001/**
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
004 *
005 * This program and the accompanying materials are dual-licensed under
006 * either the terms of the Eclipse Public License v1.0 as published by
007 * the Eclipse Foundation
008 *
009 *   or (per the licensee's choosing)
010 *
011 * under the terms of the GNU Lesser General Public License version 2.1
012 * as published by the Free Software Foundation.
013 */
014package ch.qos.logback.access.filter;
015
016abstract public class PeriodicStats {
017
018    private long nextPeriodBegins = 0;
019    private long lastTotal = 0;
020    private long lastCount = 0;
021
022    private double average;
023    private int n;
024
025    PeriodicStats() {
026        this(System.currentTimeMillis());
027    }
028
029    PeriodicStats(long now) {
030        nextPeriodBegins = computeStartOfNextPeriod(now);
031    }
032
033    void update(long now, long total) {
034        if (now > nextPeriodBegins) {
035            lastCount = total - lastTotal;
036            lastTotal = total;
037            average = (average * n + lastCount) / (++n);
038            nextPeriodBegins = computeStartOfNextPeriod(now);
039        }
040    }
041
042    public double getAverage() {
043        return average;
044    }
045
046    public long getLastCount() {
047        return lastCount;
048    }
049
050    void reset(long now) {
051        nextPeriodBegins = computeStartOfNextPeriod(now);
052        lastTotal = 0;
053        lastCount = 0;
054        average = 0.0;
055        n = 0;
056    }
057
058    void reset() {
059        reset(System.currentTimeMillis());
060    }
061
062    abstract long computeStartOfNextPeriod(long now);
063
064}