1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.eclipse.aether;
20
21 import java.util.function.Supplier;
22
23 /**
24 * Caches auxiliary data used during repository access like already processed metadata. The data in the cache is meant
25 * for exclusive consumption by the repository system and is opaque to the cache implementation. <strong>Note:</strong>
26 * Actual cache implementations must be thread-safe.
27 *
28 * @see RepositorySystemSession#getCache()
29 * @noimplement This interface is not intended to be implemented by clients.
30 * @noextend This interface is not intended to be extended by clients.
31 */
32 public interface RepositoryCache {
33
34 /**
35 * Puts the specified data into the cache. It is entirely up to the cache implementation how long this data will be
36 * kept before being purged, i.e. callers must not make any assumptions about the lifetime of cached data.
37 * <p>
38 * <em>Warning:</em> The cache will directly save the provided reference. If the cached data is mutable, i.e. could
39 * be modified after being put into the cache, the caller is responsible for creating a copy of the original data
40 * and store the copy in the cache.
41 *
42 * @param session The repository session during which the cache is accessed, must not be {@code null}.
43 * @param key The key to use for lookup of the data, must not be {@code null}.
44 * @param data The data to store in the cache, may be {@code null}.
45 */
46 void put(RepositorySystemSession session, Object key, Object data);
47
48 /**
49 * Gets the specified data from the cache.
50 * <p>
51 * <em>Warning:</em> The cache will directly return the saved reference. If the cached data is to be modified after
52 * its retrieval, the caller is responsible to create a copy of the returned data and use this instead of the cache
53 * record.
54 *
55 * @param session The repository session during which the cache is accessed, must not be {@code null}.
56 * @param key The key to use for lookup of the data, must not be {@code null}.
57 * @return The requested data or {@code null} if none was present in the cache.
58 */
59 Object get(RepositorySystemSession session, Object key);
60
61 /**
62 * Retrieve or compute the data associated with the specified key.
63 *
64 * @param key The key for which to retrieve the session data, must not be {@code null}.
65 * @param supplier The supplier will compute the new value, must not be {@code null}.
66 * @return The cache data associated with the key.
67 * @since 2.0.0
68 */
69 Object computeIfAbsent(RepositorySystemSession session, Object key, Supplier<Object> supplier);
70 }