StorageCache


1   
2   /*
3    * Copyright (c) 1998 - 2005 Versant Corporation
4    * All rights reserved. This program and the accompanying materials
5    * are made available under the terms of the Eclipse Public License v1.0
6    * which accompanies this distribution, and is available at
7    * http://www.eclipse.org/legal/epl-v10.html
8    *
9    * Contributors:
10   * Versant Corporation - initial API and implementation
11   */
12  package com.versant.core.storagemanager;
13  
14  import com.versant.core.server.CachedQueryResult;
15  import com.versant.core.server.CompiledQuery;
16  import com.versant.core.metadata.FetchGroup;
17  import com.versant.core.metadata.ClassMetaData;
18  import com.versant.core.metadata.ModelMetaData;
19  import com.versant.core.common.OID;
20  import com.versant.core.common.State;
21  import com.versant.core.common.*;
22  
23  /**
24   * Cache of State's and query results shared by multiple StorageManager's.
25   * A single class is used to cache both State's and query results so that
26   * query results can be efficiently evicted when States of classes they
27   * depend on are evicted. Only data read in a committed database transaction
28   * may be added to the cache.
29   */
30  public interface StorageCache {
31  
32      /**
33       * This is invoked when the meta data is available.
34       */
35      public void setJDOMetaData(ModelMetaData jmd);
36  
37      /**
38       * Is the cache enabled?
39       */
40      public boolean isEnabled();
41  
42      /**
43       * Is query caching enabled?
44       */
45      public boolean isQueryCacheEnabled();
46  
47      /**
48       * Begin a cache transaction and return an identifier for it. This
49       * must be called before a new database transaction is started.
50       */
51      public Object   beginTx();
52  
53      /**
54       * End a cache transaction.
55       */
56      public void endTx(Object   tx);
57  
58      /**
59       * Get the State for an OID or null if it is not in cache or does not
60       * contain the fields in the fetchGroup. This returns a copy of the
61       * data in the cache. If fetchGroup is null then if any state is
62       * present it is returned.
63       */
64      public State getState(OID oid, FetchGroup fetchGroup);
65  
66      /**
67       * Does the cache contain any data for the oid? Note that the data could
68       * be evicted at any time.
69       */
70      public boolean contains(OID oid);
71  
72      /**
73       * Get cached query results or null if there are none.
74       * @param cq
75       * @param params
76       */
77      public CachedQueryResult getQueryResult(CompiledQuery cq, Object  [] params);
78  
79      /**
80       * Get result count or -1 if there are none.
81       * @param cq
82       * @param params
83       */
84      public int getQueryResultCount(CompiledQuery cq, Object  [] params);
85  
86      /**
87       * Add all the states in the container to the cache.
88       */
89      public void add(Object   tx, StatesReturned container);
90  
91      /**
92       * Add query results to the cache.
93       */
94      public void add(Object   tx, CompiledQuery cq, Object  [] params,
95              CachedQueryResult queryData);
96  
97      /**
98       * Add query result count to the cache.
99       */
100     public void add(Object   tx, CompiledQuery cq, Object  [] params, int count);
101 
102     /**
103      * Evict length OIDs from oids starting at offset. Expected is the total
104      * number of OIDs we expect to evict in the transaction or 0 if this is
105      * not known. This may be used to optimize cache storage allocation.
106      */
107     public void evict(Object   tx, OID[] oids, int offset, int length,
108             int expected);
109 
110     /**
111      * Evict all data for the classes.
112      */
113     public void evict(Object   tx, ClassMetaData[] classes, int classCount);
114 
115     /**
116      * Evict all data.
117      */
118     public void evictAll(Object   tx);
119 
120     /**
121      * Evict any cached information for the query.
122      */
123     public void evict(Object   tx, CompiledQuery cq, Object  [] params);
124 }
125 
126
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