MessageReceiver must handle Message and not MessageWithHeader.

MessageReceiver were given MessageWithHeader. This is incorrect as this
force validation code at the Connector level, while Connector should not
impose any format on the message it receives.

R=ppi@chromium.org

Review URL: https://codereview.chromium.org/525383002

Cr-Commit-Position: refs/heads/master@{#292888}

mojo/android/javatests/src/org/chromium/mojo/bindings/BindingsTestUtils.java

@@ -24,13 +24,13 @@ public class BindingsTestUtils {
     public static class RecordingMessageReceiver extends SideEffectFreeCloseable
             implements MessageReceiver {
 
-        public final List<MessageWithHeader> messages = new ArrayList<MessageWithHeader>();
+        public final List<Message> messages = new ArrayList<Message>();
 
         /**
-         * @see MessageReceiver#accept(MessageWithHeader)
+         * @see MessageReceiver#accept(Message)
          */
         @Override
-        public boolean accept(MessageWithHeader message) {
+        public boolean accept(Message message) {
             messages.add(message);
             return true;
         }
@@ -42,15 +42,14 @@ public class BindingsTestUtils {
     public static class RecordingMessageReceiverWithResponder extends RecordingMessageReceiver
             implements MessageReceiverWithResponder {
 
-        public final List<Pair<MessageWithHeader, MessageReceiver>> messagesWithReceivers =
-                new ArrayList<Pair<MessageWithHeader, MessageReceiver>>();
+        public final List<Pair<Message, MessageReceiver>> messagesWithReceivers =
+                new ArrayList<Pair<Message, MessageReceiver>>();
 
         /**
-         * @see MessageReceiverWithResponder#acceptWithResponder(MessageWithHeader,
-         *      MessageReceiver)
+         * @see MessageReceiverWithResponder#acceptWithResponder(Message, MessageReceiver)
          */
         @Override
-        public boolean acceptWithResponder(MessageWithHeader message, MessageReceiver responder) {
+        public boolean acceptWithResponder(Message message, MessageReceiver responder) {
             messagesWithReceivers.add(Pair.create(message, responder));
             return true;
         }
@@ -91,6 +90,6 @@ public class BindingsTestUtils {
             message.putInt(4 * i, headerAsInts[i]);
         }
         message.position(0);
-        return new MessageWithHeader(new Message(message, new ArrayList<Handle>()));
+        return new SimpleMessage(message, new ArrayList<Handle>()).asMojoMessage();
     }
 }

mojo/android/javatests/src/org/chromium/mojo/bindings/ConnectorTest.java

@@ -30,7 +30,7 @@ public class ConnectorTest extends MojoTestCase {
 
     private MessagePipeHandle mHandle;
     private Connector mConnector;
-    private MessageWithHeader mTestMessage;
+    private Message mTestMessage;
     private RecordingMessageReceiver mReceiver;
     private CapturingErrorHandler mErrorHandler;
 
@@ -77,7 +77,7 @@ public class ConnectorTest extends MojoTestCase {
                 MessagePipeHandle.ReadFlags.NONE);
         assertEquals(MojoResult.OK, result.getMojoResult());
         assertEquals(DATA_LENGTH, result.getMessageSize());
-        assertEquals(mTestMessage.getMessage().buffer, received);
+        assertEquals(mTestMessage.getData(), received);
     }
 
     /**
@@ -85,14 +85,14 @@ public class ConnectorTest extends MojoTestCase {
      */
     @SmallTest
     public void testReceivingMessage() {
-        mHandle.writeMessage(mTestMessage.getMessage().buffer, new ArrayList<Handle>(),
+        mHandle.writeMessage(mTestMessage.getData(), new ArrayList<Handle>(),
                 MessagePipeHandle.WriteFlags.NONE);
         nativeRunLoop(RUN_LOOP_TIMEOUT_MS);
         assertNull(mErrorHandler.getLastMojoException());
         assertEquals(1, mReceiver.messages.size());
-        MessageWithHeader received = mReceiver.messages.get(0);
-        assertEquals(0, received.getMessage().handles.size());
-        assertEquals(mTestMessage.getMessage().buffer, received.getMessage().buffer);
+        Message received = mReceiver.messages.get(0);
+        assertEquals(0, received.getHandles().size());
+        assertEquals(mTestMessage.getData(), received.getData());
     }
 
     /**

mojo/android/javatests/src/org/chromium/mojo/bindings/MessageWithHeaderTest.java → mojo/android/javatests/src/org/chromium/mojo/bindings/ReadAndDispatchMessageTest.java

