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 3b9fcc33fdd91b02f7f9681329b2f3d523a5cd5a..14f6c163c4f3cb5b096db1b9111041b4573bfef6 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -479,8 +479,27 @@ 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.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> inRange = this.playerMobDistanceMap.getObjectsInRange(chunkX, chunkZ);
+        if (inRange != null) {
+            final Object[] set = inRange.getBackingSet();
+            for (int i = 0; i < set.length; i++) {
+                if (!(set[i] instanceof ServerPlayer serverPlayer)) {
+                    continue;
+                }
+                ++serverPlayer.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 488a253e218409b5f0b4a872cee0928578fa7582..acbcdc8cb1523044b1657e03a141fae6389a3686 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -564,7 +564,17 @@ public class ServerChunkCache extends ChunkSource {
             if ((this.spawnFriendlies || this.spawnEnemies) && this.chunkMap.playerMobDistanceMap != null) { // 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 dc5fda83a66afbfeb7897fc20b4742899d8aca08..161c40692e8d469fad4169908b9353be0f85d0d8 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -254,6 +254,7 @@ public class ServerPlayer extends Player {
     // Paper start - mob spawning rework
     public static final int MOBCATEGORY_TOTAL_ENUMS = net.minecraft.world.entity.MobCategory.values().length;
     public final int[] mobCounts = new int[MOBCATEGORY_TOTAL_ENUMS]; // Paper
+    public final int[] mobBackoffCounts = new int[MOBCATEGORY_TOTAL_ENUMS]; // Paper - per player mob count backoff
     public final com.destroystokyo.paper.util.PooledHashSets.PooledObjectLinkedOpenHashSet<ServerPlayer> cachedSingleMobDistanceMap;
     // Paper end
 
diff --git a/src/main/java/net/minecraft/world/level/NaturalSpawner.java b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
index 9ae2bd64514a83dbd8c22cc35a9ca4c39add5142..e85ddf92b4f6f044e2b5834a172f37d78e702ef3 100644
--- a/src/main/java/net/minecraft/world/level/NaturalSpawner.java
+++ b/src/main/java/net/minecraft/world/level/NaturalSpawner.java
@@ -279,6 +279,11 @@ 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
                                     }