amber.server.manager.database
Class ConnectionPool

java.lang.Object
  |
  +--java.lang.Thread
        |
        +--amber.server.manager.database.ConnectionPool

All Implemented Interfaces:

java.lang.Runnable

public class ConnectionPool

extends java.lang.Thread

This class controls a cache of connection pools. It is instantiated by the Database Manager and coordinates connections to a database and the interaction to the database system.

Version:

1.0.0

Author:

Dr. David J. Knowles

See Also:

DatabaseManager, DatabaseConnection

Field Summary

protected java.util.Vector	connectionPool The connection pool
static long	ConnectionWaitQuanta How many milliseconds to block before rechecking an event.
protected java.lang.String	databaseDriver The name of the database driver.
protected java.lang.String	databaseName The name of the database URL.
static java.lang.String	header
protected long	inactivityDuration The amount of time the thread should sleep between refreshing connections.
protected Log	loggingFile Logging file.
protected int	maxConnections The maximum number of connections to ever establish.
protected int	minConnections The minimum number of connections to establish on start up.
protected java.lang.String	password The password to use when connecting to the database.
protected java.lang.String	userName The user name to use when connecting to the database.
static java.lang.String	version

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

ConnectionPool(java.lang.String name, java.lang.String databaseDriver, java.lang.String databaseName, java.lang.String userName, java.lang.String password, int minConnections, int maxConnections, java.lang.String logFilename, int logLevel, long inactivityDuration)
The constructor for the pool.

Method Summary

protected DatabaseConnection	createNewConnection(java.lang.String databaseName, java.lang.String userName, java.lang.String password) This function creates a new connection and adds it to the pool of available database objects.
boolean	equals(java.lang.Object other) This function determines if the input object is the same as this object.
int	getAvailableConnections() Return the number of available connections.
java.sql.Connection	getConnection() Gets a connection from the available connection pool.
java.sql.Connection	getConnection(long timeout) Gets a connection from the available connection pool.
int	getMaximumConnections() Return the maximum number of connections which it is possible to raise.
int	getMinimumConnections() Return the minimum number of connections raised on creation.
java.lang.String	getPoolName() This function returns the name of the ConnectionPool.
int	getTotalConnections() Return the total number of connections raised currently to the database.
void	init(java.lang.String logFilename, int logLevel) Main initialisation function for this database system.
protected void	initialiseDataBase(java.lang.String databaseDriver, java.lang.String databaseName, java.lang.String userName, java.lang.String password) This function opens the database given the specified characteristics.
protected java.sql.Connection	openConnection(java.lang.String databaseName, java.lang.String userName, java.lang.String password) This function opens a new connection to the database.
protected void	openConnections(java.lang.String databaseName, java.lang.String userName, java.lang.String password) This function opens the specified number of connections in the properties file for the manager.
protected void	refreshConnection(DatabaseConnection entry) This function refreshes an individual connection pool entry.
void	refreshConnectionPool() This function refreshes the connection pool and ensures that the connections are still valid.
void	releaseConnection(java.sql.Connection connection) Returns the connection back to the available connection pool.
void	run() The thread run method.
void	shutDown() Termination function.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getContextClassLoader, getName, getPriority, getThreadGroup, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setName, setPriority, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

version

public static final java.lang.String version

header

public static final java.lang.String header

ConnectionWaitQuanta

public static final long ConnectionWaitQuanta

How many milliseconds to block before rechecking an event.

loggingFile

protected Log loggingFile

Logging file.

connectionPool

protected java.util.Vector connectionPool

The connection pool

databaseName

protected java.lang.String databaseName

The name of the database URL.

databaseDriver

protected java.lang.String databaseDriver

The name of the database driver.

userName

protected java.lang.String userName

The user name to use when connecting to the database.

password

protected java.lang.String password

The password to use when connecting to the database.

minConnections

protected int minConnections

The minimum number of connections to establish on start up.

maxConnections

protected int maxConnections

The maximum number of connections to ever establish.

inactivityDuration

protected long inactivityDuration

The amount of time the thread should sleep between refreshing connections.

Constructor Detail

ConnectionPool

public ConnectionPool(java.lang.String name,
                      java.lang.String databaseDriver,
                      java.lang.String databaseName,
                      java.lang.String userName,
                      java.lang.String password,
                      int minConnections,
                      int maxConnections,
                      java.lang.String logFilename,
                      int logLevel,
                      long inactivityDuration)
               throws DatabaseManagerException

The constructor for the pool.

