File Coverage

blib/lib/Plack/Middleware/Proxy/LoadBalancer.pm

Criterion	Covered	Total	%
statement	30	41	73.1
branch	5	8	62.5
condition			n/a
subroutine	6	8	75.0
pod	2	3	66.6
total	43	60	71.6

package Plack::Middleware::Proxy::LoadBalancer;
use strict;
use warnings;
use parent 'Plack::Middleware';

use Plack::Util::Accessor qw/backends/;

our $VERSION = '0.01';

sub new {
    my $class = shift;
    my %param = ref $_[0] ? %{ $_[0] } : @_;

    my $backends = delete $param{backends};

    my $self = $class->SUPER::new( \%param );
    $self->_set_backends( $backends );

    $self;
}

sub _set_backends{
    my $self = shift;
    my ( $backends ) = @_;

    # A total of 'weight' should be 1.0
    if( ref $backends eq 'ARRAY'){
        my $weight = 1 / @$backends;
        $self->backends([
            map { {remote => $_, weight => $weight} } @$backends
        ]);
    }elsif( ref $backends eq 'HASH'){
        my $total = 0;
        $total += $_ for values %$backends;
        $self->backends([ map {
            {remote => $_, weight => $backends->{$_} / $total}
        } keys %$backends ]);
    }else{
        $self->backends([ { remote => $backends, weight => 1 } ]);
    }
}

sub select_backend {
    my $self = shift;
    my $rand = rand;

    my $choice = undef;
    for( @{ $self->backends } ){
        $choice = $_->{remote};
        ($rand -= $_->{weight}) <= 0 and last;
    }

    return $choice;
}

sub call {
    my ( $self, $env ) = @_;
    $env->{'plack.proxy.remote'} = $self->select_backend;
    $self->app->($env);
}

1;

__END__