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.net;
15  
16  import java.io.IOException;
17  import java.io.ObjectOutputStream;
18  
19  /**
20   * Automatically flushes the underlying {@link java.io.ObjectOutputStream}
21   * immediately after calling it's
22   * {@link java.io.ObjectOutputStream#writeObject(Object)} method.
23   *
24   * @author Sebastian Gröbler
25   */
26  public class AutoFlushingObjectWriter implements ObjectWriter {
27  
28      private final ObjectOutputStream objectOutputStream;
29      private final int resetFrequency;
30      private int writeCounter = 0;
31  
32      /**
33       * Creates a new instance for the given {@link java.io.ObjectOutputStream}.
34       *
35       * @param objectOutputStream the stream to write to
36       * @param resetFrequency     the frequency with which the given stream will be
37       *                           automatically reset to prevent a memory leak
38       */
39      public AutoFlushingObjectWriter(ObjectOutputStream objectOutputStream, int resetFrequency) {
40          this.objectOutputStream = objectOutputStream;
41          this.resetFrequency = resetFrequency;
42      }
43  
44      @Override
45      public void write(Object object) throws IOException {
46          objectOutputStream.writeObject(object);
47          objectOutputStream.flush();
48          preventMemoryLeak();
49      }
50  
51      /**
52       * Failing to reset the object output stream every now and then creates a
53       * serious memory leak which is why the underlying stream will be reset
54       * according to the {@code resetFrequency}.
55       */
56      private void preventMemoryLeak() throws IOException {
57          if (++writeCounter >= resetFrequency) {
58              objectOutputStream.reset();
59              writeCounter = 0;
60          }
61      }
62  }