org.tentackle.db
Class DefaultConnectionManager

java.lang.Object
  org.tentackle.db.DefaultConnectionManager

All Implemented Interfaces:

ConnectionManager

Direct Known Subclasses:

MpxConnectionManager

public class DefaultConnectionManager
extends Object
implements ConnectionManager

The default implementation of a connection manager.
Each Db will get its own physical connection. This kind of manager is useful for 2-tier applications directly connecting to a database backend.

Although this manager implements a strict 1:1 mapping between dbs and connections it can be easily extended to implememt a M:N mapping, see the MpxConnectionManager.

Author:

harald

Field Summary

protected ManagedConnection[]	conList managed connections
protected Db[]	dbList Dbs logged in
protected int	freeConCount number of entries in freeConList
protected int[]	freeConList free list for conList (unused entries in conList)
protected int	freeDbCount number of entries in freeDbList
protected int[]	freeDbList free list for dbList (unused entries in dbList)
protected int	idOffset offset for connection IDs
protected int	iniSize initial size
protected int	maxConSize maximum number of connections, 0 = unlimited
protected int	maxDbSize maximum number of Dbs, 0 = unlimited
protected String	name name of the connection manager

Constructor Summary

DefaultConnectionManager()
Creates a new connection manager with an initial size of 2, a maximum of 8 concurrent connections and an id offset of 1.

DefaultConnectionManager(String name, int iniSize, int maxSize, int idOffset)
Creates a new connection manager.

Method Summary

protected int	addConnection(ManagedConnection con) Adds a connection to the list.
protected int	addDb(Db db) Adds a Db to the list.
ManagedConnection	attach(int id) Attaches a Db to a connection. A Db must be attached before it can use any statements.
void	detach(int id) Detaches a connection from a Db. A Db must be detached to release the connection for use of other Db instances.
int	getConnectionCount() Gets the number of established connections
int	getDbCount() Gets the number of valid db entries.
int	getMaxConnections() Gets the maximum number of connections.
int	getMaxCountForClearWarnings() Gets the current setting for clearWarnings() trigger
int	getMaxLogins() Gets the maximum number of allowed logins.
int	login(Db db) Logs in a Db connection. It is up to the manager how to verify whether the Db is allowed to open, a real connection is initiated or just an application level authorization is performed.
Db	logout(int id) Logs out a Db connection.
protected ManagedConnection	removeConnection(int index) Removes a connection from the list.
protected Db	removeDb(int index) Removes a Db from the list.
void	setMaxCountForClearWarnings(int maxCountForClearWarnings) Sets the countForClearWarnings trigger, 0 = app must eat the warnings!
void	shutdown() Shuts down this connection manager. All connections are closed and the threads stopped.
String	toString() Gets the name of the manager.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected String name

name of the connection manager

iniSize

protected int iniSize

initial size

idOffset

protected int idOffset

offset for connection IDs

dbList

protected Db[] dbList

Dbs logged in

maxDbSize

protected int maxDbSize

maximum number of Dbs, 0 = unlimited

freeDbList

protected int[] freeDbList

free list for dbList (unused entries in dbList)

freeDbCount

protected int freeDbCount

number of entries in freeDbList

conList

protected ManagedConnection[] conList

managed connections

maxConSize

protected int maxConSize

maximum number of connections, 0 = unlimited

freeConList

protected int[] freeConList

free list for conList (unused entries in conList)

freeConCount

protected int freeConCount

number of entries in freeConList

Constructor Detail

DefaultConnectionManager

public DefaultConnectionManager(String name,
                                int iniSize,
                                int maxSize,
                                int idOffset)

Creates a new connection manager.

Parameters:

name - the name of the connection manager

iniSize - the initial iniSize of the db table

maxSize - the maximum number of connections, 0 = unlimited (dangerous!)

idOffset - the offset for connection ids (> 0)

DefaultConnectionManager

public DefaultConnectionManager()

Creates a new connection manager with an initial size of 2, a maximum of 8 concurrent connections and an id offset of 1. This is the default connection manager for 2-tier client applications. The max connections will prevent ill behaving applications from tearing down the dbserver by opening connections excessively. The usual application holds 2 connections and temporarily 1 or 2 more. If you need more, change the connection manager in Db.

