com.deltax.util.listener
Class ListenerSupport

java.lang.Object
  com.deltax.util.listener.ListenerSupport

All Implemented Interfaces:

IListenerSupport

public class ListenerSupport

extends java.lang.Object

implements IListenerSupport

This class is the pluggable support for asynchronous listening.

It exposes registration methods for signal listeners and the notify(Signal) method to be called to actually send signals.

Version:

2.0

Author:

Cristiano Sadun

Field Summary

static long	DEFAULT_RECEIVE_TIMEOUT The default timea Listener is given to exit gracefully from the Listener.receive(Signal) method when it's removed.
protected java.lang.Object	lock A lock used in accessing the listeners/queue registry.

Constructor Summary

ListenerSupport()
Create a listener support.

ListenerSupport(int maxThreads)
Create a listener support which uses at most the given number of threads

Method Summary

void	addListener(Listener listener) Add a listener to the listeners set.
int	countListeners() Count the registered listeners.
protected com.deltax.util.listener.SignalQueue[]	getQueues() Allows subclasses to retrieve the queue threads (experimental)
long	getReceiveTimeout() Return the the amount of time (in ms.) a Listeneris given to exit gracefully from the Listener.receive(Signal) method when it's removed.
boolean	isRegistered(Listener listener) Check whether a listener is registered or not.
void	notify(Signal signal) Broadcast a signal.
void	removeAllListeners() Unconditionally unregister all the listeners.
void	removeListener(Listener listener) Remove a listener from the listeners set.
void	setReceiveTimeout(long receiveTimeout) Set the the amount of time (in ms.) a Listeneris given to exit gracefully from the Listener.receive(Signal) method when it's removed.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_RECEIVE_TIMEOUT

public static final long DEFAULT_RECEIVE_TIMEOUT

The default timea Listener is given to exit gracefully from the Listener.receive(Signal) method when it's removed.

It can be set by using setReceiveTimeout(long)after creating the listener support.

See Also:

Constant Field Values

lock

protected java.lang.Object lock

A lock used in accessing the listeners/queue registry.

Constructor Detail

ListenerSupport

public ListenerSupport(int maxThreads)

Create a listener support which uses at most the given number of threads

ListenerSupport

public ListenerSupport()

Create a listener support.

Method Detail

addListener

public void addListener(Listener listener)

Add a listener to the listeners set.

If the support has a maximum thread count, the method will block if there are no free threads for the listener, until another listener releases a thread.

Specified by:

addListener in interface IListenerSupport

Parameters:

listener - the listener to add

removeAllListeners

public void removeAllListeners()

Unconditionally unregister all the listeners.

Specified by:

removeAllListeners in interface IListenerSupport

isRegistered

public boolean isRegistered(Listener listener)

Check whether a listener is registered or not.

Specified by:

isRegistered in interface IListenerSupport

Parameters:

listener - the listener to check

Returns:

true if the listener is registered

notify

public void notify(Signal signal)

Broadcast a signal. The order of invocation is unspecified.

Specified by:

notify in interface IListenerSupport

removeListener

public void removeListener(Listener listener)
                    throws BlockedListenerException

Remove a listener from the listeners set.

Specified by:

removeListener in interface IListenerSupport

Parameters:

listener - the listener to remove

Throws:

BlockedListenerException - if the listener is blocked and cannot be removed

getQueues

protected com.deltax.util.listener.SignalQueue[] getQueues()

Allows subclasses to retrieve the queue threads (experimental)

Returns:

countListeners

public int countListeners()

Count the registered listeners.

Specified by:

countListeners in interface IListenerSupport

Returns:

the number of currently registered listeners

See Also:

IListenerSupport.countListeners()

getReceiveTimeout

public long getReceiveTimeout()

Return the the amount of time (in ms.) a Listeneris given to exit gracefully from the Listener.receive(Signal) method when it's removed.

Note that this timeout does not apply to normal operations (i.e. a listener can normally block for how long it wants) but only when a listener is removed.

Specified by:

getReceiveTimeout in interface IListenerSupport

Returns:

the timeout in milliseconds

setReceiveTimeout

public void setReceiveTimeout(long receiveTimeout)

Set the the amount of time (in ms.) a Listeneris given to exit gracefully from the Listener.receive(Signal) method when it's removed.

Note that this timeout does not apply to normal operations (i.e. a listener can normally block for how long it wants) but only when a listener is removed.

Specified by:

setReceiveTimeout in interface IListenerSupport

Parameters:

receiveTimeout - the timeout in milliseconds