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1   /************************************************************************
2    * Copyright (c) 2000-2006 The Apache Software Foundation.             *
3    * All rights reserved.                                                *
4    * ------------------------------------------------------------------- *
5    * Licensed under the Apache License, Version 2.0 (the "License"); you *
6    * may not use this file except in compliance with the License. You    *
7    * may obtain a copy of the License at:                                *
8    *                                                                     *
9    *     http://www.apache.org/licenses/LICENSE-2.0                      *
10   *                                                                     *
11   * Unless required by applicable law or agreed to in writing, software *
12   * distributed under the License is distributed on an "AS IS" BASIS,   *
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or     *
14   * implied.  See the License for the specific language governing       *
15   * permissions and limitations under the License.                      *
16   ***********************************************************************/
17  
18  
19  package org.apache.james.util.watchdog;
20  
21  import java.io.IOException;
22  import java.io.InputStream;
23  
24  /***
25   * This will reset the Watchdog each time a certain amount of data has
26   * been transferred.  This allows us to keep the timeout settings low, while
27   * not timing out during large data transfers.
28   */
29  public class BytesReadResetInputStream extends InputStream {
30  
31      /***
32       * The wrapped InputStream
33       */
34      private InputStream in = null;
35  
36      /***
37       * The Watchdog to be reset every lengthReset bytes
38       */
39      private Watchdog watchdog;
40  
41      /***
42       * The number of bytes that need to be read before the counter is reset.
43       */
44      private int lengthReset = 0;
45  
46      /***
47       * The number of bytes read since the counter was last reset
48       */
49      int readCounter = 0;
50  
51      /***
52       * @param in the InputStream to be wrapped by this stream
53       * @param watchdog the watchdog to be reset
54       * @param lengthReset the number of bytes to be read in between trigger resets
55       */
56      public BytesReadResetInputStream(InputStream in,
57                                       Watchdog watchdog, 
58                                       int lengthReset) {
59          this.in = in;
60          this.watchdog = watchdog;
61          this.lengthReset = lengthReset;
62  
63          readCounter = 0;
64      }
65  
66      /***
67       * Read an array of bytes from the stream
68       *
69       * @param b the array of bytes to read from the stream
70       * @param off the index in the array where we start writing
71       * @param len the number of bytes of the array to read
72       *
73       * @return the number of bytes read
74       *
75       * @throws IOException if an exception is encountered when reading
76       */
77      public int read(byte[] b, int off, int len) throws IOException {
78          int l = in.read(b, off, len);
79          readCounter += l;
80  
81          if (readCounter > lengthReset) {
82              readCounter = 0;
83              watchdog.reset();
84          }
85  
86          return l;
87      }
88  
89      /***
90       * Read a byte from the stream
91       *
92       * @return the byte read from the stream
93       * @throws IOException if an exception is encountered when reading
94       */
95      public int read() throws IOException {
96          int b = in.read();
97          readCounter++;
98  
99          if (readCounter > lengthReset) {
100             readCounter = 0;
101             watchdog.reset();
102         }
103 
104         return b;
105     }
106 
107     /***
108      * Close the stream
109      *
110      * @throws IOException if an exception is encountered when closing
111      */
112     public void close() throws IOException {
113         in.close();
114     }
115 }