StatCache


1   package org.shiftone.cache.decorator.stat;
2   
3   
4   
5   import org.shiftone.cache.Cache;
6   import org.shiftone.cache.util.Log;
7   
8   import java.util.Date  ;
9   
10  
11  /**
12   * Class StatCache
13   *
14   * @author <a HREF="mailto:jeff@shiftone.org">Jeff Drost</a>
15   * @version $Revision: 1.8 $
16   */
17  public class StatCache implements Cache
18  {
19  
20      private static final Log LOG = new Log(StatCache.class);
21      private final Cache      cache;
22      private final String       name;
23      private final Date         createDate  = new Date  ();
24      private Sequence         getCount    = new Sequence();
25      private Sequence         addCount    = new Sequence();
26      private Sequence         removeCount = new Sequence();
27      private Sequence         missCount   = new Sequence();
28      private Sequence         hitCount    = new Sequence();
29      private int maxSize = 0;
30  
31      public StatCache(String   name, Cache cache)
32      {
33          this.name  = name;
34          this.cache = cache;
35      }
36  
37  
38      private synchronized void updateMaxSize() {
39          int size = cache.size();
40          if (size > maxSize) {
41              maxSize = size;
42          }
43      }
44      /**
45       * Method addObject
46       */
47      public void addObject(Object   userKey, Object   cacheObject)
48      {
49          addCount.increment();
50          cache.addObject(userKey, cacheObject);
51          updateMaxSize();
52      }
53  
54  
55      /**
56       * Method getObject
57       */
58      public Object   getObject(Object   key)
59      {
60  
61          Object   object = cache.getObject(key);
62  
63          getCount.increment();
64  
65          if (object == null)
66          {
67              missCount.increment();
68          }
69          else
70          {
71              hitCount.increment();
72          }
73  
74          return object;
75      }
76  
77  
78      /**
79       * Method remove
80       */
81      public void remove(Object   key)
82      {
83          removeCount.increment();
84          cache.remove(key);
85      }
86  
87  
88      /**
89       * Method size
90       */
91      public int size()
92      {
93          return cache.size();
94      }
95  
96  
97      /**
98       * Method clear
99       */
100     public void clear()
101     {
102         cache.clear();
103     }
104 
105 
106     /**
107      * Method getHitRatio is the ratio of hits to tries.
108      * hitCount / (hitCount + missCount)
109      */
110     public double getHitRatio()
111     {
112 
113         long tryCount = hitCount.getValue() + missCount.getValue();
114 
115         return (tryCount == 0)
116                ? 0
117                : (hitCount.getValue() / tryCount);
118     }
119 
120 
121     /**
122      * Method toString
123      */
124     public String   toString()
125     {
126         return "StatCache->" + cache;
127     }
128 
129 
130     public void printStats()
131     {
132 
133         LOG.info("Stats : " + name + " - " + cache + " - " + createDate);
134         LOG.info("\t:\tgetCount    = " + getCount);
135         LOG.info("\t:\taddCount    = " + addCount);
136         LOG.info("\t:\tremoveCount = " + removeCount);
137         LOG.info("\t:\tmissCount   = " + missCount);
138         LOG.info("\t:\tgetCount    = " + getCount);
139         LOG.info("\t:\thitCount    = " + hitCount);
140     }
141 }
142
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