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1   /**
2    * Logback: the reliable, generic, fast and flexible logging framework.
3    * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
4    *
5    * This program and the accompanying materials are dual-licensed under
6    * either the terms of the Eclipse Public License v1.0 as published by
7    * the Eclipse Foundation
8    *
9    *   or (per the licensee's choosing)
10   *
11   * under the terms of the GNU Lesser General Public License version 2.1
12   * as published by the Free Software Foundation.
13   */
14  package ch.qos.logback.core.read;
15  
16  import ch.qos.logback.core.AppenderBase;
17  import ch.qos.logback.core.helpers.CyclicBuffer;
18  
19  /**
20   * CyclicBufferAppender stores events in a cyclic buffer of user-specified size. As the 
21   * name suggests, if the size of the buffer is N, only the latest N events are available.
22   * 
23   * 
24   * @author Ceki Gulcu
25   */
26  public class CyclicBufferAppender<E> extends AppenderBase<E> {
27  
28      CyclicBuffer<E> cb;
29      int maxSize = 512;
30  
31      public void start() {
32          cb = new CyclicBuffer<E>(maxSize);
33          super.start();
34      }
35  
36      public void stop() {
37          cb = null;
38          super.stop();
39      }
40  
41      @Override
42      protected void append(E eventObject) {
43          if (!isStarted()) {
44              return;
45          }
46          cb.add(eventObject);
47      }
48  
49      public int getLength() {
50          if (isStarted()) {
51              return cb.length();
52          } else {
53              return 0;
54          }
55      }
56  
57      public E get(int i) {
58          if (isStarted()) {
59              return cb.get(i);
60          } else {
61              return null;
62          }
63      }
64  
65      public void reset() {
66          cb.clear();
67      }
68  
69      /**
70       * Set the size of the cyclic buffer.
71       */
72      public int getMaxSize() {
73          return maxSize;
74      }
75  
76      public void setMaxSize(int maxSize) {
77          this.maxSize = maxSize;
78      }
79  
80  }