From 81259e2cb7b30df39c3d1b23d66ec2c1bdde2a5d Mon Sep 17 00:00:00 2001
From: Colin Godsey <crgodsey@gmail.com>
Date: Wed, 8 Aug 2018 16:10:06 -0600
Subject: [PATCH] Add entity count cache


diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 004c3ec4..09c2bc32 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -50,10 +50,41 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
     // Spigot start - guard entity list from removals
     public final List<Entity> entityList = new java.util.ArrayList<Entity>()
     {
+        // Paper start - entity count cache
+        @Override
+        public boolean addAll(Collection<? extends Entity> c) {
+            for(Entity e : c) {
+                updateEntityCount(e, true);
+            }
+
+            return super.addAll(c);
+        }
+
+        @Override
+        public boolean removeAll(Collection<?> c) {
+            for(Object e : c) {
+                if(e instanceof Entity) {
+                    updateEntityCount((Entity)e, false);
+                }
+            }
+
+            return super.removeAll(c);
+        }
+
+        @Override
+        public boolean add(Entity e) {
+            updateEntityCount(e, true);
+
+            return super.add(e);
+        }
+
+        // Paper end
+
         @Override
         public Entity remove(int index)
         {
             guard();
+            updateEntityCount(get(index), false); // Paper
             return super.remove( index );
         }
 
@@ -61,6 +92,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
         public boolean remove(Object o)
         {
             guard();
+            if(o instanceof Entity) updateEntityCount((Entity)o, false); // Paper
             return super.remove( o );
         }
 
@@ -82,6 +114,7 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
     public final Map<String, EntityHuman> playersByName = Maps.newHashMap(); // Paper - World EntityHuman Lookup Optimizations
     public final List<Entity> k = Lists.newArrayList();
     protected final IntHashMap<Entity> entitiesById = new IntHashMap();
+    private Map<Class<?>, Integer> countCache = new HashMap(); // Paper
     private final long G = 16777215L;
     private int H; public int getSkylightSubtracted() { return this.H; } public void setSkylightSubtracted(int value) { this.H = value;} // Paper - OBFHELPER
     protected int m = (new Random()).nextInt();
@@ -2439,19 +2472,16 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
 
     }
 
-    public int a(Class<?> oclass) {
+    // Paper start - entity count cache
+    private int countEntityType(Class<?> oclass) {
         int i = 0;
         Iterator iterator = this.entityList.iterator();
 
         while (iterator.hasNext()) {
             Entity entity = (Entity) iterator.next();
-            if (entity.shouldBeRemoved) continue; // Paper
             // CraftBukkit start - Split out persistent check, don't apply it to special persistent mobs
-            if (entity instanceof EntityInsentient) {
-                EntityInsentient entityinsentient = (EntityInsentient) entity;
-                if (entityinsentient.isTypeNotPersistent() && entityinsentient.isPersistent()) {
-                    continue;
-                }
+            if (shouldIgnoreForCount(entity)) {
+                continue;
             }
 
             if (oclass.isAssignableFrom(entity.getClass())) {
@@ -2464,6 +2494,52 @@ public abstract class World implements GeneratorAccess, IIBlockAccess, AutoClose
         return i;
     }
 
+    public int getEntityCount(Class<?> oclass) { return a(oclass); } // Paper - OBFHELPER
+    public int a(Class<?> oclass) {
+        if(countCache.containsKey(oclass)) {
+            return countCache.get(oclass);
+        } else {
+            int count = countEntityType(oclass);
+
+            countCache.put(oclass, count);
+
+            return count;
+        }
+    }
+
+    public boolean shouldIgnoreForCount(Entity entity) {
+        if (entity instanceof EntityInsentient) {
+            EntityInsentient entityinsentient = (EntityInsentient) entity;
+            return entityinsentient.isTypeNotPersistent() && entityinsentient.isPersistent();
+        }
+
+        return false;
+    }
+
+    protected void updateEntityCount(Entity entity, boolean incr) {
+        if(entity == null) return;
+        if(shouldIgnoreForCount(entity)) return;
+
+        countCache.replaceAll((clazz, count) -> {
+            if(clazz.isAssignableFrom(entity.getClass())) {
+                int newCount = count;
+
+                if(incr) newCount++;
+                else newCount--;
+
+                if(newCount < 0) {
+                    e.warn("Entity count cache has gone negative");
+                    newCount = 0;
+                }
+
+                return newCount;
+            } else {
+                return count;
+            }
+        });
+    }
+    // Paper end
+
     public void addChunkEntities(Collection<Entity> collection) { a(collection); } // Paper - OBFHELPER
     public void a(Collection<Entity> collection) {
         org.spigotmc.AsyncCatcher.catchOp( "entity world add"); // Spigot
-- 
2.15.2 (Apple Git-101.1)