From df54abcfdf2bbf943dbd4a193e9edcc7af8f7cdf Mon Sep 17 00:00:00 2001
From: Antony Riley <antony@cyberiantiger.org>
Date: Tue, 29 Mar 2016 06:56:23 +0300
Subject: [PATCH] Reduce IO ops opening a new region file.


diff --git a/src/main/java/net/minecraft/server/RegionFile.java b/src/main/java/net/minecraft/server/RegionFile.java
index 9299ab56a..407ac75aa 100644
--- a/src/main/java/net/minecraft/server/RegionFile.java
+++ b/src/main/java/net/minecraft/server/RegionFile.java
@@ -8,9 +8,12 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
+import java.io.EOFException;
 import java.io.File;
 import java.io.IOException;
 import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.IntBuffer;
 import java.util.List;
 import java.util.zip.DeflaterOutputStream;
 import java.util.zip.GZIPInputStream;
@@ -65,11 +68,18 @@ public class RegionFile {
             this.f.set(1, false);
             this.c.seek(0L);
 
-            int k;
+            // Paper Start
+            ByteBuffer header = ByteBuffer.allocate(8192);
+            while (header.hasRemaining())  {
+                if (this.c.getChannel().read(header) == -1) throw new EOFException();
+            }
+            header.clear();
+            IntBuffer headerAsInts = header.asIntBuffer();
+            // Paper End
 
-            for (j = 0; j < 1024; ++j) {
-                k = this.c.readInt();
-                this.d[j] = k;
+            for(int j1 = 0; j1 < 1024; ++j1) {
+                int k = headerAsInts.get(); // Paper
+                this.d[j1] = k;
                 if (k != 0 && (k >> 8) + (k & 255) <= this.f.size()) {
                     for (int l = 0; l < (k & 255); ++l) {
                         this.f.set((k >> 8) + l, false);
@@ -78,7 +88,7 @@ public class RegionFile {
             }
 
             for (j = 0; j < 1024; ++j) {
-                k = this.c.readInt();
+                int k = headerAsInts.get(); // Paper
                 this.e[j] = k;
             }
         } catch (IOException ioexception) {
-- 
2.20.1