/** Implements cooperative multitasking */
public class Scheduler {
+ // FIXME: prepending events messes with keysate -- make a "no re-ordering" invariant?
+
// 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(); }
+
+ private static Task current = null;
+ public static Task current() { return current; }
+
+ /** synchronizd so that we can safely call it from an event-delivery thread, in-context */
+ public static synchronized void renderAll() {
+ for(int i=0; i<Surface.allSurfaces.size(); i++) {
+ Surface s = ((Surface)Surface.allSurfaces.elementAt(i));
+ do { s.render(); } while(s.abort);
+ }
}
+
// 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() { }
protected static Queue runnable = new Queue(50);
public void defaultRun() {
while(true) {
- Task t = (Task)runnable.remove(true);
+ current = (Task)runnable.remove(true);
try {
- t.perform();
- // FEATURE: be smarter about this
- Surface.renderAll();
+ synchronized(this) {
+ for(int i=0; i<Surface.allSurfaces.size(); i++) {
+ Surface s = (Surface)Surface.allSurfaces.elementAt(i);
+ if (current instanceof JSFunction) {
+ s._mousex = Integer.MAX_VALUE;
+ s._mousey = Integer.MAX_VALUE;
+ } else {
+ s._mousex = s.mousex;
+ s._mousey = s.mousey;
+ }
+ }
+ current.perform();
+ }
+ renderAll();
} catch (JSExn e) {
- Log.log(Scheduler.class, e.toString());
+ Log.info(Scheduler.class, "a JavaScript thread spawned with xwt.thread() threw an exception:");
+ Log.info(Scheduler.class, e);
} catch (Exception e) {
- Log.log(Scheduler.class, e);
+ Log.info(Scheduler.class, "a Task threw an exception which was caught by the scheduler:");
+ Log.info(Scheduler.class, e);
}
+ // if an Error is thrown it will cause the engine to quit
}
}
}