jhelp.util.thread

Class MessageHandler<MESSAGE>

java.lang.Object

jhelp.util.thread.MessageHandler<MESSAGE>

Type Parameters:

MESSAGE - Message type

Direct Known Subclasses:

MessageHandlerTest

public abstract class MessageHandler<MESSAGE>
extends java.lang.Object

Handler of messages.
It reacts to messages posted for him.
Its thread safe, that is to say, if 2 threads post a message in "same time", the messageArrived(Object) is called for one of them, then AFTER the code execution its done, its called again.
In other words, messageArrived(Object) will never called in "same time". It also means, it waits that a message is completely manage (exit from messageArrived(Object)) before doing an other stuff
You have to call terminate() when you need no more the handler

Author:

JHelp

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	MessageHandler.Message<ELEMENT> A message

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	alive Indicates if handler still alive
private static int	DEFAULT_WAIT Default waiting time
private java.lang.Thread	internalThread Internal thread
private java.util.concurrent.atomic.AtomicBoolean	isLocked Indicates if lock is on or off
private java.lang.Object	LOCK Object for synchronization
private Mutex	mutex Mutex for exclusive access
private java.util.PriorityQueue<MessageHandler.Message<MESSAGE>>	priorityQueue Queue of messages to give

Constructor Summary

Constructors

Constructor and Description
MessageHandler() Create a new instance of MessageHandler

Method Summary

Methods

Modifier and Type	Method and Description
void	cancelMessage(MESSAGE message) Cancel a message.
(package private) void	doTheJob() Manage the messages to delivered
protected void	finalize() Try to free memory if user forget to call terminate() and the object is garbage collected Parent documentation:
boolean	isAlive() Indicates if the handler still alive and can be used
protected abstract void	messageArrived(MESSAGE message) Called when a message arrived.
void	postDelayedMessage(MESSAGE message, int millisecond) Post a message delayed in a given time
void	postMessage(MESSAGE message) Post a message and deliver it as soon as possible
void	terminate() Stop the handler and destroy it.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_WAIT

private static final int DEFAULT_WAIT

Default waiting time

See Also:

Constant Field Values

alive

private boolean alive

Indicates if handler still alive

internalThread

private java.lang.Thread internalThread

Internal thread

isLocked

private final java.util.concurrent.atomic.AtomicBoolean isLocked

Indicates if lock is on or off

LOCK

private final java.lang.Object LOCK

Object for synchronization

mutex

private final Mutex mutex

Mutex for exclusive access

priorityQueue

private final java.util.PriorityQueue<MessageHandler.Message<MESSAGE>> priorityQueue

Queue of messages to give

Constructor Detail

MessageHandler

public MessageHandler()

Create a new instance of MessageHandler

Method Detail

doTheJob

final void doTheJob()

Manage the messages to delivered

finalize

protected void finalize()
                 throws java.lang.Throwable

Try to free memory if user forget to call terminate() and the object is garbage collected

Parent documentation:

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable - On issue

See Also:

Object.finalize()

messageArrived

protected abstract void messageArrived(MESSAGE message)

Called when a message arrived.
It is their that the user can do the dedicated job

Parameters:

message - Message arrived

cancelMessage

public final void cancelMessage(MESSAGE message)

Cancel a message.
Usually used with message post with postDelayedMessage(Object, int) to cancel it before it is called.
If the message already delivered, this method does nothing
Can be used for timeout for example

Parameters:

message - Message to cancel

isAlive

public final boolean isAlive()

Indicates if the handler still alive and can be used

Returns:

true if the handler still alive and can be used

postDelayedMessage

public final void postDelayedMessage(MESSAGE message,
                      int millisecond)

Post a message delayed in a given time

Parameters:

message - Message to delivered

millisecond - Time in millisecond to wait before sending the message

postMessage

public final void postMessage(MESSAGE message)

Post a message and deliver it as soon as possible

Parameters:

message - Message to post

terminate

public final void terminate()

Stop the handler and destroy it.
It can't be used after the calling of this method.
It is strongly recommend to call it as soon as the handler is not still necessary