// Public API Exposed to org.xwt /////////////////////////////////////////////////
private static Scheduler singleton;
- public static abstract class Task { public abstract void perform() throws Exception; }
+ public static interface Task { public abstract void perform() throws Exception; }
+
+ /** adds a task to the back of the queue */
public static void add(Task t) { singleton.runnable.append(t); }
- public static void init() {
- if (singleton != null) return;
- singleton = Platform.getScheduler();
- singleton.run();
- }
+ /** adds a task to the front of the queue (guaranteed to run next) */
+ public static void addAtFront(Task t) { singleton.runnable.prepend(t); }
+
+ public static void init() { if (singleton == null) (singleton = Platform.getScheduler()).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.
+ * SCHEDULER 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() { }
try {
t.perform();
// FEATURE: be smarter about this
- Surface.renderAll();
+ if (t != Surface.renderAll) add(Surface.renderAll);
} catch (JSExn e) {
+ Log.log(Scheduler.class, "a JavaScript thread spawned with xwt.thread() threw an exception:");
Log.log(Scheduler.class, e.toString());
} catch (Exception e) {
+ Log.log(Scheduler.class, "a Task threw an exception which was caught by the scheduler:");
Log.log(Scheduler.class, e);
}
+ // if an Error is thrown it will cause the engine to quit
}
}
}