More robust automatic messageType detection for ChannelInboundMessageHandlerAdapter and MessageToMessageDecoder

codec-http/src/main/java/io/netty/handler/codec/http/HttpContentDecoder.java

@@ -41,21 +41,14 @@ import io.netty.handler.codec.MessageToMessageDecoder;
  * so that this handler can intercept HTTP requests after {@link HttpObjectDecoder}
  * converts {@link ByteBuf}s into HTTP requests.
  */
-public abstract class HttpContentDecoder extends MessageToMessageDecoder<Object> {
+public abstract class HttpContentDecoder extends MessageToMessageDecoder<HttpObject> {
 
     private EmbeddedByteChannel decoder;
     private HttpMessage message;
     private boolean decodeStarted;
 
-    /**
-     * Creates a new instance.
-     */
-    protected HttpContentDecoder() {
-        super(HttpObject.class);
-    }
-
     @Override
-    protected Object decode(ChannelHandlerContext ctx, Object msg) throws Exception {
+    protected Object decode(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
         if (msg instanceof HttpResponse && ((HttpResponse) msg).getStatus().code() == 100) {
             // 100-continue response must be passed through.
             return msg;
@@ -115,7 +108,7 @@ public abstract class HttpContentDecoder extends MessageToMessageDecoder<Object>
     }
 
     @Override
-    protected void freeInboundMessage(Object msg) throws Exception {
+    protected void freeInboundMessage(HttpObject msg) throws Exception {
         if (decoder == null) {
             // if the decoder was null we returned the original message so we are not allowed to free it
             return;

codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectAggregator.java

@@ -66,8 +66,6 @@ public class HttpObjectAggregator extends MessageToMessageDecoder<HttpObject> {
      *        a {@link TooLongFrameException} will be raised.
      */
     public HttpObjectAggregator(int maxContentLength) {
-        super(HttpObject.class);
-
         if (maxContentLength <= 0) {
             throw new IllegalArgumentException(
                     "maxContentLength must be a positive integer: " +

codec-http/src/main/java/io/netty/handler/codec/spdy/SpdyHttpDecoder.java

@@ -52,8 +52,6 @@ public class SpdyHttpDecoder extends MessageToMessageDecoder<Object> {
      *        a {@link TooLongFrameException} will be raised.
      */
     public SpdyHttpDecoder(int version, int maxContentLength) {
-        super(SpdyDataFrame.class, SpdyControlFrame.class);
-
         if (version < SpdyConstants.SPDY_MIN_VERSION || version > SpdyConstants.SPDY_MAX_VERSION) {
             throw new IllegalArgumentException(
                     "unsupported version: " + version);
@@ -66,6 +64,11 @@ public class SpdyHttpDecoder extends MessageToMessageDecoder<Object> {
         this.maxContentLength = maxContentLength;
     }
 
+    @Override
+    public boolean acceptInboundMessage(Object msg) throws Exception {
+        return msg instanceof SpdyDataFrame || msg instanceof SpdyControlFrame;
+    }
+
     @Override
     public Object decode(ChannelHandlerContext ctx, Object msg) throws Exception {
         if (msg instanceof SpdySynStreamFrame) {

codec/src/main/java/io/netty/handler/codec/MessageToMessageCodec.java

@@ -73,9 +73,10 @@ public abstract class MessageToMessageCodec<INBOUND_IN, OUTBOUND_IN>
 
     private final MessageToMessageDecoder<INBOUND_IN> decoder =
             new MessageToMessageDecoder<INBOUND_IN>() {
+
         @Override
-        public boolean isDecodable(Object msg) throws Exception {
+        public boolean acceptInboundMessage(Object msg) throws Exception {
-            return MessageToMessageCodec.this.isDecodable(msg);
+            return isDecodable(msg);
         }
 
         @Override

codec/src/main/java/io/netty/handler/codec/MessageToMessageDecoder.java

@@ -16,12 +16,9 @@
 package io.netty.handler.codec;
 
 import io.netty.buffer.MessageBuf;
-import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
-import io.netty.channel.ChannelHandlerUtil;
 import io.netty.channel.ChannelInboundMessageHandler;
-import io.netty.channel.ChannelPipeline;
+import io.netty.channel.ChannelInboundMessageHandlerAdapter;
-import io.netty.channel.ChannelStateHandlerAdapter;
 
