From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sat, 23 Sep 2023 21:36:36 -0700
Subject: [PATCH] Optimise chunk tick iteration

When per-player mob spawning is enabled we do not need to randomly
shuffle the chunk list. Additionally, we can use the NearbyPlayers
class to quickly retrieve nearby players instead of possible
searching all players on the server.

diff --git a/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java b/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
index c3ce8a42dddd76b7189ad5685b23f9d9f8ccadb3..f164256d59b761264876ca0c85f812d101bfd5de 100644
--- a/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
+++ b/src/main/java/io/papermc/paper/util/player/NearbyPlayers.java
@@ -17,7 +17,8 @@ public final class NearbyPlayers {
         GENERAL_SMALL,
         GENERAL_REALLY_SMALL,
         TICK_VIEW_DISTANCE,
-        VIEW_DISTANCE;
+        VIEW_DISTANCE, // Paper - optimise chunk iteration
+        SPAWN_RANGE, // Paper - optimise chunk iteration
     }
 
     private static final NearbyMapType[] MOB_TYPES = NearbyMapType.values();
@@ -26,10 +27,12 @@ public final class NearbyPlayers {
     private static final int GENERAL_AREA_VIEW_DISTANCE = 33;
     private static final int GENERAL_SMALL_VIEW_DISTANCE = 10;
     private static final int GENERAL_REALLY_SMALL_VIEW_DISTANCE = 3;
+    private static final int SPAWN_RANGE_VIEW_DISTANCE = net.minecraft.server.level.DistanceManager.MOB_SPAWN_RANGE; // Paper - optimise chunk iteration
 
     public static final int GENERAL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_AREA_VIEW_DISTANCE << 4);
     public static final int GENERAL_SMALL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_SMALL_VIEW_DISTANCE << 4);
     public static final int GENERAL_REALLY_SMALL_AREA_VIEW_DISTANCE_BLOCKS = (GENERAL_REALLY_SMALL_VIEW_DISTANCE << 4);
+    public static final int SPAWN_RANGE_VIEW_DISTANCE_BLOCKS = (SPAWN_RANGE_VIEW_DISTANCE << 4); // Paper - optimise chunk iteration
 
     private final ServerLevel world;
     private final Reference2ReferenceOpenHashMap<ServerPlayer, TrackedPlayer[]> players = new Reference2ReferenceOpenHashMap<>();
@@ -80,6 +83,7 @@ public final class NearbyPlayers {
         players[NearbyMapType.GENERAL_REALLY_SMALL.ordinal()].update(chunk.x, chunk.z, GENERAL_REALLY_SMALL_VIEW_DISTANCE);
         players[NearbyMapType.TICK_VIEW_DISTANCE.ordinal()].update(chunk.x, chunk.z, ChunkSystem.getTickViewDistance(player));
         players[NearbyMapType.VIEW_DISTANCE.ordinal()].update(chunk.x, chunk.z, ChunkSystem.getLoadViewDistance(player));
+        players[NearbyMapType.SPAWN_RANGE.ordinal()].update(chunk.x, chunk.z, SPAWN_RANGE_VIEW_DISTANCE); // Paper - optimise chunk iteration
     }
 
     public TrackedChunk getChunk(final ChunkPos pos) {
diff --git a/src/main/java/net/minecraft/server/level/ChunkHolder.java b/src/main/java/net/minecraft/server/level/ChunkHolder.java
index 13d15a135dd0373bef4a5ac9ffb56dbbf53353a0..472b9494f8a34a8ba90d6a2936b0db7530a229ad 100644
--- a/src/main/java/net/minecraft/server/level/ChunkHolder.java
+++ b/src/main/java/net/minecraft/server/level/ChunkHolder.java
@@ -77,11 +77,19 @@ public class ChunkHolder {
 
