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

        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 $