added support for Protobuf codec nano runtime

Motivation:

Netty was missing support for Protobuf nano runtime targeted at
weaker systems such as Android devices.

Modifications:

Added ProtobufDecoderNano and ProtobufDecoderNano
in order to provide support for Nano runtime.

modified ProtobufVarint32FrameDecoder and
ProtobufLengthFieldPrepender in order to remove any
on either Nano or Lite runtime by copying the code
for handling Protobuf varint32 in from Protobuf
library.

modified Licenses and NOTICE in order to reflect the
changes i made.

added Protobuf Nano runtime as optional dependency

Result:

Netty now supports Protobuf Nano runtime.

Author: RobertBorg

NOTICE.txt

@@ -146,7 +146,7 @@ and decompression library written by William Kinney. It can be obtained at:
   * HOMEPAGE:
     * https://code.google.com/p/jfastlz/
 
-This product optionally depends on 'Protocol Buffers', Google's data
+This product contains a modified portion of and optionally depends on 'Protocol Buffers', Google's data
 interchange format, which can be obtained at:
 
   * LICENSE:

codec/pom.xml

@@ -39,6 +39,11 @@
       <artifactId>protobuf-java</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>com.google.protobuf.nano</groupId>
+      <artifactId>protobuf-javanano</artifactId>
+      <optional>true</optional>
+    </dependency>
     <dependency>
       <groupId>org.jboss.marshalling</groupId>
       <artifactId>jboss-marshalling</artifactId>

codec/src/main/java/io/netty/handler/codec/protobuf/ProtobufDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012 The Netty Project
+ * Copyright 2015 The Netty Project
  *
  * The Netty Project licenses this file to you under the Apache License,
  * version 2.0 (the "License"); you may not use this file except in compliance
@@ -33,10 +33,10 @@
 /**
  * Decodes a received {@link ByteBuf} into a
  * <a href="http://code.google.com/p/protobuf/">Google Protocol Buffers</a>
- * {@link Message} and {@link MessageLite}.  Please note that this decoder must
+ * {@link Message} and {@link MessageLite}. Please note that this decoder must
  * be used with a proper {@link ByteToMessageDecoder} such as {@link ProtobufVarint32FrameDecoder}
  * or {@link LengthFieldBasedFrameDecoder} if you are using a stream-based
- * transport such as TCP/IP.  A typical setup for TCP/IP would be:
+ * transport such as TCP/IP. A typical setup for TCP/IP would be:
  * <pre>
  * {@link ChannelPipeline} pipeline = ...;
  *
@@ -53,7 +53,8 @@
  * and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
  * as a message:
  * <pre>
- * void channelRead({@link ChannelHandlerContext} ctx, MyMessage req) {
+ * void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
+ *     MyMessage req = (MyMessage) msg;
  *     MyMessage res = MyMessage.newBuilder().setText(
  *                               "Did you say '" + req.getText() + "'?").build();
  *     ch.write(res);
@@ -101,7 +102,8 @@ public ProtobufDecoder(MessageLite prototype, ExtensionRegistryLite extensionReg
     }
 
     @Override
-    protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List<Object> out) throws Exception {
+    protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List<Object> out)
+            throws Exception {
         final byte[] array;
         final int offset;
         final int length = msg.readableBytes();
@@ -122,9 +124,11 @@ protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List<Object> out)
             }
         } else {
             if (HAS_PARSER) {
-                out.add(prototype.getParserForType().parseFrom(array, offset, length, extensionRegistry));
+                out.add(prototype.getParserForType().parseFrom(
+                        array, offset, length, extensionRegistry));
             } else {
-                out.add(prototype.newBuilderForType().mergeFrom(array, offset, length, extensionRegistry).build());
+                out.add(prototype.newBuilderForType().mergeFrom(
+                        array, offset, length, extensionRegistry).build());
             }
         }
     }

