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HdrHistogram supports the recording and analyzing sampled data value counts across a configurable integer value range with configurable value precision within the range. Value precision is expressed as the number of significant digits in the value recording, and provides control over value quantization behavior across the value range and the subsequent value resolution at any given level.

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/**
 * Written by Gil Tene of Azul Systems, and released to the public domain,
 * as explained at http://creativecommons.org/publicdomain/zero/1.0/
 *
 * @author Gil Tene
 */

package org.HdrHistogram;

import java.util.Iterator;

/**
 * Used for iterating through {@link DoubleHistogram} values values according to percentile levels. The iteration is
 * performed in steps that start at 0% and reduce their distance to 100% according to the
 * percentileTicksPerHalfDistance parameter, ultimately reaching 100% when all recorded histogram
 * values are exhausted.
 */
public class DoublePercentileIterator implements Iterator {
    private final PercentileIterator integerPercentileIterator;
    private final DoubleHistogramIterationValue iterationValue;
    DoubleHistogram histogram;

    /**
     * Reset iterator for re-use in a fresh iteration over the same histogram data set.
     *
     * @param percentileTicksPerHalfDistance The number of iteration steps per half-distance to 100%.
     */
    public void reset(final int percentileTicksPerHalfDistance) {
        integerPercentileIterator.reset(percentileTicksPerHalfDistance);
    }

    /**
     * @param histogram The histogram this iterator will operate on
     * @param percentileTicksPerHalfDistance The number of iteration steps per half-distance to 100%.
     */
    public DoublePercentileIterator(final DoubleHistogram histogram, final int percentileTicksPerHalfDistance) {
        this.histogram = histogram;
        integerPercentileIterator = new PercentileIterator(
                histogram.integerValuesHistogram,
                percentileTicksPerHalfDistance
        );
        iterationValue = new DoubleHistogramIterationValue(integerPercentileIterator.currentIterationValue);
    }

    @Override
    public boolean hasNext() {
        return integerPercentileIterator.hasNext();
    }

    @Override
    public DoubleHistogramIterationValue next() {
        integerPercentileIterator.next();
        return iterationValue;
    }

    @Override
    public void remove() {
        integerPercentileIterator.remove();
    }
}