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.\" ========================================================================
.\"
.IX Title "Cache::File::Heap 3pm"
.TH Cache::File::Heap 3pm "2015-07-25" "perl v5.20.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Cache::File::Heap \- A file based heap for use by Cache::File
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Cache::File::Heap;
\&
\&  $heap = Cache::File::Heap\->new(\*(Aq/path/to/some/heap/file\*(Aq);
\&  $heap\->add($key, $val);
\&  ($key, $val) = $heap\->minimum;
\&  ($key, $val) = $heap\->extract_minimum;
\&  $heap\->delete($key, $val);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module is a wrapper around a Berkeley \s-1DB\s0 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).
.PP
See \s-1LIMITATIONS\s0 below.
.SH "CONSTRUCTOR"
.IX Header "CONSTRUCTOR"
.Vb 1
\&  my $heap = Cache::File::Heap\->new( [$dbfile] );
.Ve
.PP
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.
.SH "METHODS"
.IX Header "METHODS"
.ie n .IP "$h\->open($dbfile)" 4
.el .IP "\f(CW$h\fR\->open($dbfile)" 4
.IX Item "$h->open($dbfile)"
Opens the specified database file.
.ie n .IP "$h\->\fIclose()\fR" 4
.el .IP "\f(CW$h\fR\->\fIclose()\fR" 4
.IX Item "$h->close()"
Closes a previously opened heap database.  Note that the database will be
automatically closed when the heap reference is destroyed.
.ie n .IP "$h\->add($key, $val)" 4
.el .IP "\f(CW$h\fR\->add($key, \f(CW$val\fR)" 4
.IX Item "$h->add($key, $val)"
Adds a key and value pair to the heap.  Currently the key should be a number,
whilst the value may be any scalar.  Invokes 'die' on failure (use eval to
catch it).
.ie n .IP "$h\->delete($key, $val)" 4
.el .IP "\f(CW$h\fR\->delete($key, \f(CW$val\fR)" 4
.IX Item "$h->delete($key, $val)"
Removes a key and value pair from the heap.  Returns 1 if the pair was found
and removed, or 0 otherwise.
.ie n .IP "($key, $val) = $h\->\fIminimum()\fR" 4
.el .IP "($key, \f(CW$val\fR) = \f(CW$h\fR\->\fIminimum()\fR" 4
.IX Item "($key, $val) = $h->minimum()"
In list context, returns the smallest key and value pair from the heap.  In
scalar context only the key is returned.  Note smallest is defined via a
numerical comparison (hence keys should always be numbers).
.ie n .IP "($key, $vals) = $h\->\fIminimum_dup()\fR" 4
.el .IP "($key, \f(CW$vals\fR) = \f(CW$h\fR\->\fIminimum_dup()\fR" 4
.IX Item "($key, $vals) = $h->minimum_dup()"
In list context, returns the smallest key and an array reference containing
all the values for that key from the heap.  In scalar context only the key is
returned.
.ie n .IP "($key, $val) = $h\->\fIextract_minimum()\fR" 4
.el .IP "($key, \f(CW$val\fR) = \f(CW$h\fR\->\fIextract_minimum()\fR" 4
.IX Item "($key, $val) = $h->extract_minimum()"
As for \f(CW$h\fR\->\fIminimum()\fR, but the key and value pair is removed from the heap.
.ie n .IP "($key, $vals) = $h\->\fIextract_minimum_dup()\fR" 4
.el .IP "($key, \f(CW$vals\fR) = \f(CW$h\fR\->\fIextract_minimum_dup()\fR" 4
.IX Item "($key, $vals) = $h->extract_minimum_dup()"
As for \f(CW$h\fR\->\fIminimum_dup()\fR, but all the values are removed from the heap.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Cache::File
.SH "AUTHOR"
.IX Header "AUTHOR"
.Vb 2
\& Chris Leishman <chris@leishman.org>
\& Based on work by DeWitt Clinton <dewitt@unto.net>
.Ve
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
.Vb 1
\& Copyright (C) 2003\-2006 Chris Leishman.  All Rights Reserved.
.Ve
.PP
This module is distributed on an \*(L"\s-1AS IS\*(R"\s0 basis, \s-1WITHOUT WARRANTY OF ANY KIND,\s0
either expressed or implied. This program is free software; you can
redistribute or modify it under the same terms as Perl itself.
.PP
\&\f(CW$Id:\fR Heap.pm,v 1.6 2006/01/31 15:23:58 caleishm Exp $