Add Message and MessageReceiver classes.

Those classes are utility class to handle mojo messages.

R=viettrungluu@chromium.org,rmcilroy@chromium.org

Review URL: https://codereview.chromium.org/311363003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@280785 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 80 insertions, 0 deletions

diff --git a/mojo/bindings/java/src/org/chromium/mojo/bindings/Message.java b/mojo/bindings/java/src/org/chromium/mojo/bindings/Message.java
new file mode 100644
index 0000000..f826a8e
--- /dev/null
+++ b/mojo/bindings/java/src/org/chromium/mojo/bindings/Message.java
@@ -0,0 +1,63 @@
+// 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 org.chromium.mojo.system.MessagePipeHandle.ReadMessageResult;
+import org.chromium.mojo.system.MojoResult;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+import javax.annotation.Nullable;
+
+/**
+ * A raw message to be sent/received from a {@link MessagePipeHandle}.
+ */
+public final class Message {
+
+    /**
+     * The data of the message.
+     */
+    public final ByteBuffer buffer;
+
+    /**
+     * The handles of the message.
+     */
+    public final List<? extends Handle> handles;
+
+    /**
+     * 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 Message(ByteBuffer buffer, List<? extends Handle> handles) {
+        assert buffer.isDirect();
+        this.buffer = buffer;
+        this.handles = handles;
+    }
+
+    /**
+     * Read a message, and pass it to the given |MessageReceiver| if not null. If the
+     * |MessageReceiver| is null, the message is lost.
+     */
+    public static int readAndDispatchMessage(MessagePipeHandle handle,
+            @Nullable 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 Message(buffer, result.getHandles()));
+        }
+        return result.getMojoResult();
+    }
+}
diff --git a/mojo/bindings/java/src/org/chromium/mojo/bindings/MessageReceiver.java b/mojo/bindings/java/src/org/chromium/mojo/bindings/MessageReceiver.java
new file mode 100644
index 0000000..1736bc6
--- /dev/null
+++ b/mojo/bindings/java/src/org/chromium/mojo/bindings/MessageReceiver.java
@@ -0,0 +1,17 @@
+// 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;
+
+/**
+ * A class which implements this interface can receive {@link Message} objects.
+ */
+public interface MessageReceiver {
+
+    /**
+     * Receive a {@link Message}. The {@link MessageReceiver} is allowed to mutable the message.
+     * Returns |true| if the message has been handled, |false| otherwise.
+     */
+    boolean accept(Message message);
+}