Implemented a Ray-proposed solution where we keep track of events that were

(pre-applied and) posted before we received our object but processed (and hence
dispatched to us) after we received our object.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@4715 542714f4-19e9-0310-aa3c-eee0fc999fb1

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

@@ -93,6 +93,17 @@ public class PresentsDObjectMgr
         PresentsServer.registerReporter(this);
     }
 
+    /**
+     * Returns the id to be assigned to the next event posted to the event queue.
+     *
+     * @param increment if true, the event id will be incremented so that the caller can "claim"
+     * the returned event id.
+     */
+    public synchronized long getNextEventId (boolean increment)
+    {
+        return increment ? _nextEventId++ : _nextEventId;
+    }
+
     /**
      * Sets up an access controller that will be provided to any distributed objects created on the
      * server. The controllers can subsequently be overridden if desired, but a default controller
@@ -169,7 +180,8 @@ public class PresentsDObjectMgr
     // from interface DObjectManager
     public void postEvent (DEvent event)
     {
-        // just append it to the queue
+        // assign the event's id and append it to the queue
+        event.eventId = getNextEventId(true);
         _evqueue.append(event);
     }
 
@@ -973,6 +985,9 @@ public class PresentsDObjectMgr
     /** Used during unit profiling for timing values. */
     protected Perf _timer = Perf.getPerf();
 
+    /** A monotonically increasing counter used to assign an id to all dispatched events. */
+    protected long _nextEventId = 1;
+
     /** Used to profile our events and runnable units. */
     protected HashMap<String,UnitProfile> _profiles = new HashMap<String,UnitProfile>();