@@ -23,9 +23,9 @@ import java.util.Arrays;
 import java.util.List;
 
 /**
- * Testing {@link MessageWithHeader}.
+ * Testing {@link Connector#readAndDispatchMessage}.
  */
-public class MessageWithHeaderTest extends MojoTestCase {
+public class ReadAndDispatchMessageTest extends MojoTestCase {
 
     private static final int DATA_SIZE = 1024;
 
@@ -42,7 +42,7 @@ public class MessageWithHeaderTest extends MojoTestCase {
     protected void setUp() throws Exception {
         super.setUp();
         Core core = CoreImpl.getInstance();
-        mData = BindingsTestUtils.newRandomMessageWithHeader(DATA_SIZE).getMessage().buffer;
+        mData = BindingsTestUtils.newRandomMessageWithHeader(DATA_SIZE).getData();
         mMessageReceiver = new RecordingMessageReceiver();
         mHandles = core.createMessagePipe(new MessagePipeHandle.CreateOptions());
         Pair<DataPipe.ProducerHandle, DataPipe.ConsumerHandle> datapipe = core.createDataPipe(null);
@@ -63,43 +63,43 @@ public class MessageWithHeaderTest extends MojoTestCase {
     }
 
     /**
-     * Testing {@link MessageWithHeader#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
+     * Testing {@link Connector#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
      */
     @SmallTest
     public void testReadAndDispatchMessage() {
         mHandles.first.writeMessage(mData, mHandlesToSend, MessagePipeHandle.WriteFlags.NONE);
         assertEquals(MojoResult.OK,
-                MessageWithHeader.readAndDispatchMessage(mHandles.second, mMessageReceiver));
+                Connector.readAndDispatchMessage(mHandles.second, mMessageReceiver));
         assertEquals(1, mMessageReceiver.messages.size());
-        MessageWithHeader message = mMessageReceiver.messages.get(0);
-        mHandlesToClose.addAll(message.getMessage().handles);
-        assertEquals(mData, message.getMessage().buffer);
-        assertEquals(2, message.getMessage().handles.size());
-        for (Handle handle : message.getMessage().handles) {
+        Message message = mMessageReceiver.messages.get(0);
+        mHandlesToClose.addAll(message.getHandles());
+        assertEquals(mData, message.getData());
+        assertEquals(2, message.getHandles().size());
+        for (Handle handle : message.getHandles()) {
             assertTrue(handle.isValid());
         }
     }
 
     /**
-     * Testing {@link MessageWithHeader#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
+     * Testing {@link Connector#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
      * with no message available.
      */
     @SmallTest
     public void testReadAndDispatchMessageOnEmptyHandle() {
         assertEquals(MojoResult.SHOULD_WAIT,
-                MessageWithHeader.readAndDispatchMessage(mHandles.second, mMessageReceiver));
+                Connector.readAndDispatchMessage(mHandles.second, mMessageReceiver));
         assertEquals(0, mMessageReceiver.messages.size());
     }
 
     /**
-     * Testing {@link MessageWithHeader#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
+     * Testing {@link Connector#readAndDispatchMessage(MessagePipeHandle, MessageReceiver)}
      * on closed handle.
      */
     @SmallTest
     public void testReadAndDispatchMessageOnClosedHandle() {
         mHandles.first.close();
         try {
-            MessageWithHeader.readAndDispatchMessage(mHandles.second, mMessageReceiver);
+            Connector.readAndDispatchMessage(mHandles.second, mMessageReceiver);
             fail("MojoException should have been thrown");
         } catch (MojoException expected) {
             assertEquals(MojoResult.FAILED_PRECONDITION, expected.getMojoResult());

mojo/android/javatests/src/org/chromium/mojo/bindings/RouterTest.java

@@ -61,16 +61,14 @@ public class RouterTest extends MojoTestCase {
                 MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG, 0);
         Encoder encoder = new Encoder(CoreImpl.getInstance(), header.getSize());
         header.encode(encoder);
-        MessageWithHeader headerMessage = new MessageWithHeader(encoder.getMessage());
-        mRouter.acceptWithResponder(headerMessage, mReceiver);
+        mRouter.acceptWithResponder(encoder.getMessage(), mReceiver);
         ByteBuffer receiveBuffer = ByteBuffer.allocateDirect(header.getSize());
         MessagePipeHandle.ReadMessageResult result = mHandle.readMessage(receiveBuffer, 0,
                 MessagePipeHandle.ReadFlags.NONE);
 
