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 package net.sf.ehcache.concurrent;
17
18 import java.util.concurrent.locks.ReentrantReadWriteLock;
19 import java.util.concurrent.locks.Lock;
20 import java.util.concurrent.TimeUnit;
21 import java.util.concurrent.locks.ReadWriteLock;
22
23 /***
24 * A simple ReadWriteLock synchronizer.
25 *
26 * @author Alex Snaps
27 */
28 public class ReadWriteLockSync implements Sync {
29
30 private final ReentrantReadWriteLock rrwl;
31
32 /***
33 * default constructor.
34 */
35 public ReadWriteLockSync() {
36 this(new ReentrantReadWriteLock());
37 }
38
39 /***
40 * Constructor.
41 * @param lock
42 */
43 public ReadWriteLockSync(ReentrantReadWriteLock lock) {
44 this.rrwl = lock;
45 }
46 /***
47 * {@inheritDoc}
48 */
49 public void lock(final LockType type) {
50 getLock(type).lock();
51 }
52
53 /***
54 * {@inheritDoc}
55 */
56 public boolean tryLock(final LockType type, final long msec) throws InterruptedException {
57 return getLock(type).tryLock(msec, TimeUnit.MILLISECONDS);
58 }
59
60 /***
61 * {@inheritDoc}
62 */
63 public void unlock(final LockType type) {
64 getLock(type).unlock();
65 }
66
67 private Lock getLock(final LockType type) {
68 switch (type) {
69 case READ:
70 return rrwl.readLock();
71 case WRITE:
72 return rrwl.writeLock();
73 default:
74 throw new IllegalArgumentException("We don't support any other lock type than READ or WRITE!");
75 }
76 }
77
78 /***
79 * Gets the {@code ReadWriteLock} backing this sync.
80 *
81 * @return the backing {@code ReadWriteLock}
82 */
83 public ReadWriteLock getReadWriteLock() {
84 return rrwl;
85 }
86
87 /***
88 * {@inheritDoc}
89 */
90 public boolean isHeldByCurrentThread(LockType type) {
91 switch (type) {
92 case READ:
93 throw new UnsupportedOperationException("Querying of read lock is not supported.");
94 case WRITE:
95 return rrwl.isWriteLockedByCurrentThread();
96 default:
97 throw new IllegalArgumentException("We don't support any other lock type than READ or WRITE!");
98 }
99 }
100 }