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1
5 package org.h2.util;
6
7 import java.sql.SQLException  ;
8 import java.util.HashMap ;
9 import java.util.Iterator ;
10
11 import org.h2.message.Message;
12
13 public class SmallMap {
14 private HashMap map = new HashMap ();
15 private Object cache;
16 private int cacheId;
17 private int lastId;
18 private int maxElements;
19
20 public SmallMap(int maxElements) {
21 this.maxElements = maxElements;
22 }
23
24 public int addObject(int id, Object o) {
25 if(map.size() > maxElements * 2) {
26 Iterator it = map.keySet().iterator();
27 while(it.hasNext()) {
28 Integer k = (Integer ) it.next();
29 if(k.intValue() + maxElements < lastId) {
30 it.remove();
31 }
32 }
33 }
34 if(id > lastId) {
35 lastId = id;
36 }
37 map.put(new Integer (id), o);
38 cacheId = id;
39 cache = o;
40 return id;
41 }
42
43 public void freeObject(int id) {
44 if (cacheId == id) {
45 cacheId = -1;
46 cache = null;
47 }
48 map.remove(new Integer (id));
49 }
50
51 public Object getObject(int id, boolean ifAvailable) throws SQLException {
52 if (id == cacheId) {
53 return cache;
54 }
55 Object obj = map.get(new Integer (id));
56 if(obj == null && !ifAvailable) {
57 throw Message.getSQLException(Message.OBJECT_CLOSED);
58 }
59 return obj;
60 }
61
62 }
63 |
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