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Java > Open Source Codes > org > apache > cayenne > cache > QueryCache


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19 package org.apache.cayenne.cache;
20
21 import java.util.List JavaDoc;
22
23 import org.apache.cayenne.query.QueryMetadata;
24
25 /**
26  * An interface that defines generic QueryCache.
27  *
28  * @author Andrus Adamchik
29  * @since 3.0
30  */
31 public interface QueryCache {
32
33     /**
34      * Returns a cached query result for the given QueryMetadata or null if the result is
35      * not cached or is expired.
36      */
37     List JavaDoc get(QueryMetadata metadata);
38
39     /**
40      * Returns a cached query result for the given QueryMetadata. If the result is not
41      * cached or is expired, cache will use provided factory to rebuild the value and
42      * store it in the cache. A corollary is that this method never returns null.
43      * <p/>Compared to {@link #get(QueryMetadata)}, this method allows the cache to do
44      * appropriate synchronization when refreshing the entry, preventing multiple threads
45      * from running the same query when a missing entry is requested by multiple threads
46      * simultaneously.
47      */
48     List JavaDoc get(QueryMetadata metadata, QueryCacheEntryFactory factory);
49
50     void put(QueryMetadata metadata, List JavaDoc results);
51
52     /**
53      * Removes a single entry from cache.
54      */
55     void remove(String JavaDoc key);
56
57     /**
58      * Removes a group of entries identified by group key. This may not be supported by
59      * the implementation.
60      */
61     void removeGroup(String JavaDoc groupKey);
62
63     /**
64      * Clears all entries.
65      */
66     void clear();
67
68     int size();
69 }
70
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