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 d20112349868f4c76f43882ad0cab7be025a6303..984f5bf687f5d7364eea6cff4110a5a33c24d492 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -387,8 +387,26 @@ 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(ServerPlayer entityPlayer, net.minecraft.world.entity.MobCategory mobCategory) {
-        return entityPlayer.mobCounts[mobCategory.ordinal()];
+        return entityPlayer.mobCounts[mobCategory.ordinal()] + entityPlayer.mobBackoffCounts[mobCategory.ordinal()]; // Paper - per player mob count backoff
     }
     // Paper end
 
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index dbedc73039f53ddf042999524eec62f032a20d5d..aaaf3a60696389b4e27a45de69743311c58e5829 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -532,7 +532,17 @@ 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(l, 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 76d513c61eec05edc8b037f2567562fb677f2d95..2919c0562b3cfa48912d81e8619883493da99a36 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -253,6 +253,7 @@ 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 - mob spawning rework
+    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 d08c7b0b52065980f1f13c5533ff6355028322db..3cdddda9c0618e95288b81b975d499c8dd30c05f 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
                                     PreSpawnStatus doSpawning = isValidSpawnPostitionForType(world, group, structuremanager, chunkgenerator, biomesettingsmobs_c, blockposition_mutableblockposition, d2);
+                                    // Paper start - 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 - mob count backoff
                                     if (doSpawning == PreSpawnStatus.ABORT) {
                                         return j; // Paper
                                     }