1 /***
2 * Copyright 2003-2010 Terracotta, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.pool.impl;
18
19 import java.util.concurrent.atomic.AtomicBoolean;
20
21 import net.sf.ehcache.pool.Pool;
22 import net.sf.ehcache.pool.PoolAccessor;
23 import net.sf.ehcache.pool.Role;
24
25 /***
26 * Abstract PoolAccessor implementation providing pool to store binding functionality.
27 *
28 * @author Chris Dennis
29 *
30 * @param <T> accessing store type
31 */
32 public abstract class AbstractPoolAccessor<T> implements PoolAccessor<T> {
33
34 private final AtomicBoolean unlinked = new AtomicBoolean();
35 private final Pool<T> pool;
36 private final T store;
37
38 /***
39 * Creates an accessor for the specified store to access the specified pool.
40 *
41 * @param pool pool to be accessed
42 * @param store accessing store
43 */
44 public AbstractPoolAccessor(Pool<T> pool, T store) {
45 this.pool = pool;
46 this.store = store;
47 }
48
49 /***
50 * {@inheritDoc}
51 */
52 public long replace(Role role, Object current, Object replacement, boolean force) {
53 checkLinked();
54
55 long addedSize;
56 long sizeOf = 0;
57 switch (role) {
58 case CONTAINER:
59 sizeOf += delete(null, null, current);
60 addedSize = add(null, null, replacement, force);
61 if (addedSize < 0) {
62 add(null, null, current, false);
63 sizeOf = Long.MAX_VALUE;
64 } else {
65 sizeOf -= addedSize;
66 }
67 break;
68 case KEY:
69 sizeOf += delete(current, null, null);
70 addedSize = add(replacement, null, null, force);
71 if (addedSize < 0) {
72 add(current, null, null, false);
73 sizeOf = Long.MAX_VALUE;
74 } else {
75 sizeOf -= addedSize;
76 }
77 break;
78 case VALUE:
79 sizeOf += delete(null, current, null);
80 addedSize = add(null, replacement, null, force);
81 if (addedSize < 0) {
82 add(null, current, null, false);
83 sizeOf = Long.MAX_VALUE;
84 } else {
85 sizeOf -= addedSize;
86 }
87 break;
88 default:
89 throw new IllegalArgumentException();
90 }
91 return sizeOf;
92 }
93
94 /***
95 * {@inheritDoc}
96 */
97 public final void unlink() {
98 if (unlinked.compareAndSet(false, true)) {
99 getPool().removePoolAccessor(this);
100 }
101 }
102
103 /***
104 * {@inheritDoc}
105 */
106 public final T getStore() {
107 return store;
108 }
109
110 /***
111 * Throws {@code IllegalStateException} if this accessor is not linked to it's pool.
112 *
113 * @throws IllegalStateException if not linked
114 */
115 protected final void checkLinked() throws IllegalStateException {
116 if (unlinked.get()) {
117 throw new IllegalStateException("BoundedPoolAccessor has been unlinked");
118 }
119 }
120
121 /***
122 * Return the pool this accessor is associated with.
123 *
124 * @return associated pool
125 */
126 protected final Pool<T> getPool() {
127 return pool;
128 }
129 }