1 /*
2 * MIT License
3 *
4 * Copyright (c) 2010-2022 The Waffle Project Contributors: https://github.com/Waffle/waffle/graphs/contributors
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in all
14 * copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24 package waffle.util.cache;
25
26 import java.util.NoSuchElementException;
27 import java.util.ServiceLoader;
28
29 /**
30 * A semi-persistent mapping from keys to values.
31 *
32 * @param <K>
33 * the type of keys maintained by this cache
34 * @param <V>
35 * the type of mapped values
36 *
37 * @author Simon Legner
38 *
39 * @see <a href="https://github.com/Waffle/waffle/blob/master/Docs/CustomCache.md">Can I provide a custom cache
40 * implementation?</a>
41 */
42 public interface Cache<K, V> {
43
44 /**
45 * Creates a new cache with the specified timeout.
46 * <p>
47 * The cache implementation is obtained using {@link ServiceLoader}. To create your own implementation, implement
48 * {@link CacheSupplier} and register it using the {@code /META-INF/services/waffle.util.cache.CacheSupplier} file
49 * on your classpath.
50 *
51 * @param timeout
52 * timeout in seconds
53 * @param <K>
54 * the type of keys maintained by this cache
55 * @param <V>
56 * the type of mapped values
57 *
58 * @return a new cache
59 *
60 * @throws NoSuchElementException
61 * if no cache can be instantiated, use {@link Exception#getSuppressed()} to obtain details.
62 */
63 static <K, V> Cache<K, V> newCache(int timeout) throws NoSuchElementException {
64 final NoSuchElementException exception = new NoSuchElementException();
65 for (CacheSupplier cacheSupplier : ServiceLoader.load(CacheSupplier.class)) {
66 try {
67 return cacheSupplier.newCache(timeout);
68 } catch (Exception e) {
69 exception.addSuppressed(e);
70 }
71 }
72 throw exception;
73 }
74
75 /**
76 * Fetches the key from the cache
77 *
78 * @param key
79 * the key
80 *
81 * @return the corresponding value
82 *
83 * @see java.util.Map#get
84 */
85 V get(K key);
86
87 /**
88 * Stores a binding for the key and the value in the cache
89 *
90 * @param key
91 * the key
92 * @param value
93 * the value
94 *
95 * @see java.util.Map#put
96 */
97 void put(K key, V value);
98
99 /**
100 * Removes the binding for the key from the cache
101 *
102 * @param key
103 * the key
104 *
105 * @see java.util.Map#remove(Object)
106 */
107 void remove(K key);
108
109 /**
110 * Returns the number of bindings in this cache
111 *
112 * @return the size
113 *
114 * @see java.util.Map#size
115 */
116 int size();
117 }