org.archive.queue
Class DiskBackedDeque

java.lang.Object
  org.archive.queue.DiskBackedQueue
      org.archive.queue.DiskBackedDeque

All Implemented Interfaces:

java.io.Serializable, Deque, Queue, Stack

public class DiskBackedDeque
extends DiskBackedQueue
implements Deque, java.io.Serializable

Author:

gojomo

See Also:

Serialized Form

Field Summary

protected DiskStack

stack

Fields inherited from class org.archive.queue.DiskBackedQueue

DISCARD_BACKING_THRESHOLD, headMax, headQ, name, tailQ

Constructor Summary

DiskBackedDeque(java.io.File dir, java.lang.String name, boolean reuse, int headMax)

Method Summary

protected java.lang.Object	backingDequeue()
long	deleteMatchedItems(org.apache.commons.collections.Predicate matcher) All objects in the queue where matcher.match(object) returns true will be deleted from the queue.
protected void	discardBacking()
void	disconnect() Release any file-handles in arecoverable way.
java.util.Iterator	getIterator(boolean inCacheOnly) Returns an iterator for the queue.
protected int	headTargetSize()
long	height() Number of items in the Stack.
boolean	isEmpty() is the queue empty?
long	length() get the number of elements in the queue
int	memoryLoad()
java.lang.Object	peek() Give the top object in the queue, leaving it in place to be returned by future peek() or dequeue() invocations.
java.lang.Object	pop() Remove and return item from top of Stack
void	push(java.lang.Object object) Add object to top of Stack
void	setHeadMax(int hm) Set the number of items to keep in memory, and adjust current head to match.

Methods inherited from class org.archive.queue.DiskBackedQueue

backingUpdate, canDiscardBacking, dequeue, enqueue, fillHeadQ, release, unpeek

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.archive.queue.Queue

dequeue, enqueue, release, unpeek

Methods inherited from interface org.archive.queue.Stack

release

Field Detail

stack

protected DiskStack stack

Constructor Detail

DiskBackedDeque

public DiskBackedDeque(java.io.File dir,
                       java.lang.String name,
                       boolean reuse,
                       int headMax)
                throws java.io.IOException

Parameters:

dir -

name -

reuse -

headMax -

Throws:

java.io.IOException

Method Detail

push

public void push(java.lang.Object object)

Description copied from interface: Stack

Add object to top of Stack

Specified by:

push in interface Stack

setHeadMax

public void setHeadMax(int hm)

Set the number of items to keep in memory, and adjust current head to match.

Overrides:

setHeadMax in class DiskBackedQueue

Parameters:

hm -

pop

public java.lang.Object pop()

Description copied from interface: Stack

Remove and return item from top of Stack

Specified by:

pop in interface Stack

Returns:

Item removed from top of Stack

peek

public java.lang.Object peek()

Description copied from interface: Queue

Give the top object in the queue, leaving it in place to be returned by future peek() or dequeue() invocations.

Specified by:

peek in interface Queue

Specified by:

peek in interface Stack

Overrides:

peek in class DiskBackedQueue

Returns:

top object, without removing it

See Also:

Queue.peek()

height

public long height()

Description copied from interface: Stack

Number of items in the Stack.

Specified by:

height in interface Stack

backingDequeue

protected java.lang.Object backingDequeue()

Overrides:

backingDequeue in class DiskBackedQueue

Returns:

backing dequeue queue instance.

discardBacking

protected void discardBacking()

Overrides:

discardBacking in class DiskBackedQueue

deleteMatchedItems

public long deleteMatchedItems(org.apache.commons.collections.Predicate matcher)

Description copied from interface: Queue

All objects in the queue where matcher.match(object) returns true will be deleted from the queue.

Making other changes to the queue while this method is being processed is not safe.

Specified by:

deleteMatchedItems in interface Queue

Overrides:

deleteMatchedItems in class DiskBackedQueue

Parameters:

matcher - a predicate

Returns:

the number of deleted items

See Also:

Queue.deleteMatchedItems(org.apache.commons.collections.Predicate)

getIterator

public java.util.Iterator getIterator(boolean inCacheOnly)

Description copied from interface: Queue

Returns an iterator for the queue.

The returned iterator's remove method is considered unsafe.

Editing the queue while using the iterator is not safe.

Specified by:

getIterator in interface Queue

Overrides:

getIterator in class DiskBackedQueue

Returns:

an iterator for the queue

See Also:

Queue.getIterator(boolean)

headTargetSize

protected int headTargetSize()

Overrides:

headTargetSize in class DiskBackedQueue

Returns:

Maximum size of head queue.

isEmpty

public boolean isEmpty()

Description copied from interface: Queue

is the queue empty?

Specified by:

isEmpty in interface Queue

Specified by:

isEmpty in interface Stack

Overrides:

isEmpty in class DiskBackedQueue

Returns:

true if the queue has no elements

See Also:

Queue.isEmpty()

length

public long length()

Description copied from interface: Queue

get the number of elements in the queue

Specified by:

length in interface Queue

Overrides:

length in class DiskBackedQueue

Returns:

the number of elements in the queue

See Also:

Queue.length()

disconnect

public void disconnect()

Description copied from class: DiskBackedQueue

Release any file-handles in arecoverable way.

Overrides:

disconnect in class DiskBackedQueue

memoryLoad

public int memoryLoad()

Returns:

Memory load.