 /**
  * {@link ChannelInboundMessageHandler} which decodes from one message to an other message
@@ -45,81 +42,25 @@ import io.netty.channel.ChannelStateHandlerAdapter;
  * </pre>
  *
  */
-public abstract class MessageToMessageDecoder<I>
+public abstract class MessageToMessageDecoder<I> extends ChannelInboundMessageHandlerAdapter<I> {
-        extends ChannelStateHandlerAdapter implements ChannelInboundMessageHandler<I> {
 
-    private final Class<?>[] acceptedMsgTypes;
+    protected MessageToMessageDecoder() {
+        super(MessageToMessageDecoder.class, 0);
+    }
 
-    /**
+    protected MessageToMessageDecoder(
-     * The types which will be accepted by the decoder. If a received message is an other type it will be just forwarded
+            @SuppressWarnings("rawtypes")
-     * to the next {@link ChannelInboundMessageHandler} in the {@link ChannelPipeline}
+            Class<? extends ChannelInboundMessageHandlerAdapter> parameterizedHandlerType,
-     */
+            int messageTypeParamIndex) {
-    protected MessageToMessageDecoder(Class<?>... acceptedMsgTypes) {
+        super(parameterizedHandlerType, messageTypeParamIndex);
-        this.acceptedMsgTypes = ChannelHandlerUtil.acceptedMessageTypes(acceptedMsgTypes);
     }
 
     @Override
-    public MessageBuf<I> newInboundBuffer(ChannelHandlerContext ctx) throws Exception {
+    protected final void messageReceived(ChannelHandlerContext ctx, I msg) throws Exception {
-        return Unpooled.messageBuffer();
+        Object decoded = decode(ctx, msg);
-    }
+        if (decoded != null) {
-
+            ctx.nextInboundMessageBuffer().add(decoded);
-    @Override
-    public void inboundBufferUpdated(ChannelHandlerContext ctx)
-            throws Exception {
-        MessageBuf<I> in = ctx.inboundMessageBuffer();
-        MessageBuf<Object> out = ctx.nextInboundMessageBuffer();
-        boolean notify = false;
-        for (;;) {
-            try {
-                Object msg = in.poll();
-                if (msg == null) {
-                    break;
-                }
-                if (!isDecodable(msg)) {
-                    out.add(msg);
-                    notify = true;
-                    continue;
-                }
-
-                @SuppressWarnings("unchecked")
-                I imsg = (I) msg;
-                boolean free = true;
-                try {
-                    Object omsg = decode(ctx, imsg);
-                    if (omsg == null) {
-                        // Decoder consumed a message but returned null.
-                        // Probably it needs more messages because it's an aggregator.
-                        continue;
-                    }
-                    if (omsg == imsg) {
-                        free = false;
-                    }
-                    if (ChannelHandlerUtil.unfoldAndAdd(ctx, omsg, true)) {
-                        notify = true;
-                    }
-                } finally {
-                    if (free) {
-                        freeInboundMessage(imsg);
-                    }
-                }
-            } catch (Throwable t) {
-                if (t instanceof CodecException) {
-                    ctx.fireExceptionCaught(t);
-                } else {
-                    ctx.fireExceptionCaught(new DecoderException(t));
-                }
-            }
         }
-        if (notify) {
-            ctx.fireInboundBufferUpdated();
-        }
-    }
-
-    /**
-     * Returns {@code true} if and only if the specified message can be decoded by this decoder.
-     */
-    public boolean isDecodable(Object msg) throws Exception {
-        return ChannelHandlerUtil.acceptMessage(acceptedMsgTypes, msg);
     }
 