         assertEquals(MojoResult.OK, result.getMojoResult());
-        MessageHeader receivedHeader = new MessageWithHeader(
-                new Message(receiveBuffer, new ArrayList<Handle>()))
-                .getHeader();
+        MessageHeader receivedHeader = new SimpleMessage(
+                receiveBuffer, new ArrayList<Handle>()).asMojoMessage().getHeader();
 
         assertEquals(header.getType(), receivedHeader.getType());
         assertEquals(header.getFlags(), receivedHeader.getFlags());
@@ -82,15 +80,15 @@ public class RouterTest extends MojoTestCase {
         encoder = new Encoder(CoreImpl.getInstance(), header.getSize());
         responseHeader.encode(encoder);
         Message responseMessage = encoder.getMessage();
-        mHandle.writeMessage(responseMessage.buffer, new ArrayList<Handle>(),
+        mHandle.writeMessage(responseMessage.getData(), new ArrayList<Handle>(),
                 MessagePipeHandle.WriteFlags.NONE);
         nativeRunLoop(RUN_LOOP_TIMEOUT_MS);
 
         assertEquals(1, mReceiver.messages.size());
-        MessageWithHeader receivedResponseMessage = mReceiver.messages.get(0);
+        MessageWithHeader receivedResponseMessage = mReceiver.messages.get(0).asMojoMessage();
         assertEquals(MessageHeader.MESSAGE_IS_RESPONSE_FLAG,
                 receivedResponseMessage.getHeader().getFlags());
-        assertEquals(responseMessage.buffer, receivedResponseMessage.getMessage().buffer);
+        assertEquals(responseMessage.getData(), receivedResponseMessage.getData());
     }
 
     /**
@@ -108,27 +106,27 @@ public class RouterTest extends MojoTestCase {
         Encoder encoder = new Encoder(CoreImpl.getInstance(), header.getSize());
         header.encode(encoder);
         Message headerMessage = encoder.getMessage();
-        mHandle.writeMessage(headerMessage.buffer, new ArrayList<Handle>(),
+        mHandle.writeMessage(headerMessage.getData(), new ArrayList<Handle>(),
                 MessagePipeHandle.WriteFlags.NONE);
         nativeRunLoop(RUN_LOOP_TIMEOUT_MS);
 
         assertEquals(1, mReceiver.messagesWithReceivers.size());
-        Pair<MessageWithHeader, MessageReceiver> receivedMessage =
+        Pair<Message, MessageReceiver> receivedMessage =
                 mReceiver.messagesWithReceivers.get(0);
-        assertEquals(headerMessage.buffer, receivedMessage.first.getMessage().buffer);
+        assertEquals(headerMessage.getData(), receivedMessage.first.getData());
 
         // Sending the response.
         MessageHeader responseHeader = new MessageHeader(responseMessageType,
                 MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG, requestId);
         encoder = new Encoder(CoreImpl.getInstance(), header.getSize());
         responseHeader.encode(encoder);
-        MessageWithHeader responseHeaderMessage = new MessageWithHeader(encoder.getMessage());
-        receivedMessage.second.accept(responseHeaderMessage);
+        Message message = encoder.getMessage();
+        receivedMessage.second.accept(message);
         ByteBuffer receivedResponseMessage = ByteBuffer.allocateDirect(responseHeader.getSize());
         MessagePipeHandle.ReadMessageResult result = mHandle.readMessage(receivedResponseMessage, 0,
                 MessagePipeHandle.ReadFlags.NONE);
 
         assertEquals(MojoResult.OK, result.getMojoResult());
-        assertEquals(responseHeaderMessage.getMessage().buffer, receivedResponseMessage);
+        assertEquals(message.getData(), receivedResponseMessage);
     }
 }

mojo/public/java/BUILD.gn

@@ -46,6 +46,7 @@ android_library("bindings") {
     "bindings/src/org/chromium/mojo/bindings/Router.java",
     "bindings/src/org/chromium/mojo/bindings/SerializationException.java",
     "bindings/src/org/chromium/mojo/bindings/SideEffectFreeCloseable.java",
+    "bindings/src/org/chromium/mojo/bindings/SimpleMessage.java",
     "bindings/src/org/chromium/mojo/bindings/Struct.java",
   ]
 

mojo/public/java/bindings/src/org/chromium/mojo/bindings/AutoCloseableRouter.java

@@ -54,18 +54,18 @@ class AutoCloseableRouter implements Router {
     }
 
     /**
-     * @see MessageReceiver#accept(MessageWithHeader)
+     * @see MessageReceiver#accept(Message)
      */
     @Override
-    public boolean accept(MessageWithHeader message) {
+    public boolean accept(Message message) {
         return mRouter.accept(message);
     }
 
