1 /**
2 * This file Copyright (c) 2008-2011 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module.cache;
35
36 import info.magnolia.cms.core.AggregationState;
37
38 /**
39 * The CachePolicy determines is a requested page should be cached,
40 * retrieved from the cache or not cached at all.
41 * It is called for every request and should thus also take care of
42 * any expiration policy - i.e if the page should be recached.
43 *
44 * The CacheFilter (or any other client component) can determine its
45 * behaviour based on the return CachePolicyResult, which holds both
46 * the behaviour to take and the cache key to use when appropriate.
47 *
48 * @author gjoseph
49 * @version $Revision: $ ($Author: $)
50 */
51 public interface CachePolicy {
52
53 /**
54 * Implementations can chose whether to cache or not - but note that the
55 * aggregationState might not be completely populated. Every request should be
56 * cacheable, not only those processed through Magnolia's RenderingFilter.
57 */
58 CachePolicyResult shouldCache(final Cache cache, final AggregationState aggregationState, final FlushPolicy flushPolicy);
59
60 /**
61 * Returns cache key for the given item or null if such key can't be obtained or policy doesn't want to share it.
62 * When using aggregationState, key is expected to be composed with aggregated request in mind and policy has to choose only
63 * one such key denoting item to return to the client, if such an item indeed exists and can be served.
64 * When not existing key might be used to store the cache entry. Since only one version of the content can be streamed back to
65 * the client, it makes sense to create only one cache entry for the such a key as well.
66 */
67 Object retrieveCacheKey(final AggregationState aggregationState);
68
69
70 /**
71 * Returns cache keys for the given item or null if such keys can't be obtained or policy doesn't want to share it. Since in
72 * this case uuid is used to retrieve the cache key, it is quite possible that multiple different representations of the content
73 * denoted by uuid exist and all such keys should be returned leaving it up to requesting object to deal with such a multiplicity.
74 * Please note that returned keys might not be necessary multiple representations of the content denoted by provided uuid, but
75 * also quite possibly all the content deemed related or partially used to construct any of the returned cache keys.
76 */
77 Object[] retrieveCacheKeys(final String uuid, final String repository);
78
79 /**
80 * Presists mapping between uuid and cache key in case the given cache policy implementation cares about such details.
81 */
82 void persistCacheKey(String repo, String uuid, Object key);
83
84 /**
85 * Returns cache keys for the given item or null if such keys can't be obtained or policy doesn't want to share it. Since in
86 * this case uuid is used to retrieve the cache key, it is quite possible that multiple different representations of the content
87 * denoted by uuid exist and all such keys should be returned leaving it up to requesting object to deal with such a multiplicity.
88 * Please note that returned keys might not be necessary multiple representations of the content denoted by provided uuid, but
89 * also quite possibly all the content deemed related or partially used to construct any of the returned cache keys.
90 * At the call to this method, cache policy should not only return the keys associated with the uuid, but also remove all returned uuid-cahce key mappings.
91 */
92 Object[] removeCacheKeys(String uuid, String repository);
93 }