From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: kickash32 <kickash32@gmail.com>
Date: Mon, 5 Apr 2021 01:42:35 -0400
Subject: [PATCH] Improve cancelling PreCreatureSpawnEvent with per player mob
 spawns


diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index ccf0f7c7feaf47f451cec30ba02bea39ba192b3c..ac1a4ff5f83e53fa2983ff6e834775e51fba715e 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -306,8 +306,25 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
         }
     }
 
+    // Paper start - per player mob count backoff
+    public void updateFailurePlayerMobTypeMap(int chunkX, int chunkZ, net.minecraft.world.entity.MobCategory mobCategory) {
+        if (!this.level.paperConfig().entities.spawning.perPlayerMobSpawns) {
+            return;
+        }
+        int idx = mobCategory.ordinal();
+        final com.destroystokyo.paper.util.maplist.ReferenceList<ServerPlayer> inRange =
+            this.getNearbyPlayers().getPlayersByChunk(chunkX, chunkZ, io.papermc.paper.util.player.NearbyPlayers.NearbyMapType.TICK_VIEW_DISTANCE);
+        if (inRange == null) {
+            return;
+        }
+        final Object[] backingSet = inRange.getRawData();
+        for (int i = 0, len = inRange.size(); i < len; i++) {
+            ++((ServerPlayer)backingSet[i]).mobBackoffCounts[idx];
+        }
+    }
+    // Paper end - per player mob count backoff
     public int getMobCountNear(final ServerPlayer player, final net.minecraft.world.entity.MobCategory mobCategory) {
-        return player.mobCounts[mobCategory.ordinal()];
+        return player.mobCounts[mobCategory.ordinal()] + player.mobBackoffCounts[mobCategory.ordinal()]; // Paper - per player mob count backoff
     }
     // Paper end - Optional per player mob spawns
 
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index 059ab637adf1be576fa1fff36a91b6c5f1b5f035..5afbb5b307cc67d86dd916dc8f7521d5d021e056 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -524,7 +524,17 @@ public class ServerChunkCache extends ChunkSource {
                 if ((this.spawnFriendlies || this.spawnEnemies) && this.level.paperConfig().entities.spawning.perPlayerMobSpawns) { // don't count mobs when animals and monsters are disabled
                     // re-set mob counts
                     for (ServerPlayer player : this.level.players) {
-                        Arrays.fill(player.mobCounts, 0);
+                        // Paper start - per player mob spawning backoff
+                        for (int ii = 0; ii < ServerPlayer.MOBCATEGORY_TOTAL_ENUMS; ii++) {
+                            player.mobCounts[ii] = 0;
+
+                            int newBackoff = player.mobBackoffCounts[ii] - 1; // TODO make configurable bleed // TODO use nonlinear algorithm?
+                            if (newBackoff < 0) {
+                                newBackoff = 0;
+                            }
+                            player.mobBackoffCounts[ii] = newBackoff;
+                        }
+                        // Paper end - per player mob spawning backoff
                     }
                     spawnercreature_d = NaturalSpawner.createState(naturalSpawnChunkCount, this.level.getAllEntities(), this::getFullChunk, null, true);
                 } else {
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 7fb2c0f2576142423cd0e50b811ce4f55795e43d..acc1751324f040accc4fc18914ed281e572358eb 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -260,6 +260,7 @@ public class ServerPlayer extends Player {
     public static final int MOBCATEGORY_TOTAL_ENUMS = net.minecraft.world.entity.MobCategory.values().length;
     public final int[] mobCounts = new int[MOBCATEGORY_TOTAL_ENUMS]; // Paper
     // Paper end - Optional per player mob spawns
+    public final int[] mobBackoffCounts = new int[MOBCATEGORY_TOTAL_ENUMS]; // Paper - per player mob count backoff
 
     // CraftBukkit start
     public String displayName;
diff --git a/src/main/java/net/minecraft/world/level/NaturalSpawner.java b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
index 14f4ceb6c0be34d23b24c1695f966145c3aaee96..da7489986848316fed029b71d1bc4e1248c9c9a8 100644
--- a/src/main/java/net/minecraft/world/level/NaturalSpawner.java
+++ b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
@@ -277,6 +277,11 @@ public final class NaturalSpawner {
 
                                     // Paper start - PreCreatureSpawnEvent
                                     PreSpawnStatus doSpawning = isValidSpawnPostitionForType(world, group, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2);
+                                    // Paper start - per player mob count backoff
+                                    if (doSpawning == PreSpawnStatus.ABORT || doSpawning == PreSpawnStatus.CANCELLED) {
+                                        world.getChunkSource().chunkMap.updateFailurePlayerMobTypeMap(blockposition_mutableblockposition.getX() >> 4, blockposition_mutableblockposition.getZ() >> 4, group);
+                                    }
+                                    // Paper end - per player mob count backoff
                                     if (doSpawning == PreSpawnStatus.ABORT) {
                                         return j; // Paper - Optional per player mob spawns
                                     }