/[webpac2]/trunk/lib/WebPAC/Input.pm
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Annotation of /trunk/lib/WebPAC/Input.pm

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Revision 6 - (hide annotations)
Sat Jul 16 14:44:38 2005 UTC (19 years ago) by dpavlin
File size: 2740 byte(s)
added WebPAC::Input::ISIS

1 dpavlin 1 package WebPAC::Input;
2    
3     use warnings;
4     use strict;
5    
6     =head1 NAME
7    
8 dpavlin 3 WebPAC::Input - core module for input file format
9 dpavlin 1
10     =head1 VERSION
11    
12     Version 0.01
13    
14     =cut
15    
16     our $VERSION = '0.01';
17    
18     =head1 SYNOPSIS
19    
20 dpavlin 3 This module will load particular loader module and execute it's functions.
21 dpavlin 1
22     Perhaps a little code snippet.
23    
24     use WebPAC::Input;
25    
26 dpavlin 3 my $db = WebPAC::Input->new(
27     format => 'NULL',
28     config => $config,
29 dpavlin 6 lookup => $lookup_obj,
30 dpavlin 3 );
31 dpavlin 1
32 dpavlin 3 $db->open('/path/to/database');
33     print "database size: ",$db->size,"\n";
34     while (my $row = $db->fetch) {
35     ...
36     }
37     $db->close;
38 dpavlin 1
39     =head1 FUNCTIONS
40    
41 dpavlin 3 =head2 new
42 dpavlin 1
43 dpavlin 3 Create new input database object.
44    
45     my $db = new WebPAC::Input( format => 'NULL' );
46    
47 dpavlin 1 =cut
48    
49 dpavlin 3 sub new {
50     my $class = shift;
51     my $self = {@_};
52     bless($self, $class);
53    
54     $self ? return $self : return undef;
55 dpavlin 1 }
56    
57 dpavlin 3 =head1 MEMORY USAGE
58 dpavlin 1
59 dpavlin 3 C<low_mem> options is double-edged sword. If enabled, WebPAC
60     will run on memory constraint machines (which doesn't have enough
61     physical RAM to create memory structure for whole source database).
62 dpavlin 1
63 dpavlin 3 If your machine has 512Mb or more of RAM and database is around 10000 records,
64     memory shouldn't be an issue. If you don't have enough physical RAM, you
65     might consider using virtual memory (if your operating system is handling it
66     well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle
67     parsed structure of ISIS database (this is what C<low_mem> option does).
68 dpavlin 1
69 dpavlin 3 Hitting swap at end of reading source database is probably o.k. However,
70     hitting swap before 90% will dramatically decrease performance and you will
71     be better off with C<low_mem> and using rest of availble memory for
72     operating system disk cache (Linux is particuallary good about this).
73     However, every access to database record will require disk access, so
74     generation phase will be slower 10-100 times.
75    
76     Parsed structures are essential - you just have option to trade RAM memory
77     (which is fast) for disk space (which is slow). Be sure to have planty of
78     disk space if you are using C<low_mem> and thus L<DBM::Deep>.
79    
80     However, when WebPAC is running on desktop machines (or laptops :-), it's
81     highly undesireable for system to start swapping. Using C<low_mem> option can
82     reduce WecPAC memory usage to around 64Mb for same database with lookup
83     fields and sorted indexes which stay in RAM. Performance will suffer, but
84     memory usage will really be minimal. It might be also more confortable to
85     run WebPAC reniced on those machines.
86    
87    
88     =head1 AUTHOR
89    
90     Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>
91    
92 dpavlin 1 =head1 COPYRIGHT & LICENSE
93    
94     Copyright 2005 Dobrica Pavlinusic, All Rights Reserved.
95    
96     This program is free software; you can redistribute it and/or modify it
97     under the same terms as Perl itself.
98    
99     =cut
100    
101     1; # End of WebPAC::Input

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