一個用於實現並行執行的 Java actor 庫

  class TestActor extends AbstractActor {

    @Override
    public void activate() {
      super.activate();
    }

    @Override
    public void deactivate() {
      super.deactivate();
    }

    @Override
    protected void runBody() {
      sleeper(1);  // delay up to 1 second
      DefaultMessage dm = new DefaultMessage("init", 8);
      getManager().send(dm, null, this);
    }

    @Override
    protected Message testMessage() {
      return super.testMessage();
    }

    @Override
    protected void loopBody(Message m) {
      sleeper(1);
      String subject = m.getSubject();
      if ("repeat".equals(subject)) {
        int count = (Integer) m.getData();
        if (count > 0) {
          DefaultMessage dm = new DefaultMessage("repeat", count - 1);
          String toName = "actor" + rand.nextInt(TEST_ACTOR_COUNT);
          Actor to = testActors.get(toName);
          getManager().send(dm, this, to);
        }
      }

      else if ("init".equals(subject)) {
        int count = (Integer) m.getData();
        count = rand.nextInt(count) + 1;
        for (int i = 0; i < count; i++) {
          DefaultMessage dm = new DefaultMessage("repeat", count);
          String toName = "actor" + rand.nextInt(TEST_ACTOR_COUNT);
          Actor to = testActors.get(toName);
          getManager().send(dm, this, to);
          
          dm = new DefaultMessage("repeat", count);
          dm.setDelayUntil(new Date().getTime() + (rand.nextInt(5) + 1) * 1000);
          getManager().send(dm, this, "common");
        }
      }

      else {
        System.out.printf("TestActor:%s loopBody unknown subject: %s%n", 
          getName(), subject);
      }
    }
  }

    DefaultActorManager am = DefaultActorManager.getDefaultInstance();
    :
    Map<String, Actor> testActors = new HashMap<String, Actor>();
    for (int i = 0; i < 2; i++) {
        Actor a = am.createActor(TestActor.class, "common" + i);
        a.setCategory("common");
        testActors.put(a.getName(), a);
    }
    for (int i = 0; i < 5; i++) {
        Actor a = am.createActor(TestActor.class, "actor" + i);
        testActors.put(a.getName(), a);
    }
    for (String key : testActors.keySet()) {
       am.startActor(testActors.get(key));
    }    
    for (int i = 120; i > 0; i--) {
        if (i < 10 || i % 10 == 0) {
            System.out.printf("main waiting: %d...%n", i);
        }
        sleeper(1);
    }
    :
    am.terminateAndWait();

[main         ] - main waiting: 120...
[actor17      ] - TestActor:actor4 repeat(4)
[actor0       ] - TestActor:actor1 repeat(4)
[actor10      ] - TestActor:common1 repeat(4)
[actor1       ] - TestActor:actor2 repeat(4)
[actor3       ] - TestActor:actor0 init(8)
[actor22      ] - TestActor:actor3 repeat(4)
[actor17      ] - TestActor:actor4 init(7)
[actor20      ] - TestActor:common0 repeat(4)
[actor24      ] - TestActor:actor0 repeat(4)   
[actor0       ] - TestActor:actor1 init(3)
[actor1       ] - TestActor:actor2 repeat(4)   
[actor20      ] - TestActor:common0 repeat(4)   
[actor17      ] - TestActor:actor4 repeat(4)   
[actor17      ] - TestActor:actor4 repeat(3)   
[actor0       ] - TestActor:actor1 repeat(8)   
[actor10      ] - TestActor:common1 repeat(4)   
[actor24      ] - TestActor:actor0 repeat(8)   
[actor0       ] - TestActor:actor1 repeat(8)   
[actor24      ] - TestActor:actor0 repeat(7)   
[actor22      ] - TestActor:actor3 repeat(4)   
[actor1       ] - TestActor:actor2 repeat(3)   
[actor20      ] - TestActor:common0 repeat(4)   
[actor22      ] - TestActor:actor3 init(5)
[actor24      ] - TestActor:actor0 repeat(7)   
[actor10      ] - TestActor:common1 repeat(4)   
[actor17      ] - TestActor:actor4 repeat(8)   
[actor1       ] - TestActor:actor2 repeat(3)   
[actor17      ] - TestActor:actor4 repeat(8)   
[actor0       ] - TestActor:actor1 repeat(8)   
[actor10      ] - TestActor:common1 repeat(4)   
[actor22      ] - TestActor:actor3 repeat(8)   
[actor0       ] - TestActor:actor1 repeat(7)   
[actor1       ] - TestActor:actor2 repeat(3)   
[actor0       ] - TestActor:actor1 repeat(3)   
[actor20      ] - TestActor:common0 repeat(4)   
[actor24      ] - TestActor:actor0 repeat(7)   
[actor24      ] - TestActor:actor0 repeat(6)   
[actor10      ] - TestActor:common1 repeat(8)   
[actor17      ] - TestActor:actor4 repeat(7)

