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/*
 * Copyright 2004-2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * MutableAverageRangeStatisticImpl.java
 *
 * Created on May 11, 2004, 2:22 PM
 */

package com.sun.enterprise.admin.monitor.stats;

import javax.management.j2ee.statistics.Statistic;
import javax.management.j2ee.statistics.BoundedRangeStatistic;

/** An implementation of AverageRangeStatistic that provides ways to change the state externally through mutators.
 * Convenience class that is useful for components that gather the statistical data.
 * By merely changing the count (which is a mandatory measurement), rest of the statistical
 * information could be deduced.
 * @author Larry White
 * @author Kedar Mhaswade
 * @see AverageRangeStatisticImpl for an immutable implementation
 * @since S1AS8.1
 * @version 1.0
 */

/**
 *
 * @author  lwhite
 */
public class MutableAverageRangeStatisticImpl implements AverageRangeStatistic, MutableCountStatistic {

    /** DEFAULT_UPPER_BOUND is maximum value Long can attain */
    public static final long DEFAULT_MAX_BOUND = java.lang.Long.MAX_VALUE;
        
    private MutableBoundedRangeStatisticImpl    mutableBoundedRangeStat = null;
    private long                                numberOfSamples;
    private long                                runningTotal;
    private String                              description = null;
    
    /** Constructs an instance of MutableAverageRangeStatisticImpl that encapsulates the given Statistic.
     * The only parameter denotes the initial state of this statistic. It is
     * guaranteed that the initial state is preserved internally, so that one
     * can reset to the initial state.
     * @param initial           an instance of BoundedRangeStatistic that represents initial state
     */
    public MutableAverageRangeStatisticImpl(BoundedRangeStatistic initial) {
        mutableBoundedRangeStat = new MutableBoundedRangeStatisticImpl(initial);
        numberOfSamples = 0L;
        runningTotal = 0L;
        description = initial.getDescription();        
    }
    
    public Statistic modifiableView() {        
        return this;
    }
    
    public Statistic unmodifiableView() {        
        return ( new AverageRangeStatisticImpl(
            this.getCurrent(),               // this is the actual changing statistic
            this.getHighWaterMark(),         // highWaterMark may change per current
            this.getLowWaterMark(),          // lowWaterMark may change per current
            mutableBoundedRangeStat.getUpperBound(),    // upperBound is not designed to change
            mutableBoundedRangeStat.getLowerBound(),    // lowerBound is not designed to change
            mutableBoundedRangeStat.getName(),          // name does not change
            mutableBoundedRangeStat.getUnit(),          // unit does not change
            mutableBoundedRangeStat.getDescription(),   // description does not change
            this.getLastSampleTime(),        // changes all the time!
            this.getStartTime(),             // changes if reset is called earlier
            this.numberOfSamples,       // this is the current number of samples
            this.runningTotal           // this is the current running total
        ));        
    }    

    public void reset() {
        mutableBoundedRangeStat.reset();
        this.resetAverageStats();
    }
    
    private void resetAverageStats() {
        numberOfSamples = 0L;
        runningTotal = 0L;
    }    
    
    public void setCount(long current) {
        mutableBoundedRangeStat.setCount(current);
        if(DEFAULT_MAX_BOUND - runningTotal < current) {
            this.resetAverageStats();
        }
        numberOfSamples++;
        runningTotal += current;
    }
    
    public long getAverage() {
        if(numberOfSamples == 0) {
            return -1;
        } else {
            return runningTotal / numberOfSamples;
        }
    }
    
    public long getCurrent() {
        return mutableBoundedRangeStat.getCurrent();
    }
    
    public String getDescription() {
        return description;
        //return mutableBoundedRangeStat.getDescription();
    }
    
    public long getHighWaterMark() {
        return mutableBoundedRangeStat.getHighWaterMark();
    }
    
    public long getLastSampleTime() {
        return mutableBoundedRangeStat.getLastSampleTime();
    }
    
    public long getLowWaterMark() {
        long result = mutableBoundedRangeStat.getLowWaterMark();
        if(result == DEFAULT_MAX_BOUND) {
            result = 0L;
        }
        return result;
    }
    
    public String getName() {
        return mutableBoundedRangeStat.getName();
    }
    
    public long getStartTime() {
        return mutableBoundedRangeStat.getStartTime();
    }
    
    public String getUnit() {
        return mutableBoundedRangeStat.getUnit();
    }
    
}