Current File : C:/xampp/perl/vendor/lib/DBIx/Class/Storage/DBI/Replicated/Balancer/Random.pm
package DBIx::Class::Storage::DBI::Replicated::Balancer::Random;
use Moose;
with 'DBIx::Class::Storage::DBI::Replicated::Balancer';
use DBIx::Class::Storage::DBI::Replicated::Types 'Weight';
use namespace::clean -except => 'meta';
=head1 NAME
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 => Weight, default => sub { 0 });
=head1 METHODS
This class defines the following methods.
=head2 next_storage
Returns an active replicant at random. Please note that due to the nature of
the word 'random' this means it's possible for a particular active replicant to
be requested several times in a row.
=cut
sub next_storage {
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 FURTHER QUESTIONS?
Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
=head1 COPYRIGHT AND LICENSE
This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
redistribute it and/or modify it under the same terms as the
L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.
=cut
__PACKAGE__->meta->make_immutable;
1;
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