codec/src/main/java/io/netty/handler/codec/protobuf/ProtobufDecoderNano.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2015 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.protobuf;
+
+import com.google.protobuf.nano.MessageNano;
+
+import java.util.List;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandler.Sharable;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelPipeline;
+import io.netty.handler.codec.ByteToMessageDecoder;
+import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
+import io.netty.handler.codec.MessageToMessageDecoder;
+import io.netty.util.internal.ObjectUtil;
+
+/**
+ * Decodes a received {@link ByteBuf} into a
+ * <a href="http://code.google.com/p/protobuf/">Google Protocol Buffers</a>
+ * {@link MessageNano}. Please note that this decoder must
+ * be used with a proper {@link ByteToMessageDecoder} such as {@link LengthFieldBasedFrameDecoder}
+ * if you are using a stream-based transport such as TCP/IP. A typical setup for TCP/IP would be:
+ * <pre>
+ * {@link ChannelPipeline} pipeline = ...;
+ *
+ * // Decoders
+ * pipeline.addLast("frameDecoder",
+ *                  new {@link LengthFieldBasedFrameDecoder}(1048576, 0, 4, 0, 4));
+ * pipeline.addLast("protobufDecoder",
+ *                  new {@link ProtobufDecoderNano}(MyMessage.getDefaultInstance()));
+ *
+ * // Encoder
+ * pipeline.addLast("frameEncoder", new {@link io.netty.handler.codec.LengthFieldPrepender}(4));
+ * pipeline.addLast("protobufEncoder", new {@link ProtobufEncoderNano}());
+ * </pre>
+ * and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
+ * as a message:
+ * <pre>
+ * void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
+ *     MyMessage req = (MyMessage) msg;
+ *     MyMessage res = MyMessage.newBuilder().setText(
+ *                               "Did you say '" + req.getText() + "'?").build();
+ *     ch.write(res);
+ * }
+ * </pre>
+ */
+@Sharable
+public class ProtobufDecoderNano extends MessageToMessageDecoder<ByteBuf> {
+    private final Class<? extends MessageNano> clazz;
+    /**
+     * Creates a new instance.
+     */
+    public ProtobufDecoderNano(Class<? extends MessageNano> clazz) {
+        this.clazz = ObjectUtil.checkNotNull(clazz, "You must provide a Class");
+    }
+
+    @Override
+    protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List<Object> out)
+            throws Exception {
+        final byte[] array;
+        final int offset;
+        final int length = msg.readableBytes();
+        if (msg.hasArray()) {
+            array = msg.array();
+            offset = msg.arrayOffset() + msg.readerIndex();
+        } else {
+            array = new byte[length];
+            msg.getBytes(msg.readerIndex(), array, 0, length);
+            offset = 0;
+        }
+        MessageNano prototype = clazz.newInstance();
+        out.add(MessageNano.mergeFrom(prototype, array, offset, length));
+    }
+}

codec/src/main/java/io/netty/handler/codec/protobuf/ProtobufEncoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012 The Netty Project
+ * Copyright 2015 The Netty Project
  *
  * The Netty Project licenses this file to you under the Apache License,
  * version 2.0 (the "License"); you may not use this file except in compliance
@@ -50,7 +50,8 @@
  * and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
  * as a message:
  * <pre>
- * void channelRead({@link ChannelHandlerContext} ctx, MyMessage req) {
+ * void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
+ *     MyMessage req = (MyMessage) msg;
  *     MyMessage res = MyMessage.newBuilder().setText(
  *                               "Did you say '" + req.getText() + "'?").build();
  *     ch.write(res);
@@ -60,8 +61,8 @@
 @Sharable
 public class ProtobufEncoder extends MessageToMessageEncoder<MessageLiteOrBuilder> {
     @Override
-    protected void encode(
-            ChannelHandlerContext ctx, MessageLiteOrBuilder msg, List<Object> out) throws Exception {
+    protected void encode(ChannelHandlerContext ctx, MessageLiteOrBuilder msg, List<Object> out)
+            throws Exception {
         if (msg instanceof MessageLite) {
             out.add(wrappedBuffer(((MessageLite) msg).toByteArray()));
             return;

codec/src/main/java/io/netty/handler/codec/protobuf/ProtobufEncoderNano.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2015 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.protobuf;
+
+import com.google.protobuf.nano.CodedOutputByteBufferNano;
+import com.google.protobuf.nano.MessageNano;
+
+import java.util.List;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelPipeline;
+import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
+import io.netty.handler.codec.LengthFieldPrepender;
+import io.netty.handler.codec.MessageToMessageEncoder;
+
+/**
+ * Encodes the requested <a href="http://code.google.com/p/protobuf/">Google
+ * Protocol Buffers</a> {@link MessageNano} into a
+ * {@link ByteBuf}. A typical setup for TCP/IP would be:
+ * <pre>
+ * {@link ChannelPipeline} pipeline = ...;
+ *
+ * // Decoders
+ * pipeline.addLast("frameDecoder",
+ *                  new {@link LengthFieldBasedFrameDecoder}(1048576, 0, 4, 0, 4));
+ * pipeline.addLast("protobufDecoder",
+ *                  new {@link ProtobufDecoderNano}(MyMessage.getDefaultInstance()));
+ *
+ * // Encoder
+ * pipeline.addLast("frameEncoder", new {@link LengthFieldPrepender}(4));
+ * pipeline.addLast("protobufEncoder", new {@link ProtobufEncoderNano}());
+ * </pre>
+ * and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
+ * as a message:
+ * <pre>
+ * void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
+ *     MyMessage req = (MyMessage) msg;
+ *     MyMessage res = MyMessage.newBuilder().setText(
+ *                               "Did you say '" + req.getText() + "'?").build();
+ *     ch.write(res);
+ * }
+ * </pre>
+ */
+@ChannelHandler.Sharable
+public class ProtobufEncoderNano extends MessageToMessageEncoder<MessageNano> {
+    @Override
+    protected void encode(
+            ChannelHandlerContext ctx, MessageNano msg, List<Object> out) throws Exception {
+        final int size = msg.getSerializedSize();
+        final ByteBuf buffer = ctx.alloc().heapBuffer(size, size);
+        final byte[] array = buffer.array();
+        CodedOutputByteBufferNano cobbn = CodedOutputByteBufferNano.newInstance(array,
+                buffer.arrayOffset(), buffer.capacity());
+        msg.writeTo(cobbn);
+        buffer.writerIndex(size);
+        out.add(buffer);
+    }
+}