     /**
-     * @see MessageReceiverWithResponder#acceptWithResponder(MessageWithHeader, MessageReceiver)
+     * @see MessageReceiverWithResponder#acceptWithResponder(Message, MessageReceiver)
      */
     @Override
-    public boolean acceptWithResponder(MessageWithHeader message, MessageReceiver responder) {
+    public boolean acceptWithResponder(Message message, MessageReceiver responder) {
         return mRouter.acceptWithResponder(message, responder);
 
     }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Connector.java

@@ -7,9 +7,12 @@ package org.chromium.mojo.bindings;
 import org.chromium.mojo.system.AsyncWaiter;
 import org.chromium.mojo.system.Core;
 import org.chromium.mojo.system.MessagePipeHandle;
+import org.chromium.mojo.system.MessagePipeHandle.ReadMessageResult;
 import org.chromium.mojo.system.MojoException;
 import org.chromium.mojo.system.MojoResult;
 
+import java.nio.ByteBuffer;
+
 /**
  * A {@link Connector} owns a {@link MessagePipeHandle} and will send any received messages to the
  * registered {@link MessageReceiver}. It also acts as a {@link MessageReceiver} and will send any
@@ -92,13 +95,13 @@ public class Connector implements MessageReceiver, HandleOwner<MessagePipeHandle
     }
 
     /**
-     * @see MessageReceiver#accept(MessageWithHeader)
+     * @see MessageReceiver#accept(Message)
      */
     @Override
-    public boolean accept(MessageWithHeader message) {
+    public boolean accept(Message message) {
         try {
-            mMessagePipeHandle.writeMessage(message.getMessage().buffer,
-                    message.getMessage().handles, MessagePipeHandle.WriteFlags.NONE);
+            mMessagePipeHandle.writeMessage(message.getData(),
+                    message.getHandles(), MessagePipeHandle.WriteFlags.NONE);
             return true;
         } catch (MojoException e) {
             onError(e);
@@ -194,8 +197,7 @@ public class Connector implements MessageReceiver, HandleOwner<MessagePipeHandle
         int result;
         do {
             try {
-                result = MessageWithHeader.readAndDispatchMessage(mMessagePipeHandle,
-                        mIncomingMessageReceiver);
+                result = readAndDispatchMessage(mMessagePipeHandle, mIncomingMessageReceiver);
             } catch (MojoException e) {
                 onError(e);
                 return;
@@ -214,4 +216,26 @@ public class Connector implements MessageReceiver, HandleOwner<MessagePipeHandle
             mCancellable = null;
         }
     }
+
+    /**
+     * Read a message, and pass it to the given |MessageReceiver| if not null. If the
+     * |MessageReceiver| is null, the message is lost.
+     *
+     * @param receiver The {@link MessageReceiver} that will receive the read {@link Message}. Can
+     *            be <code>null</code>, in which case the message is discarded.
+     */
+    static int readAndDispatchMessage(MessagePipeHandle handle, MessageReceiver receiver) {
+        // TODO(qsr) Allow usage of a pool of pre-allocated buffer for performance.
+        ReadMessageResult result = handle.readMessage(null, 0, MessagePipeHandle.ReadFlags.NONE);
+        if (result.getMojoResult() != MojoResult.RESOURCE_EXHAUSTED) {
+            return result.getMojoResult();
+        }
+        ByteBuffer buffer = ByteBuffer.allocateDirect(result.getMessageSize());
+        result = handle.readMessage(buffer, result.getHandlesCount(),
+                MessagePipeHandle.ReadFlags.NONE);
+        if (receiver != null && result.getMojoResult() == MojoResult.OK) {
+            receiver.accept(new SimpleMessage(buffer, result.getHandles()));
+        }
+        return result.getMojoResult();
+    }
 }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Decoder.java

@@ -103,12 +103,12 @@ public class Decoder {
      * @param message The message to decode.
      */
     public Decoder(Message message) {
-        this(message, new Validator(message.buffer.limit(), message.handles.size()), 0);
+        this(message, new Validator(message.getData().limit(), message.getHandles().size()), 0);
     }
 
     private Decoder(Message message, Validator validator, int baseOffset) {
         mMessage = message;
-        mMessage.buffer.order(ByteOrder.nativeOrder());
+        mMessage.getData().order(ByteOrder.nativeOrder());
         mBaseOffset = baseOffset;
         mValidator = validator;
     }
@@ -146,7 +146,7 @@ public class Decoder {
      * Deserializes a byte at the given offset.
      */
     public byte readByte(int offset) {
-        return mMessage.buffer.get(mBaseOffset + offset);
+        return mMessage.getData().get(mBaseOffset + offset);
     }
 
