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1 package org.roller.util;
2 import java.util.ArrayList  ;
3 import java.util.Collections ;
4 import java.util.Iterator ;
5 import java.util.LinkedHashMap ;
6 import java.util.List ;
7 import java.util.Map ;
8
13 public class LRUCache2
14 {
15 private long timeout;
16 private Map cache = null;
17 private Environment environment = null;
18
19
27 public LRUCache2(int maxsize, long timeout)
28 {
29 this.environment = new DefaultEnvironment();
30 this.timeout = timeout;
31 this.cache = new LRULinkedHashMap(maxsize);
32 }
33
34
42 public LRUCache2(Environment environment, int maxsize, long timeout)
43 {
44 this.environment = environment;
45 this.timeout = timeout;
46 this.cache = new LRULinkedHashMap(maxsize);
47 }
48
49 public synchronized void put(Object key, Object value)
50 {
51 CacheEntry entry = new CacheEntry(value, environment
52 .getCurrentTimeInMillis());
53 cache.put(key, entry);
54 }
55
56 public Object get(Object key)
57 {
58 Object value = null;
59 CacheEntry entry = null;
60 synchronized(this)
61 {
62 entry = (CacheEntry) cache.get(key);
63 }
64 if (entry != null)
65 {
66 if (environment.getCurrentTimeInMillis() - entry.getTimeCached() < timeout)
67 {
68 value = entry.getValue();
69 }
70 else
71 {
72 cache.remove(entry);
73 }
74 }
75 return value;
76 }
77
78 public synchronized void purge()
79 {
80 cache.clear();
81 }
82
83 public synchronized void purge(String [] patterns)
84 {
85 List purgeList = new ArrayList ();
86 Iterator keys = cache.keySet().iterator();
87 while (keys.hasNext())
88 {
89 String key = (String ) keys.next();
90 for (int i = 0; i < patterns.length; i++)
91 {
92 if (key.indexOf(patterns[i]) != -1)
93 {
94 purgeList.add(key);
95 break;
96 }
97 }
98 }
99 Iterator purgeIter = purgeList.iterator();
100 while (purgeIter.hasNext())
101 {
102 String key = (String ) purgeIter.next();
103 cache.remove(key);
104 }
105 }
106
107 public int size()
108 {
109 return cache.size();
110 }
111 public interface Environment
112 {
113 public long getCurrentTimeInMillis();
114 }
115 public static class DefaultEnvironment implements Environment
116 {
117 public long getCurrentTimeInMillis()
118 {
119 return System.currentTimeMillis();
120 }
121 }
122 private static class CacheEntry
123 {
124 private Object value;
125 private long timeCached = -1;
126
127 public CacheEntry(Object value, long timeCached)
128 {
129 this.timeCached = timeCached;
130 this.value = value;
131 }
132
133 public long getTimeCached()
134 {
135 return timeCached;
136 }
137
138 public Object getValue()
139 {
140 return value;
141 }
142 }
143
144 private static class LRULinkedHashMap extends LinkedHashMap
146 {
147 protected int maxsize;
148
149 public LRULinkedHashMap(int maxsize)
150 {
151 super(maxsize * 4 / 3 + 1, 0.75f, true);
152 this.maxsize = maxsize;
153 }
154
155 protected boolean removeEldestEntry(Map.Entry eldest)
156 {
157 return this.size() > this.maxsize;
158 }
159 }
160 }
161 |
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