     /**
@@ -133,18 +74,4 @@ public abstract class MessageToMessageDecoder<I>
      * @throws Exception    is thrown if an error accour
      */
     protected abstract Object decode(ChannelHandlerContext ctx, I msg) throws Exception;
-
-    /**
-     * Is called after a message was processed via {@link #decode(ChannelHandlerContext, Object)} to free
-     * up any resources that is held by the inbound message. You may want to override this if your implementation
-     * just pass-through the input message or need it for later usage.
-     */
-    protected void freeInboundMessage(I msg) throws Exception {
-        ChannelHandlerUtil.freeMessage(msg);
-    }
-
-    @Override
-    public void freeInboundBuffer(ChannelHandlerContext ctx) throws Exception {
-        ctx.inboundMessageBuffer().free();
-    }
 }

codec/src/main/java/io/netty/handler/codec/base64/Base64Decoder.java

@@ -53,8 +53,6 @@ public class Base64Decoder extends MessageToMessageDecoder<ByteBuf> {
     }
 
     public Base64Decoder(Base64Dialect dialect) {
-        super(ByteBuf.class);
-
         if (dialect == null) {
             throw new NullPointerException("dialect");
         }

codec/src/main/java/io/netty/handler/codec/bytes/ByteArrayDecoder.java

@@ -48,10 +48,6 @@ import io.netty.handler.codec.MessageToMessageDecoder;
  */
 public class ByteArrayDecoder extends MessageToMessageDecoder<ByteBuf> {
 
-    public ByteArrayDecoder() {
-        super(ByteBuf.class);
-    }
-
     @Override
     protected Object decode(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
         byte[] array;

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

@@ -15,6 +15,9 @@
  */
 package io.netty.handler.codec.protobuf;
 
+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;
@@ -25,10 +28,6 @@ import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
 import io.netty.handler.codec.LengthFieldPrepender;
 import io.netty.handler.codec.MessageToMessageDecoder;
 
-import com.google.protobuf.ExtensionRegistry;
-import com.google.protobuf.Message;
-import com.google.protobuf.MessageLite;
-
 /**
  * Decodes a received {@link ByteBuf} into a
  * <a href="http://code.google.com/p/protobuf/">Google Protocol Buffers</a>
@@ -74,8 +73,6 @@ public class ProtobufDecoder extends MessageToMessageDecoder<ByteBuf> {
     }
 
     public ProtobufDecoder(MessageLite prototype, ExtensionRegistry extensionRegistry) {
-        super(ByteBuf.class);
-
         if (prototype == null) {
             throw new NullPointerException("prototype");
         }

codec/src/main/java/io/netty/handler/codec/string/StringDecoder.java

@@ -68,8 +68,6 @@ public class StringDecoder extends MessageToMessageDecoder<ByteBuf> {
      * Creates a new instance with the specified character set.
      */
     public StringDecoder(Charset charset) {
-        super(ByteBuf.class);
-
         if (charset == null) {
             throw new NullPointerException("charset");
         }

codec/src/test/java/io/netty/handler/codec/bytes/ByteArrayDecoderTest.java

@@ -15,18 +15,19 @@
  */
 package io.netty.handler.codec.bytes;
 
-import static io.netty.buffer.Unpooled.*;
-import static org.hamcrest.core.Is.*;
-import static org.junit.Assert.*;
 import io.netty.channel.embedded.EmbeddedMessageChannel;
-
-import java.util.Random;
-
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.Random;
+
+import static io.netty.buffer.Unpooled.*;
+import static org.hamcrest.core.Is.*;
+import static org.junit.Assert.*;
+
 /**
  */
+@SuppressWarnings("ZeroLengthArrayAllocation")
 public class ByteArrayDecoderTest {
 
     private EmbeddedMessageChannel ch;

transport-sctp/src/main/java/io/netty/handler/codec/sctp/SctpInboundByteStreamHandler.java

@@ -40,8 +40,8 @@ public class SctpInboundByteStreamHandler extends ChannelInboundMessageHandlerAd
     }
 
     @Override
-    public boolean isSupported(Object msg) throws Exception {
+    public boolean acceptInboundMessage(Object msg) throws Exception {
-        if (super.isSupported(msg)) {
+        if (super.acceptInboundMessage(msg)) {
             return isDecodable((SctpMessage) msg);
         }
         return false;

transport-sctp/src/main/java/io/netty/handler/codec/sctp/SctpMessageToMessageDecoder.java

@@ -23,7 +23,7 @@ import io.netty.handler.codec.MessageToMessageDecoder;
 public abstract class SctpMessageToMessageDecoder extends MessageToMessageDecoder<SctpMessage> {
 
