com.lutris.appserver.server.sql.datasource
Class SimpleDataSourceConnectionAllocator

java.lang.Object
  com.lutris.appserver.server.sql.datasource.SimpleDataSourceConnectionAllocator

All Implemented Interfaces:

ConnectionAllocator, ExtendedConnectionAllocator

public class SimpleDataSourceConnectionAllocator
extends java.lang.Object
implements ExtendedConnectionAllocator

Brief description of the patch: Since each long-time used connection holds too much memory (about 15Mb after several hours of work) it was decided to close and recreate connections that were allocated more than the MaxConnectionUsages value set in the proper config file. We also changed the stack-like structure of the connection pool to queue-like. This guarantees that no connections become stagnant. 4.07.2003

Field Summary

protected java.lang.String	connectionAllocateCheckSql database "ConnectionCheckSql" string
protected java.lang.String	connectionReleaseCheckSql database "ConnectionReleaseCheckSql" string
protected javax.sql.DataSource	dataSource JDBC URL of database.
protected boolean	disableConnectionPool Indicates dods not to use connection pool.
protected int	generation Generation number.
protected LogicalDatabase	logicalDatabase Reference to the logical database for easy access to the connection pool.
protected int	maxPreparedStatements Maximum number of prepared statements to use; if less-than zero, then JDBC is queried for this value.
protected int	maxWaitingConnections JP Patch Maximum number of DBConnections that will be waiting in the pool
protected long	numRequests Number of queries or transactions on this logical database.
protected java.lang.String	password SQL password..
protected int	queryTimeOut Maximum amount of time in seconds to block on a query.
protected java.lang.String	shutDownStr database "ShutDown" string
protected boolean	sqlLogging Indicates if logging is enabled.
protected int	transactionTimeOut Maximum amount of time in seconds to block on a transaction.
protected java.lang.String	url JDBC URL of database.
protected java.lang.String	user SQL user name.

Constructor Summary

SimpleDataSourceConnectionAllocator(LogicalDatabase logicalDatabase, Config conConfig)
Initialize the connection allocator object.

Method Summary

DBConnection	allocate() If pool is used: Allocate a connection to a thread.
protected DBConnection	createConnection() Create a new connection in the pool.
void	drop(DBConnection dbConnection) Called when a connection in this pool has an SQL error.
void	dropAllNow() Called when the database manager is shutting down: Close all connections immediately.
protected void	finalize() Finalizer.
int	getActiveCount() Return the number of currently active connections.
java.lang.String	getDatabaseName()
int	getMaxCount() Return the maximum number of connections active at one time.
java.util.Date	getMaxCountDate() Return the time when the maximum connection count occured.
long	getRequestCount() Return the number of database requests.
void	incrementRequesteCount()
boolean	performRollbackOnReset()
void	release(DBConnection dbConnection) Return a connection to the pool (if used else only close connection).
void	resetMaxCount() Reset the maximum connection count and date.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logicalDatabase

protected LogicalDatabase logicalDatabase

Reference to the logical database for easy access to the connection pool.

dataSource

protected javax.sql.DataSource dataSource

JDBC URL of database.

url

protected java.lang.String url

JDBC URL of database.

user

protected java.lang.String user

SQL user name.

password

protected java.lang.String password

SQL password..

shutDownStr

protected java.lang.String shutDownStr

database "ShutDown" string

connectionAllocateCheckSql

protected java.lang.String connectionAllocateCheckSql

database "ConnectionCheckSql" string

connectionReleaseCheckSql

protected java.lang.String connectionReleaseCheckSql

database "ConnectionReleaseCheckSql" string

numRequests

protected long numRequests

Number of queries or transactions on this logical database.

maxWaitingConnections

protected int maxWaitingConnections

JP Patch Maximum number of DBConnections that will be waiting in the pool

sqlLogging

protected boolean sqlLogging

Indicates if logging is enabled.

disableConnectionPool

protected boolean disableConnectionPool

Indicates dods not to use connection pool.

queryTimeOut

protected int queryTimeOut

Maximum amount of time in seconds to block on a query. The DBQuery object will retrieve this value from the connection.

transactionTimeOut

protected int transactionTimeOut

Maximum amount of time in seconds to block on a transaction. The DBTransaction object will retrieve this value from the connection.

maxPreparedStatements

protected int maxPreparedStatements

Maximum number of prepared statements to use; if less-than zero, then JDBC is queried for this value.

generation

protected int generation

Generation number. When an SQL error occurs, all objects of the same generation or earlier are dropped.

