org.xmlBlaster.contrib.db
Class DbPool

java.lang.Object
  org.xmlBlaster.contrib.db.DbPool

All Implemented Interfaces:

I_DbPool, I_ContribPlugin, I_PoolManager

public class DbPool
extends java.lang.Object
implements I_DbPool, I_PoolManager

Simple implementation of the database JDBC connection pool.

Following configuration paramaters are available:

 db.url=jdbc:oracle:thin:@localhost:1521:orcl
 db.user=system
 db.password=manager
 db.maxInstances=10
 db.busyToIdleTimeout=0             // How long may a query last [millis]
 db.idleToEraseTimeout=10*60*1000L  // How long does an unused connection survive (10 min)
 db.maxResourceExhaustRetries=5
 db.resourceExhaustSleepGap=1000    // [millis]
 

Author:

Marcel Ruff

Field Summary

private I_DbCreateInterceptor	createInterceptor
private java.lang.String	dbPasswd
private java.lang.String	dbUrl
private java.lang.String	dbUser
private I_Info	info
private int	initCount
private static java.util.logging.Logger	log
private int	maxResourceExhaustRetries If the pool is exhausted, we poll the given times
private java.lang.Object	meetingPoint
private PoolManager	poolManager
private long	resourceExhaustSleepGap If the pool is exhausted, we poll every given millis Please note that the current request thread will block for maxResourceExhaustRetries*resourceExhaustSleepGap millis.

Constructor Summary

DbPool()
Default constructor, you need to call init(info) thereafter.

Method Summary

void	busyToIdle(java.lang.Object resource) This callback does nothing (enforced by interface I_PoolManager
private void	destroy() Cleanup and destroy everything.
void	erase(java.sql.Connection con) Destroy the JDBC connection
I_Info	getInfo() may be empty and just contains db.* properties
java.util.Set	getUsedPropertyKeys() Gets all property keys which may be used by this object.
java.lang.String	getUser()
void	idleToBusy(java.lang.Object resource) This callback does nothing (enforced by interface I_PoolManager)
void	init(I_Info info) Needs to be called after construction.
private void	initDrivers() Load the JDBC drivers given in environment.
static void	main(java.lang.String[] args)
void	release(java.sql.Connection con) Return the JDBC connection to the pool.
java.sql.Connection	reserve() Access a JDBC connection.
java.sql.Connection	select(java.sql.Connection connection, java.lang.String command, boolean autoCommit, I_ResultCb cb) To have full control.
java.sql.Connection	select(java.sql.Connection connection, java.lang.String command, I_ResultCb cb) Convenience method to execute a SELECT SQL command.
void	select(java.lang.String command, I_ResultCb cb) Convenience method to execute a SELECT SQL command in auto commit mode.
void	shutdown() Close all open connections and destroy the pool.
java.lang.Object	toCreate(java.lang.String instanceId) Create a new JDBC connection, the driver must be registered already.
void	toErased(java.lang.Object resource) Destroy the JDBC connection.
int	update(java.sql.Connection conn, java.lang.String command)
int	update(java.lang.String command) Convenience method to execute a INSERT/UPDATE/CREATE or DROP SQL command in auto commit mode.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static java.util.logging.Logger log

info

private I_Info info

poolManager

private PoolManager poolManager

dbUrl

private java.lang.String dbUrl

dbUser

private java.lang.String dbUser

dbPasswd

private java.lang.String dbPasswd

maxResourceExhaustRetries

private int maxResourceExhaustRetries

If the pool is exhausted, we poll the given times

resourceExhaustSleepGap

private long resourceExhaustSleepGap

If the pool is exhausted, we poll every given millis
Please note that the current request thread will block for maxResourceExhaustRetries*resourceExhaustSleepGap millis.

meetingPoint

private final java.lang.Object meetingPoint

initCount

private int initCount

createInterceptor

private I_DbCreateInterceptor createInterceptor

Constructor Detail

DbPool

public DbPool()

Default constructor, you need to call init(info) thereafter.

Method Detail

getUsedPropertyKeys

public java.util.Set getUsedPropertyKeys()

Description copied from interface: I_ContribPlugin

Gets all property keys which may be used by this object.

Specified by:

getUsedPropertyKeys in interface I_ContribPlugin

Returns:

See Also:

I_ContribPlugin.getUsedPropertyKeys()

init

public void init(I_Info info)

Description copied from interface: I_DbPool

Needs to be called after construction.

Specified by:

init in interface I_DbPool

Specified by:

init in interface I_ContribPlugin

Parameters:

info - The configuration

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#init(I_Info)

getUser

public java.lang.String getUser()

Specified by:

getUser in interface I_DbPool

Returns:

the name of the user

initDrivers

private void initDrivers()

Load the JDBC drivers given in environment.

Default is JdbcDriver.drivers=sun.jdbc.odbc.JdbcOdbcDriver

reserve

public java.sql.Connection reserve()
                            throws java.lang.Exception

Description copied from interface: I_DbPool

Access a JDBC connection.

Specified by:

reserve in interface I_DbPool

Returns:

The JDBC connection

Throws:

java.lang.Exception - of type XmlBlasterException or IllegalArgumentException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#reserve()

release

public void release(java.sql.Connection con)
             throws java.lang.Exception

Description copied from interface: I_DbPool

Return the JDBC connection to the pool.

