workrequest.java

pastry的java实现的2.0b版

/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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- Redistributions of source code must retain the above copyright
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- Redistributions in binary form must reproduce the above copyright
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documentation and/or other materials provided with the distribution.

- Neither  the name  of Rice  University (RICE) nor  the names  of its
contributors may be  used to endorse or promote  products derived from
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This software is provided by RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
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********************************************************************************/
/*
 *  Created on Aug 16, 2005
 */
package rice.environment.processing;

import rice.Continuation;
import rice.selector.SelectorManager;

/**
 * Extend this class and implement doWork() if you need to do blocking disk IO.
 * This is primarily used by Persistence.
 *
 * @version $Id: pretty.settings 2305 2005-03-11 20:22:33Z jeffh $
 * @author Jeff Hoye
 */
public abstract class WorkRequest implements Runnable {
  private Continuation c;
  private SelectorManager selectorManager;

  /**
   * Constructor for WorkRequest.
   *
   * @param c DESCRIBE THE PARAMETER
   * @param sm DESCRIBE THE PARAMETER
   */
  public WorkRequest(Continuation c, SelectorManager sm) {
    this.c = c;
    this.selectorManager = sm;
  }

  /**
   * Constructor for WorkRequest.
   */
  public WorkRequest() {
    /*
     *  do nothing
     */
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param o DESCRIBE THE PARAMETER
   */
  public void returnResult(Object o) {
    c.receiveResult(o);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param e DESCRIBE THE PARAMETER
   */
  public void returnError(Exception e) {
    c.receiveException(e);
  }

  /**
   * Main processing method for the WorkRequest object
   */
  public void run() {
    try {
      // long start = environment.getTimeSource().currentTimeMillis();
      final Object result = doWork();
      // System.outt.println("PT: " + (environment.getTimeSource().currentTimeMillis() - start) + " " + toString());
      selectorManager.invoke(
        new Runnable() {
          public void run() {
            returnResult(result);
          }

          public String toString() {
            return "invc result of " + c;
          }
        });
    } catch (final Exception e) {
      selectorManager.invoke(
        new Runnable() {
          public void run() {
            returnError(e);
          }

          public String toString() {
            return "invc error of " + c;
          }
        });
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   * @exception Exception DESCRIBE THE EXCEPTION
   */
  public abstract Object doWork() throws Exception;
}