     /**
@@ -160,35 +160,35 @@ public class Decoder {
      * Deserializes a short at the given offset.
      */
     public short readShort(int offset) {
-        return mMessage.buffer.getShort(mBaseOffset + offset);
+        return mMessage.getData().getShort(mBaseOffset + offset);
     }
 
     /**
      * Deserializes an int at the given offset.
      */
     public int readInt(int offset) {
-        return mMessage.buffer.getInt(mBaseOffset + offset);
+        return mMessage.getData().getInt(mBaseOffset + offset);
     }
 
     /**
      * Deserializes a float at the given offset.
      */
     public float readFloat(int offset) {
-        return mMessage.buffer.getFloat(mBaseOffset + offset);
+        return mMessage.getData().getFloat(mBaseOffset + offset);
     }
 
     /**
      * Deserializes a long at the given offset.
      */
     public long readLong(int offset) {
-        return mMessage.buffer.getLong(mBaseOffset + offset);
+        return mMessage.getData().getLong(mBaseOffset + offset);
     }
 
     /**
      * Deserializes a double at the given offset.
      */
     public double readDouble(int offset) {
-        return mMessage.buffer.getDouble(mBaseOffset + offset);
+        return mMessage.getData().getDouble(mBaseOffset + offset);
     }
 
     /**
@@ -221,8 +221,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         byte[] bytes = new byte[si.numFields + 7 / BindingsHelper.ALIGNMENT];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.get(bytes);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().get(bytes);
         boolean[] result = new boolean[si.numFields];
         for (int i = 0; i < bytes.length; ++i) {
             for (int j = 0; j < BindingsHelper.ALIGNMENT; ++j) {
@@ -245,8 +245,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         byte[] result = new byte[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().get(result);
         return result;
     }
 
@@ -260,8 +260,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         short[] result = new short[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.asShortBuffer().get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().asShortBuffer().get(result);
         return result;
     }
 
@@ -275,8 +275,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         int[] result = new int[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.asIntBuffer().get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().asIntBuffer().get(result);
         return result;
     }
 
@@ -290,8 +290,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         float[] result = new float[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.asFloatBuffer().get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().asFloatBuffer().get(result);
         return result;
     }
 
@@ -305,8 +305,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         long[] result = new long[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.asLongBuffer().get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().asLongBuffer().get(result);
         return result;
     }
 
@@ -320,8 +320,8 @@ public class Decoder {
         }
         DataHeader si = d.readArrayDataHeader(expectedLength);
         double[] result = new double[si.numFields];
-        d.mMessage.buffer.position(d.mBaseOffset + DataHeader.HEADER_SIZE);
-        d.mMessage.buffer.asDoubleBuffer().get(result);
+        d.mMessage.getData().position(d.mBaseOffset + DataHeader.HEADER_SIZE);
+        d.mMessage.getData().asDoubleBuffer().get(result);
         return result;
     }
 
@@ -338,7 +338,7 @@ public class Decoder {
             return InvalidHandle.INSTANCE;
         }
         mValidator.claimHandle(index);
-        return mMessage.handles.get(index);
+        return mMessage.getHandles().get(index);
     }
 
     /**
@@ -579,5 +579,4 @@ public class Decoder {
     private Decoder getDecoderAtPosition(int offset) {
         return new Decoder(mMessage, mValidator, offset);
     }
-
 }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Encoder.java

@@ -112,7 +112,7 @@ public class Encoder {
     public Message getMessage() {
         mEncoderState.byteBuffer.position(0);
         mEncoderState.byteBuffer.limit(mEncoderState.dataEnd);
-        return new Message(mEncoderState.byteBuffer, mEncoderState.handles);
+        return new SimpleMessage(mEncoderState.byteBuffer, mEncoderState.handles);
     }
 
     /**

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Message.java

@@ -11,29 +11,25 @@ import java.nio.ByteBuffer;
 import java.util.List;
 
 /**
- * A raw message to be sent/received from a {@link MessagePipeHandle}.
+ * A raw message to be sent/received from a {@link MessagePipeHandle}. Note that this can contain
+ * any data, not necessarily a Mojo message with a proper header. See also {@link MessageWithHeader}
+ * and {@link SimpleMessage}.
  */
-public final class Message {
+public interface Message {
 
     /**
-     * The data of the message.
+     * The data part of the message.
      */
-    public final ByteBuffer buffer;
+    public ByteBuffer getData();
 
