New very safe shutdown scheme. An Invoker.Unit runs on both the Invoker

and dobj thread until they're both empty (or it has been passed 50 times)
and then shuts the threads down.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@2744 542714f4-19e9-0310-aa3c-eee0fc999fb1

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

@@ -1,5 +1,5 @@
 //
-// $Id: PresentsDObjectMgr.java,v 1.34 2003/06/15 16:47:33 mdb Exp $
+// $Id: PresentsDObjectMgr.java,v 1.35 2003/08/08 03:11:55 ray Exp $
 
 package com.threerings.presents.server;
 
@@ -254,12 +254,6 @@ public class PresentsDObjectMgr
      */
     protected void processEvent (DEvent event)
     {
-        // handle graceful shutdown
-        if (event instanceof ShutdownEvent) {
-            _running = false;
-            return;
-        }
-
         // look up the target object
         DObject target = (DObject)_objects.get(event.getTargetOid());
         if (target == null) {
@@ -325,14 +319,17 @@ public class PresentsDObjectMgr
     }
 
     /**
-     * Requests that the dobjmgr shut itself down. It will exit the event
-     * processing loop which cause <code>run()</code> to return.
+     * Requests that the dobjmgr shut itself down soon- you may
+     * want to try using {@link Invoker#shutdown} which will make sure that
+     * both the Invoker and DObjectMgr are empty and then shut them both down.
      */
-    public void shutdown ()
+    public void harshShutdown ()
     {
-        // stick a bogus object on the event queue to ensure that the mgr
-        // wakes up and smells the coffee
-        _evqueue.append(new ShutdownEvent());
+        postUnit(new Runnable() {
+            public void run () {
+                _running = false;
+            }
+        });
     }
 
     /**
@@ -568,6 +565,15 @@ public class PresentsDObjectMgr
         return true;
     }
 
+    /**
+     * Should not need to be called except by the invoker during shutdown
+     * to ensure that things are proceeding smoothly.
+     */
+    public boolean queueIsEmpty ()
+    {
+        return !_evqueue.hasElements();
+    }
+
     protected synchronized boolean isRunning ()
     {
         return _running;
@@ -768,21 +774,6 @@ public class PresentsDObjectMgr
         protected int _action;
     }
 
-    protected class ShutdownEvent extends DEvent
-    {
-        public ShutdownEvent ()
-        {
-            super(0); // target the bogus object
-        }
-
-        public boolean applyToObject (DObject target)
-            throws ObjectAccessException
-        {
-            // nothing doing!
-            return false;
-        }
-    }
-
     /**
      * Registers our event helper methods.
      */