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Java > Open Source Codes > com > quadcap > sql > file > FileRandomAccess


1 package com.quadcap.sql.file;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import java.io.IOException JavaDoc;
42 import java.io.RandomAccessFile JavaDoc;
43
44 /**
45  *
46  *
47  * @author Stan Bailes
48  */
49 public class FileRandomAccess extends RandomAccess {
50     long pos;
51     long maxSize;
52     RandomAccessFile JavaDoc ra;
53
54     public FileRandomAccess(RandomAccessFile JavaDoc ra, long maxSize) {
55         this.maxSize = maxSize;
56         this.ra = ra;
57     }
58
59     /**
60      * Return the size of the managed region.
61      */
62     public long size() {
63         try {
64             return ra.length();
65         } catch (IOException JavaDoc ex) {
66             return -1;
67         }
68     }
69
70     /**
71      * Resize the managed region.
72      */
73     public void resize(long newSize) throws IOException JavaDoc {
74         ra.setLength(newSize);
75     }
76
77     /* Write <tt>len</tt> bytes from position <tt>offset</tt> in buffer
78      * <tt>buf</tt> to position <tt>pos</tt> bytes into the managed
79      * area.
80      */
81     public void write(long p, byte[] b, int offset, int len)
82         throws IOException JavaDoc
83     {
84         checkCapacity(p+len);
85         if (p != pos) {
86             ra.seek(p);
87             pos = p;
88         }
89     ra.write(b, offset, len);
90         pos += len;
91     }
92
93     /**
94      * Read <tt>len</tt> bytes from location <tt>pos</tt> of the region
95      * into the buffer <tt>buf</tt>, starting at <tt>offset</tt>.
96      */
97     public void read(long p, byte[] b, int offset, int len)
98         throws IOException JavaDoc
99     {
100         if (p != pos) {
101             ra.seek(p);
102             pos = p;
103         }
104         ra.read(b, offset, len);
105         pos += len;
106     }
107
108     /**
109      * Finalization...
110      */
111     public void close() throws IOException JavaDoc {
112         ra.close();
113     }
114
115     public void flush() throws IOException JavaDoc {
116         try {
117             ra.getFD().sync();
118         } catch (Throwable JavaDoc t) {
119         }
120     }
121
122     final void checkCapacity(long t) throws IOException JavaDoc {
123         if (t > ra.length()) {
124             if (t > maxSize) {
125                 throw new IOException JavaDoc("full");
126             }
127             try {
128                 ra.setLength(t);
129             } catch (IOException JavaDoc e) {
130                 if (e.toString().indexOf("extended attributes") > 0) {
131                     return;
132                 }
133                 throw e;
134             }
135         }
136     }
137 }
138
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