[main         ] - main waiting: 20...
[actor0       ] - TestActor:actor4 repeat(0)   
[actor2       ] - TestActor:actor2 repeat(1)   
[actor3       ] - TestActor:actor0 repeat(0)   
[actor17      ] - TestActor:actor4 repeat(0)   
[actor0       ] - TestActor:actor1 repeat(2)   
[actor3       ] - TestActor:actor2 repeat(1)   
[actor14      ] - TestActor:actor1 repeat(2)   
[actor5       ] - TestActor:actor4 repeat(0)   
[actor14      ] - TestActor:actor2 repeat(0)   
[actor21      ] - TestActor:actor1 repeat(0)   
[actor14      ] - TestActor:actor0 repeat(1)   
[actor14      ] - TestActor:actor4 repeat(0)   
[actor5       ] - TestActor:actor2 repeat(1)   
[actor5       ] - TestActor:actor4 repeat(1)   
[actor6       ] - TestActor:actor1 repeat(1)   
[actor5       ] - TestActor:actor3 repeat(0)   
[actor6       ] - TestActor:actor2 repeat(1)   
[actor4       ] - TestActor:actor0 repeat(0)   
[actor5       ] - TestActor:actor4 repeat(1)   
[actor12      ] - TestActor:actor1 repeat(0)   
[actor20      ] - TestActor:actor2 repeat(2)   
[main         ] - main waiting: 10...
[actor7       ] - TestActor:actor4 repeat(2)   
[actor23      ] - TestActor:actor1 repeat(0)   
[actor13      ] - TestActor:actor2 repeat(1)   
[actor8       ] - TestActor:actor0 repeat(0)   
[main         ] - main waiting: 9...
[actor2       ] - TestActor:actor1 repeat(0)   
[main         ] - main waiting: 8...
[actor7       ] - TestActor:actor2 repeat(0)   
[actor13      ] - TestActor:actor1 repeat(0)   
[main         ] - main waiting: 7...
[actor2       ] - TestActor:actor2 repeat(2)   
[main         ] - main waiting: 6...
[main         ] - main waiting: 5...
[actor18      ] - TestActor:actor1 repeat(1)   
[main         ] - main waiting: 4...
[actor15      ] - TestActor:actor2 repeat(0)   
[actor16      ] - TestActor:actor1 repeat(1)   
[main         ] - main waiting: 3...
[main         ] - main waiting: 2...
[main         ] - main waiting: 1...
[actor4       ] - TestActor:actor1 repeat(0)   
[actor6       ] - TestActor:actor2 repeat(0)

public class ProducerActor extends AbstractActor {
  Map<String , Integer> expected = new ConcurrentHashMap<String
        , Integer>();

  @Override
  protected void loopBody(Message m) {
    String subject = m.getSubject();
    if ("produceN".equals(subject)) {
      Object[] input = (Object[]) m.getData();
      int count = (Integer) input[0];
      if (count > 0) {
        DefaultActorTest.sleeper(1); // this takes some time
        String type = (String) input[1];
        // request the consumers to consume work (i.e., produce)
        Integer mcount = expected.get(type);
        if (mcount == null) {
          mcount = new Integer(0);
        }
        mcount += count;
        expected.put(type, mcount);

        DefaultMessage dm = new DefaultMessage("produce1", 
          new Object[] { count, type });
        getManager().send(dm, this, this);
      }

    } else if ("produce1".equals(subject)) {
      Object[] input = (Object[]) m.getData();
      int count = (Integer) input[0];
      if (count > 0) {
        sleep(100); // take a little time
        String type = (String) input[1];
        m = new DefaultMessage("construct", type);
        getManager().send(m, this, getConsumerCategory());

        m = new DefaultMessage("produce1", new Object[] { count - 1, type });
        getManager().send(m, this, this);
      }

