/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package com.sun.corba.se.spi.monitoring;

import java.util.*;

/**

 * <p>

 *

 * @author Hemanth Puttaswamy

 * </p>

 * <p>

 * StatisticsMonitoredAttribute is provided as a convenience to collect the

 * Statistics of any entity. The getValue() call will be delegated to the

 * StatisticsAccumulator set by the user.

 * </p>

 */

public class StatisticMonitoredAttribute extends MonitoredAttributeBase {

    // Every StatisticMonitoredAttribute will have a StatisticAccumulator. User

    // will use Statisticsaccumulator to accumulate the samples associated with

    // this Monitored Attribute

    private StatisticsAccumulator statisticsAccumulator;

    // Mutex is passed from the user class which is providing the sample values.

    // getValue() and clearState() is synchronized on this user provided mutex

    private Object  mutex;

  ///////////////////////////////////////

  // operations

/**

 * <p>

 * Constructs the StaisticMonitoredAttribute, builds the required

 * MonitoredAttributeInfo with Long as the class type and is always

 * readonly attribute.

 * </p>

 * <p>

 *

 * @param name Of this attribute

 * </p>

 * <p>

 * @return a StatisticMonitoredAttribute

 * </p>

 * <p>

 * @param desc should provide a good description on the kind of statistics

 * collected, a good example is "Connection Response Time Stats will Provide the

 * detailed stats based on the samples provided from every request completion

 * time"

 * </p>

 * <p>

 * @param s is the StatisticsAcumulator that user will use to accumulate the

 * samples and this Attribute Object will get the computed statistics values

 * from.

 * </p>

 * <p>

 * @param mutex using which clearState() and getValue() calls need to be locked.

 * </p>

 */

    public  StatisticMonitoredAttribute(String name, String desc,

        StatisticsAccumulator s, Object mutex)

    {

        super( name );

        MonitoredAttributeInfoFactory f =

            MonitoringFactories.getMonitoredAttributeInfoFactory();

        MonitoredAttributeInfo maInfo = f.createMonitoredAttributeInfo(

                desc, String.class, false, true );

        this.setMonitoredAttributeInfo( maInfo );

        this.statisticsAccumulator = s;

        this.mutex = mutex;

    } // end StatisticMonitoredAttribute

/**

 *  Gets the value from the StatisticsAccumulator, the value will be a formatted

 *  String with the computed statistics based on the samples accumulated in the

 *  Statistics Accumulator.

 */

    public Object getValue( ) {

        synchronized( mutex ) {

            return statisticsAccumulator.getValue( );

        }

    }

/**

 *  Clears the state on Statistics Accumulator, After this call all samples are

 *  treated fresh and the old sample computations are disregarded.

 */

    public void clearState( ) {

        synchronized( mutex ) {

            statisticsAccumulator.clearState( );

        }

    }

/**

 *  Gets the statistics accumulator associated with StatisticMonitoredAttribute.

 *  Usually, the user don't need to use this method as they can keep the handle

 *  to Accumulator to collect the samples.

 */

    public StatisticsAccumulator getStatisticsAccumulator( ) {

        return statisticsAccumulator;

    }

} // end StatisticMonitoredAttribute