Fetch tile entities from chunks instead of world. Fixes BUKKIT-4055

When looking up tile entities for a chunk to send to a player we currently
loop through every tile entity in the world checking if it is within the
bounds of the relevant chunk. Instead of doing this we can just use the
tile entities list stored in the chunk to avoid this costly searching.

As a further optimization, we also modify the generic range-based lookup
to use chunks as well. For most lookups this will give a smaller search
pool which will result in faster lookups.

Thanks to @mikeprimm for the idea and most of the implementation.

src/main/java/net/minecraft/server/EntityPlayer.java

@@ -173,8 +173,11 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
 
                 iterator1.remove();
                 if (chunkcoordintpair != null && this.world.isLoaded(chunkcoordintpair.x << 4, 0, chunkcoordintpair.z << 4)) {
-                    arraylist.add(this.world.getChunkAt(chunkcoordintpair.x, chunkcoordintpair.z));
-                    arraylist1.addAll(((WorldServer) this.world).getTileEntities(chunkcoordintpair.x * 16, 0, chunkcoordintpair.z * 16, chunkcoordintpair.x * 16 + 16, 256, chunkcoordintpair.z * 16 + 16));
+                    // CraftBukkit start - Get tile entities directly from the chunk instead of the world
+                    Chunk chunk = this.world.getChunkAt(chunkcoordintpair.x, chunkcoordintpair.z);
+                    arraylist.add(chunk);
+                    arraylist1.addAll(chunk.tileEntities.values());
+                    // CraftBukkit end
                 }
             }
 

src/main/java/net/minecraft/server/WorldServer.java

@@ -643,17 +643,24 @@ public class WorldServer extends World implements org.bukkit.BlockChangeDelegate
 
     public List getTileEntities(int i, int j, int k, int l, int i1, int j1) {
         ArrayList arraylist = new ArrayList();
-        // CraftBukkit start - Use iterator
-        Iterator iterator = this.tileEntityList.iterator();
 
-        while (iterator.hasNext()) {
-            TileEntity tileentity = (TileEntity) iterator.next();
-            // CraftBukkit end
+        // CraftBukkit start - Get tile entities from chunks instead of world
+        for (int chunkX = (i >> 4); chunkX <= ((l - 1) >> 4); chunkX++) {
+            for (int chunkZ = (k >> 4); chunkZ <= ((j1 - 1) >> 4); chunkZ++) {
+                Chunk chunk = getChunkAt(chunkX, chunkZ);
+                if (chunk == null) {
+                    continue;
+                }
 
-            if (tileentity.x >= i && tileentity.y >= j && tileentity.z >= k && tileentity.x < l && tileentity.y < i1 && tileentity.z < j1) {
+                for (Object te : chunk.tileEntities.values()) {
+                    TileEntity tileentity = (TileEntity) te;
+                    if ((tileentity.x >= i) && (tileentity.y >= j) && (tileentity.z >= k) && (tileentity.x < l) && (tileentity.y < i1) && (tileentity.z < j1)) {
                         arraylist.add(tileentity);
                     }
                 }
+            }
+        }
+        // CraftBukkit end
 
         return arraylist;
     }