    } else if ("constructionComplete".equals(subject)) {
      String type = (String) m.getData();
      Integer mcount = expected.get(type);
      if (mcount != null) {
        mcount--;
        expected.put(type, mcount);
      }

    } else if ("init".equals(subject)) {
      // create some consumers; 1 to 3 x consumers per producer
      for (int i = 0; i < DefaultActorTest.nextInt(3) + 1; i++) {
        Actor a = getManager().createAndStartActor(ConsumerActor.class,
            String.format("%s_consumer%02d", getName(), i));
        a.setCategory(getConsumerCategory());
        if (actorTest != null) {
          actorTest.getTestActors().put(a.getName(), a);
        }
      }
      // request myself create some work items
      for (int i = 0; i < DefaultActorTest.nextInt(10) + 1; i++) {
        m = new DefaultMessage("produceN", new Object[] 
             { DefaultActorTest.nextInt(10) + 1,
               DefaultActorTest.getItemTypes()[
                  DefaultActorTest.nextInt(DefaultActorTest.getItemTypes().length)] });
        getManager().send(m, this, this);
      }

    } else {
      System.out.printf("ProducerActor:%s loopBody unknown subject: %s%n", 
         getName(), subject);
    }
  }

  protected String getConsumerCategory() {
    return getName() + "_consumer";
  }
}

public class ConsumerActor extends AbstractActor {

  @Override
  protected void loopBody(Message m) {
    String subject = m.getSubject();
    if ("construct".equals(subject)) {
      String type = (String) m.getData();
      delay(type); // takes ~ 1 to N seconds

      DefaultMessage dm = new 
         DefaultMessage("constructionComplete", type);
      getManager().send(dm, this, m.getSource());
    } else if ("init".equals(subject)) {
      // nothing to do
    } else {
      System.out.printf("ConsumerActor:%s loopBody unknown subject: %s%n", 
        getName(), subject);
    }
  }

  protected void delay(String type) {
    int delay = 1;
    for (int i = 0; i < DefaultActorTest.getItemTypes().length; i++) {
      if (DefaultActorTest.getItemTypes()[i].equals(type)) {
        break;
      }
      delay++;
    }
    DefaultActorTest.sleeper(DefaultActorTest.nextInt(delay) + 1);
  }
}

public class CommandActor extends AbstractActor {

  @Override
  protected void loopBody(Message m) {
    String subject = m.getSubject();
    if ("execute".equals(subject)) {
      excuteMethod(m, false);
    } else if ("executeStatic".equals(subject)) {
      excuteMethod(m, true);
    } else if ("init".equals(subject)) {
      // nothing to do
    } else {
      System.out.printf("CommandActor:%s loopBody unknown subject: %s",
          getName(), subject);
    }
  }

  private void excuteMethod(Message m, boolean fstatic) {
    Object res = null;
    Object id = null;
    try {
      Object[] params = (Object[]) m.getData();
      id = params[0];
      String className = (String) params[1];
      params = params.length > 2 ? (Object[]) params[2] : null;
      Class<?> clazz = Class.forName(className);
      Method method = clazz.getMethod(fstatic ? "executeStatic"
          : "execute", new Class[] { Object.class });
      if (Modifier.isStatic(method.getModifiers()) == fstatic) {
        Object target = fstatic ? null : clazz.newInstance();
        res = method.invoke(target, params);
      }
    } catch (Exception e) {
      res = e;
    }

    DefaultMessage dm = new DefaultMessage("executeComplete", new Object[] {
        id, res });
    getManager().send(dm, this, m.getSource());
  }
}

public class DelegatingActor extends AbstractActor {
  private List<MessageListener> listeners = new LinkedList<MessageListener>();

  public void addMessageListener(MessageListener ml) {
    if (!listeners.contains(ml)) {
      listeners.add(ml);
    }
  }

  public void removeMessageListener(MessageListener ml) {
    listeners.remove(ml);
  }

  protected void fireMessageListeners(MessageEvent me) {
    for (MessageListener ml : listeners) {
      if (me.isConsumed()) {
        break;
      }
      ml.onMessage(me);
    }
  }

  @Override
  protected void loopBody(Message m) {
    fireMessageListeners(new MessageEvent(this, m));
  }
}

