Upgrade to protobuf 2.5 and take advantage of MessageLite.getParserFromType()

- also fall back to MessageBuilder if getParserFromType() is not available.

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

@@ -19,7 +19,6 @@ import com.google.protobuf.ExtensionRegistry;
 import com.google.protobuf.Message;
 import com.google.protobuf.MessageLite;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufInputStream;
 import io.netty.channel.ChannelHandler.Sharable;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPipeline;
@@ -61,6 +60,21 @@ import io.netty.handler.codec.MessageToMessageDecoder;
 @Sharable
 public class ProtobufDecoder extends MessageToMessageDecoder<ByteBuf> {
 
+    private static final boolean HAS_PARSER;
+
+    static {
+        boolean hasParser = false;
+        try {
+            // MessageLite.getParsetForType() is not available until protobuf 2.5.0.
+            MessageLite.class.getDeclaredMethod("getParserForType");
+            hasParser = true;
+        } catch (Throwable t) {
+            // Ignore
+        }
+
+        HAS_PARSER = hasParser;
+    }
+
     private final MessageLite prototype;
     private final ExtensionRegistry extensionRegistry;
 
@@ -81,22 +95,29 @@ public class ProtobufDecoder extends MessageToMessageDecoder<ByteBuf> {
 
     @Override
     protected Object decode(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
+        final byte[] array;
+        final int offset;
+        final int length = msg.readableBytes();
         if (msg.hasArray()) {
-            final int offset = msg.readerIndex();
-            if (extensionRegistry == null) {
-                return prototype.newBuilderForType().mergeFrom(
-                        msg.array(), msg.arrayOffset() + offset, msg.readableBytes()).build();
+            array = msg.array();
+            offset = msg.arrayOffset() + msg.readerIndex();
+        } else {
+            array = new byte[length];
+            msg.getBytes(msg.readerIndex(), array, 0, length);
+            offset = 0;
+        }
+
+        if (extensionRegistry == null) {
+            if (HAS_PARSER) {
+                return prototype.getParserForType().parseFrom(array, offset, length);
             } else {
-                return prototype.newBuilderForType().mergeFrom(
-                        msg.array(), msg.arrayOffset() + offset, msg.readableBytes(), extensionRegistry).build();
+                return prototype.newBuilderForType().mergeFrom(array, offset, length).build();
             }
         } else {
-            if (extensionRegistry == null) {
-                return prototype.newBuilderForType().mergeFrom(
-                        new ByteBufInputStream(msg)).build();
+            if (HAS_PARSER) {
+                return prototype.getParserForType().parseFrom(array, offset, length, extensionRegistry);
             } else {
-                return prototype.newBuilderForType().mergeFrom(
-                        new ByteBufInputStream(msg), extensionRegistry).build();
+                return prototype.newBuilderForType().mergeFrom(array, offset, length, extensionRegistry).build();
             }
         }
     }

pom.xml

@@ -106,7 +106,7 @@
       <dependency>
         <groupId>com.google.protobuf</groupId>
         <artifactId>protobuf-java</artifactId>
-        <version>2.4.1</version>
+        <version>2.5.0</version>
       </dependency>
       <dependency>
         <groupId>com.jcraft</groupId>