com.dpslink.base.as400

Class AS400ConnectionPool

java.lang.Object

com.dpslink.base.as400.AS400ConnectionPool

All Implemented Interfaces:

java.io.Serializable

public class AS400ConnectionPool
extends java.lang.Object
implements java.io.Serializable

A pool of connections to a configured AS400 system. Provides methods to retrieve connections from the pool and to return connections to the pool.

Direct references to this class and its methods should only be made by the AS400PoolManager class.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	AS400ConnectionPool.KeepAliveTask A timer task used to generate keep-alive activity for pooled connections.

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.ArrayList<AS400ConnectionInfo>	ivAllConnections A list of all AS400 connections ever created by the pool.
private int	ivCheckedOut The number of checked out connections from the pool.
protected java.util.ArrayList<AS400ConnectionInfo>	ivFreeConnections The pool of free AS400 connections available for clients.
private long	ivKeepAlive The number of milliseconds between keep-alive task executions.
private java.util.Timer	ivKeepAliveTimer The timer used to control how often keep-alive activity is generated on a pooled connection.
private int	ivMaxConns The maximum number of connections in the pool.
private java.lang.String	ivPassword The password for the system account.
private java.lang.String	ivSystem The URL for the AS400 system.
private long	ivTimeOut The number of milliseconds to wait for a connection if none is available and the maximum limit is reached.
private java.util.Hashtable<com.ibm.as400.access.AS400,java.lang.String>	ivUsedConnections A list of the in-use AS400 connections.
private java.lang.String	ivUserId The user id for the system account.
private static long	serialVersionUID The class' serialization version id.

Constructor Summary

Constructors

Constructor and Description
AS400ConnectionPool(java.lang.String name, java.lang.String system, java.lang.String userid, java.lang.String password, int maxconns, int initconns, int waittimeout, int idletimeout) Constructs a new AS400ConnectionPool object.

Method Summary

Modifier and Type	Method and Description
private void	addToUsedList(com.ibm.as400.access.AS400 conn, java.lang.String consumer) Adds the given connection to the list of used connections.
private void	enableKeepAlive(boolean enable) Enables or disables the connection keep-alive timer.
void	freeBadConnection(com.ibm.as400.access.AS400 conn) Frees a used connection.
void	freeConnection(com.ibm.as400.access.AS400 conn) Frees a used connection.
com.ibm.as400.access.AS400	getConnection() Retrieves a connection from the pool.
private AS400ConnectionInfo	getConnection(java.lang.String consumer, long timeout) Retrieves a connection from the pool using the given maximum wait time.
private java.lang.String	getConnectionConsumer() Returns the consumer of a connection (the reference point within the code where a connection is being requested or returned).
protected java.lang.String	getConnectionConsumers() Returns a sorted list of the connection consumers associated with the connections currently in-use, suitable for display in a listbox (list is delimited by newline character).
protected java.lang.String	getConnectionStats() Returns a formatted string containing information on the total number of AS400 connections, the number of available connections and the number of checked out connections.
private AS400ConnectionInfo	getPooledConnection() Retrieves a connection if one is available from the pool.
private void	initializePool(int initconns) Opens the initial AS400 connections for the pool.
private boolean	isConnectionOK(AS400ConnectionInfo conn) Checks if the given connection is functioning properly.
protected void	logServiceState(com.ibm.as400.access.AS400 conn) Logs the current state of connected services for the given AS400 connection.
private AS400ConnectionInfo	newConnection() Retrieves a newly created connection.
void	release() Releases all connections in the pool.
private java.lang.String	removeFromUsedList(com.ibm.as400.access.AS400 conn) Removes the given connection from the list of used connections.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

The class' serialization version id.

See Also:

Constant Field Values

ivSystem

private java.lang.String ivSystem

The URL for the AS400 system.

ivUserId

private java.lang.String ivUserId

The user id for the system account.

ivPassword

private java.lang.String ivPassword

The password for the system account.

ivMaxConns

private int ivMaxConns

The maximum number of connections in the pool.

ivTimeOut

private long ivTimeOut

The number of milliseconds to wait for a connection if none is available and the maximum limit is reached.

ivKeepAlive

private long ivKeepAlive

The number of milliseconds between keep-alive task executions.

ivCheckedOut

private int ivCheckedOut

The number of checked out connections from the pool.

ivFreeConnections

protected java.util.ArrayList<AS400ConnectionInfo> ivFreeConnections

The pool of free AS400 connections available for clients.

ivAllConnections

private java.util.ArrayList<AS400ConnectionInfo> ivAllConnections

A list of all AS400 connections ever created by the pool.

ivUsedConnections

private java.util.Hashtable<com.ibm.as400.access.AS400,java.lang.String> ivUsedConnections

A list of the in-use AS400 connections.

ivKeepAliveTimer

private java.util.Timer ivKeepAliveTimer

The timer used to control how often keep-alive activity is generated on a pooled connection.

