NAME

URL::List - Helper class for creating distributed lists of URLs based on their host name, domain name or TLDs.

VERSION

Version 0.13

SYNOPSIS

    use URL::List;

    my $list = URL::List->new;
    $list->add( 'http://www.google.com/' );
    $list->add( 'http://www.bbc.co.uk/' );

    # or

    my $list = URL::List->new(
        allow_duplicates => 1,       # default false
        urls             => [ ... ], # arrayref of URLs
    );

    my $distributed_by_hosts = $list->distributed_by_host;

    # $VAR1 = {
    #     'www.google.com' => [
    #         'http://www.google.com/',
    #     ],
    #     'www.bbc.co.uk' => [
    #         'http://www.bbc.co.uk/',
    #     ],
    # };

    my $distributed_by_domains = $list->distributed_by_domain;

    # $VAR1 = {
    #     'google.com' => [
    #         'http://www.google.com/',
    #     ],
    #     'bbc.co.uk' => [
    #         'http://www.bbc.co.uk/',
    #     ],
    # };

    my $distributed_by_tlds = $list->distributed_by_tld;

    # $VAR1 = {
    #     'com' => [
    #         'http://www.google.com/',
    #     ],
    #     'co.uk' => [
    #         'http://www.bbc.co.uk/',
    #     ],
    # };

    my $urls = $list->all; # All the URLs are still there, so use this...
    $list->clear;          # ...to clear the list.

DESCRIPTION

URL:List is a module which helps you with distributing a list of URLs "evenly" based on the URLs' host name, domain name or TLD (top-level domain).

This can be useful for crawlers, ie. giving out a list of URLs within specific hostnames, domain names and/or TLD names to different workers.

METHODS

new

Returns an instance of URL::List.

Takes one optional parameter, 'allow_duplicates', which is default 0. By setting it to true (1), URL::List will not filter out duplicate articles.

add( $url )

Add a URL to the list. $url can be an array reference of URLs.

all

Returns an array reference of all the URLs in the list.

count

Returns the number of URLs in the list, including potential duplicates, depending on the 'allow_duplicates' setting.

clear

Clears the URL list.

flush

An alias for clear.

distributions

Returns a hash reference of all the possible distributions.

This method should not be used directly. Instead, the distributed_by_* methods should be used.

distributed_by_host

Returns a hash reference where the key is the host name, like "www.google.com", and the value is an array reference to the host name's URLs.

distributed_by_domain

Returns a hash reference where the key is the domain name, like "google.com", and the value is an array reference to the domain name's URLs.

distributed_by_tld

Returns a hash reference where the key is the top-level domain name, like "com", and the value is an array reference to the top-level domain name's URLs.

blocks_by_host, blocks_by_domain, blocks_by_tld

Returns "blocks" of URLs distributed by their host/domain/TLD, i.e. an array reference of array references containing URLs distributed as evenly as possible;

    my $list = URL::List->new(
        urls => [qw(
            http://www.businessinsider.com/1.html
            http://www.businessinsider.com/2.html
            http://www.businessinsider.com/3.html
            http://www.engadget.com/1.html
            http://www.engadget.com/2.html
            http://www.engadget.com/3.html
            http://www.engadget.com/4.html
            http://www.independent.co.uk/1.html
            http://www.independent.co.uk/2.html
            http://www.pcmag.com/1.html
            http://www.pcmag.com/2.html
            http://www.pcmag.com/3.html
            http://www.technologyreview.com/1.html
            http://www.technologyreview.com/2.html
            http://www.technologyreview.com/3.html
            http://www.technologyreview.com/4.html
            http://www.zdnet.com/1.html
            http://www.zdnet.com/2.html
            http://www.zdnet.com/3.html
        )],
    );

    # $list->blocks_by_host = [
    #     [qw(
    #         http://www.businessinsider.com/1.html
    #         http://www.engadget.com/1.html
    #         http://www.independent.co.uk/1.html
    #         http://www.pcmag.com/1.html
    #         http://www.technologyreview.com/1.html
    #         http://www.zdnet.com/1.html
    #     )],
    #
    #     [qw(
    #         http://www.businessinsider.com/2.html
    #         http://www.engadget.com/2.html
    #         http://www.independent.co.uk/2.html
    #         http://www.pcmag.com/2.html
    #         http://www.technologyreview.com/2.html
    #         http://www.zdnet.com/2.html
    #     )],
    #
    #     [qw(
    #         http://www.businessinsider.com/3.html
    #         http://www.engadget.com/3.html
    #         http://www.pcmag.com/3.html
    #         http://www.technologyreview.com/3.html
    #         http://www.zdnet.com/3.html
    #     )],
    #
    #     [qw(
    #         http://www.engadget.com/4.html
    #         http://www.technologyreview.com/4.html
    #     )],
    # ],

This is useful if you want to crawl many URLs, but also want to pause between each visit to host/domain/TLD;

    my $list = URL::List->new( urls => [...] );

    foreach my $urls ( @{$list->blocks_by_domain} ) {
        # get $urls in parallel, you will only visit each domain once, or you
        # can delegate $urls to other workers (crawlers) to spread load etc.

        sleep( 5 ); # let's be nice and pause
    }

LICENSE AND COPYRIGHT

Copyright 2012-2017 Tore Aursand.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

http://www.perlfoundation.org/artistic_license_2_0

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.