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1   /*
2    * $Id: Counter.java 7976 2007-08-21 14:26:13Z dirk.olmes $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSource, Inc.  All rights reserved.  http://www.mulesource.com
5    *
6    * The software in this package is published under the terms of the CPAL v1.0
7    * license, a copy of which has been included with this distribution in the
8    * LICENSE.txt file.
9    */
10  
11  package org.mule.util.counters;
12  
13  /**
14   * This interface is the interface implemented for all counter types. A Counter can
15   * represent a real counter or a virtual counter that will be computed using one or
16   * more other counters.<br/>
17   * <h3>Real counters</h3>
18   * are counters which represent real values. The user will call methods of such
19   * counters to modify the associated value of the counter.
20   * <h3>Computed counters</h3>
21   * are computed using one or more associated counters. Such counters represent
22   * operations computed on associated counters. Usually, these counters will never be
23   * used directly, but will only used to retrieve the computed values.
24   * 
25   * @author <a href="mailto:gnt@codehaus.org">Guillaume Nodet</a>
26   * @version $Revision: 7976 $
27   */
28  public interface Counter
29  {
30  
31      /**
32       * Accessor for the counter type.
33       * 
34       * @return the type of the counter
35       */
36      CounterFactory.Type getType();
37  
38      /**
39       * Accessor for the counter's name.
40       * 
41       * @return the name of the counter
42       */
43      String getName();
44  
45      /**
46       * Increment the counter's value by 1.0.
47       * 
48       * @return the new value of the counter
49       */
50      double increment();
51  
52      /**
53       * Increment the counter's value by the specified amount.
54       * 
55       * @param value the amount to increment the counter by
56       * @return the new value of the counter
57       */
58      double incrementBy(double value);
59  
60      /**
61       * Decrement the counter's value by 1.0.
62       * 
63       * @return the new value of the counter
64       */
65      double decrement();
66  
67      /**
68       * Set the counter's value to a new value.
69       * 
70       * @param value the new value of the counter
71       */
72      void setRawValue(double value);
73  
74      /**
75       * Compute and return the value of the counter.
76       * 
77       * @return the value of the counter
78       */
79      double nextValue();
80  
81  }