Parameters:

name - String containing the name of the connection pool object.

databaseDriver - String name of the JDBC driver.

databaseName - String JDBC URL of the database.

userName - String name to use when authenticating this server.

password - String password to use when authenticating this server.

minConnections - int number of connections to start pool with.

maxConnections - int number of upper limit of connections to create.

logFilename - String containing the name of the log file.

logLevel - int containing the log level to log.

inactivityDuration - long time that the thread should sleep between refreshes.

Throws:

DatabaseManagerException - containing errors.

Method Detail

init

public void init(java.lang.String logFilename,
                 int logLevel)
          throws DatabaseManagerException

Main initialisation function for this database system.

Parameters:

logFilename - String containing the name of the log file.

logLevel - int containing the log level to log.

Throws:

DatabaseManagerException - containing errors.

initialiseDataBase

protected void initialiseDataBase(java.lang.String databaseDriver,
                                  java.lang.String databaseName,
                                  java.lang.String userName,
                                  java.lang.String password)
                           throws DatabaseManagerException

This function opens the database given the specified characteristics.

Parameters:

databaseDriver - String name of the JDBC driver.

databaseName - String JDBC URL of the database.

userName - String name to use when authenticating this server.

password - String password to use when authenticating this server.

Throws:

DatabaseManagerException - containing errors.

openConnections

protected void openConnections(java.lang.String databaseName,
                               java.lang.String userName,
                               java.lang.String password)
                        throws DatabaseManagerException

This function opens the specified number of connections in the properties file for the manager.

Parameters:

databaseName - String JDBC URL of the database.

userName - String name to use when authenticating this server.

password - String password to use when authenticating this server.

Throws:

DatabaseManagerException - containing errors.

createNewConnection

protected DatabaseConnection createNewConnection(java.lang.String databaseName,
                                                 java.lang.String userName,
                                                 java.lang.String password)

This function creates a new connection and adds it to the pool of available database objects.

Parameters:

databaseName - String JDBC URL of the database.

userName - String name to use when authenticating this server.

password - String password to use when authenticating this server.

Returns:

DatabaseConnection which was created.

openConnection

protected java.sql.Connection openConnection(java.lang.String databaseName,
                                             java.lang.String userName,
                                             java.lang.String password)

This function opens a new connection to the database.

Parameters:

databaseName - String JDBC URL of the database.

userName - String name to use when authenticating this server.

password - String password to use when authenticating this server.

Returns:

Connection which was created to the database.

getConnection

public java.sql.Connection getConnection(long timeout)

Gets a connection from the available connection pool. This function will check that the connection is live before handing it off to the client. This function waits until a connection becomes available or the timeout expires.

Parameters:

timeout - long time in milliseconds to wait for the connection to become available.

Returns:

Connection to the database or null if there are no available connections.

getConnection

public java.sql.Connection getConnection()

Gets a connection from the available connection pool. This function will check that the connection is live before handing it off to the client. This function will return instantly.

Returns:

Connection to the database or null if there are no available connections.

releaseConnection

public void releaseConnection(java.sql.Connection connection)

Returns the connection back to the available connection pool.

Parameters:

connection - Connection to return to the pool.

getTotalConnections

public int getTotalConnections()

Return the total number of connections raised currently to the database.

Returns:

int number of total connections.

getMinimumConnections

public int getMinimumConnections()

Return the minimum number of connections raised on creation.

Returns:

int number of minimum connections.

getMaximumConnections

public int getMaximumConnections()

Return the maximum number of connections which it is possible to raise.

Returns:

int number of maximum connections.

getAvailableConnections

public int getAvailableConnections()

Return the number of available connections.

Returns:

int number of available connections.

refreshConnectionPool

public void refreshConnectionPool()

This function refreshes the connection pool and ensures that the connections are still valid.

refreshConnection

protected void refreshConnection(DatabaseConnection entry)

This function refreshes an individual connection pool entry. It does this one of two ways: if the connection is still valid it pings the database connection. If the connection is closed then it reinitiates a new connection.

Parameters:

entry - DatabaseConnection to refresh.

run

public void run()

The thread run method. This is concerned with ensuring that the connections remain open.

Overrides:

run in class java.lang.Thread

shutDown

public void shutDown()

Termination function. When called it terminates the thread.

getPoolName

public java.lang.String getPoolName()

This function returns the name of the ConnectionPool.

Returns:

String containing the Connection pool name.

equals

public boolean equals(java.lang.Object other)

This function determines if the input object is the same as this object. It does this by name. For this reason ConnectionPools MUST NOT HAVE THE SAME NAME.

Overrides:

equals in class java.lang.Object

Parameters:

other - Object to match against.

Returns:

boolean state of the comparison.