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Cache::File::Heap - A file based heap for use by Cache::File

Cache::File::Heap(3pm) User Contributed Perl Documentation Cache::File::Heap(3pm)

NAME

Cache::File::Heap - A file based heap for use by Cache::File

SYNOPSIS

  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);

DESCRIPTION

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.

CONSTRUCTOR

  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.

METHODS

$h->open($dbfile)
Opens the specified database file.
$h->close()
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.

SEE ALSO

Cache::File

AUTHOR

 Chris Leishman <chris@leishman.org>
 Based on work by DeWitt Clinton <dewitt@unto.net>
 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 $
2015-07-25 perl v5.20.2