1 package org.eclipse.aether.named;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.concurrent.TimeUnit;
23
24 /**
25 * A named lock, functionally similar to existing JVM and other implementations. Must support boxing (reentrancy), but
26 * no lock upgrade is supported. The lock instance obtained from lock factory must be treated as a resource, best in
27 * try-with-resource block. Usual pattern to use this lock:
28 * <pre>
29 * try (NamedLock lock = factory.getLock("resourceName")) {
30 * if (lock.lockExclusively(10L, Timeunit.SECONDS)) {
31 * try {
32 * ... exclusive access to "resourceName" resource gained here
33 * }
34 * finally {
35 * lock.unlock();
36 * }
37 * }
38 * else {
39 * ... failed to gain access within specified time, handle it
40 * }
41 * }
42 * </pre>
43 */
44 public interface NamedLock extends AutoCloseable
45 {
46 /**
47 * Returns this instance name, never null
48 */
49 String name();
50
51 /**
52 * Tries to lock shared, may block for given time. If successful, returns {@code true}.
53 */
54 boolean lockShared( long time, TimeUnit unit ) throws InterruptedException;
55
56 /**
57 * Tries to lock exclusively, may block for given time. If successful, returns {@code true}.
58 */
59 boolean lockExclusively( long time, TimeUnit unit ) throws InterruptedException;
60
61 /**
62 * Unlocks the lock, must be invoked by caller after one of the {@link #lockShared(long, TimeUnit)} or {@link
63 * #lockExclusively(long, TimeUnit)}.
64 */
65 void unlock();
66
67 /**
68 * Closes the lock resource. Lock MUST be unlocked using {@link #unlock()} in case any locking happened on it. After
69 * invoking this method, the lock instance MUST NOT be used anymore. If lock for same name needed, a new instance
70 * should be obtained from factory using {@link NamedLockFactory#getLock(String)}. Ideally, instances are to be used
71 * within try-with-resource blocks, so calling this method directly is not really needed, nor advised.
72 */
73 @Override
74 void close();
75 }