aggregator.java

jrobin,使用纯java实现的RRD数据库,使用RRD数据库来统计数据.

/* ============================================================
 * JRobin : Pure java implementation of RRDTool's functionality
 * ============================================================
 *
 * Project Info:  http://www.jrobin.org
 * Project Lead:  Sasa Markovic ([e-mail]);
 *
 * (C) Copyright 2003-2005, by Sasa Markovic.
 *
 * Developers:    Sasa Markovic ([e-mail])
 *
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 */

package org.jrobin.data;

import org.jrobin.core.ConsolFuns;
import org.jrobin.core.Util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

class Aggregator implements ConsolFuns {
	private long timestamps[], step;
	private double[] values;

	Aggregator(long[] timestamps, double[] values) {
		assert timestamps.length == values.length: "Incompatible timestamps/values arrays (unequal lengths)";
		assert timestamps.length >= 2: "At least two timestamps must be supplied";
		this.timestamps = timestamps;
		this.values = values;
		this.step = timestamps[1] - timestamps[0];
	}

	Aggregates getAggregates(long tStart, long tEnd) {
		Aggregates agg = new Aggregates();
		long totalSeconds = 0;
		boolean firstFound = false;
		for (int i = 0; i < timestamps.length; i++) {
			long left = Math.max(timestamps[i] - step, tStart);
			long right = Math.min(timestamps[i], tEnd);
			long delta = right - left;
			if (delta > 0) {
				double value = values[i];
				agg.min = Util.min(agg.min, value);
				agg.max = Util.max(agg.max, value);
				if (!firstFound) {
					agg.first = value;
					firstFound = true;
				}
				agg.last = value;
				if (!Double.isNaN(value)) {
					agg.total = Util.sum(agg.total, delta * value);
					totalSeconds += delta;
				}
			}
		}
		agg.average = totalSeconds > 0 ? (agg.total / totalSeconds) : Double.NaN;
		return agg;
	}

	double getPercentile(long tStart, long tEnd, double percentile) {
		List<Double> valueList = new ArrayList<Double>();
		// create a list of included datasource values (different from NaN)
		for (int i = 0; i < timestamps.length; i++) {
			long left = Math.max(timestamps[i] - step, tStart);
			long right = Math.min(timestamps[i], tEnd);
			if (right > left && !Double.isNaN(values[i])) {
				valueList.add(values[i]);
			}
		}
		// create an array to work with
		int count = valueList.size();
		if (count > 1) {
			double[] valuesCopy = new double[count];
			for (int i = 0; i < count; i++) {
				valuesCopy[i] = valueList.get(i);
			}
			// sort array
			Arrays.sort(valuesCopy);
			// skip top (100% - percentile) values
			double topPercentile = (100.0 - percentile) / 100.0;
			count -= (int) Math.ceil(count * topPercentile);
			// if we have anything left...
			if (count > 0) {
				return valuesCopy[count - 1];
			}
		}
		// not enough data available
		return Double.NaN;
	}
}