/[webpac2]/trunk/lib/WebPAC/Input.pm
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revision 1 by dpavlin, Sat Jun 25 20:23:23 2005 UTC revision 11 by dpavlin, Sat Jul 16 20:54:28 2005 UTC
# Line 5  use strict; Line 5  use strict;
5    
6  =head1 NAME  =head1 NAME
7    
8  WebPAC::Input - The great new WebPAC::Input!  WebPAC::Input - core module for input file format
9    
10  =head1 VERSION  =head1 VERSION
11    
# Line 17  our $VERSION = '0.01'; Line 17  our $VERSION = '0.01';
17    
18  =head1 SYNOPSIS  =head1 SYNOPSIS
19    
20  Quick summary of what the module does.  This module will load particular loader module and execute it's functions.
21    
22  Perhaps a little code snippet.  Perhaps a little code snippet.
23    
24      use WebPAC::Input;      use WebPAC::Input;
25    
26      my $foo = WebPAC::Input->new();      my $db = WebPAC::Input->new(
27      ...          format => 'NULL',
28            config => $config,
29            lookup => $lookup_obj,
30            low_mem => 1,
31        );
32    
33        $db->open('/path/to/database');
34        print "database size: ",$db->size,"\n";
35        while (my $row = $db->fetch) {
36            ...
37        }
38    
39  =head1 EXPORT  =head1 FUNCTIONS
40    
41  A list of functions that can be exported.  You can delete this section  =head2 new
 if you don't export anything, such as for a purely object-oriented module.  
42    
43  =head1 FUNCTIONS  Create new input database object.
44    
45      my $db = new WebPAC::Input(
46            format => 'NULL'
47            code_page => 'ISO-8859-2',
48            low_mem => 1,
49      );
50    
51  =head2 function1  Optional parametar C<code_page> specify application code page (which will be
52    used internally). This should probably be your terminal encoding, and by
53    default, it C<ISO-8859-2>.
54    
55    Default is not to use C<low_mem> options (see L<MEMORY USAGE> below).
56    
57  =cut  =cut
58    
59  sub function1 {  sub new {
60  }          my $class = shift;
61            my $self = {@_};
62            bless($self, $class);
63    
64  =head2 function2          $self->{'code_page'} ||= 'ISO-8859-2';
65    
66  =cut          my $log = $self->_get_logger;
67    
68            # running with low_mem flag? well, use DBM::Deep then.
69            if ($self->{'low_mem'}) {
70                    $log->info("running with low_mem which impacts performance (<32 Mb memory usage)");
71    
72                    my $db_file = "data.db";
73    
74                    if (-e $db_file) {
75                            unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
76                            $log->debug("removed '$db_file' from last run");
77                    }
78    
79  sub function2 {                  require DBM::Deep;
80    
81                    my $db = new DBM::Deep $db_file;
82    
83                    $log->logdie("DBM::Deep error: $!") unless ($db);
84    
85                    if ($db->error()) {
86                            $log->logdie("can't open '$db_file' under low_mem: ",$db->error());
87                    } else {
88                            $log->debug("using file '$db_file' for DBM::Deep");
89                    }
90    
91                    $self->{'db'} = $db;
92            }
93    
94            $self ? return $self : return undef;
95  }  }
96    
97  =head1 AUTHOR  =head1 MEMORY USAGE
98    
99  Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>  C<low_mem> options is double-edged sword. If enabled, WebPAC
100    will run on memory constraint machines (which doesn't have enough
101    physical RAM to create memory structure for whole source database).
102    
103    If your machine has 512Mb or more of RAM and database is around 10000 records,
104    memory shouldn't be an issue. If you don't have enough physical RAM, you
105    might consider using virtual memory (if your operating system is handling it
106    well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle
107    parsed structure of ISIS database (this is what C<low_mem> option does).
108    
109    Hitting swap at end of reading source database is probably o.k. However,
110    hitting swap before 90% will dramatically decrease performance and you will
111    be better off with C<low_mem> and using rest of availble memory for
112    operating system disk cache (Linux is particuallary good about this).
113    However, every access to database record will require disk access, so
114    generation phase will be slower 10-100 times.
115    
116    Parsed structures are essential - you just have option to trade RAM memory
117    (which is fast) for disk space (which is slow). Be sure to have planty of
118    disk space if you are using C<low_mem> and thus L<DBM::Deep>.
119    
120    However, when WebPAC is running on desktop machines (or laptops :-), it's
121    highly undesireable for system to start swapping. Using C<low_mem> option can
122    reduce WecPAC memory usage to around 64Mb for same database with lookup
123    fields and sorted indexes which stay in RAM. Performance will suffer, but
124    memory usage will really be minimal. It might be also more confortable to
125    run WebPAC reniced on those machines.
126    
 =head1 BUGS  
127    
128  Please report any bugs or feature requests to  =head1 AUTHOR
 C<bug-webpac-input@rt.cpan.org>, or through the web interface at  
 L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=WebPAC>.  
 I will be notified, and then you'll automatically be notified of progress on  
 your bug as I make changes.  
129    
130  =head1 ACKNOWLEDGEMENTS  Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >>
131    
132  =head1 COPYRIGHT & LICENSE  =head1 COPYRIGHT & LICENSE
133    
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