Constructor Detail

AS400ConnectionPool

public AS400ConnectionPool(java.lang.String name,
                           java.lang.String system,
                           java.lang.String userid,
                           java.lang.String password,
                           int maxconns,
                           int initconns,
                           int waittimeout,
                           int idletimeout)

Constructs a new AS400ConnectionPool object. Any Exceptions possibly caused by the system unavailability are ignored here (only logged) because, by the time the application asks for a connection from the pool, the connection might then be successfully created. If the problem still persists, it is handled at that time.

Parameters:

name - (String) The connection pool name.

system - (String) The URL for the AS400 system.

userid - (String) The user id for the system account.

password - (String) The password for the system account.

maxconns - (int) The maximum number of connections in the pool. 0 means no limit.

initconns - (int) The number of initial connections to open for the pool.

waittimeout - (int) The number of seconds to wait for a connection if none is available and the maximum limit is reached.

idletimeout - (int) The number of minutes between keep-alive task executions.

Method Detail

enableKeepAlive

private void enableKeepAlive(boolean enable)

Enables or disables the connection keep-alive timer.

Parameters:

enable - (boolean) true if enabling the timer, otherwise false.

freeConnection

public void freeConnection(com.ibm.as400.access.AS400 conn)

Frees a used connection. Returns the connection back to the pool.

Parameters:

conn - (AS400) The connection to free.

freeBadConnection

public void freeBadConnection(com.ibm.as400.access.AS400 conn)

Frees a used connection. Does not return the connection back to the pool. Only the counter of checked-out connections is decreased. The actual connection is dropped.

Parameters:

conn - (AS400) The AS400 connection to free.

getConnection

public com.ibm.as400.access.AS400 getConnection()
                                         throws java.lang.Exception

Retrieves a connection from the pool. If a connection cannot be retrieved, an Exception is logged and then thrown back to the invoker.

Returns:

AS400 - An AS400 connection from the pool.

Throws:

java.lang.Exception - - if an error occurs while obtaining a connection.

getConnection

private AS400ConnectionInfo getConnection(java.lang.String consumer,
                                          long timeout)
                                   throws java.lang.Exception

Retrieves a connection from the pool using the given maximum wait time. The connection is returned immediately if one is available or, if the maximum number of connections has not been reached yet, a new one is created.

Parameters:

consumer - (String) The connection consumer (the reference point within the code where the connection is being requested).

timeout - (long) The maximum wait time for a connection.

Returns:

AS400ConnectionInfo - An AS400 connection information object.

Throws:

java.lang.Exception - - if an error occurs while obtaining a connection.

getConnectionConsumer

private java.lang.String getConnectionConsumer()

Returns the consumer of a connection (the reference point within the code where a connection is being requested or returned).

Returns:

String - The connection consumer, generally formatted as "at package.class.method(class.java:statement)".

getConnectionConsumers

protected java.lang.String getConnectionConsumers()

Returns a sorted list of the connection consumers associated with the connections currently in-use, suitable for display in a listbox (list is delimited by newline character).

Returns:

String - The connection consumers for the connections currently being used.

getConnectionStats

protected java.lang.String getConnectionStats()

Returns a formatted string containing information on the total number of AS400 connections, the number of available connections and the number of checked out connections.

Returns:

String - A formatted string of statistics.

getPooledConnection

private AS400ConnectionInfo getPooledConnection()
                                         throws java.lang.Exception

Retrieves a connection if one is available from the pool. If one is not available, invokes the newConnection method.

Returns:

AS400ConnectionInfo - An AS400 connection information object.

Throws:

java.lang.Exception - - if an error occurs while obtaining a connection.

initializePool

private void initializePool(int initconns)
                     throws java.lang.Exception

Opens the initial AS400 connections for the pool.

Parameters:

initconns - (int) The number of initial connections.

Throws:

java.lang.Exception - - if an error occurs while opening the connections.

isConnectionOK

private boolean isConnectionOK(AS400ConnectionInfo conn)

Checks if the given connection is functioning properly.

Parameters:

conn - (AS400ConnectionInfo) The AS400 connection to check.

Returns:

boolean - true if the connection is okay, otherwise false.

logServiceState

protected void logServiceState(com.ibm.as400.access.AS400 conn)

Logs the current state of connected services for the given AS400 connection.

Parameters:

conn - (AS400) An AS400 connection.

newConnection

private AS400ConnectionInfo newConnection()
                                   throws java.lang.Exception

Retrieves a newly created connection.

Returns:

AS400ConnectionInfo - An AS400 connection information object.

Throws:

java.lang.Exception - - if an error occurs while creating the connection.

release

public void release()

Releases all connections in the pool.

addToUsedList

private void addToUsedList(com.ibm.as400.access.AS400 conn,
                           java.lang.String consumer)

Adds the given connection to the list of used connections.

Parameters:

conn - (AS400) The connection to add to the list.

consumer - (String) The connection's consumer.

removeFromUsedList

private java.lang.String removeFromUsedList(com.ibm.as400.access.AS400 conn)

Removes the given connection from the list of used connections.

Parameters:

conn - (AS400) The connection to remove from the list.

Returns:

String - The consumer associated with the connection.