package DBIx::Class::Storage::DBI::Replicated::Balancer::Random;
-use List::Util qw(shuffle);
-use Moose;
+use Moo;
+use DBIx::Class::Storage::DBI::Replicated::Types qw(PositiveNumber);
with 'DBIx::Class::Storage::DBI::Replicated::Balancer';
=head1 NAME
-DBIx::Class::Storage::DBI::Replicated::Balancer::Random; A 'random' Balancer
+DBIx::Class::Storage::DBI::Replicated::Balancer::Random - A 'random' Balancer
=head1 SYNOPSIS
This class is used internally by L<DBIx::Class::Storage::DBI::Replicated>. You
shouldn't need to create instances of this class.
-
+
=head1 DESCRIPTION
Given a pool (L<DBIx::Class::Storage::DBI::Replicated::Pool>) of replicated
database's (L<DBIx::Class::Storage::DBI::Replicated::Replicant>), defines a
method by which query load can be spread out across each replicant in the pool.
-This Balancer uses L<List::Util> keyword 'shuffle' to randomly pick an active
-replicant from the associated pool. This may or may not be random enough for
-you, patches welcome.
-
=head1 ATTRIBUTES
This class defines the following attributes.
+=head2 master_read_weight
+
+A number greater than 0 that specifies what weight to give the master when
+choosing which backend to execute a read query on. A value of 0, which is the
+default, does no reads from master, while a value of 1 gives it the same
+priority as any single replicant.
+
+For example: if you have 2 replicants, and a L</master_read_weight> of C<0.5>,
+the chance of reading from master will be C<20%>.
+
+You can set it to a value higher than 1, making master have higher weight than
+any single replicant, if for example you have a very powerful master.
+
+=cut
+
+has master_read_weight => (
+ is => 'rw',
+ isa => PositiveNumber(err => sub {"weight must be a positive number, not $_[0]"}),
+ default => sub { 0 },
+);
+
=head1 METHODS
This class defines the following methods.
=cut
sub next_storage {
- my $self = shift @_;
- my @active_replicants = $self->pool->active_replicants;
- my $count_active_replicants = $#active_replicants +1;
-
- return $active_replicants[int(rand($count_active_replicants +1))];
+ my $self = shift;
+ my @replicants = $self->pool->active_replicants;
+
+ if (not @replicants) {
+ # will fall back to master anyway
+ return;
+ }
+
+ my $master = $self->master;
+ my $rnd = $self->_random_number(@replicants + $self->master_read_weight);
+
+ return $rnd >= @replicants ? $master : $replicants[int $rnd];
+}
+
+sub _random_number {
+ rand($_[1]);
}
=head1 AUTHOR
-John Napiorkowski <john.napiorkowski@takkle.com>
+John Napiorkowski <jjnapiork@cpan.org>
=head1 LICENSE
=cut
-__PACKAGE__->meta->make_immutable;
-
-1;
\ No newline at end of file
+1;