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Java > Open Source Codes > org > hsqldb > lib > HsqlThreadFactory


1 /* Copyright (c) 2001-2005, The HSQL Development Group
2  * All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  * Redistributions of source code must retain the above copyright notice, this
8  * list of conditions and the following disclaimer.
9  *
10  * Redistributions in binary form must reproduce the above copyright notice,
11  * this list of conditions and the following disclaimer in the documentation
12  * and/or other materials provided with the distribution.
13  *
14  * Neither the name of the HSQL Development Group nor the names of its
15  * contributors may be used to endorse or promote products derived from this
16  * software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
22  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
26  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30
31
32 package org.hsqldb.lib;
33
34 /**
35  * The default HSQLDB thread factory implementation. This factory can be
36  * used to wrap other thread factories using the setImpl method, but, by
37  * default simply produces new, vanilla thread objects constructed with
38  * the supplied runnable object.
39  *
40  * @author boucherb@users
41  * @version 1.7.2
42  * @since 1.7.2
43  */
44 class HsqlThreadFactory implements ThreadFactory {
45
46     /**
47      * The factory implementation. Typically, this will be the
48      * HsqlThreadFactory object itself.
49      */
50     protected ThreadFactory factory;
51
52     /**
53      * Constructs a new HsqlThreadFactory that uses itself as the factory
54      * implementation.
55      */
56     public HsqlThreadFactory() {
57         this(null);
58     }
59
60     /**
61      * Constructs a new HsqlThreadFactory whose retrieved threads come from the
62      * specified ThreadFactory object or from this factory implementation, if'
63      * the specified implementation is null.
64      *
65      * @param f the factory implementation this factory uses
66      */
67     public HsqlThreadFactory(ThreadFactory f) {
68         setImpl(f);
69     }
70
71     /**
72      * Retreives a thread instance for running the specified Runnable
73      * @param r The runnable that the retrieved thread handles
74      * @return the requested thread inatance
75      */
76     public Thread JavaDoc newThread(Runnable JavaDoc r) {
77         return factory == this ? new Thread JavaDoc(r)
78                                : factory.newThread(r);
79     }
80
81     /**
82      * Sets the factory implementation that this factory will use to
83      * produce threads. If the specified argument, f, is null, then
84      * this factory uses itself as the implementation.
85      *
86      * @param f the factory implementation that this factory will use
87      * to produce threads
88      * @return the previously installed factory implementation
89      */
90     public synchronized ThreadFactory setImpl(ThreadFactory f) {
91
92         ThreadFactory old;
93
94         old = factory;
95         factory = (f == null) ? this
96                               : f;
97
98         return old;
99     }
100
101     /**
102      * Retrieves the factory implementation that this factory is using
103      * to produce threads.
104      *
105      * @return the factory implementation that this factory is using to produce
106      * threads.
107      */
108     public synchronized ThreadFactory getImpl() {
109         return factory;
110     }
111 }
112
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