1 /*
2 * Copyright 2001-2004 The Apache Software Foundation
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 org.apache.commons.cache;
17
18 import java.io.Serializable;
19
20 /**
21 * A {@link Cache} defines an API for storing and later
22 * retrieving {@link Object}s based upon key values.
23 * <p>
24 * A {@link Cache} supports an event subscription/publication
25 * system.
26 *
27 * @version $Id: Cache.java 155435 2005-02-26 13:17:27Z dirkv $
28 * @author Rodney Waldhoff
29 */
30 public interface Cache extends Serializable {
31 /**
32 * Store the specified <i>val</i> under the specified
33 * <i>key</i>.
34 *
35 * @param key the key used to later obtain the <i>val</i> from me,
36 * which MUST NOT be <tt>null</tt>.
37 * @param val the val to store, which MUST NOT be <tt>null</tt>.
38 * @param expiry the timestamp at which the given <i>val</i> becomes stale, or <tt>null</tt>.
39 * @param cost the implemenation dependent cost of generating the <i>val</i>, or <tt>null</tt>.
40 * @return <tt>true</tt> if the <i>val</i> was stored, <tt>false</tt> otherwise.
41 */
42 public boolean store(Serializable key, Serializable val, Long expiry, Long cost);
43
44 /**
45 * Store the specified <i>val</i> under the specified
46 * <i>key</i> and the specified <i>group</i>.
47 *
48 * @param key the key used to later obtain the <i>val</i> from me,
49 * which MUST NOT be <tt>null</tt>.
50 * @param group a meta-key which can be used to clear the object later
51 * @param val the val to store, which MUST NOT be <tt>null</tt>.
52 * @param expiry the timestamp at which the given <i>val</i> becomes stale, or <tt>null</tt>.
53 * @param cost the implemenation dependent cost of generating the <i>val</i>, or <tt>null</tt>.
54 * @return <tt>true</tt> if the <i>val</i> was stored, <tt>false</tt> otherwise.
55 */
56 public boolean store(Serializable key, Serializable val, Long expiry, Long cost, Serializable group);
57
58 /**
59 * Obtain the value previously {@link #store stored} under
60 * the given <i>key</i>.
61 *
62 * @param key the key which MUST NOT be <tt>null</tt>.
63 * @return the previously {@link #store stored} value, or <tt>null</tt>.
64 */
65 public Serializable retrieve(Serializable key);
66
67 public Serializable[] getKeysForGroup(Serializable group);
68
69 /**
70 * Returns <tt>true</tt> if I have a value associated with
71 * the given <i>key</i>, <tt>false</tt> otherwise.
72 *
73 * @param key the key which MUST NOT be <tt>null</tt>.
74 * @return <tt>true</tt> if I have a value associated with
75 * the given <i>key</i>, <tt>false</tt> otherwise.
76 */
77 public boolean contains(Serializable key);
78
79 /**
80 * Remove any value previously {@link #store stored} under
81 * the given <i>key</i>.
82 *
83 * @param key the key which MUST NOT be <tt>null</tt>.
84 */
85 public void clear(Serializable key);
86
87 /**
88 * Remove any value previously {@link #store stored} under
89 * the given <i>group</i>.
90 *
91 * @param group the group which MUST NOT be <tt>null</tt>.
92 */
93 public void clearGroup(Serializable group);
94
95 /**
96 * Remove all values previously {@link #store stored}.
97 */
98 public void clear();
99
100 /**
101 * Add the given {@link StorageListener} to my
102 * set of {@link StorageListener}s.
103 * @link obs the observer to add
104 */
105 public abstract void registerStorageListener(StorageListener obs);
106
107 /**
108 * Remove the given {@link StorageListener} from my
109 * set of {@link StorageListener}s.
110 * @link obs the observer to remove
111 */
112 public abstract void unregisterStorageListener(StorageListener obs);
113
114 /**
115 * Clear my set of {@link StorageListener}s.
116 */
117 public abstract void unregisterStorageListeners();
118
119 /**
120 * Add the given {@link RetrievalListener} to my
121 * set of {@link RetrievalListener}s.
122 * @link obs the observer to add
123 */
124 public abstract void registerRetrievalListener(RetrievalListener obs);
125
126 /**
127 * Remove the given {@link RetrievalListener} from my
128 * set of {@link RetrievalListener}s.
129 * @link obs the observer to remove
130 */
131 public abstract void unregisterRetrievalListener(RetrievalListener obs);
132
133 /**
134 * Clear my set of {@link RetrievalListener}s.
135 */
136 public abstract void unregisterRetrievalListeners();
137
138 public abstract long getStat(CacheStat stat) throws UnsupportedOperationException;
139 }