propose-patch

[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..9e939a3 100644 (file)
--- a/src/org/xwt/Scheduler.java
+++ b/src/org/xwt/Scheduler.java
@@ -1,4 +1,4 @@
-// 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.*;
@@ -8,25 +8,83 @@ 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 interface Task { public abstract void perform() throws Exception; }
+    public static void add(Task t) { singleton.runnable.append(t); }
+    public static void init() { if (singleton == null) (singleton = Platform.getScheduler()).run(); }
+
+    private static Task current = null;
+
+    private static volatile boolean rendering = false;
+    private static volatile boolean again = false;
+
+    /** synchronizd so that we can safely call it from an event-delivery thread, in-context */
+    public static void renderAll() {
+        if (rendering) { again = true; return; }
+        synchronized(Scheduler.class) {
+            try {
+                rendering = true;
+                do {
+                    // FEATURE: this could be cleaner
+                    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() {
+    public void defaultRun() {
         while(true) {
-            Task t = (Task)runnable.remove(true);
+            current = (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();
+                // FIXME hideous
+                synchronized(this) {
+                    for(int i=0; i<Surface.allSurfaces.size(); i++) {
+                        Surface s = (Surface)Surface.allSurfaces.elementAt(i);
+                        if (current instanceof JS) {
+                            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.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
         }
     }
 }