/** Defines a message arrival event. */
public static class MessageEvent extends EventObject {
  private Message message;

  public Message getMessage() {
    return message;
  }

  public void setMessage(Message message) {
    this.message = message;
  }

  private boolean consumed;

  public boolean isConsumed() {
    return consumed;
  }

  public void setConsumed(boolean consumed) {
    this.consumed = consumed;
  }

  public MessageEvent(Object source, Message msg) {
    super(source);
    setMessage(msg);
  }
}

/** Defines the message arrival call back. */
public interface MessageListener {
  void onMessage(MessageEvent me);
}

public static void addDelegate(DelegatingActor da) {
  MessageListener ml = new Echo("Hello world!");
  da.addMessageListener(ml);
}
	
	
public class Echo implements MessageListener {
  protected String message;

  public Echo(String message) {
    this.message = message;
  }

  @Override
  public void onMessage(MessageEvent me) {
    if ("echo".equals(me.getMessage().getSubject())) {
      System.out.printf("%s says \"%s\".%n", 
         me.getMessage().getSource(), message);
      me.setConsumed(true);
    }
  }
}

public interface MapReduceer {
  /**
   * Map (in place) the elements of an array.
   * 
   * @param values elements to map
   * @param start start position in values
   * @param end end position in values
   */
  void map(Object[] values, int start, int end);

  /**
   * Reduce the elements of an array.
   * 
   * @param values elements to reduce
   * @param start start position in values
   * @param end end position in values
   * @param target place to set reduced value
   * @param posn position in target to place the value
   */
  void reduce(Object[] values, int start, int end, Object[] target, int posn);
}

public class SumOfSquaresReducer implements MapReduceer {
  @Override
  public void map(Object[] values, int start, int end) {
    for (int i = start; i <= end; i++) {
      values[i] = ((BigInteger) values[i]).multiply((BigInteger) values[i]);
      sleep(200); // fake taking time
    }
  }

  @Override
  public void reduce(Object[] values, int start, int end, Object[] target, int posn) {
    BigInteger res = new BigInteger("0");
    for (int i = start; i <= end; i++) {
      res = res.add((BigInteger) values[i]);
      sleep(100); // fake taking time
    }
    target[posn] = res;
  }
}

  @Override
  protected void loopBody(Message m) {
    ActorManager manager = getManager();
    String subject = m.getSubject();
    if ("mapReduce".equals(subject)) {
      try {
        MapReduceParameters p = (MapReduceParameters) m.getData();
        int index = 0;
        int count = (p.end - p.start + 1 + partitionSize - 1) / partitionSize;
        sleep(1000);
        // split up into partition size chunks
        while (p.end - p.start + 1 >= partitionSize) {
          MapReduceParameters xp = new MapReduceParameters(p);
          xp.end = xp.start + partitionSize - 1;
          DefaultMessage lm = new DefaultMessage("createPartition", 
            new Object[] { xp, index, count });
          manager.send(lm, this, getCategory());
          p.start += partitionSize;
          index++;
        }
        if (p.end - p.start + 1 > 0) {
          DefaultMessage lm = new DefaultMessage("createPartition", 
            new Object[] { p, index, count });
          manager.send(lm, this, getCategory());
        }
      } catch (Exception e) {
        triageException("mapFailed", m, e);
      }
}

    } else if ("createPartition".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        int index = (Integer) oa[1];
        int count = (Integer) oa[2];
        sleep(500);
        createMapReduceActor(this);
        DefaultMessage lm = new DefaultMessage("mapWorker", 
          new Object[] { p, index, count });
        manager.send(lm, this, getCategory());
      } catch (Exception e) {
        triageException("createPartitionFailed", m, e);
      }
}

    } else if ("mapWorker".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        int index = (Integer) oa[1];
        int count = (Integer) oa[2];
        sleep(100);
        p.mr.map(p.values, p.start, p.end);
        DefaultMessage rm = new DefaultMessage("mapResponse", 
          new Object[] { p, index, count });
        manager.send(rm, this, getCategoryName());
      } catch (Exception e) {
        triageException("mapWorkerFailed", m, e);
      }
}

    } else if ("mapResponse".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        int index = (Integer) oa[1];
        int count = (Integer) oa[2];
        sleep(100);
        p.complete();
        DefaultMessage rm = new DefaultMessage("reduce", 
          new Object[] { p, index, count });
        manager.send(rm, this, getCategoryName());
      } catch (Exception e) {
        triageException("mapResponseFailed", m, e);
      }
}

