From 41d875c7e36f75f62b78271e77b560488d58a68a Mon Sep 17 00:00:00 2001
From: Eric Anderson <ejona@google.com>
Date: Mon, 3 Aug 2015 13:02:33 -0700
Subject: [PATCH] Notify transportReady() in Netty

---
 .../grpc/transport/netty/NettyClientHandler.java   |  8 ++++++++
 .../grpc/transport/netty/NettyClientTransport.java | 14 ++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/netty/src/main/java/io/grpc/transport/netty/NettyClientHandler.java b/netty/src/main/java/io/grpc/transport/netty/NettyClientHandler.java
index 1f169179d4..9125453fbc 100644
--- a/netty/src/main/java/io/grpc/transport/netty/NettyClientHandler.java
+++ b/netty/src/main/java/io/grpc/transport/netty/NettyClientHandler.java
@@ -44,6 +44,7 @@ import io.grpc.transport.ClientTransport.PingCallback;
 import io.grpc.transport.Http2Ping;
 import io.grpc.transport.HttpUtil;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelFutureListener;
@@ -75,6 +76,11 @@ import javax.annotation.Nullable;
  */
 class NettyClientHandler extends Http2ConnectionHandler {
   private static final Logger logger = Logger.getLogger(NettyClientHandler.class.getName());
+  /**
+   * A message that simply passes through the channel without any real processing. It is useful to
+   * check if buffers have been drained and test the health of the channel in a single operation.
+   */
+  static final Object NOOP_MESSAGE = new Object();
 
   private final Http2Connection.PropertyKey streamKey;
   private final Ticker ticker;
@@ -160,6 +166,8 @@ class NettyClientHandler extends Http2ConnectionHandler {
       ((RequestMessagesCommand) msg).requestMessages();
     } else if (msg instanceof SendPingCommand) {
       sendPingFrame(ctx, (SendPingCommand) msg, promise);
+    } else if (msg == NOOP_MESSAGE) {
+      ctx.write(Unpooled.EMPTY_BUFFER, promise);
     } else {
       throw new AssertionError("Write called for unexpected type: " + msg.getClass().getName());
     }
diff --git a/netty/src/main/java/io/grpc/transport/netty/NettyClientTransport.java b/netty/src/main/java/io/grpc/transport/netty/NettyClientTransport.java
index 3a9e81b9dd..497e838820 100644
--- a/netty/src/main/java/io/grpc/transport/netty/NettyClientTransport.java
+++ b/netty/src/main/java/io/grpc/transport/netty/NettyClientTransport.java
@@ -173,6 +173,20 @@ class NettyClientTransport implements ClientTransport {
     channel = b.connect(address).channel();
     // Start the write queue as soon as the channel is constructed
     handler.startWriteQueue(channel);
+    // This write will have no effect, yet it will only complete once the negotiationHandler
+    // flushes any pending writes.
+    channel.write(NettyClientHandler.NOOP_MESSAGE).addListener(new ChannelFutureListener() {
+      @Override
+      public void operationComplete(ChannelFuture future) throws Exception {
+        if (future.isSuccess()) {
+          listener.transportReady();
+        } else {
+          // Need to notify of this failure, because handler.connectionError() is not guaranteed to
+          // have seen this cause.
+          notifyTerminated(future.cause());
+        }
+      }
+    });
     // Handle transport shutdown when the channel is closed.
     channel.closeFuture().addListener(new ChannelFutureListener() {
       @Override