ERXJDBCConnectionBroker Class Reference

Inherits er::extensions::jdbc::ERXJDBCAdaptor::ConnectionBroker.

Collaboration diagram for ERXJDBCConnectionBroker:

[legend]

List of all members.

Classes
class	ConnectionWrapper
Public Member Functions
void	freeConnection (Connection conn)
Connection	getConnection ()
boolean	supportsTransaction ()
String	toString ()
Static Public Member Functions
static ERXJDBCConnectionBroker	connectionBrokerForAdaptor (EOAdaptor adaptor)
static ERXJDBCConnectionBroker	connectionBrokerForEntityNamed (String ename)
static ERXJDBCConnectionBroker	connectionBrokerForEoInEditingContext (EOEnterpriseObject eo)
static ERXJDBCConnectionBroker	connectionBrokerForModel (EOModel model)
static ERXJDBCConnectionBroker	connectionBrokerForModelWithName (String modelName)
Static Public Attributes
static final Logger	log = Logger.getLogger(ERXJDBCConnectionBroker.class)
Package Attributes
long	maxConnectionMillis
Private Member Functions
Connection	createConnection () throws SQLException
synchronized void	createWrapper () throws SQLException
void	destroy (int millis) throws SQLException
	ERXJDBCConnectionBroker (NSDictionary dict)
int	getOpenChannelCount ()
void	setup (NSDictionary dict, int maxCheckoutSecond)
ConnectionWrapper	wrapperForConnection (Connection conn)
Static Private Member Functions
static synchronized ERXJDBCConnectionBroker	connectionBrokerForConnectionDictionary (NSDictionary d)
static ERXJDBCConnectionBroker	newConnectionBrokerWithConnectionDictionary (NSDictionary dict)
Private Attributes
boolean	active = true
int	activeConnections
String	dbDriver
String	dbLogin
String	dbPassword
String	dbServer
int	lastRoundRobinIndex
int	maxCheckoutMillis
int	maximumConnections
int	minimumConnections
Thread	pinger
Thread	reaper
boolean	supportsTransactions = false
ConnectionWrapper[]	wrappers
Static Private Attributes
static Hashtable	brokers = new Hashtable()
static final int	DEFAULTMAXCHECKOUTSECONDS = 600

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Detailed Description

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

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Constructor & Destructor Documentation

ERXJDBCConnectionBroker

(

NSDictionary

dict

)

[private]

---

Member Function Documentation

static ERXJDBCConnectionBroker connectionBrokerForAdaptor

(

EOAdaptor

adaptor

)

[static]

static synchronized ERXJDBCConnectionBroker connectionBrokerForConnectionDictionary

(

NSDictionary

d

)

[static, private]

static ERXJDBCConnectionBroker connectionBrokerForEntityNamed

(

String

ename

)

[static]

static ERXJDBCConnectionBroker connectionBrokerForEoInEditingContext

(

EOEnterpriseObject

eo

)

[static]

static ERXJDBCConnectionBroker connectionBrokerForModel

(

EOModel

model

)

[static]

static ERXJDBCConnectionBroker connectionBrokerForModelWithName

(

String

modelName

)

[static]

Connection createConnection

(

)

throws SQLException [private]

synchronized void createWrapper

(

)

throws SQLException [private]

void destroy

(

int

millis

)

throws SQLException [private]

void freeConnection

(

Connection

conn

)

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

Implements ERXJDBCAdaptor.ConnectionBroker.

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.

Implements ERXJDBCAdaptor.ConnectionBroker.

int getOpenChannelCount

(

)

[private]

static ERXJDBCConnectionBroker newConnectionBrokerWithConnectionDictionary

(

NSDictionary

dict

)

[static, private]

void setup	(	NSDictionary	dict,
		int	maxCheckoutSecond
	)			[private]

Housekeeping thread. Runs in the background with low CPU overhead. Connections are checked for warnings and closure and are periodically restarted. This thread is a catchall for corrupted connections and prevents the buildup of open cursors. (Open cursors result when the application fails to close a Statement). This method acts as fault tolerance for bad connection/statement programming.

Less safe shutdown. Uses default timeout value. This method simply calls the destroy() method with a millis value of 10000 (10 seconds) and ignores SQLException thrown by that method.

See also:

destroy(int)

boolean supportsTransaction

(

)

String toString

(

)

ConnectionWrapper wrapperForConnection

(

Connection

conn

)

[private]

Returns the local JDBC ID for a connection.

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Member Data Documentation

boolean active = true [private]

int activeConnections [private]

Hashtable brokers = new Hashtable() [static, private]

String dbDriver [private]

String dbLogin [private]

String dbPassword [private]

String dbServer [private]

final int DEFAULTMAXCHECKOUTSECONDS = 600 [static, private]

int lastRoundRobinIndex [private]

final Logger log = Logger.getLogger(ERXJDBCConnectionBroker.class) [static]

int maxCheckoutMillis [private]

long maxConnectionMillis [package]

int maximumConnections [private]

int minimumConnections [private]

Thread pinger [private]

Thread reaper [private]

boolean supportsTransactions = false [private]

ConnectionWrapper [] wrappers [private]

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The documentation for this class was generated from the following file:

• /opt/source/Wonder/Frameworks/Core/ERExtensions/Sources/er/extensions/jdbc/ERXJDBCConnectionBroker.java