com.espertech.esper.epl.agg.BigDecimalAvgAggregator.java Source code

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Here is the source code for com.espertech.esper.epl.agg.BigDecimalAvgAggregator.java

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/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * http://www.espertech.com                                                           *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the GPL license       *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package com.espertech.esper.epl.agg;

import com.espertech.esper.epl.core.MethodResolutionService;

import java.math.BigDecimal;
import java.math.BigInteger;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Average that generates a BigDecimal numbers.
 */
public class BigDecimalAvgAggregator implements AggregationMethod {
    private static final Log log = LogFactory.getLog(BigDecimalAvgAggregator.class);
    private BigDecimal sum;
    private long numDataPoints;

    /**
     * Ctor.
     */
    public BigDecimalAvgAggregator() {
        sum = new BigDecimal(0.0);
    }

    public void clear() {
        sum = new BigDecimal(0.0);
        numDataPoints = 0;
    }

    public void enter(Object object) {
        if (object == null) {
            return;
        }
        numDataPoints++;
        if (object instanceof BigInteger) {
            sum = sum.add(new BigDecimal((BigInteger) object));
            return;
        }
        sum = sum.add((BigDecimal) object);
    }

    public void leave(Object object) {
        if (object == null) {
            return;
        }
        numDataPoints--;
        if (object instanceof BigInteger) {
            sum = sum.subtract(new BigDecimal((BigInteger) object));
            return;
        }
        sum = sum.subtract((BigDecimal) object);
    }

    public Object getValue() {
        if (numDataPoints == 0) {
            return null;
        }
        try {
            return sum.divide(new BigDecimal(numDataPoints));
        } catch (ArithmeticException ex) {
            log.error("Error computing avg aggregation result: " + ex.getMessage(), ex);
            return new BigDecimal(0);
        }
    }

    public Class getValueType() {
        return Double.class;
    }

    public AggregationMethod newAggregator(MethodResolutionService methodResolutionService) {
        return methodResolutionService.makeAvgAggregator(BigDecimal.class, false);
    }
}