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Java > Open Source Codes > org > apache > derby > iapi > services > cache > CacheableFactory


1 /*
2
3    Derby - Class org.apache.derby.iapi.services.cache.CacheableFactory
4
5    Licensed to the Apache Software Foundation (ASF) under one or more
6    contributor license agreements. See the NOTICE file distributed with
7    this work for additional information regarding copyright ownership.
8    The ASF licenses this file to you under the Apache License, Version 2.0
9    (the "License"); you may not use this file except in compliance with
10    the License. You may obtain a copy of the License at
11
12       http://www.apache.org/licenses/LICENSE-2.0
13
14    Unless required by applicable law or agreed to in writing, software
15    distributed under the License is distributed on an "AS IS" BASIS,
16    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17    See the License for the specific language governing permissions and
18    limitations under the License.
19
20  */
21
22 package org.apache.derby.iapi.services.cache;
23
24 /**
25     Any object that implements this interface can be cached using the services of
26     the CacheManager/CacheFactory. In addition to implementing this interface the
27     class must be public and it must have a public no-arg constructor. This is because
28     the cache manager will construct objects itself and then set their identity
29     by calling the setIdentity method.
30     <P>
31     A Cacheable object has five states:
32     <OL>
33     <OL>
34     <LI> No identity - The object is only accessable by the cache manager
35     <LI> Identity, clean, unkept - The object has an identity, is clean but is only accessable by the cache manager
36     <LI> Identity, clean, kept - The object has an identity, is clean, and is in use by one or more threads
37     <LI> Identity, kept, dirty - The object has an identity, is dirty, and is in use by one or more threads
38     <LI> Identity, unkept, dirty - The object has an identity, is dirty but is only accessable by the cache manager
39     </OL>
40     </OL>
41     <BR>
42     While the object is kept it is guaranteed
43     not to change identity. While it is unkept no-one outside of the
44     cache manager can have a reference to the object.
45     The cache manager returns kept objects and they return to the unkept state
46     when all the current users of the object have released it.
47     <BR>
48     It is required that the object can only move into a dirty state while it is kept.
49
50     <BR> MT - Mutable : thread aware - Calls to Cacheable method must only be made by the
51     cache manager or the object itself.
52
53     @see CacheManager
54     @see CacheFactory
55     @see Class#newInstance
56 */
57 public interface CacheableFactory {
58
59     public Cacheable newCacheable(CacheManager cm);
60 }
61
62
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