     @Override
-    public boolean isDecodable(Object msg) throws Exception {
+    public boolean acceptInboundMessage(Object msg) throws Exception {
         if (msg instanceof SctpMessage) {
             SctpMessage sctpMsg = (SctpMessage) msg;
             if (sctpMsg.isComplete()) {

transport/src/main/java/io/netty/channel/ChannelInboundMessageHandlerAdapter.java

@@ -18,7 +18,8 @@ package io.netty.channel;
 import io.netty.buffer.MessageBuf;
 import io.netty.buffer.Unpooled;
 
-import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
@@ -50,34 +51,36 @@ public abstract class ChannelInboundMessageHandlerAdapter<I>
     private static final ConcurrentMap<Class<?>, Class<?>> messageTypeMap =
             new ConcurrentHashMap<Class<?>, Class<?>>();
 
-    private final Class<?> acceptedMsgType = findMessageType();
+    private final Class<?> acceptedMsgType;
 
-    private Class<?> findMessageType() {
+    protected ChannelInboundMessageHandlerAdapter() {
-        Class<?> thisClass = getClass();
+        this(ChannelInboundMessageHandlerAdapter.class, 0);
+    }
+
+    protected ChannelInboundMessageHandlerAdapter(
+            @SuppressWarnings("rawtypes")
+            Class<? extends ChannelInboundMessageHandlerAdapter> parameterizedHandlerType,
+            int messageTypeParamIndex) {
+        acceptedMsgType = findMessageType(parameterizedHandlerType, messageTypeParamIndex);
+    }
+
+    private Class<?> findMessageType(Class<?> parameterizedHandlerType, int messageTypeParamIndex) {
+        final Class<?> thisClass = getClass();
         Class<?> messageType = messageTypeMap.get(thisClass);
         if (messageType == null) {
-            for (Method m: getClass().getDeclaredMethods()) {
+            Class<?> currentClass = thisClass;
-                if (!"messageReceived".equals(m.getName())) {
+            for (;;) {
-                    continue;
+                if (currentClass.getSuperclass() == parameterizedHandlerType) {
-                }
+                    Type[] types = ((ParameterizedType) currentClass.getGenericSuperclass()).getActualTypeArguments();
-                if (m.isSynthetic() || m.isBridge()) {
+                    if (types.length - 1 < messageTypeParamIndex || !(types[0] instanceof Class)) {
-                    continue;
+                        throw new IllegalStateException(
-                }
+                                "cannot determine the inbound message type of " + thisClass.getSimpleName());
-                Class<?>[] p = m.getParameterTypes();
+                    }
-                if (p.length != 2) {
-                    continue;
-                }
-                if (p[0] != ChannelHandlerContext.class) {
-                    continue;
-                }
 
-                messageType = p[1];
+                    messageType = (Class<?>) types[0];
-                break;
+                    break;
-            }
+                }
-
+                currentClass = currentClass.getSuperclass();
-            if (messageType == null) {
-                throw new IllegalStateException(
-                        "cannot determine the inbound message type of " + thisClass.getSimpleName());
             }
 
             messageTypeMap.put(thisClass, messageType);
@@ -114,7 +117,7 @@ public abstract class ChannelInboundMessageHandlerAdapter<I>
                 }
 
                 try {
-                    if (!isSupported(msg)) {
+                    if (!acceptInboundMessage(msg)) {
                         out.add(msg);
                         unsupportedFound = true;
                         continue;
@@ -153,7 +156,7 @@ public abstract class ChannelInboundMessageHandlerAdapter<I>
      *
      * @param msg the message
      */
-    public boolean isSupported(Object msg) throws Exception {
+    public boolean acceptInboundMessage(Object msg) throws Exception {
         return acceptedMsgType.isInstance(msg);
     }
 

transport/src/test/java/io/netty/channel/DefaultChannelPipelineTest.java

@@ -156,9 +156,9 @@ public class DefaultChannelPipelineTest {
         boolean called;
 
         @Override
-        public boolean isSupported(Object msg) throws Exception {
+        public boolean acceptInboundMessage(Object msg) throws Exception {
             called = true;
-            return super.isSupported(msg);
+            return super.acceptInboundMessage(msg);
         }
 
         @Override