Added an extra step to the datagram negotation process. Before

the server starts sending datagrams willy-nilly, it must wait for 
a (reliable) go-ahead from the client.  Otherwise, it's possible 
that the server may be successfully receiving datagrams but not 
sending them.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5792 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/server/PresentsSession.java

@@ -63,6 +63,7 @@ import com.threerings.presents.net.PingRequest;
 import com.threerings.presents.net.PongResponse;
 import com.threerings.presents.net.SubscribeRequest;
 import com.threerings.presents.net.ThrottleUpdatedMessage;
+import com.threerings.presents.net.TransmitDatagramsRequest;
 import com.threerings.presents.net.UnsubscribeRequest;
 import com.threerings.presents.net.UnsubscribeResponse;
 import com.threerings.presents.net.UpdateThrottleMessage;
@@ -1085,6 +1086,18 @@ public class PresentsSession
         }
     }
 
+    /**
+     * Processes datagram transmission requests.
+     */
+    protected static class TransmitDatagramsDispatcher implements MessageDispatcher
+    {
+        public void dispatch (PresentsSession client, Message msg)
+        {
+            log.debug("Client requested datagram transmission", "client", client);
+            client.getConnection().setTransmitDatagrams(true);
+        }
+    }
+
     /**
      * Processes throttle updated messages.
      */
@@ -1158,6 +1171,7 @@ public class PresentsSession
         _disps.put(UnsubscribeRequest.class, new UnsubscribeDispatcher());
         _disps.put(ForwardEventRequest.class, new ForwardEventDispatcher());
         _disps.put(PingRequest.class, new PingDispatcher());
+        _disps.put(TransmitDatagramsRequest.class, new TransmitDatagramsDispatcher());
         _disps.put(ThrottleUpdatedMessage.class, new ThrottleUpdatedDispatcher());
         _disps.put(LogoffRequest.class, new LogoffDispatcher());
     }

src/java/com/threerings/presents/server/net/Connection.java

@@ -121,6 +121,22 @@ public class Connection implements NetEventHandler
         return (_channel == null) ? null : _channel.socket().getInetAddress();
     }
 
+    /**
+     * Sets whether we should transmit datagrams.
+     */
+    public void setTransmitDatagrams (boolean transmit)
+    {
+        _transmitDatagrams = transmit;
+    }
+
+    /**
+     * Checks whether we should transmit datagrams.
+     */
+    public boolean getTransmitDatagrams ()
+    {
+        return _transmitDatagrams;
+    }
+
     /**
      * Returns the address to which datagrams should be sent or null if no datagram address has
      * been established.
@@ -435,6 +451,7 @@ public class Connection implements NetEventHandler
 
     protected InetSocketAddress _datagramAddress;
     protected byte[] _datagramSecret;
+    protected boolean _transmitDatagrams;
 
     protected MessageDigest _digest;
     protected DatagramSequencer _sequencer;

src/java/com/threerings/presents/server/net/ConnectionManager.java

@@ -61,6 +61,7 @@ import com.threerings.presents.annotation.AuthInvoker;
 import com.threerings.presents.client.Client;
 import com.threerings.presents.data.ConMgrStats;
 import com.threerings.presents.net.Message;
+import com.threerings.presents.net.PongResponse;
 import com.threerings.presents.server.Authenticator;
 import com.threerings.presents.server.ChainedAuthenticator;
 import com.threerings.presents.server.ClientManager;
@@ -902,9 +903,11 @@ public class ConnectionManager extends LoopingThread
         }
 
         try {
-            // send it as a datagram if hinted and possible
-            if (!msg.getTransport().isReliable() && conn.getDatagramAddress() != null &&
-                    postDatagram(conn, msg)) {
+            // send it as a datagram if hinted and possible (pongs must be sent as part of the
+            // negotation process)
+            if (!msg.getTransport().isReliable() &&
+                    (conn.getTransmitDatagrams() || msg instanceof PongResponse) &&
+                        postDatagram(conn, msg)) {
                 return;
             }