     // Paper start
     public void onChunkAdd() {
-
+        // Paper start - optimise chunk tick iteration
+        if (this.needsBroadcastChanges()) {
+            this.chunkMap.needsChangeBroadcasting.add(this);
+        }
+        // Paper end - optimise chunk tick iteration
     }
 
     public void onChunkRemove() {
-
+        // Paper start - optimise chunk tick iteration
+        if (this.needsBroadcastChanges()) {
+            this.chunkMap.needsChangeBroadcasting.remove(this);
+        }
+        // Paper end - optimise chunk tick iteration
     }
     // Paper end
 
@@ -216,7 +224,7 @@ public class ChunkHolder {
 
             if (i < 0 || i >= this.changedBlocksPerSection.length) return; // CraftBukkit - SPIGOT-6086, SPIGOT-6296
             if (this.changedBlocksPerSection[i] == null) {
-                this.hasChangedSections = true;
+                this.hasChangedSections = true; this.addToBroadcastMap(); // Paper - optimise chunk tick iteration
                 this.changedBlocksPerSection[i] = new ShortOpenHashSet();
             }
 
@@ -236,6 +244,7 @@ public class ChunkHolder {
                 int k = this.lightEngine.getMaxLightSection();
 
                 if (y >= j && y <= k) {
+                    this.addToBroadcastMap(); // Paper - optimise chunk tick iteration
                     int l = y - j;
 
                     if (lightType == LightLayer.SKY) {
@@ -254,9 +263,19 @@ public class ChunkHolder {
         this.broadcast(this.getPlayers(onChunkViewEdge), packet); // Paper - rewrite chunk system
     }
     // Paper end - starlight
+    // Paper start - optimise chunk tick iteration
+    public final boolean needsBroadcastChanges() {
+        return this.hasChangedSections || !this.skyChangedLightSectionFilter.isEmpty() || !this.blockChangedLightSectionFilter.isEmpty();
+    }
+
+    private void addToBroadcastMap() {
+        io.papermc.paper.util.TickThread.ensureTickThread(this.chunkMap.level, this.pos, "Asynchronous ChunkHolder update is not allowed");
+        this.chunkMap.needsChangeBroadcasting.add(this);
+    }
+    // Paper end - optimise chunk tick iteration
 
     public void broadcastChanges(LevelChunk chunk) {
-        if (this.hasChangedSections || !this.skyChangedLightSectionFilter.isEmpty() || !this.blockChangedLightSectionFilter.isEmpty()) {
+        if (this.needsBroadcastChanges()) { // Paper - optimise chunk tick iteration; moved into above, other logic needs to call
             Level world = chunk.getLevel();
             List list;
 
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index 48f7997e8a20f5a5a77516cbde990d0aacc2078a..dbe9df1e1973db133f7c8516256697ef7c968137 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -194,6 +194,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             this.playerEntityTrackerTrackMaps[i].remove(player);
         }
         // Paper end - use distance map to optimise tracker
+        this.playerMobSpawnMap.remove(player); // Paper - optimise chunk tick iteration
     }
 
     void updateMaps(ServerPlayer player) {
@@ -243,6 +244,10 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     }
     public final io.papermc.paper.util.player.NearbyPlayers nearbyPlayers;
     // Paper end
+    // Paper start - optimise chunk tick iteration
+    public final it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<ChunkHolder> needsChangeBroadcasting = new it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<>();
+    public final com.destroystokyo.paper.util.misc.PlayerAreaMap playerMobSpawnMap = new com.destroystokyo.paper.util.misc.PlayerAreaMap(this.pooledLinkedPlayerHashSets);
+    // Paper end - optimise chunk tick iteration
 
     public ChunkMap(ServerLevel world, LevelStorageSource.LevelStorageAccess session, DataFixer dataFixer, StructureTemplateManager structureTemplateManager, Executor executor, BlockableEventLoop<Runnable> mainThreadExecutor, LightChunkGetter chunkProvider, ChunkGenerator chunkGenerator, ChunkProgressListener worldGenerationProgressListener, ChunkStatusUpdateListener chunkStatusChangeListener, Supplier<DimensionDataStorage> persistentStateManagerFactory, int viewDistance, boolean dsync) {
         super(new RegionStorageInfo(session.getLevelId(), world.dimension(), "chunk"), session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync);
@@ -411,7 +416,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
     }
     // Paper end - Optional per player mob spawns
 