    } else if ("reduce".equals(subject)) {
      try {
        MapReduceParameters p = null;
        int index = 0, count = 0;
        Object o = m.getData();
        if (o instanceof MapReduceParameters) {
          p = (MapReduceParameters) o;
        } else {
          Object[] oa = (Object[]) o;
          p = (MapReduceParameters) oa[0];
          index = (Integer) oa[1];
          count = (Integer) oa[2];
        }
        sleep(100);
        if (p.end - p.start + 1 > 0) {
          createMapReduceActor(this);
          MapReduceParameters xp = new MapReduceParameters(p);
          DefaultMessage lm = new DefaultMessage("reduceWorker", 
            new Object[] { xp, index, count });
          manager.send(lm, this, getCategory());
        }
      } catch (Exception e) {
        triageException("reduceFailed", m, e);
      }
}

    } else if ("reduceWorker".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        int index = (Integer) oa[1];
        int count = (Integer) oa[2];
        sleep(100);
        if (index >= 0) {
          p.mr.reduce(p.values, p.start, p.end, p.target, index);
          DefaultMessage rm = new DefaultMessage("reduceResponse", 
            new Object[] { p, index, count });
          manager.send(rm, this, getCategory());
        } else {
          Object[] res = new Object[1];
          p.mr.reduce(p.target, 0, count - 1, res, 0);
          DefaultMessage rm = new DefaultMessage("done", 
            new Object[] { p, res[0] });
          manager.send(rm, this, getCategory());
        }
      } catch (Exception e) {
        triageException("reduceWorkerFailed", m, e);
      }
}

    } else if ("reduceResponse".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        int index = (Integer) oa[1];
        int count = (Integer) oa[2];
        sleep(100);
        p.complete();
        if (p.isSetComplete()) {
          if (count > 0) {
            createMapReduceActor(this);
            MapReduceParameters xp = new MapReduceParameters(p);
            DefaultMessage lm = new DefaultMessage("reduceWorker", 
              new Object[] { xp, -1, count });
            manager.send(lm, this, getCategory());
          }
        }
      } catch (Exception e) {
        triageException("mapResponseFailed", m, e);
      }
}

    } else if ("done".equals(subject)) {
      try {
        Object[] oa = (Object[]) m.getData();
        MapReduceParameters p = (MapReduceParameters) oa[0];
        Object res = oa[1];
        sleep(100);
        System.out.printf("**** mapReduce done with result %s", res);
      } catch (Exception e) {
        triageException("mapResponseFailed", m, e);
      }
}

    } else if ("init".equals(subject)) {
      try {
        Object[] params = (Object[]) m.getData();
        if (params != null) {
          Object[] values = (Object[]) params[0];
          Object[] targets = (Object[]) params[1];
          Class clazz = (Class) params[2];
          MapReduceer mr = (MapReduceer) clazz.newInstance();
          sleep(2 * 1000);
          MapReduceParameters p = new MapReduceParameters("mrSet_" + setCount++, 
            values, targets, mr, this);
          DefaultMessage rm = new DefaultMessage("mapReduce", p);
          manager.send(rm, this, getCategoryName());
        }
      } catch (Exception e) {
        triageException("initFailed", m, e);
      }
    } else {
      System.out.printf("**** MapReduceActor:%s loopBody unexpected subject: %s", 
        getName(), subject);
    }
  }
}

BigInteger[] values = new BigInteger[1000];
for (int i = 0; i < values.length; i++) {
  values[i] = new BigInteger(Long.toString((long)rand.nextInt(values.length)));
}
BigInteger[] targets = new BigInteger[Math.max(1, values.length / 10)];

// start at least 5 actors
DefaultActorManager am = new DefaultActorManager();
MapReduceActor.createMapReduceActor(am, 10);
MapReduceActor.createMapReduceActor(am, 10);
MapReduceActor.createMapReduceActor(am, 10);
MapReduceActor.createMapReduceActor(am, 10);
MapReduceActor.createMapReduceActor(am, 10);
        
DefaultMessage dm = new DefaultMessage("init", new Object[] 
    { values, targets, SumOfSquaresReducer.class });
am.send(dm, null, MapReduceActor.getCategoryName());

public abstract class AbstractActor implements Actor {
  protected DefaultActorManager manager;

