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1
5 package org.h2.schema;
6
7 import java.sql.SQLException  ;
8
9 import org.h2.engine.DbObject;
10 import org.h2.engine.Session;
11 import org.h2.jdbc.JdbcSQLException;
12 import org.h2.message.Message;
13 import org.h2.message.Trace;
14 import org.h2.table.Table;
15
16 public class Sequence extends SchemaObject {
17 private static final int BLOCK_INCREMENT = 32;
18 private long value = 1;
19 private long valueWithMargin;
20 private long increment = 1;
21 private boolean belongsToTable;
22
23 public Sequence(Schema schema, int id, String name, boolean belongsToTable) {
24 super(schema, id, name, Trace.SEQUENCE);
25 this.belongsToTable = belongsToTable;
26 }
27
28 public synchronized void setStartValue(long value) {
29 this.value = value;
30 this.valueWithMargin = value;
31 }
32
33 public boolean getBelongsToTable() {
34 return belongsToTable;
35 }
36
37 public long getIncrement() {
38 return increment;
39 }
40
41 public void setIncrement(long inc) throws JdbcSQLException {
42 if(increment == 0) {
43 throw Message.getSQLException(Message.INVALID_VALUE_2, new String []{"0", "INCREMENT"}, null);
44 }
45 this.increment = inc;
46 }
47
48 public String getCreateSQLForCopy(Table table, String quotedName) {
49 throw Message.getInternalError();
50 }
51
52 public synchronized String getCreateSQL() {
53 StringBuffer buff = new StringBuffer ();
54 buff.append("CREATE SEQUENCE ");
55 buff.append(getSQL());
56 buff.append(" START WITH ");
57 buff.append(value);
58 if(increment != 1) {
59 buff.append(" INCREMENT BY ");
60 buff.append(increment);
61 }
62 if(belongsToTable) {
63 buff.append(" BELONGS_TO_TABLE");
64 }
65 return buff.toString();
66 }
67
68 public synchronized long getNext() throws SQLException {
69 if((increment > 0 && value >= valueWithMargin) || (increment < 0 && value <= valueWithMargin)) {
70 valueWithMargin += increment*BLOCK_INCREMENT;
71 flush();
72 }
73 long v = value;
74 value += increment;
75 return v;
76 }
77
78 public void flush() throws SQLException {
79 Session s = database.getSystemSession();
82 synchronized(this) {
83 long realValue = value;
85 try {
86 value = valueWithMargin;
87 database.update(s, this);
88 } finally {
89 value = realValue;
90 }
91 }
92 s.commit();
93 }
94
95 public void close() throws SQLException {
96 valueWithMargin = value;
97 flush();
98 }
99
100 public int getType() {
101 return DbObject.SEQUENCE;
102 }
103
104 public void removeChildrenAndResources(Session session) {
105 invalidate();
106 }
107
108 public void checkRename() {
109 }
111
112 public synchronized long getCurrentValue() {
113 return value - increment;
114 }
115
116 public void setBelongsToTable(boolean b) {
117 this.belongsToTable = b;
118 }
119
120 }
121 |
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