From ba11879c9f8a2d8aae308d83be9f240606ab0d32 Mon Sep 17 00:00:00 2001
From: Scott Mitchell <scott_mitchell@apple.com>
Date: Fri, 11 Sep 2015 09:12:22 -0700
Subject: [PATCH] HTTP/2 codec heap buffer usage

Motivation:
The HTTP/2 codec has a few static buffers sent over the network which are allocated on the heap. This results in a copy operation when the buffer is sent out on the network.

Modifications:
- Ensure these static buffers are allocated using direct memory.

Result:
No copy operation necessary when writing static buffers to network.
---
 .../handler/codec/http2/Http2CodecUtil.java   | 20 +++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2CodecUtil.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2CodecUtil.java
index 1567d2a2d3..107b803d0b 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2CodecUtil.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2CodecUtil.java
@@ -15,8 +15,6 @@
 
 package io.netty.handler.codec.http2;
 
-import static io.netty.util.CharsetUtil.UTF_8;
-
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
@@ -27,14 +25,15 @@ import io.netty.channel.DefaultChannelPromise;
 import io.netty.handler.ssl.ApplicationProtocolNames;
 import io.netty.util.concurrent.EventExecutor;
 
+import static io.netty.buffer.Unpooled.directBuffer;
+import static io.netty.buffer.Unpooled.unmodifiableBuffer;
+import static io.netty.buffer.Unpooled.unreleasableBuffer;
+import static io.netty.util.CharsetUtil.UTF_8;
+
 /**
  * Constants and utility method used for encoding/decoding HTTP2 frames.
  */
 public final class Http2CodecUtil {
-
-    private static final byte[] CONNECTION_PREFACE = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".getBytes(UTF_8);
-    private static final byte[] EMPTY_PING = new byte[8];
-
     public static final int CONNECTION_STREAM_ID = 0;
     public static final int HTTP_UPGRADE_STREAM_ID = 1;
     public static final String HTTP_UPGRADE_SETTINGS_HEADER = "HTTP2-Settings";
@@ -52,6 +51,11 @@ public final class Http2CodecUtil {
     public static final short MAX_WEIGHT = 256;
     public static final short MIN_WEIGHT = 1;
 
+    private static final ByteBuf CONNECTION_PREFACE = unmodifiableBuffer(
+            unreleasableBuffer(directBuffer(24).writeBytes("PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".getBytes(UTF_8))));
+    private static final ByteBuf EMPTY_PING = unmodifiableBuffer(
+            unreleasableBuffer(directBuffer(PING_FRAME_PAYLOAD_LENGTH).writeZero(PING_FRAME_PAYLOAD_LENGTH)));
+
     private static final int MAX_PADDING_LENGTH_LENGTH = 1;
     public static final int DATA_FRAME_HEADER_LENGTH = FRAME_HEADER_LENGTH + MAX_PADDING_LENGTH_LENGTH;
     public static final int HEADERS_FRAME_HEADER_LENGTH =
@@ -109,7 +113,7 @@ public final class Http2CodecUtil {
      */
     public static ByteBuf connectionPrefaceBuf() {
         // Return a duplicate so that modifications to the reader index will not affect the original buffer.
-        return Unpooled.wrappedBuffer(CONNECTION_PREFACE);
+        return CONNECTION_PREFACE.duplicate().retain();
     }
 
     /**
@@ -117,7 +121,7 @@ public final class Http2CodecUtil {
      */
     public static ByteBuf emptyPingBuf() {
         // Return a duplicate so that modifications to the reader index will not affect the original buffer.
-        return Unpooled.wrappedBuffer(EMPTY_PING);
+        return EMPTY_PING.duplicate().retain();
     }
 
     /**