er.extensions.jdbc
Class ERXJDBCConnectionBroker

java.lang.Object
  er.extensions.jdbc.ERXJDBCConnectionBroker

All Implemented Interfaces:

ERXJDBCAdaptor.ConnectionBroker

public class ERXJDBCConnectionBroker
extends java.lang.Object
implements ERXJDBCAdaptor.ConnectionBroker

Creates and manages a pool of JDBC connections. Useful for SQL statements without using / blocking EOF. Maintains one broker per each distinct connection dictionary. Connections are created on demand but not freed. You can change the behaviour of the broker by setting some parameters either via the system properties as dbSomePropertyGLOBAL, ModelName.DBSomeProperty or as someProperty in the connection dictionary.

minConnections

Minimum number of connections, default 1

maxConnections

Maximum number of connections, default 1

maxCheckout

Maximum number of seconds a connection should stay checked out, default 600

connectionRecycle

Number of days a connection should stay active, default 1.0

The er.extensions.components.ERXConfigurationManager adds these entries to each EOModels connectionDictionary.
Usage: check out a connection:

 java.sql.Connection con = ERXJDBCConnectionBroker.connectionBrokerForModel(myModel).getConnection();
 try {
     java.sql.Statement s = con.createStatement();
     //now do something with the Statement
 } finally {
     ERXJDBCConnectionBroker.connectionBrokerForModel(myModel).freeConnection(con);
 }
 

Author:

Marc A. Mnich, based on version 1.0.13 3/12/02, david@cluster9.com original Wonder version, ak Major refactoring

Field Summary

static org.apache.log4j.Logger

log

Method Summary

static ERXJDBCConnectionBroker	connectionBrokerForAdaptor(com.webobjects.eoaccess.EOAdaptor adaptor)
static ERXJDBCConnectionBroker	connectionBrokerForEntityNamed(java.lang.String ename)
static ERXJDBCConnectionBroker	connectionBrokerForEoInEditingContext(com.webobjects.eocontrol.EOEnterpriseObject eo)
static ERXJDBCConnectionBroker	connectionBrokerForModel(com.webobjects.eoaccess.EOModel model)
static ERXJDBCConnectionBroker	connectionBrokerForModelWithName(java.lang.String modelName)
void	freeConnection(java.sql.Connection conn) Frees a connection.
java.sql.Connection	getConnection() This method hands out the connections in round-robin order.
boolean	supportsTransaction()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

log

public static final org.apache.log4j.Logger log

Method Detail

connectionBrokerForModelWithName

public static ERXJDBCConnectionBroker connectionBrokerForModelWithName(java.lang.String modelName)

connectionBrokerForModel

public static ERXJDBCConnectionBroker connectionBrokerForModel(com.webobjects.eoaccess.EOModel model)

connectionBrokerForEoInEditingContext

public static ERXJDBCConnectionBroker connectionBrokerForEoInEditingContext(com.webobjects.eocontrol.EOEnterpriseObject eo)

connectionBrokerForEntityNamed

public static ERXJDBCConnectionBroker connectionBrokerForEntityNamed(java.lang.String ename)

connectionBrokerForAdaptor

public static ERXJDBCConnectionBroker connectionBrokerForAdaptor(com.webobjects.eoaccess.EOAdaptor adaptor)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getConnection

public java.sql.Connection getConnection()

This method hands out the connections in round-robin order. This prevents a faulty connection from locking up an application entirely. A browser 'refresh' will get the next connection while the faulty connection is cleaned up by the housekeeping thread. If the min number of threads are ever exhausted, new threads are added up the the max thread count. Finally, if all threads are in use, this method waits 2 seconds and tries again, up to ten times. After that, it returns a null.

Specified by:

getConnection in interface ERXJDBCAdaptor.ConnectionBroker

freeConnection

public void freeConnection(java.sql.Connection conn)

Frees a connection. Replaces connection back into the main pool for reuse.

Specified by:

freeConnection in interface ERXJDBCAdaptor.ConnectionBroker

supportsTransaction

public boolean supportsTransaction()