org.xmlBlaster.util.queue.jdbc
Class JdbcConnectionPool

java.lang.Object
  org.xmlBlaster.util.queue.jdbc.JdbcConnectionPool

All Implemented Interfaces:

I_StorageProblemNotifier, I_Timeout

public class JdbcConnectionPool

extends java.lang.Object

implements I_Timeout, I_StorageProblemNotifier

A Pool of connections to the database to be used for a persistent queue. To keep genericity, queries and update strings are read from properties.

See Also:

The queue.jdbc.commontable requirement

Constructor Summary

JdbcConnectionPool()
The default constructor currently does nothing.

Method Summary

void	discardConnection(java.sql.Connection conn) Discards the passed connection from the pool and instead adds a new fresh connection to the pool.
void	disconnect() Closes all connections to the Database.
void	dumpMetaData()
void	finalize()
java.lang.String	getColNamePrefix()
java.sql.Connection	getConnection() Returns a free connection.
Global	getGlobal() Returns the global object associated with this pool.
static java.lang.String	getIsolationLevel(java.sql.Connection conn)
java.util.Hashtable	getMapping() The mapping is taken out of the xmlBlaster.properties file.
java.util.Properties	getPluginProperties() returns the plugin properties, i.e.
int	getProp(java.lang.String key, int def)
java.lang.String	getProp(java.lang.String key, java.lang.String def)
int	getQueryTimeout()
int	getStatus() returns true if the connection is temporarly lost (and the pool is polling for new connections)
int	getTableAllocationIncrement()
java.lang.String	getTableNamePrefix()
java.lang.String	getUrl()
java.lang.String	getUserName()
void	initialize(Global glob, java.util.Properties pluginProperties) Is called after the instance is created.
boolean	isBatchModeEnabled() The batch mode means that insertions in the database are made in batch mode, i.e.
boolean	isCascadeDeleteSuppported()
boolean	isDbAdmin()
boolean	isInitialized() returns true if the pool already is initialized, false otherwise.
boolean	isNestedBracketsSuppported()
static java.lang.String	isolationToString(int isolation)
static void	main(java.lang.String[] args)
void	registerManager(JdbcManagerCommonTable manager)
boolean	registerStorageProblemListener(I_StorageProblemListener storageProblemListener) Sets the connection listener.
void	releaseConnection(java.sql.Connection conn, boolean success) Used to give back a connection to the pool.
void	setConnectionLost() informs this pool that the connection to the DB has been lost
void	shutdown()
void	timeout(java.lang.Object userData) Invoked by the timer when a check for reconnection is wanted again
void	unregisterManager(JdbcManagerCommonTable manager)
boolean	unRegisterStorageProblemListener(I_StorageProblemListener storageProblemListener) Unregisters the storageProblemListener.

Methods inherited from class java.lang.Object

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

Constructor Detail

JdbcConnectionPool

public JdbcConnectionPool()

The default constructor currently does nothing. Initialization is done in the initialize() method.

Method Detail

getPluginProperties

public java.util.Properties getPluginProperties()

returns the plugin properties, i.e. the specific properties passed to the jdbc queue plugin. These are commonly used by the jdbc manager.

timeout

public void timeout(java.lang.Object userData)

Invoked by the timer when a check for reconnection is wanted again

Specified by:

timeout in interface I_Timeout

Parameters:

userData - You get bounced back your userData which you passed with Timeout.addTimeoutListener()

See Also:

I_Timeout.timeout(Object)

registerStorageProblemListener

public boolean registerStorageProblemListener(I_StorageProblemListener storageProblemListener)

Sets the connection listener. Only one is allowed at a time. So if there is already a connection listener, it will be overwritten (and the old one will not get anyu notification anymore).

Specified by:

registerStorageProblemListener in interface I_StorageProblemNotifier

unRegisterStorageProblemListener

public boolean unRegisterStorageProblemListener(I_StorageProblemListener storageProblemListener)

Unregisters the storageProblemListener. If no one has been defined, or if the one you want to unregister is different from the one you have registered, nothing is done and 'false' is returned.

Specified by:

unRegisterStorageProblemListener in interface I_StorageProblemNotifier

getGlobal

public Global getGlobal()

Returns the global object associated with this pool.

isInitialized

public boolean isInitialized()

returns true if the pool already is initialized, false otherwise.

discardConnection

public void discardConnection(java.sql.Connection conn)
                       throws XmlBlasterException

Discards the passed connection from the pool and instead adds a new fresh connection to the pool. This method is to be invoked when an exception occured and it can be supposed that the connection is not good anymore.