-    private static double euclideanDistanceSquared(ChunkPos pos, Entity entity) {
+    public static double euclideanDistanceSquared(ChunkPos pos, Entity entity) { // Paper - optimise chunk iteration; public
         double d0 = (double) SectionPos.sectionToBlockCoord(pos.x, 8);
         double d1 = (double) SectionPos.sectionToBlockCoord(pos.z, 8);
         double d2 = d0 - entity.getX();
diff --git a/src/main/java/net/minecraft/server/level/DistanceManager.java b/src/main/java/net/minecraft/server/level/DistanceManager.java
index ed5154e41ca858f4d6b4d1c276c66831c038d2a6..cdb3c2cde5d9133ef60cf96d91762e6a7c8aeb4a 100644
--- a/src/main/java/net/minecraft/server/level/DistanceManager.java
+++ b/src/main/java/net/minecraft/server/level/DistanceManager.java
@@ -49,7 +49,7 @@ public abstract class DistanceManager {
     private static final int INITIAL_TICKET_LIST_CAPACITY = 4;
     final Long2ObjectMap<ObjectSet<ServerPlayer>> playersPerChunk = new Long2ObjectOpenHashMap();
     // Paper - rewrite chunk system
-    private final DistanceManager.FixedPlayerDistanceChunkTracker naturalSpawnChunkCounter = new DistanceManager.FixedPlayerDistanceChunkTracker(8);
+    public static final int MOB_SPAWN_RANGE = 8; //private final DistanceManager.FixedPlayerDistanceChunkTracker naturalSpawnChunkCounter = new DistanceManager.FixedPlayerDistanceChunkTracker(8); // Paper - optimise chunk tick iteration
     // Paper - rewrite chunk system
     private final ChunkMap chunkMap; // Paper
 
@@ -135,7 +135,7 @@ public abstract class DistanceManager {
         long i = chunkcoordintpair.toLong();
 
         // Paper - no longer used
-        this.naturalSpawnChunkCounter.update(i, 0, true);
+        //this.naturalSpawnChunkCounter.update(i, 0, true); // Paper - optimise chunk tick iteration
         //this.playerTicketManager.update(i, 0, true); // Paper - no longer used
         //this.tickingTicketsTracker.addTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair); // Paper - no longer used
     }
@@ -149,7 +149,7 @@ public abstract class DistanceManager {
         if (objectset != null) objectset.remove(player); // Paper - some state corruption happens here, don't crash, clean up gracefully
         if (objectset == null || objectset.isEmpty()) { // Paper
             this.playersPerChunk.remove(i);
-            this.naturalSpawnChunkCounter.update(i, Integer.MAX_VALUE, false);
+            //this.naturalSpawnChunkCounter.update(i, Integer.MAX_VALUE, false); // Paper - optimise chunk tick iteration
             //this.playerTicketManager.update(i, Integer.MAX_VALUE, false); // Paper - no longer used
             //this.tickingTicketsTracker.removeTicket(TicketType.PLAYER, chunkcoordintpair, this.getPlayerTicketLevel(), chunkcoordintpair); // Paper - no longer used
         }
@@ -191,13 +191,11 @@ public abstract class DistanceManager {
     }
 
     public int getNaturalSpawnChunkCount() {
-        this.naturalSpawnChunkCounter.runAllUpdates();
-        return this.naturalSpawnChunkCounter.chunks.size();
+        return this.chunkMap.playerMobSpawnMap.size(); // Paper - optimise chunk tick iteration
     }
 
     public boolean hasPlayersNearby(long chunkPos) {
-        this.naturalSpawnChunkCounter.runAllUpdates();
-        return this.naturalSpawnChunkCounter.chunks.containsKey(chunkPos);
+        return this.chunkMap.playerMobSpawnMap.getObjectsInRange(chunkPos) != null; // Paper - optimise chunk tick iteration
     }
 
