NAME

Stack::Persistent - A persistent stack

SYNOPSIS

This module implements a named, persistent stack for usage by programs that need to recover the items on a stack when something unexpected happens. The stack is LIFO based.

DESCRIPTION

This module can be used as follows:

use Stack::Persistent;

$stack = Stack::Persistent->new();

$stack->push('default', 'some really cool stuff');
printf("There are %s items on the stack\n", $stack->items('default'));
printf("My data is: %s\n", $stack->pop('default'));

The main purpose of this module was to have a persistent stack that could survive the restart of a program. Multiple, named stacks can be maintained.

METHODS

new

There are several named parameters that can be used with this method. Since this module use Cache::FastMmap to manage the backing store. You should read that modules documentation. They are the following:

-initialize

This initializes the stacks backing cache. You will not want to do this if your program needs to retireve items after a restart. The default is to not initialize.

-pages

What the number of pages for your stacks backing cache should be. The default is 64.

-size

The size of those pages in bytes. The default is 64KB.

-expiration

The expiration of item with the stacks cache.

-filename

The name of the file that is being used. The default is /tmp/stack-persistent.cache.

Example

$stack = Stack::Persistent->new(-filename => '/tmp/stack.cache');

push

Push a data element onto the named stack.

Example

$stack->push('default', $data);

pop

Remove a data element from the top of a named stack. Once an element has been "popped" it is no longer avaiable within the cache.

Example

$data = $stack->pop('default');

peek

Retrieve the data element from the top of the stack. The data element is not removed from the stack. To remove an element, you need to use pop().

Example

$data = $stack->peek('default');

items

Return the number of data elements that are currently on the stack.

Example

$items1 = $stack->items('default');
$items2 = $stack->items('worker');

clear

Remove all data elements from the stack. Once a stack has been "cleared" there are no data elements left within the cache.

Example

$stack->clear('default');

dump

Dump all the backing cache for the stack. This is can be used for debugging purposes.

Example

$stack->dump('default');

ACCESSORS

handle

This accessor returns the underling handle for Cache::FastMmap. You can then use any of methods that are available to that module.

Example

$handle = $stack->handle;
$handle->purge();

EXPORT

None by default.

SEE ALSO

Cache::FastMmap

AUTHOR

Kevin L. Esteb, <kesteb@wsipc.org>

COPYRIGHT AND LICENSE

Copyright (C) 2007 by Kevin L. Esteb

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.5 or, at your option, any later version of Perl 5 you may have available.