org.deepsymmetry.beatlink.dbserver

Class ConnectionManager

java.lang.Object

org.deepsymmetry.beatlink.LifecycleParticipant

org.deepsymmetry.beatlink.dbserver.ConnectionManager

public class ConnectionManager
extends LifecycleParticipant

Manges connections to dbserver ports on the players, offering sessions that can be used to perform transactions, and allowing the connections to close when there are no active sessions.

Author:

James Elliott

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ConnectionManager.ClientTask<T> An interface for all the kinds of activities that need a connection to the dbserver, so we can keep track of how many sessions are in effect, clean up after them, and know when the client is idle and can be closed.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_SOCKET_TIMEOUT The default value we will use for timeouts on opening and reading from sockets.

Method Summary

Modifier and Type	Method and Description
int	getIdleLimit() Check how long an idle connection will be kept open for reuse.
static ConnectionManager	getInstance() Get the singleton instance of this class.
int	getPlayerDBServerPort(int player) Look up the database server port reported by a given player.
int	getSocketTimeout() Check how long we will wait for a socket to connect or for a read operation to complete.
<T> T	invokeWithClientSession(int targetPlayer, ConnectionManager.ClientTask<T> task, String description) Obtain a dbserver client session that can be used to perform some task, call that task with the client, then release the client.
boolean	isRunning() Check whether we are currently running.
void	setIdleLimit(int seconds) Determine how long an idle connection will be kept open for reuse.
void	setSocketTimeout(int timeout) Set how long we will wait for a socket to connect or for a read operation to complete.
void	start() Start offering shared dbserver sessions.
void	stop() Stop offering shared dbserver sessions.
String	toString()

Methods inherited from class org.deepsymmetry.beatlink.LifecycleParticipant

addLifecycleListener, deliverLifecycleAnnouncement, ensureRunning, getLifecycleListeners, removeLifecycleListener

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_SOCKET_TIMEOUT

public static final int DEFAULT_SOCKET_TIMEOUT

The default value we will use for timeouts on opening and reading from sockets.

See Also:

Constant Field Values

Method Detail

setIdleLimit

public void setIdleLimit(int seconds)

Determine how long an idle connection will be kept open for reuse. Once this time has elapsed, the connection will be closed. Setting this to zero will close connections immediately after use, which might be somewhat inefficient when multiple queries need to happen in a row, since each will require the establishment of a new connection. The default value is 1.

Parameters:

seconds - how many seconds a connection will be kept open while not being used

Throws:

IllegalArgumentException - if a negative value is supplied

getIdleLimit

public int getIdleLimit()

Check how long an idle connection will be kept open for reuse. Once this time has elapsed, the connection will be closed. Setting this to zero will close connections immediately after use, which might be somewhat inefficient when multiple queries need to happen in a row, since each will require the establishment of a new connection. The default value is 1.

Returns:

how many seconds a connection will be kept open while not being used

invokeWithClientSession

public <T> T invokeWithClientSession(int targetPlayer,
                                     ConnectionManager.ClientTask<T> task,
                                     String description)
                              throws Exception

Obtain a dbserver client session that can be used to perform some task, call that task with the client, then release the client.

Type Parameters:

T - the type that will be returned by the task to be performed

Parameters:

targetPlayer - the player number whose dbserver we wish to communicate with

task - the activity that will be performed with exclusive access to a dbserver connection

description - a short description of the task being performed for error reporting if it fails, should be a verb phrase like "requesting track metadata"

Returns:

the value returned by the completed task

Throws:

IOException - if there is a problem communicating

Exception - from the underlying task, if any

getPlayerDBServerPort

public int getPlayerDBServerPort(int player)

Look up the database server port reported by a given player. You should not use this port directly; instead ask this class for a session to use while you communicate with the database.

Parameters:

player - the player number of interest

Returns:

the port number on which its database server is running, or -1 if unknown

Throws:

IllegalStateException - if not running

setSocketTimeout

public void setSocketTimeout(int timeout)

Set how long we will wait for a socket to connect or for a read operation to complete. Adjust this if your players or network require it.

Parameters:

timeout - after how many milliseconds will an attempt to open or read from a socket fail

getSocketTimeout

public int getSocketTimeout()

Check how long we will wait for a socket to connect or for a read operation to complete. Adjust this if your players or network require it.

Returns:

the number of milliseconds after which an attempt to open or read from a socket will fail

isRunning

public boolean isRunning()

Check whether we are currently running.

Specified by:

isRunning in class LifecycleParticipant

Returns:

true if we are offering shared dbserver sessions

start

public void start()
           throws SocketException

Start offering shared dbserver sessions.

Throws:

SocketException - if there is a problem opening connections

stop

public void stop()

Stop offering shared dbserver sessions.

getInstance

public static ConnectionManager getInstance()

Get the singleton instance of this class.

Returns:

the only instance of this class which exists.

toString

public String toString()

Overrides:

toString in class Object