Break out registration of scene resolution listeners into its own function

so it's easily accessible to subclasses that are managing scene loading in
their own special ways.


git-svn-id: svn+ssh://src.earth.threerings.net/vilya/trunk@549 c613c5cb-e716-0410-b11b-feb51c14d237

src/java/com/threerings/whirled/server/SceneRegistry.java

@@ -164,18 +164,9 @@ public class SceneRegistry
 
         // otherwise we've got to resolve the scene and call them back later; we can manipulate the
         // penders table with impunity here because we only do so on the dobjmgr thread
-        ArrayList<ResolutionListener> penders = _penders.get(sceneId);
-
-        // if we're already in the process of resolving this scene, just add these guys to the list
-        // to be notified when it finally is resolved
-        if (penders != null) {
-            penders.add(target);
-
-        } else {
-            // otherwise we've got to initiate the resolution process, create the penders list
-            _penders.put(sceneId, penders = new ArrayList<ResolutionListener>());
-            penders.add(target);
         
+        // Add this guy to be notified, and if nobody has yet, start resolving the scene
+        if (addResolutionListener(sceneId, target)) {
             // i don't like cluttering up method declarations with final keywords...
             final int fsceneId = sceneId;
 
@@ -251,6 +242,26 @@ public class SceneRegistry
         CrowdServer.plreg.locprov.leaveOccupiedPlace(source);
     }
     
+    /**
+     * Adds a callback for when the scene is resolved. Returns true if this is the first such
+     * thing (and thusly, the caller should actually fire off scene resolution) or false if we've
+     * already got a list and have just added this listener to it.
+     */
+    protected boolean addResolutionListener (int sceneId, ResolutionListener rl)
+    {
+        ArrayList<ResolutionListener> penders = _penders.get(sceneId);
+        boolean newList = false;
+        
+        if (penders == null) {
+            _penders.put(sceneId, penders = new ArrayList<ResolutionListener>());
+            newList = true;
+        }
+        
+        penders.add(rl);
+        return newList;
+    }
+
+
     /**
      * Called when the scene resolution has completed successfully.
      */