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1
22 package org.jboss.ejb.plugins.keygenerator.hilo;
23 import org.jboss.ejb.plugins.keygenerator.KeyGenerator;
24 import org.jboss.ejb.plugins.cmp.jdbc.JDBCUtil;
25 import org.jboss.logging.Logger;
26
27 import javax.sql.DataSource  ;
28 import javax.transaction.TransactionManager ;
29 import javax.transaction.Transaction ;
30 import javax.transaction.SystemException ;
31 import java.sql.PreparedStatement ;
32 import java.sql.Connection ;
33 import java.sql.SQLException ;
34 import java.sql.ResultSet ;
35
39 public class HiLoKeyGenerator
40 implements KeyGenerator
41 {
42 private static long highestHi = 0;
43
44 public static synchronized long getHighestHi()
45 {
46 return highestHi;
47 }
48
49 public static synchronized void setHighestHi(long highestHi)
50 {
51 HiLoKeyGenerator.highestHi = highestHi;
52 }
53
54 private final Logger log;
55 private final DataSource ds;
56 private final long blockSize;
57
58 private long hi;
59 private long lo;
60
61 private TransactionManager tm;
62 private String updateHiSql;
63 private String selectHiSql;
64
65 public HiLoKeyGenerator(
66 DataSource ds,
67 String tableName,
68 String sequenceColumn,
69 String sequenceName,
70 String idColumnName,
71 String selectHiSql,
72 long blockSize,
73 TransactionManager tm
74 )
75 {
76 this.ds = ds;
77 this.blockSize = blockSize;
78 this.tm = tm;
79 this.log = Logger.getLogger(getClass().getName() + "#" + tableName + "_" + sequenceName);
80
81 updateHiSql = "update " +
82 tableName +
83 " set " +
84 idColumnName +
85 "=?" +
86 " where " + sequenceColumn + "='" + sequenceName + "' and " +
87 idColumnName + "=?";
88
89 this.selectHiSql = selectHiSql;
90 }
91
92 public synchronized Object generateKey()
93 {
94 if(lo < hi)
95 {
96 ++lo;
97 }
98 else
99 {
100 Transaction curTx = null;
101 try
102 {
103 curTx = tm.suspend();
104 }
105 catch(SystemException e)
106 {
107 throw new IllegalStateException ("Failed to suspend current transaction.");
108 }
109
110 try
111 {
112 tm.begin();
113 }
114 catch(Exception e)
115 {
116 throw new IllegalStateException ("Failed to begin a new transaction.");
117 }
118
119 try
120 {
121 doGenerate();
122 tm.commit();
123 }
124 catch(SQLException e)
125 {
126 log.error("Failed to update table: " + e.getMessage(), e);
127
128 try
129 {
130 tm.rollback();
131 }
132 catch(SystemException e1)
133 {
134 log.error("Failed to rollback.", e1);
135 }
136
137 throw new IllegalStateException (e.getMessage());
138 }
139 catch(Exception e)
140 {
141 log.error("Failed to commit.", e);
142 }
143 finally
144 {
145 if(curTx != null)
146 {
147 try
148 {
149 tm.resume(curTx);
150 }
151 catch(Exception e)
152 {
153 throw new IllegalStateException ("Failed to resume transaction: " + e.getMessage());
154 }
155 }
156 }
157 }
158
159 return new Long (lo);
160 }
161
162 private void doGenerate() throws SQLException
163 {
164 long curHi;
165 do
166 {
167 curHi = getCurrentHi();
168 lo = curHi + 1;
169 hi = curHi + blockSize;
170 }
171 while(!updateHi(curHi, hi));
172 }
173
174 private long getCurrentHi() throws SQLException
175 {
176 return selectHiSql != null ? selectHi() : getHighestHi();
177 }
178
179 private boolean updateHi(long curHi, long newHi) throws SQLException
180 {
181 if(selectHiSql == null)
182 {
183 setHighestHi(newHi);
184 }
185 return updateTable(curHi, newHi);
186 }
187
188 private long selectHi() throws SQLException
189 {
190 Connection con = null;
191 PreparedStatement selectHiSt = null;
192 ResultSet rs = null;
193
194 if(log.isTraceEnabled())
195 {
196 log.trace("Executing SQL: " + selectHiSql);
197 }
198
199 try
200 {
201 con = ds.getConnection();
202 selectHiSt = con.prepareStatement(selectHiSql);
203 rs = selectHiSt.executeQuery();
204 if(!rs.next())
205 {
206 throw new IllegalStateException ("The sequence has not been initialized in the service start phase!");
207 }
208 return rs.getLong(1);
209 }
210 finally
211 {
212 JDBCUtil.safeClose(rs);
213 JDBCUtil.safeClose(selectHiSt);
214 JDBCUtil.safeClose(con);
215 }
216 }
217
218 private boolean updateTable(long curHi, long newHi) throws SQLException
219 {
220 Connection con = null;
221 PreparedStatement updateHi = null;
222
223 if(log.isTraceEnabled())
224 {
225 log.trace("Executing SQL: " + updateHiSql + ", [" + newHi + "," + curHi + "]");
226 }
227
228 try
229 {
230 con = ds.getConnection();
231 updateHi = con.prepareStatement(updateHiSql);
232 updateHi.setLong(1, newHi);
233 updateHi.setLong(2, curHi);
234 return updateHi.executeUpdate() == 1;
235 }
236 finally
237 {
238 JDBCUtil.safeClose(updateHi);
239 JDBCUtil.safeClose(con);
240 }
241 }
242 } |
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