IdbXAConnection


1   /*
2    * XAPool: Open Source XA JDBC Pool
3    * Copyright (C) 2003 Objectweb.org
4    * Initial Developer: Lutris Technologies Inc.
5    * Contact: xapool-public@lists.debian-sf.objectweb.org
6    *
7    * This library is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU Lesser General Public
9    * License as published by the Free Software Foundation; either
10   * version 2.1 of the License, or any later version.
11   *
12   * This library is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this library; if not, write to the Free Software
19   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
20   * USA
21   */
22  package org.enhydra.jdbc.instantdb;
23  
24  import org.enhydra.jdbc.standard.StandardXAConnection;
25  import org.enhydra.jdbc.standard.StandardXADataSource;
26  import org.enhydra.jdbc.standard.StandardXAStatefulConnection;
27  import org.enhydra.instantdb.jdbc.ConnectionExtensions;
28  
29  import javax.transaction.xa.XAException  ;
30  import javax.transaction.xa.Xid  ;
31  import javax.transaction.xa.XAResource  ;
32  import java.sql.SQLException  ;
33  
34  
35  /**
36   * Provides and InstantDB specific instance of StandardXAConnection. Almost all of
37   * the required functionality is provided curtesy of the generic super class
38   * which looks after most of the transaction state management. InstantDB's
39   * own Transaction object is informed that it is part of a global transaction
40   * and looks after the detail thereafter.
41   */
42  public final class IdbXAConnection extends StandardXAConnection {
43  
44      /**
45       * Creates the first free connection.
46       */
47      public IdbXAConnection (StandardXADataSource dataSource, String   user, String   password) throws SQLException   {
48          super (dataSource, user, password);                 // creates the first Connection object
49      }
50  
51      /**
52       * Associates this XAConnection with a global transaction. This
53       * is the only method which can associate the current connection
54       * with a global transaction. It acts only on the current
55       * connection which must have been previously established using
56       * getConnection.
57       */
58      public void start(Xid   xid, int flags) throws XAException   {
59          doStart (xid, flags);                               // do state checks and set state
60          curCon.commitOnPrepare = false;                     // we will do a REAL prepare
61          ConnectionExtensions conExt
62                  = (ConnectionExtensions)curCon.con;             // get the InstantDB connection
63          conExt.startGlobalTransaction (xid);                // associate the transaction with the global TX
64          curCon = null;                                      // no longer owned by this object
65          con = null;                                         // ditto
66      }
67  
68      // We don't override "end" as all it does is change the state of a connection.
69  
70      /**
71       * Prepares to perform a commit.
72       */
73      public int prepare(Xid   xid) throws XAException   {
74          StandardXAStatefulConnection stateCon = checkPreparedState (xid);// do generic state checking etc.
75          ConnectionExtensions con
76                  = (ConnectionExtensions)stateCon.con;           // get the InstantDB connection
77          int status = con.prepare();                         // prepare to commit
78          if (status == XA_RDONLY) {                          // if transaction didn't update the database
79              xaDataSource.freeConnection (xid, false);           // free the connection
80          } // if
81          return status;
82      }
83  
84      // We don't override commit or rollback. Connection.commit and
85      // Connection.rollback already know that they're part of a global
86      // transaction and will behave accordingly.
87  
88      /**
89       * Checks to see if two XAResource objects correspond to the
90       * same Resource Manager. This can go one better than its
91       * super class as it can actually check the InstantDB database
92       * objects.
93       */
94      public boolean isSameRM(XAResource   xares) throws XAException   {
95          if (super.isSameRM(xares)) {                        // if super class can figure it out
96              return true;                                    // then accept its conclusion
97          } // if
98          if (xares instanceof IdbXAConnection) {             // if it's one of our wrappers
99              IdbXAConnection xac = (IdbXAConnection)xares;   // cast to something more convenient
100             IdbXADataSource cmpds = (IdbXADataSource)xac.dataSource;// get the data source to compare
101             IdbXADataSource ds = (IdbXADataSource)dataSource;// get our own data source
102             if (ds.databaseId.equals (cmpds.databaseId)) {  // if using the same database
103                 return true;                                // they're the same resource
104             } // if
105         } // if
106         return false;
107     }
108 
109 }
110
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