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1
10
11 package com.triactive.jdo.util;
12
13 import java.lang.ref.Reference  ;
14 import java.lang.ref.ReferenceQueue ;
15 import java.util.ArrayList ;
16 import java.util.Iterator ;
17 import java.util.Map ;
18 import java.util.HashMap ;
19 import java.util.Set ;
20 import java.util.Collection ;
21 import java.util.Collections ;
22 import org.apache.log4j.Category;
23
24
25
37
38 public abstract class ReferenceValueMap implements Map , Cloneable
39 {
40 private static final Category LOG = Category.getInstance(ReferenceValueMap.class);
41
42 private HashMap map;
43 private ReferenceQueue reaped = new ReferenceQueue ();
44 private long lastLogTime = 0;
45 private int hits = 0;
46 private int misses = 0;
47 private int cleared = 0;
48
49
50 public ReferenceValueMap()
51 {
52 map = new HashMap ();
53 }
54
55
56 public ReferenceValueMap(int initialCapacity)
57 {
58 map = new HashMap (initialCapacity);
59 }
60
61
62 public ReferenceValueMap(int initialCapacity, float loadFactor)
63 {
64 map = new HashMap (initialCapacity, loadFactor);
65 }
66
67
68 public ReferenceValueMap(Map m)
69 {
70 map = new HashMap ();
71 putAll(m);
72 }
73
74
75 public Object clone()
76 {
77 reap();
78
79 ReferenceValueMap rvm = null;
80
81 try { rvm = (ReferenceValueMap)super.clone(); } catch (CloneNotSupportedException e) {}
82
83 rvm.map = (HashMap )map.clone();
84 rvm.map.clear();
85 rvm.reaped = new ReferenceQueue ();
86 rvm.putAll(entrySet());
87
88 return rvm;
89 }
90
91
92
96
97 public interface ValueReference
98 {
99
103
104 Object getKey();
105 }
106
107
108
118
119 protected abstract ValueReference newValueReference(Object key, Object value, ReferenceQueue queue);
120
121
122 public Object put(Object key, Object value)
123 {
124 reap();
125 return map.put(key, newValueReference(key, value, reaped));
126 }
127
128 public void putAll(Map m)
129 {
130 putAll(m.entrySet());
131 }
132
133 private void putAll(Set entrySet)
134 {
135 Iterator i = entrySet.iterator();
136
137 while (i.hasNext())
138 {
139 Map.Entry entry = (Map.Entry )i.next();
140 put(entry.getKey(), entry.getValue());
141 }
142 }
143
144 public Object get(Object key)
145 {
146 reap();
147 Reference ref = (Reference )map.get(key);
148
149 Object value = ref == null ? null : ref.get();
150
151 if (value == null)
152 ++misses;
153 else
154 ++hits;
155
156 if (LOG.isDebugEnabled())
157 {
158 if ((System.currentTimeMillis() - lastLogTime) > 1000)
159 {
160 LOG.debug(getClass().getName() + "(" + System.identityHashCode(this) + ") size = " + size() + ", hits = " + hits + ", misses = " + misses + ", cleared = " + cleared);
161 lastLogTime = System.currentTimeMillis();
162 }
163 }
164
165 return value;
166 }
167
168 public void clear()
169 {
170 reap();
171 map.clear();
172 }
173
174 public int size()
175 {
176 reap();
177 return map.size();
178 }
179
180 public boolean containsKey(Object obj)
181 {
182 reap();
183 return map.containsKey(obj);
184 }
185
186 public boolean containsValue(Object obj)
187 {
188 reap();
189
190 if (obj != null)
191 {
192 Iterator i = map.values().iterator();
193
194 while (i.hasNext())
195 {
196 Reference ref = (Reference )i.next();
197
198 if (obj.equals(ref.get()))
199 return true;
200 }
201 }
202
203 return false;
204 }
205
206 public boolean isEmpty()
207 {
208 reap();
209 return map.isEmpty();
210 }
211
212 public Set keySet()
213 {
214 reap();
215 return map.keySet();
216 }
217
218 public Collection values()
219 {
220 reap();
221
222 Collection c = map.values();
223 Iterator i = c.iterator();
224 ArrayList l = new ArrayList (c.size());
225
226 while (i.hasNext())
227 {
228 Reference ref = (Reference )i.next();
229 Object obj = ref.get();
230
231 if (obj != null)
232 l.add(obj);
233 }
234
235 return Collections.unmodifiableList(l);
236 }
237
238 public Set entrySet()
239 {
240 reap();
241
242 Set s = map.entrySet();
243 Iterator i = s.iterator();
244 HashMap m = new HashMap (s.size());
245
246 while (i.hasNext())
247 {
248 Map.Entry entry = (Map.Entry )i.next();
249 Reference ref = (Reference )entry.getValue();
250 Object obj = ref.get();
251
252 if (obj != null)
253 m.put(entry.getKey(), obj);
254 }
255
256 return Collections.unmodifiableSet(m.entrySet());
257 }
258
259 public Object remove(Object key)
260 {
261 reap();
262 return map.remove(key);
263 }
264
265 public int hashCode()
266 {
267 reap();
268 return map.hashCode();
269 }
270
271 public boolean equals(Object o)
272 {
273 reap();
274 return map.equals(o);
275 }
276
277 public void reap()
278 {
279 ValueReference ref;
280
281 while ((ref = (ValueReference)reaped.poll()) != null)
282 {
283 map.remove(ref.getKey());
284 ++cleared;
285 }
286 }
287 }
288 |
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