     /**
-     * The handles of the message.
+     * The handles part of the message.
      */
-    public final List<? extends Handle> handles;
+    public List<? extends Handle> getHandles();
 
     /**
-     * Constructor.
-     *
-     * @param buffer The buffer containing the bytes to send. This must be a direct buffer.
-     * @param handles The list of handles to send.
+     * Returns the message considered as a message with a header.
      */
-    public Message(ByteBuffer buffer, List<? extends Handle> handles) {
-        assert buffer.isDirect();
-        this.buffer = buffer;
-        this.handles = handles;
-    }
+    public MessageWithHeader asMojoMessage();
+
 }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/MessageReceiver.java

@@ -15,7 +15,7 @@ public interface MessageReceiver extends Closeable {
      * Receive a {@link MessageWithHeader}. The {@link MessageReceiver} is allowed to mutable the
      * message. Returns |true| if the message has been handled, |false| otherwise.
      */
-    boolean accept(MessageWithHeader message);
+    boolean accept(Message message);
 
     /**
      * @see java.io.Closeable#close()

mojo/public/java/bindings/src/org/chromium/mojo/bindings/MessageReceiverWithResponder.java

@@ -11,11 +11,11 @@ package org.chromium.mojo.bindings;
 public interface MessageReceiverWithResponder extends MessageReceiver {
 
     /**
-     * A variant on {@link #accept(MessageWithHeader)} that registers a {@link MessageReceiver}
+     * A variant on {@link #accept(Message)} that registers a {@link MessageReceiver}
      * (known as the responder) to handle the response message generated from the given message. The
-     * responder's {@link #accept(MessageWithHeader)} method may be called as part of the call to
-     * {@link #acceptWithResponder(MessageWithHeader, MessageReceiver)}, or some time after its
+     * responder's {@link #accept(Message)} method may be called as part of the call to
+     * {@link #acceptWithResponder(Message, MessageReceiver)}, or some time after its
      * return.
      */
-    boolean acceptWithResponder(MessageWithHeader message, MessageReceiver responder);
+    boolean acceptWithResponder(Message message, MessageReceiver responder);
 }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/MessageWithHeader.java

@@ -4,18 +4,17 @@
 
 package org.chromium.mojo.bindings;
 
-import org.chromium.mojo.system.MessagePipeHandle;
-import org.chromium.mojo.system.MessagePipeHandle.ReadMessageResult;
-import org.chromium.mojo.system.MojoResult;
+import org.chromium.mojo.system.Handle;
 
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.util.List;
 
 /**
  * Represents a {@link Message} which contains a {@link MessageHeader}. Deals with parsing the
  * {@link MessageHeader} for a message.
  */
-public class MessageWithHeader {
+public class MessageWithHeader implements Message {
 
     private final Message mBaseMessage;
     private final MessageHeader mHeader;
@@ -35,10 +34,34 @@ public class MessageWithHeader {
      * Reinterpret the given |message| as a message with a header. The |message| must contain a
      * header as the start of it's raw data, which will be parsed by this constructor.
      */
-    public MessageWithHeader(Message baseMessage) {
+    MessageWithHeader(Message baseMessage) {
         this(baseMessage, new org.chromium.mojo.bindings.MessageHeader(baseMessage));
     }
 
+    /**
+     * @see Message#getData()
+     */
+    @Override
+    public ByteBuffer getData() {
+        return mBaseMessage.getData();
+    }
+
+    /**
+     * @see Message#getHandles()
+     */
+    @Override
+    public List<? extends Handle> getHandles() {
+        return mBaseMessage.getHandles();
+    }
+
+    /**
+     * @see Message#asMojoMessage()
+     */
+    @Override
+    public MessageWithHeader asMojoMessage() {
+        return this;
+    }
+
     /**
      * Returns the header of the given message. This will throw a {@link DeserializationException}
      * if the start of the message is not a valid header.
@@ -52,47 +75,19 @@ public class MessageWithHeader {
      */
     public Message getPayload() {
         if (mPayload == null) {
-            ByteBuffer truncatedBuffer = ((ByteBuffer) mBaseMessage.buffer.position(
+            ByteBuffer truncatedBuffer = ((ByteBuffer) mBaseMessage.getData().position(
                     getHeader().getSize())).slice();
             truncatedBuffer.order(ByteOrder.nativeOrder());
-            mPayload = new Message(truncatedBuffer, mBaseMessage.handles);
+            mPayload = new SimpleMessage(truncatedBuffer, mBaseMessage.getHandles());
         }
         return mPayload;
     }
 