     public String getDebugStatus() {
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index 01577dbb16ff6abc9edcf897f7fadaad14350184..e2c67c011503c9c37b9d637c0268717baac13e32 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -499,18 +499,10 @@ public class ServerChunkCache extends ChunkSource {
 
             gameprofilerfiller.push("pollingChunks");
             gameprofilerfiller.push("filteringLoadedChunks");
-            List<ServerChunkCache.ChunkAndHolder> list = Lists.newArrayListWithCapacity(this.chunkMap.size());
-            Iterator iterator = this.chunkMap.getChunks().iterator();
+            // Paper - optimise chunk tick iteration
             if (this.level.getServer().tickRateManager().runsNormally()) this.level.timings.chunkTicks.startTiming(); // Paper
 
-            while (iterator.hasNext()) {
-                ChunkHolder playerchunk = (ChunkHolder) iterator.next();
-                LevelChunk chunk = playerchunk.getTickingChunk();
-
-                if (chunk != null) {
-                    list.add(new ServerChunkCache.ChunkAndHolder(chunk, playerchunk));
-                }
-            }
+            // Paper - optimise chunk tick iteration
 
             if (this.level.tickRateManager().runsNormally()) {
                 gameprofilerfiller.popPush("naturalSpawnCount");
@@ -545,38 +537,109 @@ public class ServerChunkCache extends ChunkSource {
                 gameprofilerfiller.popPush("spawnAndTick");
                 boolean flag = this.level.getGameRules().getBoolean(GameRules.RULE_DOMOBSPAWNING) && !this.level.players().isEmpty(); // CraftBukkit
 
-                Util.shuffle(list, this.level.random);
-                // Paper start - PlayerNaturallySpawnCreaturesEvent
-                int chunkRange = level.spigotConfig.mobSpawnRange;
-                chunkRange = (chunkRange > level.spigotConfig.viewDistance) ? (byte) level.spigotConfig.viewDistance : chunkRange;
-                chunkRange = Math.min(chunkRange, 8);
-                for (ServerPlayer entityPlayer : this.level.players()) {
-                    entityPlayer.playerNaturallySpawnedEvent = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(entityPlayer.getBukkitEntity(), (byte) chunkRange);
-                    entityPlayer.playerNaturallySpawnedEvent.callEvent();
+                // Paper start - optimise chunk tick iteration
+                ChunkMap playerChunkMap = this.chunkMap;
+                for (ServerPlayer player : this.level.players) {
+                    if (!player.affectsSpawning || player.isSpectator()) {
+                        playerChunkMap.playerMobSpawnMap.remove(player);
+                        player.playerNaturallySpawnedEvent = null;
+                        player.lastEntitySpawnRadiusSquared = -1.0;
+                        continue;
+                    }
+
+                    int viewDistance = io.papermc.paper.chunk.system.ChunkSystem.getTickViewDistance(player);
+
+                    // copied and modified from isOutisdeRange
+                    int chunkRange = (int)level.spigotConfig.mobSpawnRange;
+                    chunkRange = (chunkRange > viewDistance) ? viewDistance : chunkRange;
+                    chunkRange = (chunkRange > DistanceManager.MOB_SPAWN_RANGE) ? DistanceManager.MOB_SPAWN_RANGE : chunkRange;
+
+                    com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent event = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(player.getBukkitEntity(), (byte)chunkRange);
+                    event.callEvent();
+                    if (event.isCancelled() || event.getSpawnRadius() < 0) {
+                        playerChunkMap.playerMobSpawnMap.remove(player);
+                        player.playerNaturallySpawnedEvent = null;
+                        player.lastEntitySpawnRadiusSquared = -1.0;
+                        continue;
+                    }
+
+                    int range = Math.min(event.getSpawnRadius(), DistanceManager.MOB_SPAWN_RANGE); // limit to max spawn range
+                    int chunkX = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getX());
+                    int chunkZ = io.papermc.paper.util.CoordinateUtils.getChunkCoordinate(player.getZ());
+
+                    playerChunkMap.playerMobSpawnMap.addOrUpdate(player, chunkX, chunkZ, range);
+                    player.lastEntitySpawnRadiusSquared = (double)((range << 4) * (range << 4)); // used in anyPlayerCloseEnoughForSpawning
+                    player.playerNaturallySpawnedEvent = event;
                 }
-                // Paper end - PlayerNaturallySpawnCreaturesEvent
+                // Paper end - optimise chunk tick iteration
                 int l = this.level.getGameRules().getInt(GameRules.RULE_RANDOMTICKING);
                 boolean flag1 = this.level.ticksPerSpawnCategory.getLong(org.bukkit.entity.SpawnCategory.ANIMAL) != 0L && this.level.getLevelData().getGameTime() % this.level.ticksPerSpawnCategory.getLong(org.bukkit.entity.SpawnCategory.ANIMAL) == 0L; // CraftBukkit
-                Iterator iterator1 = list.iterator();
+                // Paper - optimise chunk tick iteration
 