Parameters:

conn -

Throws:

XmlBlasterException

isolationToString

public static java.lang.String isolationToString(int isolation)

getIsolationLevel

public static java.lang.String getIsolationLevel(java.sql.Connection conn)

getProp

public java.lang.String getProp(java.lang.String key,
                                java.lang.String def)

getProp

public int getProp(java.lang.String key,
                   int def)

initialize

public void initialize(Global glob,
                       java.util.Properties pluginProperties)
                throws java.lang.ClassNotFoundException,
                       java.sql.SQLException,
                       XmlBlasterException

Is called after the instance is created. It reads the needed properties, sets the driver and then connects to the database as many times as specified in the properties.

Note that prefix is the string which identifies a certain database. It is called prefix because it is the prefix in the xmlBlaster.properties for the properties bound to the database.
A pool instance is created for every such database. For example if you want the history queue (the queue which stores the published messages) on a different database than the callback queues, then you could define different databases.

prefix.driverName DEFAULTS TO "org.postgresql.Driver"

prefix.connectionPoolSize "DEFAULTS TO 2"

prefix.url DEFAULTS TO "jdbc:postgresql://localhost/test"

prefix.user DEFAULTS TO "postgres"

prefix.password DEFAULTS TO ""

Throws:

java.lang.ClassNotFoundException

java.sql.SQLException

XmlBlasterException

getTableNamePrefix

public java.lang.String getTableNamePrefix()

Returns:

the prefix for the name of the tables to associate to the queues

getUserName

public java.lang.String getUserName()

getColNamePrefix

public java.lang.String getColNamePrefix()

Returns:

the prefix for the name of the columns in each DB table

getTableAllocationIncrement

public int getTableAllocationIncrement()

Returns:

the number of tables to add each time no free tables are available when creating a new queue.

getMapping

public java.util.Hashtable getMapping()

The mapping is taken out of the xmlBlaster.properties file. It is an Hashtable where the keys are the logical names used for a type in the JdbcQueuePlugin and the values are the real names to be used in the database used (which may be vendor specific).

disconnect

public void disconnect()

Closes all connections to the Database. It should not throw any exception. Exceptions coming from the backend or the communication layer are catched and logged. When this occurs, the affected connections are set to null.

finalize

public void finalize()

getStatus

public final int getStatus()

returns true if the connection is temporarly lost (and the pool is polling for new connections)

setConnectionLost

public final void setConnectionLost()

informs this pool that the connection to the DB has been lost

getConnection

public java.sql.Connection getConnection()
                                  throws XmlBlasterException

Returns a free connection. If no connection is currently available it waits no more than what specified in the configuration. If after that time still no connection is available it throws an XmlBlasterException. It also throws an XmlBlasterException if the number of threads which are waiting is already too high (also configurable).

Throws:

XmlBlasterException

releaseConnection

public void releaseConnection(java.sql.Connection conn,
                              boolean success)
                       throws XmlBlasterException

Used to give back a connection to the pool. If the pool is already full it will throw an exception. If the success flag is true, it well release the connection back to the pool, otherwise it will throw away the current connection and add to the pool a new one.

Throws:

XmlBlasterException

dumpMetaData

public void dumpMetaData()

isDbAdmin

public boolean isDbAdmin()

getQueryTimeout

public int getQueryTimeout()

main

public static void main(java.lang.String[] args)

shutdown

public void shutdown()

registerManager

public void registerManager(JdbcManagerCommonTable manager)

unregisterManager

public void unregisterManager(JdbcManagerCommonTable manager)

isBatchModeEnabled

public boolean isBatchModeEnabled()

The batch mode means that insertions in the database are made in batch mode, i.e. several entries in one sweep. This can increase perfomance significantly on some DBs.

Returns:

true if batch mode has been enabled, false otherwise (defaults to true).

isCascadeDeleteSuppported

public boolean isCascadeDeleteSuppported()

Returns:

true if 'cascadeDeleteSupported' has been set to true

isNestedBracketsSuppported

public boolean isNestedBracketsSuppported()

Returns:

true if 'nestedBracketsSupported' has been set to true

getUrl

public java.lang.String getUrl()

Returns:

the url