureSpawnEvent
                                         Mob entityinsentient = NaturalSpawner.getMobForSpawn(world, biomesettingsmobs_c.type);
 
                                         if (entityinsentient == null) {
@@ -0,0 +0,0 @@ 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) {
+    // Paper start - PreCreatureSpawnEvent
+    private enum PreSpawnStatus {
+        FAIL,
+        SUCCESS,
+        CANCELLED,
+        ABORT
+    }
+    private static PreSpawnStatus isValidSpawnPostitionForType(ServerLevel world, MobCategory group, StructureManager structureAccessor, ChunkGenerator chunkGenerator, MobSpawnSettings.SpawnerData spawnEntry, BlockPos.MutableBlockPos pos, double squaredDistance) {
+        // Paper end - PreCreatureSpawnEvent
         EntityType<?> entitytypes = spawnEntry.type;
 
-        return entitytypes.getCategory() == MobCategory.MISC ? false : (!entitytypes.canSpawnFarFromPlayer() && squaredDistance > (double) (entitytypes.getCategory().getDespawnDistance() * entitytypes.getCategory().getDespawnDistance()) ? false : (entitytypes.canSummon() && NaturalSpawner.canSpawnMobAt(world, structureAccessor, chunkGenerator, group, spawnEntry, pos) ? (!SpawnPlacements.isSpawnPositionOk(entitytypes, world, pos) ? false : (!SpawnPlacements.checkSpawnRules(entitytypes, world, EntitySpawnReason.NATURAL, pos, world.random) ? false : world.noCollision(entitytypes.getSpawnAABB((double) pos.getX() + 0.5D, (double) pos.getY(), (double) pos.getZ() + 0.5D)))) : false));
+        // Paper start - PreCreatureSpawnEvent
+        com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent event = new com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent(
+            io.papermc.paper.util.MCUtil.toLocation(world, pos),
+            org.bukkit.craftbukkit.entity.CraftEntityType.minecraftToBukkit(entitytypes), SpawnReason.NATURAL
+        );
+        if (!event.callEvent()) {
+            if (event.shouldAbortSpawn()) {
+                return PreSpawnStatus.ABORT;
+            }
+            return PreSpawnStatus.CANCELLED;
+        }
+        // Paper end - PreCreatureSpawnEvent
+
+        return entitytypes.getCategory() == MobCategory.MISC ? PreSpawnStatus.FAIL : (!entitytypes.canSpawnFarFromPlayer() && squaredDistance > (double) (entitytypes.getCategory().getDespawnDistance() * entitytypes.getCategory().getDespawnDistance()) ? PreSpawnStatus.FAIL : (entitytypes.canSummon() && NaturalSpawner.canSpawnMobAt(world, structureAccessor, chunkGenerator, group, spawnEntry, pos) ? (!SpawnPlacements.isSpawnPositionOk(entitytypes, world, pos) ? PreSpawnStatus.FAIL : (!SpawnPlacements.checkSpawnRules(entitytypes, world, EntitySpawnReason.NATURAL, pos, world.random) ? PreSpawnStatus.FAIL : world.noCollision(entitytypes.getSpawnAABB((double) pos.getX() + 0.5D, (double) pos.getY(), (double) pos.getZ() + 0.5D)) ? PreSpawnStatus.SUCCESS : PreSpawnStatus.FAIL)) : PreSpawnStatus.FAIL)); // Paper - PreCreatureSpawnEvent
     }
 
     @Nullable