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