papermc/CraftBukkit-Patches/0021-Only-send-maps-in-item-frames-upon-tracking.patch

From 17b87c50187fe2dd65832d1b8bd5e1b627425d2c Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 19 Feb 2013 17:26:20 -0500
Subject: [PATCH] Only send maps in item frames upon tracking

Maps in item frames are full of bugs.
1) It sends an update of the Maps data to ALL players in the world, not just the players tracking it.
2) It sends an update EVERY tick, not every 10 ticks as intended.

To optimize performance of maps in item frames, we will only send it once a player tracks the ItemFrame until it completes, then that player will not receive more updates.

This means cursors will not dynamically update, but the map data should refresh every time the player moves away then back.
---
 .../net/minecraft/server/EntityTrackerEntry.java   | 25 ++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/main/java/net/minecraft/server/EntityTrackerEntry.java b/src/main/java/net/minecraft/server/EntityTrackerEntry.java
index ae9ed52..6fa425c 100644
--- a/src/main/java/net/minecraft/server/EntityTrackerEntry.java
+++ b/src/main/java/net/minecraft/server/EntityTrackerEntry.java
@@ -36,6 +36,7 @@ public class EntityTrackerEntry {
     public boolean n = false;
     public Set trackedPlayers = new HashSet();
 
+    public List<EntityPlayer> playersToUpdate = new java.util.ArrayList<EntityPlayer>(); // Spigot
     public EntityTrackerEntry(Entity entity, int i, int j, boolean flag) {
         this.tracker = entity;
         this.b = i;
@@ -73,17 +74,17 @@ public class EntityTrackerEntry {
             this.broadcast(new Packet39AttachEntity(this.tracker, this.tracker.vehicle));
         }
 
-        if (this.tracker instanceof EntityItemFrame && this.m % 10 == 0) {
+        if (this.tracker instanceof EntityItemFrame) { // Spigot - has to be ran every tick for general frames or they may pop off?
             EntityItemFrame i4 = (EntityItemFrame) this.tracker;
             ItemStack i5 = i4.i();
 
-            if (i5 != null && i5.getItem() instanceof ItemWorldMap) {
+            if (this.m++ % 10 == 0 && i5 != null && i5.getItem() instanceof ItemWorldMap && playersToUpdate.size() > 0) { // Spigot
                 WorldMap i7 = Item.MAP.getSavedMap(i5, this.tracker.world);
-                Iterator j0 = list.iterator();
+                Iterator j0 = playersToUpdate.iterator(); // Spigot
 
                 while (j0.hasNext()) {
-                    EntityHuman j1 = (EntityHuman) j0.next();
-                    EntityPlayer j2 = (EntityPlayer) j1;
+                    //EntityHuman j1 = (EntityHuman) j0.next(); // Spigot - unused
+                    EntityPlayer j2 = (EntityPlayer) j0.next(); // Spigot
 
                     i7.a(j2, i5);
                     if (j2.playerConnection.lowPriorityCount() <= 5) {
@@ -91,7 +92,7 @@ public class EntityTrackerEntry {
 
                         if (j3 != null) {
                             j2.playerConnection.sendPacket(j3);
-                        }
+                        } else { j0.remove(); } // Spigot
                     }
                 }
             }
@@ -332,6 +333,17 @@ public class EntityTrackerEntry {
                         }
                     }
 
+                    // Spigot start - add player to list to receive initial map updates.
+                    if (this.tracker instanceof EntityItemFrame) {
+                        EntityItemFrame i4 = (EntityItemFrame) this.tracker;
+                        ItemStack i5 = i4.i();
+
+                        if (i5 != null && i5.getItem() instanceof ItemWorldMap) {
+                            this.playersToUpdate.add(entityplayer);
+                        }
+                    }
+                    // Spigot end
+
                     if (this.tracker instanceof EntityHuman) {
                         EntityHuman entityhuman = (EntityHuman) this.tracker;
 
@@ -358,6 +370,7 @@ public class EntityTrackerEntry {
                 }
             } else if (this.trackedPlayers.contains(entityplayer)) {
                 this.trackedPlayers.remove(entityplayer);
+                this.playersToUpdate.remove(entityplayer); // Spigot
                 entityplayer.removeQueue.add(Integer.valueOf(this.tracker.id));
             }
         }
-- 
1.8.1-rc2