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package WebPAC::Input; |
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|
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use warnings; |
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use strict; |
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|
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=head1 NAME |
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|
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WebPAC::Input - core module for input file format |
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|
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=head1 VERSION |
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|
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Version 0.01 |
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|
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=cut |
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|
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our $VERSION = '0.01'; |
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|
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=head1 SYNOPSIS |
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|
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This module will load particular loader module and execute it's functions. |
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|
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Perhaps a little code snippet. |
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|
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use WebPAC::Input; |
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|
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my $db = WebPAC::Input->new( |
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format => 'NULL', |
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config => $config, |
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lookup => $lookup_obj, |
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low_mem => 1, |
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); |
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|
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$db->open('/path/to/database'); |
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print "database size: ",$db->size,"\n"; |
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while (my $row = $db->fetch) { |
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... |
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} |
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$db->close; |
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|
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=head1 FUNCTIONS |
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|
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=head2 new |
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|
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Create new input database object. |
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|
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my $db = new WebPAC::Input( |
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format => 'NULL' |
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code_page => 'ISO-8859-2', |
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low_mem => 1, |
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); |
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|
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Optional parametar C<code_page> specify application code page (which will be |
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used internally). This should probably be your terminal encoding, and by |
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default, it C<ISO-8859-2>. |
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|
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Default is not to use C<low_mem> options (see L<MEMORY USAGE> below). |
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|
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=cut |
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|
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sub new { |
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my $class = shift; |
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my $self = {@_}; |
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bless($self, $class); |
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|
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$self->{'code_page'} ||= 'ISO-8859-2'; |
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|
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my $log = $self->_get_logger; |
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|
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# running with low_mem flag? well, use DBM::Deep then. |
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if ($self->{'low_mem'}) { |
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$log->info("running with low_mem which impacts performance (<32 Mb memory usage)"); |
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|
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my $db_file = "data.db"; |
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|
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if (-e $db_file) { |
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unlink $db_file or $log->logdie("can't remove '$db_file' from last run"); |
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$log->debug("removed '$db_file' from last run"); |
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} |
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|
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require DBM::Deep; |
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|
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my $db = new DBM::Deep $db_file; |
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|
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$log->logdie("DBM::Deep error: $!") unless ($db); |
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|
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if ($db->error()) { |
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$log->logdie("can't open '$db_file' under low_mem: ",$db->error()); |
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} else { |
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$log->debug("using file '$db_file' for DBM::Deep"); |
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} |
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|
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$self->{'db'} = $db; |
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} |
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|
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$self ? return $self : return undef; |
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} |
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|
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=head1 MEMORY USAGE |
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|
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C<low_mem> options is double-edged sword. If enabled, WebPAC |
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will run on memory constraint machines (which doesn't have enough |
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physical RAM to create memory structure for whole source database). |
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|
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If your machine has 512Mb or more of RAM and database is around 10000 records, |
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memory shouldn't be an issue. If you don't have enough physical RAM, you |
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might consider using virtual memory (if your operating system is handling it |
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well, like on FreeBSD or Linux) instead of dropping to L<DBM::Deep> to handle |
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parsed structure of ISIS database (this is what C<low_mem> option does). |
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|
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Hitting swap at end of reading source database is probably o.k. However, |
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hitting swap before 90% will dramatically decrease performance and you will |
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be better off with C<low_mem> and using rest of availble memory for |
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operating system disk cache (Linux is particuallary good about this). |
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However, every access to database record will require disk access, so |
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generation phase will be slower 10-100 times. |
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|
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Parsed structures are essential - you just have option to trade RAM memory |
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(which is fast) for disk space (which is slow). Be sure to have planty of |
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disk space if you are using C<low_mem> and thus L<DBM::Deep>. |
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|
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However, when WebPAC is running on desktop machines (or laptops :-), it's |
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highly undesireable for system to start swapping. Using C<low_mem> option can |
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reduce WecPAC memory usage to around 64Mb for same database with lookup |
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fields and sorted indexes which stay in RAM. Performance will suffer, but |
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memory usage will really be minimal. It might be also more confortable to |
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run WebPAC reniced on those machines. |
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|
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|
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=head1 AUTHOR |
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|
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Dobrica Pavlinusic, C<< <dpavlin@rot13.org> >> |
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|
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=head1 COPYRIGHT & LICENSE |
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|
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Copyright 2005 Dobrica Pavlinusic, All Rights Reserved. |
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|
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This program is free software; you can redistribute it and/or modify it |
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under the same terms as Perl itself. |
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|
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=cut |
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|
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1; # End of WebPAC::Input |
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