-// Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
+// Copyright 2004 Adam Megacz, see the COPYING file for licensing [GPL]
package org.xwt;
import java.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 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) (singleton = Platform.getScheduler()).run(); }
+
+ private static Task currentTask = null;
+ public static Task current() { return currentTask; }
+
+ /** synchronizd so that we can safely call it from an event-delivery thread, in-context */
+ private static volatile boolean rendering = false;
+ private static volatile boolean again = false;
+ public static void renderAll() {
+ if (rendering) { again = true; return; }
+ synchronized(Scheduler.class) {
+ try {
+ rendering = true;
+ do {
+ again = false;
+ for(int i=0; i<Surface.allSurfaces.size(); i++) {
+ Surface s = ((Surface)Surface.allSurfaces.elementAt(i));
+ do { s.render(); } while(s.abort);
+ }
+ } while(again);
+ } finally {
+ rendering = false;
+ }
+ }
+ }
+
+
+
+ // API which must be supported by subclasses /////////////////////////////////////
+
+ /**
+ * 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() { }
- 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() {
- while(true) {
- Task t = (Task)runnable.remove(true);
+ public void defaultRun() {
+ try {while(true) {
+ currentTask = (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();
+ synchronized(this) {
+ for(int i=0; i<Surface.allSurfaces.size(); i++) {
+ Surface s = (Surface)Surface.allSurfaces.elementAt(i);
+ if (currentTask instanceof JS) {
+ s._mousex = Integer.MAX_VALUE;
+ s._mousey = Integer.MAX_VALUE;
+ } else {
+ s._mousex = s.mousex;
+ s._mousey = s.mousey;
+ }
+ }
+ currentTask.perform();
+ }
+ renderAll();
+ } catch (JSExn e) {
+ Log.info(Scheduler.class, "a JavaScript thread spawned with xwt.thread() threw an exception:");
+ Log.info(Scheduler.class, "JS Exception: " + e.getObject() + "\n" + e.backtrace());
+ Log.info(Scheduler.class,e);
} catch (Exception e) {
- Log.log(Scheduler.class, "Task threw an 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
+} } catch (Throwable t) {
+ t.printStackTrace();
}
}
}