/*
Derby - Class org.apache.derby.diag.TransactionTable
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package org.apache.derby.diag;
import org.apache.derby.iapi.sql.conn.LanguageConnectionContext;
import org.apache.derby.iapi.sql.conn.ConnectionUtil;
import org.apache.derby.iapi.store.access.TransactionInfo;
import org.apache.derby.vti.VTITemplate;
import org.apache.derby.vti.VTICosting;
import org.apache.derby.vti.VTIEnvironment;
import org.apache.derby.iapi.sql.ResultColumnDescriptor;
import org.apache.derby.impl.jdbc.EmbedResultSetMetaData;
import org.apache.derby.iapi.reference.Limits;
import org.apache.derby.iapi.util.StringUtil;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Types;
/**
TransactionTable is a virtual table that shows all transactions
currently in the database.
This virtual table can be invoked by calling it
directly
<PRE> select * from SYSCS_DIAG.TRANSACTION_TABLE </PRE>
<P>The TransactionTable virtual table takes a snap shot of the
transaction table while the system is in flux, so it is possible that some
transactions may be in transition state while the snap shot is taken.
We choose to do this rather then impose extraneous timing restrictions so
that the use of this tool will not alter the normal timing and flow of
execution in the application.
<P>The TransactionTable virtual table has the following columns:
<UL>
<LI>XID varchar(15) - not nullable. The transaction id, this can be joined
with the LockTable virtual table's XID.</LI>
<LI>GLOBAL_XID varchar(140) - nullable. The global transaction id, only
set if this transaction is a participant in a distributed transaction.</LI>
<LI>USERNAME varchar(128) - nullable. The user name, or APP by default.
May appear null if the transaction is started by Derby.</LI>
<LI>TYPE varchar(30) - not nullable. UserTransaction or an internal
transaction spawned by Derby.</LI>
<LI>STATUS varchar(8) - not nullable. IDLE or ACTIVE. A transaction is
IDLE only when it is first created or right after it commits. Any
transaction that holds or has held any resource in the database is ACTIVE.
Accessing the TransactionTable virtual table without using the class alias
will not activate the transaction.</LI>
<LI>FIRST_INSTANT varchar(20) - nullable. If null, this is a read only
transaction. If not null, this is the first log record instant written by
the transaction.</LI>
<LI>SQL_TEXT VARCHAR(32672) - nullable. if null, this transaction is
currently not being executed in the database. If not null, this is the SQL
statement currently being executed in the database.</LI>
</UL>
*/
public class TransactionTable extends VTITemplate implements VTICosting {
private TransactionInfo[] transactionTable;
boolean initialized;
int currentRow;
private boolean wasNull;
/**
@see java.sql.ResultSet#getMetaData
*/
public ResultSetMetaData getMetaData()
{
return metadata;
}
/**
@see java.sql.ResultSet#next
@exception SQLException if no transaction context can be found
*/
public boolean next() throws SQLException
{
if (!initialized)
{
LanguageConnectionContext lcc = ConnectionUtil.getCurrentLCC();
transactionTable = lcc.getTransactionExecute().
getAccessManager().getTransactionInfo();
initialized = true;
currentRow = -1;
}
if (transactionTable == null)
return false;
for (currentRow++;
currentRow < transactionTable.length;
currentRow++)
{
TransactionInfo info = transactionTable[currentRow];
if (info == null)
continue; // transaction object in flux while the
// snap shot was taken, get another row
return true;
}
// currentRow >= transactionTable.length
transactionTable = null;
return false;
}
/**
@see java.sql.ResultSet#close
*/
public void close()
{
transactionTable = null;
}
/**
All columns in TransactionTable VTI is of String type.
@see java.sql.ResultSet#getString
*/
public String getString(int columnNumber)
{
TransactionInfo info = transactionTable[currentRow];
String str = null;
switch(columnNumber)
{
case 1:
str = info.getTransactionIdString(); break;
case 2:
str = info.getGlobalTransactionIdString(); break;
case 3:
str = info.getUsernameString(); break;
case 4:
str = info.getTransactionTypeString(); break;
case 5:
str = info.getTransactionStatusString(); break;
case 6:
str = info.getFirstLogInstantString(); break;
case 7:
str = info.getStatementTextString();
str = StringUtil.truncate(str, Limits.DB2_VARCHAR_MAXWIDTH);
break;
default:
str = null;
}
wasNull = (str == null);
return str;
}
/**
@see java.sql.ResultSet#wasNull
*/
public boolean wasNull()
{
return wasNull;
}
/** VTI costing interface */
/**
@see VTICosting#getEstimatedRowCount
*/
public double getEstimatedRowCount(VTIEnvironment vtiEnvironment)
{
return VTICosting.defaultEstimatedRowCount;
}
/**
@see VTICosting#getEstimatedCostPerInstantiation
*/
public double getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment)
{
return VTICosting.defaultEstimatedCost;
}
/**
@return false
@see VTICosting#supportsMultipleInstantiations
*/
public boolean supportsMultipleInstantiations(VTIEnvironment vtiEnvironment)
{
return false;
}
/*
** Metadata
*/
private static final ResultColumnDescriptor[] columnInfo = {
EmbedResultSetMetaData.getResultColumnDescriptor("XID", Types.VARCHAR, false, 15),
EmbedResultSetMetaData.getResultColumnDescriptor("GLOBAL_XID", Types.VARCHAR, true, 140),
EmbedResultSetMetaData.getResultColumnDescriptor("USERNAME", Types.VARCHAR, true, 128),
EmbedResultSetMetaData.getResultColumnDescriptor("TYPE", Types.VARCHAR, false, 30),
EmbedResultSetMetaData.getResultColumnDescriptor("STATUS", Types.VARCHAR, false, 8),
EmbedResultSetMetaData.getResultColumnDescriptor("FIRST_INSTANT", Types.VARCHAR, true, 20),
EmbedResultSetMetaData.getResultColumnDescriptor("SQL_TEXT", Types.VARCHAR, true, Limits.DB2_VARCHAR_MAXWIDTH),
};
private static final ResultSetMetaData metadata = new EmbedResultSetMetaData(columnInfo);
}