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Java > Open Source Codes > com > quadcap > sql > AutoNumberStep


1 package com.quadcap.sql;
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.BufferedInputStream JavaDoc;
42 import java.io.BufferedOutputStream JavaDoc;
43 import java.io.Externalizable JavaDoc;
44 import java.io.IOException JavaDoc;
45 import java.io.ObjectInput JavaDoc;
46 import java.io.ObjectOutput JavaDoc;
47
48 import java.sql.SQLException JavaDoc;
49
50 import com.quadcap.sql.file.BlockFile;
51 import com.quadcap.sql.file.PageManager;
52 import com.quadcap.sql.file.RandomAccess;
53 import com.quadcap.sql.file.RandomAccessInputStream;
54 import com.quadcap.sql.file.RandomAccessOutputStream;
55
56 import com.quadcap.sql.io.ObjectInputStream;
57 import com.quadcap.sql.io.ObjectOutputStream;
58 import com.quadcap.sql.io.Extern;
59
60 import com.quadcap.sql.types.Value;
61 import com.quadcap.sql.types.ValueNull;
62
63 import com.quadcap.io.CountedInputStream;
64
65 import com.quadcap.util.Debug;
66
67 /**
68  * Log step to record allocations of auto numbers...
69  *
70  * @author Stan Bailes
71  */
72 public class AutoNumberStep extends LogStep implements Externalizable JavaDoc {
73     String JavaDoc tableName = null;
74     long num = 0;
75
76     /**
77      * Default constructor for serialization
78      */
79     public AutoNumberStep() {}
80
81     /**
82      * Explicit constructor
83      */
84     public AutoNumberStep(Session session, Table table, long num) {
85         super(session);
86     this.tableName = table.getName();
87         this.num = num;
88     }
89
90     /**
91      * We don't bother to undo this -- we don't mind gaps.
92      */
93     public void undo(Session session) throws IOException JavaDoc, SQLException JavaDoc {}
94
95     /**
96      * "Redo" keeps the constraint number in sync. We don't care about
97      * the rows for which this was generated, we just need the max number
98      * that we ever gave out....
99      */
100     public void redo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
101     Database db = session.getDatabase();
102         db.updateTableIdentity(tableName, num);
103     }
104
105     
106     public void prepare(Session session) throws IOException JavaDoc, SQLException JavaDoc {
107     }
108     
109     public void readExternal(ObjectInput JavaDoc in)
110     throws IOException JavaDoc, ClassNotFoundException JavaDoc
111     {
112     super.readExternal(in);
113     this.tableName = (String JavaDoc)in.readObject();
114         this.num = in.readLong();
115     }
116     
117     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
118     super.writeExternal(out);
119     out.writeObject(tableName);
120         out.writeLong(num);
121     }
122
123     //#ifdef DEBUG
124 public String JavaDoc toString() {
125     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(super.toString());
126         sb.append(" AutoNumberStep(");
127     sb.append(tableName);
128     sb.append(',');
129     sb.append(num);
130     return sb.toString();
131     }
132     //#endif
133
134     /**
135      * Exposed so a careful client can avoid an allocation
136      */
137     public void setCurrentId(long x) { this.num = x; }
138
139     static Extern extern;
140     public void setExtern(Extern extern) { AutoNumberStep.extern = extern; }
141     public Extern getExtern() { return extern; }
142 }
143
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