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From "Mamta A. Satoor (JIRA)" <derby-...@db.apache.org>
Subject [jira] Updated: (DERBY-421) starting an XA transaction resets the isolation level set with SET CURRENT ISOLATION
Date Tue, 23 Aug 2005 06:09:08 GMT
     [ http://issues.apache.org/jira/browse/DERBY-421?page=all ]

Mamta A. Satoor updated DERBY-421:
----------------------------------

    Attachment: derby421XAIsolation082205.txt

Attaching a patch for this JIRA entry. Following is some information on the patch.

When a connection object is obtained through XADataSource, it can be part of a local transaction
or it can be attached to a global transaction. The state of the connection object can be different
depending on whether it is used in local transaction or global transaction. Among other state
information, isolation level is saved as part of the connection object's state information.
This isolation level state is set correctly when isolation level is set using JDBC api. But
it gets out of sync when SQL is used to set the isolation level state. In order to fix this,
I have added a flag in GenericLanguageConnectionContext which will get set to true anytime
isolation level is set using JDBC/SQL api. And this flag is later used to keep the isolation
level state information uptodate in BrokeredConnection. The classes changed by this fix are
as follows.

svn stat
M      java\engine\org\apache\derby\impl\sql\conn\GenericLanguageConnectionContext.java
M      java\engine\org\apache\derby\iapi\sql\conn\LanguageConnectionContext.java
M      java\engine\org\apache\derby\iapi\jdbc\BrokeredConnection.java
M      java\engine\org\apache\derby\iapi\jdbc\BrokeredConnectionControl.java
M      java\engine\org\apache\derby\jdbc\EmbedPooledConnection.java
M      java\engine\org\apache\derby\jdbc\EmbedXAConnection.java
M      java\testing\org\apache\derbyTesting\functionTests\tests\jdbcapi\checkDataSource.java
M      java\testing\org\apache\derbyTesting\functionTests\master\checkDataSource.out
M      java\testing\org\apache\derbyTesting\functionTests\master\checkDataSource30.out


> starting an XA transaction resets the isolation level set with SET CURRENT ISOLATION
> ------------------------------------------------------------------------------------
>
>          Key: DERBY-421
>          URL: http://issues.apache.org/jira/browse/DERBY-421
>      Project: Derby
>         Type: Sub-task
>   Components: JDBC
>     Reporter: Kathey Marsden
>     Assignee: Mamta A. Satoor
>  Attachments: derby421XAIsolation082205.txt
>
> When an XA Transaction is started the isolation level set with SET CURRENT ISOLATION
gets reset to CS.
> Embedded setTransactionIsolation  does not have this problem but this problem is the
root cause of DERBY-414 because client implements setTransactionIsolation by sending SET CURRENT
ISOLATION
> $ java TestSetCurrentIsolation
> Database product: Apache Derby
> Database version: 10.2.0.0 alpha
> Driver name:      Apache Derby Embedded JDBC Driver
> Driver version:   10.2.0.0 alpha
> SET CURRENT ISOLATION = UR
> CURRENT ISOLATION: UR
> getTransactionIsolation:TRANSACTION_READ_UNCOMMITTED:1
> Isolation level after xa start
> CURRENT ISOLATION: CS
> getTransactionIsolation:TRANSACTION_READ_COMMITTED:2
> $
> import java.sql.*;
> import javax.sql.*;
> import javax.transaction.xa.*;
> public class TestSetCurrentIsolation
> {
>     public static void main(String[] args) throws Throwable
>     {
>         try
>         {
>              final org.apache.derby.jdbc.EmbeddedXADataSource ds =
>              new org.apache.derby.jdbc.EmbeddedXADataSource();
>              ds.setDatabaseName("C:\\drivers\\derby\\databases\\SCHEDDB");
>              ds.setUser("dbuser1");
>              ds.setPassword("******");
>             XAConnection xaConn = ds.getXAConnection();
>             Connection conn = xaConn.getConnection();
>             conn.setAutoCommit(true);
>             System.out.println("Database product: " + conn.getMetaData().getDatabaseProductName());
>             System.out.println("Database version: " + conn.getMetaData().getDatabaseProductVersion());
>             System.out.println("Driver name:      " + conn.getMetaData().getDriverName());
>             System.out.println("Driver version:   " + conn.getMetaData().getDriverVersion());
>             Statement stmt = conn.createStatement();
>             System.out.println("SET CURRENT ISOLATION = UR");
>             stmt.executeUpdate("SET CURRENT ISOLATION = UR");
>             showIsolationLevel(conn);
>             conn.setAutoCommit(false);
>             XAResource xaRes = xaConn.getXAResource();
>             Xid xid = new TestXid(1,(byte) 32, (byte) 32);
>             xaRes.start(xid, XAResource.TMNOFLAGS);
>             System.out.println("Isolation level after xa start");
>             showIsolationLevel(conn);
>             
>             xaRes.end(xid, XAResource.TMSUCCESS);
>             xaRes.rollback(xid);
>             conn.close();
>             xaConn.close();
>         }
>         catch (SQLException sqlX)
>         {
>             System.out.println("Error on thread 1.");
>             do sqlX.printStackTrace();
>             while ((sqlX = sqlX.getNextException()) != null);
>         }
>         catch (Throwable th)
>         {
>             System.out.println("Error on thread 1.");
>             do th.printStackTrace();
>             while ((th = th.getCause()) != null);
>         }
>     }
> 	/**
> 	 * @param conn
> 	 * @throws SQLException
> 	 */
> 	private static void showIsolationLevel(Connection conn) throws SQLException {
> 		PreparedStatement ps = conn.prepareStatement("VALUES CURRENT ISOLATION");
> 		ResultSet rs = ps.executeQuery();
> 		//ResultSet rs = conn.createStatement().executeQuery("VALUES CURRENT ISOLATION");
> 		rs.next();
> 		System.out.println("CURRENT ISOLATION: " +  rs.getString(1));
> 		System.out.println("getTransactionIsolation:" + 
> 					getIsoLevelName(conn.getTransactionIsolation()));						
> 	}
> 	
> 	public static String getIsoLevelName(int level)
> 	{
> 		switch (level) {
> 			case java.sql.Connection.TRANSACTION_REPEATABLE_READ:
> 				return "TRANSACTION_REAPEATABLE_READ:" + level;
> 					
> 			case java.sql.Connection.TRANSACTION_READ_COMMITTED:
> 				return "TRANSACTION_READ_COMMITTED:" + level;
> 			case java.sql.Connection.TRANSACTION_SERIALIZABLE:
> 				return "TRANSACTION_SERIALIZABLE:" + level;
> 			case java.sql.Connection.TRANSACTION_READ_UNCOMMITTED:
> 				return "TRANSACTION_READ_UNCOMMITTED:" + level;
> 		}
> 		return "UNEXPECTED_ISO_LEVEL";
> 	}
> }

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