Constructor Detail

SimpleDataSourceConnectionAllocator

public SimpleDataSourceConnectionAllocator(LogicalDatabase logicalDatabase,
                                           Config conConfig)
                                    throws ConfigException

Initialize the connection allocator object. Connections are opened on demand and stored in a pool.

Parameters:

logicalDatabase - LogicalDatabase.

conConfig - LogicalDatabase Config object

Throws:

ConfigException - if bad configuration information is given in the config file.

Method Detail

createConnection

protected DBConnection createConnection()
                                 throws java.sql.SQLException

Create a new connection in the pool.

Throws:

java.sql.SQLException - If a SQL error occures.

allocate

public DBConnection allocate()
                      throws java.sql.SQLException

If pool is used: Allocate a connection to a thread. If none are available, grow the pool. If the pool is alredy its maximum size, then the thread waits. If pool is not used (disableConnectionPool=true) then only create new transaction.

Specified by:

allocate in interface ConnectionAllocator

Returns:

The allocated connection object.

Throws:

java.sql.SQLException - If a SQL error occures.

release

public void release(DBConnection dbConnection)

Return a connection to the pool (if used else only close connection).

Specified by:

release in interface ConnectionAllocator

Parameters:

dbConnection - The connection object to return.

drop

public void drop(DBConnection dbConnection)

Called when a connection in this pool has an SQL error. All unallocated connections in the pool are dropped if they have a generation number less than or equal to the error connection. If the current generation number is the same as this generation number, increment it. This way so that all outstanding connections (including the one passed in) of the same generation are dropped when returned.

Specified by:

drop in interface ConnectionAllocator

Parameters:

dbConnection - The connection object to drop. The connection should be returned to the pool after this function returns.

dropAllNow

public void dropAllNow()

Called when the database manager is shutting down: Close all connections immediately.

Specified by:

dropAllNow in interface ConnectionAllocator

getActiveCount

public int getActiveCount()

Return the number of currently active connections.

Specified by:

getActiveCount in interface ConnectionAllocator

Returns:

The number of connections.

getMaxCount

public int getMaxCount()

Return the maximum number of connections active at one time.

Specified by:

getMaxCount in interface ConnectionAllocator

Returns:

The number of connections.

getMaxCountDate

public java.util.Date getMaxCountDate()

Return the time when the maximum connection count occured.

Specified by:

getMaxCountDate in interface ConnectionAllocator

Returns:

The Date when the maximum connection count occured.

resetMaxCount

public void resetMaxCount()

Reset the maximum connection count and date.

Specified by:

resetMaxCount in interface ConnectionAllocator

getRequestCount

public long getRequestCount()

Return the number of database requests.

Specified by:

getRequestCount in interface ConnectionAllocator

Returns:

The number of database requests (queries or transactions).

finalize

protected void finalize()

Finalizer. If any connections allocated by this object have not been closed, this method ensures that garbage collection does so.

Overrides:

finalize in class java.lang.Object

getDatabaseName

public java.lang.String getDatabaseName()

Specified by:

getDatabaseName in interface ConnectionAllocator

Returns:

database name of current connection

incrementRequesteCount

public void incrementRequesteCount()

Specified by:

incrementRequesteCount in interface ExtendedConnectionAllocator

performRollbackOnReset

public boolean performRollbackOnReset()

Specified by:

performRollbackOnReset in interface ExtendedConnectionAllocator