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package com.sun.btrace.aggregation;

/**
 * An element of aggregated data stored in an {@link Aggregation}.
 * 
 * Concrete implementations of this interface will implement different aggregating functions.
 * <p>
 * 
 * @author Christian Glencross
 */
public interface AggregationValue {

    /**
     * Adds a data item to the aggregated value.
     * 
     * @param data
     *            the data value
     */
    void add(long data);

    /**
     * Removes all data items previously added.
     */
    void clear();

    /**
     * @return the aggregated value of all data items added since the aggregation was created or last cleared. The
     *         aggregation function is determined by the concrete implementation of the interface.
     */
    long getValue();

    /**
     * @return an object representation of the aggregated value. For most implementations this may be equivalent to
     *         <code>Integer.valueOf( getValue() )</code>. More complex aggregations such may return objects
     *         representing histograms, etc.
     */
    Object getData();
}