  @Override
  public boolean receive() {
    Message m = testMessage();
    boolean res = m != null;
    if (res) {
      remove(m);
      try {
        loopBody(m);
      } catch (Exception e) {
        System.out.printf("loop exception: %s%n", e);
      }
    }
    manager.awaitMessage(this);
    return res;
  }

  abstract protected void loopBody(Message m);

  @Override
  public boolean willReceive(String subject) {
    return !isEmpty(subject); 
  }

  protected Message testMessage() {
    return getMatch(null, false);
  }

  protected Message getMatch(String subject, boolean isRegExpr) {
    Message res = null;
    synchronized (messages) {
      res = peekNext(subject, isRegExpr);
    }
    return res;
  }

  public static final int DEFAULT_MAX_MESSAGES = 100;
  protected List<DefaultMessage> messages = new LinkedList<DefaultMessage>();

  @Override
  public int getMessageCount() {
    synchronized (messages) {
      return messages.size();
    }
  }

  @Override
  public int getMaxMessageCount() {
    return DEFAULT_MAX_MESSAGES;
  }

  public void addMessage(Message message) {
    synchronized (messages) {
      if (messages.size() < getMaxMessageCount()) {
        messages.add(message);
      } else {
        throw new IllegalStateException("too many messages, cannot add");
      }
    }
  }

  @Override
  public boolean remove(Message message) {
    synchronized (messages) {
      return messages.remove(message);
    }
  }

  @Override
  public Message peekNext() {
    return peekNext(null);
  }

  @Override
  public Message peekNext(String subject) {
    return peekNext(subject, false);
  }

  @Override
  public Message peekNext(String subject, boolean isRegExpr) {
    long now = new Date().getTime();
    Message res = null;
    Pattern p = subject != null ? (isRegExpr ? Pattern.compile(subject) : null) : null;
    synchronized (messages) {
      for (DefaultMessage m : messages) {
        if (m.getDelayUntil() <= now) {
          boolean match = subject == null || 
            (isRegExpr ? m.subjectMatches(p) : m.subjectMatches(subject));
          if (match) {
            res = m;
            break;
          }
        }
      }
    }
    return res;
  }

  @Override
  public void activate() {
    // defaults to no action
  }

  @Override
  public void deactivate() {
    // defaults to no action
  }

  /** Do startup processing. */
  protected abstract void runBody();

  @Override
  public void run() {
    runBody();
    ((DefaultActorManager) getManager()).awaitMessage(this);
  }
}

public class DefaultActorManager implements ActorManager {

  public static final int DEFAULT_ACTOR_THREAD_COUNT = 25;

  protected static DefaultActorManager instance;
  public static DefaultActorManager getDefaultInstance() {
    if (instance == null) {
      instance = new DefaultActorManager();
    }
    return instance;
  }

  protected Map<String , AbstractActor> actors = 
    new LinkedHashMap<String , AbstractActor>();

  protected Map<String , AbstractActor> runnables = 
    new LinkedHashMap<String , AbstractActor>();

  protected Map<String , AbstractActor> waiters = 
    new LinkedHashMap<String , AbstractActor>();

  protected List<Thread> threads = new LinkedList<Thread>();

  @Override
  public void detachActor(Actor actor) {
    synchronized (actors) {
      actor.deactivate();
      ((AbstractActor)actor).setManager(null);
      String name = actor.getName();
      actors.remove(name);
      runnables.remove(name);
      waiters.remove(name);
    }
  }

  @Override
  public int send(Message message, Actor from, Actor to) {
    int count = 0;
    AbstractActor aa = (AbstractActor) to;
    if (aa != null) {
      if (aa.willReceive(message.getSubject())) {
        DefaultMessage xmessage = (DefaultMessage) 
           ((DefaultMessage) message).assignSender(from);
        aa.addMessage(xmessage);
        count++;
        synchronized (actors) {
          actors.notifyAll();
        }
      }
    }
    return count;
  }

  @Override
  public int send(Message message, Actor from, Actor[] to) {
    int count = 0;
    for (Actor a : to) {
      count += send(message, from, a);
    }
    return count;
  }

  @Override
  public int send(Message message, Actor from, Collection<Actor> to) {
    int count = 0;
    for (Actor a : to) {
      count += send(message, from, a);
    }
    return count;
  }

