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Java > Open Source Codes > com > db4o > cluster > Cluster


1 /* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
2
3 This file is part of the db4o open source object database.
4
5 db4o is free software; you can redistribute it and/or modify it under
6 the terms of version 2 of the GNU General Public License as published
7 by the Free Software Foundation and as clarified by db4objects' GPL
8 interpretation policy, available at
9 http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10 Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11 Suite 350, San Mateo, CA 94403, USA.
12
13 db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 package com.db4o.cluster;
22
23 import com.db4o.*;
24 import com.db4o.inside.cluster.*;
25 import com.db4o.query.*;
26
27 /**
28  * allows running Queries against multiple ObjectContainers.
29  * @exclude
30  */
31 public class Cluster {
32     
33     public final ObjectContainer[] _objectContainers;
34     
35     /**
36      * use this constructor to create a Cluster and call
37      * add() to add ObjectContainers
38      */
39     public Cluster(ObjectContainer[] objectContainers){
40         if(objectContainers == null){
41             throw new NullPointerException JavaDoc();
42         }
43         if(objectContainers.length < 1){
44             throw new IllegalArgumentException JavaDoc();
45         }
46         for (int i = 0; i < objectContainers.length; i++) {
47             if(objectContainers[i] == null){
48                 throw new IllegalArgumentException JavaDoc();
49             }
50         }
51         _objectContainers = objectContainers;
52     }
53     
54     /**
55      * starts a query against all ObjectContainers in
56      * this Cluster.
57      * @return the Query
58      */
59     public Query query(){
60         synchronized(this){
61             Query[] queries = new Query[_objectContainers.length];
62             for (int i = 0; i < _objectContainers.length; i++) {
63                 queries[i] = _objectContainers[i].query();
64             }
65             return new ClusterQuery(this, queries);
66         }
67     }
68     
69     /**
70      * returns the ObjectContainer in this cluster where the passed object
71      * is stored or null, if the object is not stored to any ObjectContainer
72      * in this cluster
73      * @param obj the object
74      * @return the ObjectContainer
75      */
76     public ObjectContainer objectContainerFor(Object JavaDoc obj){
77         synchronized(this){
78             for (int i = 0; i < _objectContainers.length; i++) {
79                 if(_objectContainers[i].ext().isStored(obj)){
80                     return _objectContainers[i];
81                 }
82             }
83         }
84         return null;
85     }
86     
87 }
88
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