Method Detail

toString

public String toString()

Gets the name of the manager.

Overrides:

toString in class Object

Returns:

a string representation of the object.

setMaxCountForClearWarnings

public void setMaxCountForClearWarnings(int maxCountForClearWarnings)

Sets the countForClearWarnings trigger, 0 = app must eat the warnings!

Parameters:

maxCountForClearWarnings - the maxcount

getMaxCountForClearWarnings

public int getMaxCountForClearWarnings()

Gets the current setting for clearWarnings() trigger

Returns:

the countForClearWarnings trigger, 0 = app must eat the warnings!

addDb

protected int addDb(Db db)

Adds a Db to the list.

Parameters:

db - the db to add

Returns:

the index of db in the dblist

removeDb

protected Db removeDb(int index)

Removes a Db from the list.

Parameters:

index - the index of db in the dblist

Returns:

the removed db

getDbCount

public int getDbCount()

Gets the number of valid db entries.

Returns:

the number of db entries

addConnection

protected int addConnection(ManagedConnection con)

Adds a connection to the list.

Parameters:

con - the connection to add

Returns:

the index of connection in the conlist

removeConnection

protected ManagedConnection removeConnection(int index)

Removes a connection from the list.

Parameters:

index - the index of connection in the conlist

Returns:

the removed connection

getConnectionCount

public int getConnectionCount()

Gets the number of established connections

Returns:

the number of connections

getMaxLogins

public int getMaxLogins()

Description copied from interface: ConnectionManager

Gets the maximum number of allowed logins.

Specified by:

getMaxLogins in interface ConnectionManager

Returns:

max. number of concurrent logins, 0 = unlimited

getMaxConnections

public int getMaxConnections()

Description copied from interface: ConnectionManager

Gets the maximum number of connections.

Specified by:

getMaxConnections in interface ConnectionManager

Returns:

max. number of concurrent connections, 0 = unlimited

login

public int login(Db db)
          throws DbRuntimeException

Description copied from interface: ConnectionManager

Logs in a Db connection.
It is up to the manager how to verify whether the Db is allowed to open, a real connection is initiated or just an application level authorization is performed. Note that the ID may be recycled by the manager after a Db is logged out.

Specified by:

login in interface ConnectionManager

Parameters:

db - the db to login

Returns:

the connection ID of the db (> 0)

Throws:

DbRuntimeException - if login failed.

logout

public Db logout(int id)
          throws DbRuntimeException

Description copied from interface: ConnectionManager

Logs out a Db connection. The Db is not allowed to attach anymore. If the Db is still attached, a rollback of any pending tx is done and an exception thrown.

Specified by:

logout in interface ConnectionManager

Parameters:

id - the connection ID of the db

Returns:

the logged out Db

Throws:

DbRuntimeException - if logout failed.

attach

public ManagedConnection attach(int id)
                         throws DbRuntimeException

Description copied from interface: ConnectionManager

Attaches a Db to a connection.
A Db must be attached before it can use any statements. The framework will attach at the begining of a transaction or when getting a prepared statement or when getting a one-shot non-prepared statement. Note that attachments can be nested to any depth, i.e. only the first attach really binds the connection to the Db.

Specified by:

attach in interface ConnectionManager

Parameters:

id - the connection ID of the db

Returns:

the connection attached to be used by subsequent operations

Throws:

DbRuntimeException - if attach failed.

detach

public void detach(int id)
            throws DbRuntimeException

Description copied from interface: ConnectionManager

Detaches a connection from a Db.
A Db must be detached to release the connection for use of other Db instances. The framework will detach the db on every commit or rollback, after executeUpdate or after a resultset is closed for an executeQuery. Note that attachments can be nested to any depth, i.e. only the last detach really unbinds the connection from the Db.

Specified by:

detach in interface ConnectionManager

Parameters:

id - the connection ID of the db

Throws:

DbRuntimeException - if detach failed.

shutdown

public void shutdown()

Description copied from interface: ConnectionManager

Shuts down this connection manager.
All connections are closed and the threads stopped. Application servers should invoke this method when shut down.

Specified by:

shutdown in interface ConnectionManager