ch.cern.dirq

Class QueueNull

java.lang.Object

ch.cern.dirq.QueueNull

All Implemented Interfaces:

Queue, Iterable<String>

public class QueueNull
extends Object
implements Queue

QueueNull - object oriented interface to a null directory based queue.

The goal of this module is to offer a null queue system using the same API as the other directory queue implementations. The queue will behave like a black hole: added data will disappear immediately so the queue will therefore always appear empty.

This can be used for testing purposes or to discard data like one would do on Unix by redirecting output to /dev/null.

Please refer to Queue for general information about directory queues.

Author:

Lionel Cons <lionel.cons@cern.ch>, Massimo Paladin <massimo.paladin@gmail.com> Copyright (C) CERN 2012-2013

Constructor Summary

Constructors

Constructor and Description
QueueNull() Constructor creating a null directory queue with no parameters.

Method Summary

Modifier and Type	Method and Description
String	add(byte[] data) Add data as byte array to the queue.
String	add(String data) Add data as a string to the queue.
String	addPath(String path) Add the given file (identified by its path) to the queue.
int	count() Return the number of elements in the queue.
String	get(String name) Not implemented, always throws UnsupportedOperationException.
byte[]	getAsByteArray(String name) Not implemented, always throws UnsupportedOperationException.
String	getId() Return the queue id.
String	getPath(String path) Not implemented, always throws UnsupportedOperationException.
Iterator<String>	iterator() Iterator over QueueNull implementation.
boolean	lock(String name) Not implemented, always throws UnsupportedOperationException.
boolean	lock(String name, boolean permissive) Not implemented, always throws UnsupportedOperationException.
void	purge() Does not do anything.
void	purge(Integer maxLock) Does not do anything.
void	purge(Integer maxLock, Integer maxTemp) Does not do anything.
void	remove(String name) Not implemented, always throws UnsupportedOperationException.
boolean	unlock(String name) Not implemented, always throws UnsupportedOperationException.
boolean	unlock(String name, boolean permissive) Not implemented, always throws UnsupportedOperationException.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

QueueNull

public QueueNull()

Constructor creating a null directory queue with no parameters.

Method Detail

getId

public String getId()

Return the queue id.

Specified by:

getId in interface Queue

Returns:

the String "NULL"

add

public String add(String data)

Add data as a string to the queue.

Specified by:

add in interface Queue

Parameters:

data - data to be added to the queue

Returns:

an empty String

add

public String add(byte[] data)

Add data as byte array to the queue.

Specified by:

add in interface Queue

Parameters:

data - data to be added to the queue

Returns:

an empty String

addPath

public String addPath(String path)

Add the given file (identified by its path) to the queue.

Specified by:

addPath in interface Queue

Parameters:

path - the path of the file to be added

Returns:

an empty String

get

public String get(String name)

Not implemented, always throws UnsupportedOperationException.

Specified by:

get in interface Queue

Parameters:

name - the name of the element to be returned

Returns:

return the value associated to the given name

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

getAsByteArray

public byte[] getAsByteArray(String name)

Not implemented, always throws UnsupportedOperationException.

Specified by:

getAsByteArray in interface Queue

Parameters:

name - the name of the element to be returned

Returns:

the value associated to the given name

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

getPath

public String getPath(String path)

Not implemented, always throws UnsupportedOperationException.

Specified by:

getPath in interface Queue

Parameters:

path - the name of the element

Returns:

the path of the element

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

lock

public boolean lock(String name)

Not implemented, always throws UnsupportedOperationException.

Specified by:

lock in interface Queue

Parameters:

name - name of the element to be locked

Returns:

true on success, false if the element could not be locked

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

lock

public boolean lock(String name,
                    boolean permissive)

Not implemented, always throws UnsupportedOperationException.

Specified by:

lock in interface Queue

Parameters:

name - name of the element to be locked

permissive - work in permissive mode

Returns:

true on success, false if the element could not be locked

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

unlock

public boolean unlock(String name)

Not implemented, always throws UnsupportedOperationException.

Specified by:

unlock in interface Queue

Parameters:

name - name of the element to be locked

Returns:

true on success, false if the element could not be unlocked

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

unlock

public boolean unlock(String name,
                      boolean permissive)

Not implemented, always throws UnsupportedOperationException.

Specified by:

unlock in interface Queue

Parameters:

name - name of the element to be locked

permissive - work in permissive mode

Returns:

true on success, false if the element could not be unlocked

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

remove

public void remove(String name)

Not implemented, always throws UnsupportedOperationException.

Specified by:

remove in interface Queue

Parameters:

name - name of the element to be removed

Throws:

UnsupportedOperationException - as it does not make sense for a null queue.

count

public int count()

Return the number of elements in the queue.

Specified by:

count in interface Queue

Returns:

zero

purge

public void purge()

Does not do anything.

Specified by:

purge in interface Queue

purge

public void purge(Integer maxLock)

Does not do anything.

Specified by:

purge in interface Queue

Parameters:

maxLock - maximum time for a locked element (in seconds); if set to 0, locked elements will not be unlocked; if set to null, the object's default value will be used

purge

public void purge(Integer maxLock,
                  Integer maxTemp)

Does not do anything.

Specified by:

purge in interface Queue

Parameters:

maxLock - maximum time for a locked element (in seconds); if set to 0, locked elements will not be unlocked; if set to null, the object's default value will be used

maxTemp - maximum time for a temporary element (in seconds); if set to 0, temporary elements will not be removed if set to null, the object's default value will be used

iterator

public Iterator<String> iterator()

Iterator over QueueNull implementation.

Specified by:

iterator in interface Iterable<String>