Specifically ACK unsubscribe requests so that we don't see a bunch of

warning messages saying that we couldn't deliver events on the client that
come in after all client-side subscribers have been removed.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@2204 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/client/ClientDObjectMgr.java

@@ -1,5 +1,5 @@
 //
-// $Id: ClientDObjectMgr.java,v 1.18 2002/12/04 22:04:46 shaper Exp $
+// $Id: ClientDObjectMgr.java,v 1.19 2003/01/21 22:02:37 mdb Exp $
 
 package com.threerings.presents.client;
 
@@ -91,11 +91,8 @@ public class ClientDObjectMgr
     // inherit documentation from the interface
     public void removedLastSubscriber (DObject obj)
     {
-        // if object has no subscribers, we no longer need to proxy it;
+        // ship off an unsubscribe message to the server; we'll remove the
-        // first remove it from the object table
+        // object from our table when we get the unsub ack
-        _ocache.remove(obj.getOid());
-
-        // then ship off an unsubscribe message to the server
         _comm.postMessage(new UnsubscribeRequest(obj.getOid()));
     }
 
@@ -133,6 +130,17 @@ public class ClientDObjectMgr
             } else if (obj instanceof ObjectResponse) {
                 registerObjectAndNotify(((ObjectResponse)obj).getObject());
 
+            } else if (obj instanceof UnsubscribeResponse) {
+                // now that the server has removed our subscription, we
+                // can remove the object from our local table because we
+                // should not receive further events for this object; it's
+                // possible that the object was destroyed (and thus
+                // removed from our table) in between our request to
+                // unsubscribe and the unsub response from the server,
+                // otherwise we'd log a warning if we failed to remove the
+                // object from our local table here
+                _ocache.remove(((UnsubscribeResponse)obj).getOid());
+
             } else if (obj instanceof FailureResponse) {
                 int oid = ((FailureResponse)obj).getOid();
                 notifyFailure(oid);

src/java/com/threerings/presents/net/UnsubscribeResponse.java

@@ -0,0 +1,40 @@
+//
+// $Id: UnsubscribeResponse.java,v 1.1 2003/01/21 22:02:37 mdb Exp $
+
+package com.threerings.presents.net;
+
+/**
+ * Used to communicate to the client that we received their unsubscribe
+ * request and that it is now OK to remove an object mapping from their
+ * local object table.
+ */
+public class UnsubscribeResponse extends DownstreamMessage
+{
+    /**
+     * Zero argument constructor used when unserializing an instance.
+     */
+    public UnsubscribeResponse ()
+    {
+        super();
+    }
+
+    /**
+     * Constructs an unsubscribe response with the supplied oid.
+     */
+    public UnsubscribeResponse (int oid)
+    {
+        _oid = oid;
+    }
+
+    public int getOid ()
+    {
+        return _oid;
+    }
+
+    public String toString ()
+    {
+        return "[type=UNACK, msgid=" + messageId + ", oid=" + _oid + "]";
+    }
+
+    protected int _oid;
+}

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

@@ -1,5 +1,5 @@
 //
-// $Id: PresentsClient.java,v 1.49 2002/12/22 19:16:31 mdb Exp $
+// $Id: PresentsClient.java,v 1.50 2003/01/21 22:02:37 mdb Exp $
 
 package com.threerings.presents.server;
 
@@ -34,6 +34,7 @@ import com.threerings.presents.net.UnsubscribeRequest;
 import com.threerings.presents.net.FailureResponse;
 import com.threerings.presents.net.ObjectResponse;
 import com.threerings.presents.net.PongResponse;
+import com.threerings.presents.net.UnsubscribeResponse;
 
 import com.threerings.presents.server.net.Connection;
 import com.threerings.presents.server.net.MessageHandler;
@@ -728,13 +729,22 @@ public class PresentsClient
         public void dispatch (PresentsClient client, UpstreamMessage msg)
         {
             UnsubscribeRequest req = (UnsubscribeRequest)msg;
-//              Log.info("Unsubscribing [client=" + client +
+            int oid = req.getOid();
-//                       ", oid=" + req.getOid() + "].");
+//             Log.info("Unsubscribing " + client + " [oid=" + oid + "].");
 
             // forward the unsubscribe request to the omgr for processing
-            PresentsServer.omgr.unsubscribeFromObject(req.getOid(), client);
+            PresentsServer.omgr.unsubscribeFromObject(oid, client);
             // update our subscription tracking table
-            client.unmapSubscrip(req.getOid());
+            client.unmapSubscrip(oid);
+
+            // post a response to the client letting them know that we
+            // will no longer send them events regarding this object
+            Connection conn = client.getConnection();
+            if (conn != null) {
+                conn.postMessage(new UnsubscribeResponse(oid));
+            } else {
+                Log.info("Dropped unsub ack " + client + " [oid=" + oid + "].");
+            }
         }
     }