We're getting datagram PONGs on resumed connections that haven't yet sent

datagram PINGs.  Let's make sure that the connection to which we're sending
the pong is the same one from which we received the ping.  Ping, pong, ping,
pong.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6618 542714f4-19e9-0310-aa3c-eee0fc999fb1

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

@@ -874,11 +874,21 @@ public class PresentsSession
      * Callable from non-dobjmgr thread, this queues up a runnable on the dobjmgr thread to post
      * the supplied message to this client.
      */
-    protected final void safePostMessage (final DownstreamMessage msg)
+    protected final void safePostMessage (DownstreamMessage msg)
+    {
+        safePostMessage(msg, null);
+    }
+
+    /**
+     * Callable from non-dobjmgr thread, this queues up a runnable on the dobjmgr thread to post
+     * the supplied message to this client.
+     */
+    protected final void safePostMessage (
+        final DownstreamMessage msg, final PresentsConnection expect)
     {
         _omgr.postRunnable(new Runnable() {
             public void run () {
-                postMessage(msg, null);
+                postMessage(msg, expect);
             }
         });
     }
@@ -1165,7 +1175,8 @@ public class PresentsSession
             if (PING_DEBUG) {
                 log.info("Got ping, ponging", "client", client.getAuthName());
             }
-            client.safePostMessage(new PongResponse(req.getUnpackStamp(), req.getTransport()));
+            client.safePostMessage(new PongResponse(req.getUnpackStamp(), req.getTransport()),
+                client.getConnection());
         }
     }