                 int chunksTicked = 0; // Paper
-                while (iterator1.hasNext()) {
-                    ServerChunkCache.ChunkAndHolder chunkproviderserver_a = (ServerChunkCache.ChunkAndHolder) iterator1.next();
-                    LevelChunk chunk1 = chunkproviderserver_a.chunk;
+                // Paper start - optimise chunk tick iteration
+                io.papermc.paper.util.player.NearbyPlayers nearbyPlayers = this.chunkMap.getNearbyPlayers(); // Paper - optimise chunk tick iteration
+                Iterator<LevelChunk> chunkIterator;
+                if (this.level.paperConfig().entities.spawning.perPlayerMobSpawns) {
+                    chunkIterator = this.tickingChunks.iterator();
+                } else {
+                    chunkIterator = this.tickingChunks.unsafeIterator();
+                    List<LevelChunk> shuffled = Lists.newArrayListWithCapacity(this.tickingChunks.size());
+                    while (chunkIterator.hasNext()) {
+                        shuffled.add(chunkIterator.next());
+                    }
+                    Util.shuffle(shuffled, this.level.random);
+                    chunkIterator = shuffled.iterator();
+                }
+                try {
+                // Paper end - optimise chunk tick iteration
+                while (chunkIterator.hasNext()) {
+                    LevelChunk chunk1 = chunkIterator.next();
+                    // Paper end - optimise chunk tick iteration
                     ChunkPos chunkcoordintpair = chunk1.getPos();
 
-                    if (this.level.isNaturalSpawningAllowed(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(chunkcoordintpair)) {
+                    // Paper start - optimise chunk tick iteration
+                    com.destroystokyo.paper.util.maplist.ReferenceList<ServerPlayer> playersNearby
+                        = nearbyPlayers.getPlayers(chunkcoordintpair, io.papermc.paper.util.player.NearbyPlayers.NearbyMapType.SPAWN_RANGE);
+                    if (playersNearby == null) {
+                        continue;
+                    }
+                    Object[] rawData = playersNearby.getRawData();
+                    boolean spawn = false;
+                    boolean tick = false;
+                    for (int itr = 0, len = playersNearby.size(); itr < len; ++itr) {
+                        ServerPlayer player = (ServerPlayer)rawData[itr];
+                        if (player.isSpectator()) {
+                            continue;
+                        }
+
+                        double distance = ChunkMap.euclideanDistanceSquared(chunkcoordintpair, player);
+                        spawn |= player.lastEntitySpawnRadiusSquared >= distance;
+                        tick |= ((double)io.papermc.paper.util.player.NearbyPlayers.SPAWN_RANGE_VIEW_DISTANCE_BLOCKS) * ((double)io.papermc.paper.util.player.NearbyPlayers.SPAWN_RANGE_VIEW_DISTANCE_BLOCKS) >= distance;
+                        if (spawn & tick) {
+                            break;
+                        }
+                    }
+                    if (tick && chunk1.chunkStatus.isOrAfter(net.minecraft.server.level.FullChunkStatus.ENTITY_TICKING)) {
+                        // Paper end - optimise chunk tick iteration
                         chunk1.incrementInhabitedTime(j);
-                        if (flag && (this.spawnEnemies || this.spawnFriendlies) && this.level.getWorldBorder().isWithinBounds(chunkcoordintpair) && this.chunkMap.anyPlayerCloseEnoughForSpawning(chunkcoordintpair, true)) { // Spigot
+                        if (spawn && flag && (this.spawnEnemies || this.spawnFriendlies) && this.level.getWorldBorder().isWithinBounds(chunkcoordintpair)) { // Spigot // Paper - optimise chunk tick iteration
                             NaturalSpawner.spawnForChunk(this.level, chunk1, spawnercreature_d, this.spawnFriendlies, this.spawnEnemies, flag1);
                         }
 
