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1   /*
2    * $Id: Counter.java 19191 2010-08-25 21:05:23Z tcarlson $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.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  public interface Counter
26  {
27  
28      /**
29       * Accessor for the counter type.
30       * 
31       * @return the type of the counter
32       */
33      CounterFactory.Type getType();
34  
35      /**
36       * Accessor for the counter's name.
37       * 
38       * @return the name of the counter
39       */
40      String getName();
41  
42      /**
43       * Increment the counter's value by 1.0.
44       * 
45       * @return the new value of the counter
46       */
47      double increment();
48  
49      /**
50       * Increment the counter's value by the specified amount.
51       * 
52       * @param value the amount to increment the counter by
53       * @return the new value of the counter
54       */
55      double incrementBy(double value);
56  
57      /**
58       * Decrement the counter's value by 1.0.
59       * 
60       * @return the new value of the counter
61       */
62      double decrement();
63  
64      /**
65       * Set the counter's value to a new value.
66       * 
67       * @param value the new value of the counter
68       */
69      void setRawValue(double value);
70  
71      /**
72       * Compute and return the value of the counter.
73       * 
74       * @return the value of the counter
75       */
76      double nextValue();
77  
78  }