src/org/ibex/util/Scheduler.java

   1 // Copyright 2004 Adam Megacz, see the COPYING file for licensing [GPL]
   2 package org.ibex.util;
   3
   4 import java.io.IOException;
   5
   6 import org.ibex.js.*;
   7 import org.ibex.util.*;
   8 import org.ibex.graphics.*;
   9 import org.ibex.plat.*;
  10
  11 /** Implements cooperative multitasking */
  12 public class Scheduler {
  13
  14     // Public API Exposed to org.ibex /////////////////////////////////////////////////
  15
  16     private static Scheduler singleton;
  17     private static String taskDesc(Task t) { return t instanceof JS ? JS.debugToString((JS)t) : t.toString(); }
  18     public static void add(Task t) { Log.debug(Scheduler.class, "scheduling " + taskDesc(t)); Scheduler.runnable.append(t); }
  19     public static void init() { if (singleton == null) (singleton = Platform.getScheduler()).run(); }
  20
  21     private static Task current = null;
  22
  23     private static volatile boolean rendering = false;
  24     private static volatile boolean again = false;
  25
  26     /** synchronizd so that we can safely call it from an event-delivery thread, in-context */
  27     public static void renderAll() {
  28         if (rendering) { again = true; return; }
  29         synchronized(Scheduler.class) {
  30             try {
  31                 rendering = true;
  32                 do {
  33                     // FEATURE: this could be cleaner
  34                     again = false;
  35                     for(int i=0; i<Surface.allSurfaces.size(); i++) {
  36                         Surface s = ((Surface)Surface.allSurfaces.elementAt(i));
  37                         do { s.render(); } while(s.abort);
  38                     }
  39                 } while(again);
  40             } finally {
  41                 rendering = false;
  42             }
  43         }
  44     }
  45
  46
  47
  48     // API which must be supported by subclasses /////////////////////////////////////
  49
  50     /**
  51      *  SCHEDULER INVARIANT: all scheduler implementations MUST invoke
  52      *  Surface.renderAll() after performing a Task if no tasks remain
  53      *  in the queue.  A scheduler may choose to invoke
  54      *  Surface.renderAll() more often than that if it so chooses.
  55      */
  56     public void run() { defaultRun(); }
  57     public Scheduler() { }
  58
  59
  60     // Default Implementation //////////////////////////////////////////////////////
  61
  62     protected static Queue runnable = new Queue(50);
  63     public void defaultRun() {
  64         while(true) {
  65             current = (Task)runnable.remove(true);
  66             try {
  67                 // FIXME hideous
  68                 synchronized(this) {
  69                     for(int i=0; i<Surface.allSurfaces.size(); i++) {
  70                         Surface s = (Surface)Surface.allSurfaces.elementAt(i);
  71                         if (current instanceof JS) {
  72                             s._mousex = Integer.MAX_VALUE;
  73                             s._mousey = Integer.MAX_VALUE;
  74                         } else {
  75                             s._mousex = s.mousex;
  76                             s._mousey = s.mousey;
  77                         }
  78                     }
  79                     Log.debug(Scheduler.class, "performing " + taskDesc(current));
  80                     current.perform();
  81                 }
  82                 renderAll();
  83             } catch (JSExn e) {
  84                 Log.info(Scheduler.class, "a JavaScript thread spawned with ibex.thread() threw an exception:");
  85                 Log.info(Scheduler.class,e);
  86             } catch (Exception e) {
  87                 Log.info(Scheduler.class, "a Task threw an exception which was caught by the scheduler:");
  88                 Log.info(Scheduler.class, e);
  89             } catch (Throwable t) {
  90                 t.printStackTrace();
  91             }
  92             // if an Error is thrown it will cause the engine to quit
  93         }
  94     }
  95 }