1 package org.eclipse.aether;
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.io.Closeable;
23 import java.util.Collection;
24
25 import org.eclipse.aether.artifact.Artifact;
26 import org.eclipse.aether.metadata.Metadata;
27
28 /**
29 * A synchronization context used to coordinate concurrent access to artifacts or metadatas. The typical usage of a
30 * synchronization context looks like this:
31 *
32 * <pre>
33 * SyncContext syncContext = repositorySystem.newSyncContext( ... );
34 * try {
35 * syncContext.acquire( artifacts, metadatas );
36 * // work with the artifacts and metadatas
37 * } finally {
38 * syncContext.close();
39 * }
40 * </pre>
41 *
42 * Within one thread, synchronization contexts may be nested which can naturally happen in a hierarchy of method calls.
43 * The nested synchronization contexts may also acquire overlapping sets of artifacts/metadatas as long as the following
44 * conditions are met. If the outer-most context holding a particular resource is exclusive, that resource can be
45 * reacquired in any nested context. If however the outer-most context is shared, the resource may only be reacquired by
46 * nested contexts if these are also shared.
47 * <p>
48 * A synchronization context is meant to be utilized by only one thread and as such is not thread-safe.
49 * <p>
50 * Note that the level of actual synchronization is subject to the implementation and might range from OS-wide to none.
51 *
52 * @see RepositorySystem#newSyncContext(RepositorySystemSession, boolean)
53 */
54 public interface SyncContext
55 extends Closeable
56 {
57
58 /**
59 * Acquires synchronized access to the specified artifacts and metadatas. The invocation will potentially block
60 * until all requested resources can be acquired by the calling thread. Acquiring resources that are already
61 * acquired by this synchronization context has no effect. Please also see the class-level documentation for
62 * information regarding reentrancy. The method may be invoked multiple times on a synchronization context until all
63 * desired resources have been acquired.
64 *
65 * @param artifacts The artifacts to acquire, may be {@code null} or empty if none.
66 * @param metadatas The metadatas to acquire, may be {@code null} or empty if none.
67 */
68 void acquire( Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas );
69
70 /**
71 * Releases all previously acquired artifacts/metadatas. If no resources have been acquired before or if this
72 * synchronization context has already been closed, this method does nothing.
73 */
74 void close();
75
76 }