-    /**
-     * Returns the raw message.
-     */
-    public Message getMessage() {
-        return mBaseMessage;
-    }
-
     /**
      * Set the request identifier on the message.
      */
     void setRequestId(long requestId) {
-        mHeader.setRequestId(mBaseMessage.buffer, requestId);
+        mHeader.setRequestId(mBaseMessage.getData(), requestId);
     }
 
-    /**
-     * Read a message, and pass it to the given |MessageReceiver| if not null. If the
-     * |MessageReceiver| is null, the message is lost.
-     *
-     * @param receiver The {@link MessageReceiver} that will receive the read {@link Message}. Can
-     *            be <code>null</code>, in which case the message is discarded.
-     */
-    public static int readAndDispatchMessage(MessagePipeHandle handle, MessageReceiver receiver) {
-        // TODO(qsr) Allow usage of a pool of pre-allocated buffer for performance.
-        ReadMessageResult result = handle.readMessage(null, 0, MessagePipeHandle.ReadFlags.NONE);
-        if (result.getMojoResult() != MojoResult.RESOURCE_EXHAUSTED) {
-            return result.getMojoResult();
-        }
-        ByteBuffer buffer = ByteBuffer.allocateDirect(result.getMessageSize());
-        result = handle.readMessage(buffer, result.getHandlesCount(),
-                MessagePipeHandle.ReadFlags.NONE);
-        if (receiver != null && result.getMojoResult() == MojoResult.OK) {
-            receiver.accept(new MessageWithHeader(new Message(buffer, result.getHandles())));
-        }
-        return result.getMojoResult();
-    }
 }

mojo/public/java/bindings/src/org/chromium/mojo/bindings/RouterImpl.java

@@ -21,10 +21,10 @@ public class RouterImpl implements Router {
     private class ResponderThunk implements MessageReceiver {
 
         /**
-         * @see MessageReceiver#accept(MessageWithHeader)
+         * @see MessageReceiver#accept(Message)
          */
         @Override
-        public boolean accept(MessageWithHeader message) {
+        public boolean accept(Message message) {
             return handleIncomingMessage(message);
         }
 
@@ -97,21 +97,23 @@ public class RouterImpl implements Router {
     }
 
     /**
-     * @see MessageReceiver#accept(MessageWithHeader)
+     * @see MessageReceiver#accept(Message)
      */
     @Override
-    public boolean accept(MessageWithHeader message) {
+    public boolean accept(Message message) {
         // A message without responder is directly forwarded to the connector.
         return mConnector.accept(message);
     }
 
     /**
-     * @see MessageReceiverWithResponder#acceptWithResponder(MessageWithHeader, MessageReceiver)
+     * @see MessageReceiverWithResponder#acceptWithResponder(Message, MessageReceiver)
      */
     @Override
-    public boolean acceptWithResponder(MessageWithHeader message, MessageReceiver responder) {
+    public boolean acceptWithResponder(Message message, MessageReceiver responder) {
+        // The message must have a header.
+        MessageWithHeader messageWithHeader = message.asMojoMessage();
         // Checking the message expects a response.
-        assert message.getHeader().hasFlag(MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG);
+        assert messageWithHeader.getHeader().hasFlag(MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG);
 
         // Compute a request id for being able to route the response.
         long requestId = mNextRequestId++;
@@ -122,8 +124,8 @@ public class RouterImpl implements Router {
         if (mResponders.containsKey(requestId)) {
             throw new IllegalStateException("Unable to find a new request identifier.");
         }
-        message.setRequestId(requestId);
-        if (!mConnector.accept(message)) {
+        messageWithHeader.setRequestId(requestId);
+        if (!mConnector.accept(messageWithHeader)) {
             return false;
         }
         // Only keep the responder is the message has been accepted.
@@ -158,8 +160,8 @@ public class RouterImpl implements Router {
     /**
      * Receive a message from the connector. Returns |true| if the message has been handled.
      */
-    private boolean handleIncomingMessage(MessageWithHeader message) {
-        MessageHeader header = message.getHeader();
+    private boolean handleIncomingMessage(Message message) {
+        MessageHeader header = message.asMojoMessage().getHeader();
         if (header.hasFlag(MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG)) {
             if (mIncomingMessageReceiver != null) {
                 return mIncomingMessageReceiver.acceptWithResponder(message, this);

