2003/11/29 03:06:09

[org.ibex.core.git] / src / org / xwt / Scheduler.java

diff --git a/src/org/xwt/Scheduler.java b/src/org/xwt/Scheduler.java
index 2cb7892..1f57fe7 100644 (file)
--- a/src/org/xwt/Scheduler.java
+++ b/src/org/xwt/Scheduler.java
@@ -8,23 +8,41 @@ import org.xwt.util.*;
 /** Implements cooperative multitasking */
 public class Scheduler {
 
-    public static final Scheduler singleton = Platform.getScheduler();
+    // Public API Exposed to org.xwt /////////////////////////////////////////////////
+
+    private static Scheduler singleton;
+    public static abstract class Task { public abstract void perform() throws Exception; }
+    public static void add(Task t) { singleton.runnable.append(t); }
+    public static void init() {
+        if (singleton != null) return;
+        singleton = Platform.getScheduler();
+        singleton.run();
+    }
+
+
+    // API which must be supported by subclasses /////////////////////////////////////
+
+    /**
+     *  INVARIANT: all scheduler implementations MUST invoke Surface.renderAll() after performing a Task if no tasks remain
+     *  in the queue.  A scheduler may choose to invoke Surface.renderAll() more often than that if it so chooses.
+     */
+    public void run() { defaultRun(); }
     protected Scheduler() { }
 
-    public static abstract class Task { public abstract void perform(); }
+
+    // Default Implementation //////////////////////////////////////////////////////
 
     protected static Queue runnable = new Queue(50);
-    public static void add(Task t) { singleton.runnable.append(t); }
-    public void run() {
+    public void defaultRun() {
         while(true) {
             Task t = (Task)runnable.remove(true);
             try {
                 t.perform();
-                // FIXME: be smarter about this
-                for(int i=0; i<Surface.allSurfaces.size(); i++)
-                    ((Surface)Surface.allSurfaces.elementAt(i)).render();
+                // FEATURE: be smarter about this
+                Surface.renderAll();
+            } catch (JSExn e) {
+                Log.log(Scheduler.class, e.toString());
             } catch (Exception e) {
-                Log.log(Scheduler.class, "Task threw an exception: " + e);
                 Log.log(Scheduler.class, e);
             }
         }