waitableboolean.java

一个很好的微工作流内核

/*
  File: WaitableBoolean.java

  Originally written by Doug Lea and released into the public domain.
  This may be used for any purposes whatsoever without acknowledgment.
  Thanks for the assistance and support of Sun Microsystems Labs,
  and everyone contributing, testing, and using this code.

  History:
  Date       Who                What
  19Jun1998  dl               Create public version
*/

package EDU.oswego.cs.dl.util.concurrent;

/**
 * A class useful for offloading synch for boolean instance variables.
 *
 * <p>[<a href="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html"> Introduction to this package. </a>]
 **/

public class WaitableBoolean extends SynchronizedBoolean {

  /** Make a new WaitableBoolean with the given initial value **/
  public WaitableBoolean(boolean initialValue) { super(initialValue); }


  /** 
   * Make a new WaitableBoolean with the given initial value,
   * and using the supplied lock.
   **/
  public WaitableBoolean(boolean initialValue, Object lock) { 
    super(initialValue, lock); 
  }


  public boolean set(boolean newValue) { 
    synchronized (lock_) {
      lock_.notifyAll();
      return super.set(newValue);
    }
  }

  public boolean commit(boolean assumedValue, boolean newValue) {
    synchronized (lock_) {
      boolean success = super.commit(assumedValue, newValue);
      if (success) lock_.notifyAll();
      return success;
    }
  }

  public  boolean complement() { 
    synchronized (lock_) {
      lock_.notifyAll();
      return super.complement();
    }
  }

  public  boolean and(boolean b) { 
    synchronized (lock_) {
      lock_.notifyAll();
      return super.and(b);
    }
  }

  public  boolean or(boolean b) { 
    synchronized (lock_) {
      lock_.notifyAll();
      return super.or(b);
    }
  }

  public  boolean xor(boolean b) { 
    synchronized (lock_) {
      lock_.notifyAll();
      return super.xor(b);
    }
  }

  /**
   * Wait until value is false, then run action if nonnull.
   * The action is run with the synchronization lock held.
   **/

  public  void whenFalse(Runnable action) throws InterruptedException {
    synchronized (lock_) {
      while (value_) lock_.wait();
      if (action != null) action.run();
    }
  }

  /**
   * wait until value is true, then run action if nonnull.
   * The action is run with the synchronization lock held.
   **/
  public  void whenTrue(Runnable action) throws InterruptedException {
    synchronized (lock_) {
      while (!value_) lock_.wait();
      if (action != null) action.run();
    }
  }

  /**
   * Wait until value equals c, then run action if nonnull.
   * The action is run with the synchronization lock held.
   **/

  public  void whenEqual(boolean c, Runnable action) throws InterruptedException {
    synchronized (lock_) {
      while (!(value_ == c)) lock_.wait();
      if (action != null) action.run();
    }
  }

  /**
   * wait until value not equal to c, then run action if nonnull.
   * The action is run with the synchronization lock held.
   **/
  public  void whenNotEqual(boolean c, Runnable action) throws InterruptedException {
    synchronized (lock_) {
      while (!(value_ != c)) lock_.wait();
      if (action != null) action.run();
    }
  }

}