-                        if (this.level.shouldTickBlocksAt(chunkcoordintpair.toLong())) {
+                        if (true || this.level.shouldTickBlocksAt(chunkcoordintpair.toLong())) { // Paper - optimise chunk tick iteration
                             this.level.tickChunk(chunk1, l);
                             if ((chunksTicked++ & 1) == 0) net.minecraft.server.MinecraftServer.getServer().executeMidTickTasks(); // Paper
                         }
                     }
                 }
+                // Paper start - optimise chunk tick iteration
+                } finally {
+                    if (chunkIterator instanceof io.papermc.paper.util.maplist.IteratorSafeOrderedReferenceSet.Iterator safeIterator) {
+                        safeIterator.finishedIterating();
+                    }
+                }
+                // Paper end - optimise chunk tick iteration
                 this.level.timings.chunkTicks.stopTiming(); // Paper
 
                 gameprofilerfiller.popPush("customSpawners");
@@ -588,11 +651,23 @@ public class ServerChunkCache extends ChunkSource {
             }
 
             gameprofilerfiller.popPush("broadcast");
-            list.forEach((chunkproviderserver_a1) -> {
+            // Paper - optimise chunk tick iteration
                 this.level.timings.broadcastChunkUpdates.startTiming(); // Paper - timing
-                chunkproviderserver_a1.holder.broadcastChanges(chunkproviderserver_a1.chunk);
+            // Paper start - optimise chunk tick iteration
+            if (!this.chunkMap.needsChangeBroadcasting.isEmpty()) {
+                it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet<ChunkHolder> copy = this.chunkMap.needsChangeBroadcasting.clone();
+                this.chunkMap.needsChangeBroadcasting.clear();
+                for (ChunkHolder holder : copy) {
+                    holder.broadcastChanges(holder.getFullChunkNowUnchecked()); // LevelChunks are NEVER unloaded
+                    if (holder.needsBroadcastChanges()) {
+                        // I DON'T want to KNOW what DUMB plugins might be doing.
+                        this.chunkMap.needsChangeBroadcasting.add(holder);
+                    }
+                }
+            }
+            // Paper end - optimise chunk tick iteration
                 this.level.timings.broadcastChunkUpdates.stopTiming(); // Paper - timing
-            });
+            // Paper - optimise chunk tick iteration
             gameprofilerfiller.pop();
             gameprofilerfiller.pop();
         }
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 09a80b6816e50ea0d733725c59164520136308d6..6a4637eef14cbd84bbe26ef16f004b8f93367a3d 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -342,6 +342,9 @@ public class ServerPlayer extends Player {
         });
     }
     // Paper end - replace player chunk loader
+    // Paper start - optimise chunk tick iteration
+    public double lastEntitySpawnRadiusSquared = -1.0;
+    // Paper end - optimise chunk tick iteration
 
     public ServerPlayer(MinecraftServer server, ServerLevel world, GameProfile profile, ClientInformation clientOptions) {
         super(world, world.getSharedSpawnPos(), world.getSharedSpawnAngle(), profile);