mojo/public/java/bindings/src/org/chromium/mojo/bindings/SimpleMessage.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.mojo.bindings;
+
+import org.chromium.mojo.system.Handle;
+import org.chromium.mojo.system.MessagePipeHandle;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+/**
+ * A raw message to be sent/received from a {@link MessagePipeHandle}.
+ */
+public final class SimpleMessage implements Message {
+
+    /**
+     * The data of the message.
+     */
+    private final ByteBuffer mBuffer;
+
+    /**
+     * The handles of the message.
+     */
+    private final List<? extends Handle> mHandle;
+
+    /**
+     * This message interpreted with headers.
+     */
+    private MessageWithHeader mWithHeader = null;
+
+    /**
+     * Constructor.
+     *
+     * @param buffer The buffer containing the bytes to send. This must be a direct buffer.
+     * @param handles The list of handles to send.
+     */
+    public SimpleMessage(ByteBuffer buffer, List<? extends Handle> handles) {
+        assert buffer.isDirect();
+        mBuffer = buffer;
+        mHandle = handles;
+    }
+
+    /**
+     * @see Message#getData()
+     */
+    @Override
+    public ByteBuffer getData() {
+        return mBuffer;
+    }
+
+    /**
+     * @see Message#getHandles()
+     */
+    @Override
+    public List<? extends Handle> getHandles() {
+        return mHandle;
+    }
+
+    /**
+     * @see Message#asMojoMessage()
+     */
+    @Override
+    public MessageWithHeader asMojoMessage() {
+        if (mWithHeader == null) {
+            mWithHeader = new MessageWithHeader(this);
+        }
+        return mWithHeader;
+    }
+}

mojo/public/tools/bindings/generators/java_templates/interface_definition.tmpl

@@ -93,7 +93,9 @@ public static final {{manager_class(interface, client, True)}} MANAGER =
 {% if (interface|has_method_with_response and with_response) or
       (interface|has_method_without_response and not with_response) %}
 try {
-    org.chromium.mojo.bindings.MessageHeader header = message.getHeader();
+    org.chromium.mojo.bindings.MessageWithHeader messageWithHeader =
+            message.asMojoMessage();
+    org.chromium.mojo.bindings.MessageHeader header = messageWithHeader.getHeader();
     if (!header.validateHeader({{flags(with_response, True)}})) {
         return false;
     }
@@ -108,9 +110,9 @@ try {
         case {{method|method_ordinal_name}}: {
 {%       if method.parameters %}
             {{request_struct|name}} data =
-                    {{request_struct|name}}.deserialize(message.getPayload());
+                    {{request_struct|name}}.deserialize(messageWithHeader.getPayload());
 {%       else %}
-            {{request_struct|name}}.deserialize(message.getPayload());
+            {{request_struct|name}}.deserialize(messageWithHeader.getPayload());
 {%       endif %}
             getImpl().{{method|name}}({{run_callback('data', method.parameters)}}{% if with_response %}{% if method.parameters %}, {% endif %}new {{response_struct|name}}ProxyToResponder(getCore(), receiver, header.getRequestId()){% endif %});
             return true;
@@ -204,12 +206,12 @@ class {{interface|name}}_Internal {
         }
 
         @Override
-        public boolean accept(org.chromium.mojo.bindings.MessageWithHeader message) {
+        public boolean accept(org.chromium.mojo.bindings.Message message) {
             {{accept_body(interface, False)|indent(12)}}
         }
 
         @Override
-        public boolean acceptWithResponder(org.chromium.mojo.bindings.MessageWithHeader message, org.chromium.mojo.bindings.MessageReceiver receiver) {
+        public boolean acceptWithResponder(org.chromium.mojo.bindings.Message message, org.chromium.mojo.bindings.MessageReceiver receiver) {
             {{accept_body(interface, True)|indent(12)}}
         }
     }
@@ -230,14 +232,16 @@ class {{interface|name}}_Internal {
         }
 
         @Override
-        public boolean accept(org.chromium.mojo.bindings.MessageWithHeader message) {
+        public boolean accept(org.chromium.mojo.bindings.Message message) {
             try {
-                org.chromium.mojo.bindings.MessageHeader header = message.getHeader();
+                org.chromium.mojo.bindings.MessageWithHeader messageWithHeader =
+                        message.asMojoMessage();
+                org.chromium.mojo.bindings.MessageHeader header = messageWithHeader.getHeader();
                 if (!header.validateHeader({{method|method_ordinal_name}},
                                            {{flags_for_method(method, False)}})) {
                     return false;
                 }
-                {{response_struct|name}} response = {{response_struct|name}}.deserialize(message.getPayload());
+                {{response_struct|name}} response = {{response_struct|name}}.deserialize(messageWithHeader.getPayload());
                 mCallback.call({{run_callback('response', method.response_parameters)}});
                 return true;
             } catch (org.chromium.mojo.bindings.DeserializationException e) {