From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 23 May 2020 17:03:41 -0400
Subject: [PATCH] Optimize sending packets to nearby locations (sounds/effects)

Instead of using the entire world or player list, use the distance
maps to only iterate players who are even seeing the chunk the packet
is originating from.

This will drastically cut down on packet sending cost for worlds with
lots of players in them.

diff --git a/src/main/java/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
index 9b726de6daeba42120f3a948fbdcf080d0e72917..ada082e67ac8a3e79bab5b360f09c9402f683b86 100644
--- a/src/main/java/net/minecraft/server/PlayerList.java
+++ b/src/main/java/net/minecraft/server/PlayerList.java
@@ -1027,11 +1027,30 @@ public abstract class PlayerList {
             world = (WorldServer) entityhuman.world;
         }
 
-        List<? extends EntityHuman> players1 = world == null ? players : world.players;
-        for (int j = 0; j < players1.size(); ++j) {
-            EntityHuman entity = players1.get(j);
-            if (!(entity instanceof EntityPlayer)) continue;
-            EntityPlayer entityplayer = (EntityPlayer) entity;
+        // Paper start
+        if ((world == null || world.chunkProvider == null) && dimensionmanager != null) {
+            world = dimensionmanager.world;
+        }
+        if (world == null) {
+            LOGGER.error("Sending packet to invalid world" + entityhuman + " " + dimensionmanager + " - " + packet.getClass().getName(), new Throwable());
+            return; // ??? shouldn't happen...
+        }
+        PlayerChunkMap chunkMap = world.chunkMap;
+        Object[] backingSet;
+        if (chunkMap == null) {
+            // Really shouldn't happen...
+            backingSet = world.players.toArray();
+        } else {
+            com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<EntityPlayer> nearbyPlayers = chunkMap.playerViewDistanceBroadcastMap.getObjectsInRange(MCUtil.fastFloor(d0) >> 4, MCUtil.fastFloor(d2) >> 4);
+            if (nearbyPlayers == null) {
+                return;
+            }
+            backingSet = nearbyPlayers.getBackingSet();
+        }
+
+        for (Object object : backingSet) {
+            if (!(object instanceof EntityPlayer)) continue;
+            EntityPlayer entityplayer = (EntityPlayer) object;
             // Paper end
 
             // CraftBukkit start - Test if player receiving packet can see the source of the packet
diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
index 9e32e2db10f5faaa3c5f4adc5cbc2c1a2e4d3073..854c97bddb711ed252c2ae8398247641fdfb10be 100644
--- a/src/main/java/net/minecraft/server/WorldServer.java
+++ b/src/main/java/net/minecraft/server/WorldServer.java
@@ -70,6 +70,7 @@ public class WorldServer extends World {
         }
     }
     // Paper end
+    public final PlayerChunkMap chunkMap; // Paper
     private final MinecraftServer server;
     private final WorldNBTStorage dataManager;
     public boolean savingDisabled;
@@ -208,6 +209,8 @@ public class WorldServer extends World {
         }, gameprofilerfiller, false, gen, env);
         this.pvpMode = minecraftserver.getPVP();
         worlddata.world = this;
+        if (chunkProvider == null) { chunkMap = null; new Throwable("World created without a ChunkProvider!").printStackTrace(); } // Paper - figure out if something weird happened here
+        else chunkMap = ((ChunkProviderServer) chunkProvider).playerChunkMap;
         // CraftBukkit end
         if (com.destroystokyo.paper.PaperConfig.useOptimizedTickList) {
             this.nextTickListBlock = new com.destroystokyo.paper.server.ticklist.PaperTickList<>(this, (block) -> { // Paper - optimise TickListServer