/**

  * Copyright (c) 2012, University of Konstanz, Distributed Systems Group

  * All rights reserved.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  * * Redistributions of source code must retain the above copyright

  * notice, this list of conditions and the following disclaimer.

  * * Redistributions in binary form must reproduce the above copyright

  * notice, this list of conditions and the following disclaimer in the

  * documentation and/or other materials provided with the distribution.

  * * Neither the name of the University of Konstanz nor the

  * names of its contributors may be used to endorse or promote products

  * derived from this software without specific prior written permission.

  * 

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY

  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package org.perfidix.meter;

 /**

  * This class measures the number of threads in the runtime.

  * 

  * @author Sebastian Graf, University of Konstanz

  */

 public final class ThreadMeter extends AbstractMeter {

     /**

      * the threadgroup to analyse.

      */

     private transient final ThreadGroup topThreadGroup;

     /** Name of the Meter. */

     private static final String NAME = "ThreadMeter";

     /** Unit of the Meter. */

     private static final String UNIT = "threads";

     /** UnitDescription of the Meter. */

     private static final String DESCRIPTION = "Number of Threads";

     /**

      * Constructor;

      */

     public ThreadMeter() {

         super();

         final Thread ownThread = Thread.currentThread();

         final ThreadGroup ownGroup = ownThread.getThreadGroup();

         ThreadGroup group = null;

         do {

             group = ownGroup.getParent();

         } while (group.getParent() != null);

         this.topThreadGroup = group;

     }

     /**

      * Constructor.

      * 

      * @param group

      *            the group of number of threads to analyse.

      */

     public ThreadMeter(final ThreadGroup group) {

         super();

         this.topThreadGroup = group;

     }

     /** {@inheritDoc} */

     @Override

     public String getName() {

         return NAME;

     }

     /** {@inheritDoc} */

     @Override

     public String getUnit() {

         return UNIT;

     }

     /** {@inheritDoc} */

     @Override

     public String getUnitDescription() {

         return DESCRIPTION;

     }

     /** {@inheritDoc} */

     @Override

     public double getValue() {

         return topThreadGroup.activeCount();

     }

     /** {@inheritDoc} */

     @Override

     public int hashCode() {

         final int prime = 31;

         int result = prime;

         result = prime * result;

         return result;

     }

     /** {@inheritDoc} */

     @Override

     public boolean equals(final Object obj) {

         boolean returnVal = true;

         if (this == obj) {

             returnVal = true;

         }

         if (getClass() == obj.getClass()) {

             returnVal = true;

         } else {

             returnVal = false;

         }

         return returnVal;

     }

 }