Cache::File::Heap - A file based heap for use by Cache::File
use Cache::File::Heap; $heap = Cache::File::Heap->new('/path/to/some/heap/file'); $heap->add($key, $val); ($key, $val) = $heap->minimum; ($key, $val) = $heap->extract_minimum; $heap->delete($key, $val);
This module is a wrapper around a Berkeley DB using a btree structure to implement a heap. It is specifically for use by Cache::File for storing expiry times (although with a bit of work it could be made more general).
See LIMITATIONS below.
my $heap = Cache::File::Heap->new( [$dbfile] );
The heap constructor takes an optional argument which is the name of the database file to open. If specified, it will attempt to open the database during construction. A new Cache::File::Heap blessed reference will be returned, or undef if the open failed.
Opens the specified database file.
Closes a previously opened heap database. Note that the database will be automatically closed when the heap reference is destroyed.
- $h->add($key, $val)
Adds a key and value pair to the heap. Currently the key should be a number, whilst the value may be any scalar. Invokes 'die' on failure (use eval to catch it).
- $h->delete($key, $val)
Removes a key and value pair from the heap. Returns 1 if the pair was found and removed, or 0 otherwise.
- ($key, $val) = $h->minimum()
In list context, returns the smallest key and value pair from the heap. In scalar context only the key is returned. Note smallest is defined via a numerical comparison (hence keys should always be numbers).
- ($key, $vals) = $h->minimum_dup()
In list context, returns the smallest key and an array reference containing all the values for that key from the heap. In scalar context only the key is returned.
- ($key, $val) = $h->extract_minimum()
As for $h->minimum(), but the key and value pair is removed from the heap.
- ($key, $vals) = $h->extract_minimum_dup()
As for $h->minimum_dup(), but all the values are removed from the heap.
Chris Leishman <firstname.lastname@example.org> Based on work by DeWitt Clinton <email@example.com>
Copyright (C) 2003-2006 Chris Leishman. All Rights Reserved.
This module is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either expressed or implied. This program is free software; you can redistribute or modify it under the same terms as Perl itself.
$Id: Heap.pm,v 1.6 2006/01/31 15:23:58 caleishm Exp $