  @Override
  public int send(Message message, Actor from, String category) {
    int count = 0;
    Map<String, Actor> xactors = cloneActors();
    List<Actor> catMembers = new LinkedList<Actor>();
    for (String key : xactors.keySet()) {
      Actor to = xactors.get(key);
      if (category.equals(to.getCategory()) && 
            (to.getMessageCount() < to.getMaxMessageCount())) {
        catMembers.add(to);
      }
    }
    // find an actor with lowest message count
    int min = Integer.MAX_VALUE;
    Actor amin = null;
    for (Actor a : catMembers) {
      int mcount = a.getMessageCount();
      if (mcount < min) {
        min = mcount;
        amin = a;
      }
    }
    if (amin != null) {
      count += send(message, from, amin);
    }
    return count;
  }

  @Override
  public int broadcast(Message message, Actor from) {
    int count = 0;
    Map<String, Actor> xactors = cloneActors();
    for (String key : xactors.keySet()) {
      Actor to = xactors.get(key);
      count += send(message, from, to);
    }
    return count;
  }

  public void awaitMessage(AbstractActor a) {
    synchronized (actors) {
      waiters.put(a.getName(), a);
    }
  }

  protected static int groupCount;

  @Override
  public void initialize(Map<String, Object> options) {
    int count = getThreadCount(options);
    ThreadGroup tg = new ThreadGroup("ActorManager" + groupCount++);
    for (int i = 0; i < count; i++) {
      Thread t = new Thread(tg, new ActorRunnable(), "actor" + i);
      threads.add(t);
      t.setDaemon(true);
      t.setPriority(Math.max(Thread.MIN_PRIORITY, 
         Thread.currentThread().getPriority() - 1));
    }
    running = true;
    for (Thread t : threads) {
      t.start();
    }
  }

  public class ActorRunnable implements Runnable {
    public void run() {
      int delay = 1;
      while (running) {
        try {
          if (!procesNextActor()) {
            synchronized (actors) {
              actors.wait(delay * 1000);
            }
            delay = Math.max(5, delay + 1);
          } else {
            delay = 1;
          }
        } catch (InterruptedException e) {
        } catch (Exception e) {
          System.out.printf("procesNextActor exception %s%n", e);
        }
      }
    }
  }

  protected boolean procesNextActor() {
    boolean run = false, wait = false, res = false;
    AbstractActor a = null;
    synchronized (actors) {
      for (String key : runnables.keySet()) {
        a = runnables.remove(key);
        break;
      }
    }
    if (a != null) {
      run = true;
      a.run();
    } else {
      synchronized (actors) {
        for (String key : waiters.keySet()) {
          a = waiters.remove(key);
          break;
        }
      }
      if (a != null) {
        // then waiting for responses
        wait = true;
        res = a.receive();
      }
    }
    return run || res;
  }

@Override
  public void terminateAndWait() {
    terminate();
    for (Thread t : threads) {
      try {
        t.join();
      } catch (InterruptedException e) {
      }
    }
  }

  boolean running;

  @Override
  public void terminate() {
    running = false;
    for(Thread t: threads) {
      t.interrupt();
    }
    synchronized (actors) {
      for (String key : actors.keySet()) {
        actors.get(key).deactivate();
      }
    }
  }

@Override
  public Actor createAndStartActor(Class<? extends Actor> clazz, String name, 
        Map<String, Object> options) {
    Actor res = createActor(clazz, name, options);
    startActor(res);
    return res;
  }

  @Override
  public Actor createActor(Class<? extends Actor> clazz, String name, 
       Map<String, Object> options) {
    AbstractActor a = null;
    synchronized (actors) {
      if (!actors.containsKey(name)) {
        try {
          a = (AbstractActor) clazz.newInstance();
          a.setName(name);
          a.setManager(this);
        } catch (Exception e) {
          throw e instanceof RuntimeException ? 
             (RuntimeException) e : new RuntimeException(
              "mapped exception: " + e, e);
        }
      } else {
        throw new IllegalArgumentException("name already in use: " + name);
      }
    }
    return a;
  }
}

  @Override
  public void startActor(Actor a) {
    a.activate();
    synchronized (actors) {
      String name = a.getName();
      actors.put(name, (AbstractActor) a);
      runnables.put(name, (AbstractActor) a);
    }
  }