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.core.read;
015
016import ch.qos.logback.core.AppenderBase;
017import ch.qos.logback.core.helpers.CyclicBuffer;
018
019/**
020 * CyclicBufferAppender stores events in a cyclic buffer of user-specified size.
021 * As the name suggests, if the size of the buffer is N, only the latest N
022 * events are available.
023 * 
024 * 
025 * @author Ceki Gulcu
026 */
027public class CyclicBufferAppender<E> extends AppenderBase<E> {
028
029    CyclicBuffer<E> cb;
030    int maxSize = 512;
031
032    public void start() {
033        cb = new CyclicBuffer<E>(maxSize);
034        super.start();
035    }
036
037    public void stop() {
038        cb = null;
039        super.stop();
040    }
041
042    @Override
043    protected void append(E eventObject) {
044        if (!isStarted()) {
045            return;
046        }
047        cb.add(eventObject);
048    }
049
050    public int getLength() {
051        if (isStarted()) {
052            return cb.length();
053        } else {
054            return 0;
055        }
056    }
057
058    public E get(int i) {
059        if (isStarted()) {
060            return cb.get(i);
061        } else {
062            return null;
063        }
064    }
065
066    public void reset() {
067        cb.clear();
068    }
069
070    /**
071     * Set the size of the cyclic buffer.
072     */
073    public int getMaxSize() {
074        return maxSize;
075    }
076
077    public void setMaxSize(int maxSize) {
078        this.maxSize = maxSize;
079    }
080
081}