Specified by:

release in interface I_DbPool

Parameters:

con - The JDBC connection

Throws:

java.lang.Exception - of type XmlBlasterException or IllegalArgumentException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#release(java.sql.Connection)

erase

public void erase(java.sql.Connection con)
           throws java.lang.IllegalArgumentException

Description copied from interface: I_DbPool

Destroy the JDBC connection

Specified by:

erase in interface I_DbPool

Parameters:

con - The JDBC connection

Throws:

java.lang.IllegalArgumentException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#erase(java.sql.Connection)

destroy

private void destroy()

Cleanup and destroy everything.

idleToBusy

public void idleToBusy(java.lang.Object resource)

This callback does nothing (enforced by interface I_PoolManager)

Specified by:

idleToBusy in interface I_PoolManager

Parameters:

resource - The Connection object

See Also:

I_PoolManager.idleToBusy(Object)

busyToIdle

public void busyToIdle(java.lang.Object resource)

This callback does nothing (enforced by interface I_PoolManager

Specified by:

busyToIdle in interface I_PoolManager

Parameters:

resource - The Connection object

See Also:

I_PoolManager.busyToIdle(Object)

toCreate

public java.lang.Object toCreate(java.lang.String instanceId)

Create a new JDBC connection, the driver must be registered already.

Specified by:

toCreate in interface I_PoolManager

Parameters:

instanceId - A unique identifier

Returns:

The JDBC connection

toErased

public void toErased(java.lang.Object resource)

Destroy the JDBC connection. The driver remains.

Specified by:

toErased in interface I_PoolManager

Parameters:

resource - The Connection object

update

public int update(java.lang.String command)
           throws java.lang.Exception

Description copied from interface: I_DbPool

Convenience method to execute a INSERT/UPDATE/CREATE or DROP SQL command in auto commit mode.

Specified by:

update in interface I_DbPool

Parameters:

command - for example INSERT INTO TEST_POLL VALUES ('1', 'EDDI')

Returns:

Number of touched entries

Throws:

java.lang.Exception - Typically a SQLException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#update(String)

update

public int update(java.sql.Connection conn,
                  java.lang.String command)
           throws java.lang.Exception

Specified by:

update in interface I_DbPool

Throws:

java.lang.Exception

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#update(String)

select

public void select(java.lang.String command,
                   I_ResultCb cb)
            throws java.lang.Exception

Description copied from interface: I_DbPool

Convenience method to execute a SELECT SQL command in auto commit mode.

Specified by:

select in interface I_DbPool

Parameters:

command - for example SELECT * FROM TEST_POLL

cb - The callback handle for the retrieved ResultSet

Throws:

java.lang.Exception - Typically a SQLException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#select(String, I_ResultCb)

select

public java.sql.Connection select(java.sql.Connection connection,
                                  java.lang.String command,
                                  I_ResultCb cb)
                           throws java.lang.Exception

Description copied from interface: I_DbPool

Convenience method to execute a SELECT SQL command.

On first call pass connection with null and a valid connection with an open transaction is returned by this method. You can now call this method passing the connection multiple times in the same transaction. When you are done you need to close the connection and put it back into the pool.

Example:

      Connection conn = null;

      try {
         conn = this.dbPool.select(conn, "SELECT A FROM B", new I_ResultCb() {
            public void result(ResultSet rs) throws Exception {
               // Processing result set
            }
         });

         conn = this.dbPool.select(conn, "SELECT B FROM  C", new I_ResultCb() {
            public void result(ResultSet rs) throws Exception {
               // Processing result set
            }
         });
      }
      finally {
         if (conn != null) {
            conn.commit();
            this.dbPool.release(conn);
         }
      }
 

Specified by:

select in interface I_DbPool

Parameters:

connection - If null a connection is created

command - for example SELECT * FROM TEST_POLL

cb - The callback handle for the retrieved ResultSet

Returns:

If not null you need to put the connection back to the pool yourself

Throws:

java.lang.Exception - Typically a SQLException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#select(java.sql.Connection, String, I_ResultCb)

select

public java.sql.Connection select(java.sql.Connection connection,
                                  java.lang.String command,
                                  boolean autoCommit,
                                  I_ResultCb cb)
                           throws java.lang.Exception

Description copied from interface: I_DbPool

To have full control.

Specified by:

select in interface I_DbPool

Parameters:

connection - If null a connection is created

command - for example SELECT * FROM TEST_POLL

autoCommit - if true force auto commit and cleanup the connection, in this case we return null

cb - The callback handle for the retrieved ResultSet

Returns:

If not null you need to put the connection back to the pool yourself

Throws:

java.lang.Exception - Typically a SQLException

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#select(java.sql.Connection, String, I_ResultCb, boolean)

shutdown

public void shutdown()

Description copied from interface: I_DbPool

Close all open connections and destroy the pool. All resources are released.

Specified by:

shutdown in interface I_DbPool

Specified by:

shutdown in interface I_ContribPlugin

See Also:

org.xmlBlaster.contrib.dbwatcher.db.I_DbPool#shutdown

getInfo

public I_Info getInfo()

may be empty and just contains db.* properties

Specified by:

getInfo in interface I_DbPool

Returns:

main

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