Commit | Line | Data |
cb6ec758 |
1 | package DBIx::Class::Storage::DBI::Replicated::Balancer::Random; |
2 | |
80666849 |
3 | use Moo; |
17b05c13 |
4 | with 'DBIx::Class::Storage::DBI::Replicated::Balancer'; |
80666849 |
5 | use DBIx::Class::_Types qw(PositiveNumber); |
6 | |
7 | use namespace::clean; |
cb6ec758 |
8 | |
9 | =head1 NAME |
10 | |
f09cd1d4 |
11 | DBIx::Class::Storage::DBI::Replicated::Balancer::Random - A 'random' Balancer |
cb6ec758 |
12 | |
13 | =head1 SYNOPSIS |
14 | |
15 | This class is used internally by L<DBIx::Class::Storage::DBI::Replicated>. You |
16 | shouldn't need to create instances of this class. |
d4daee7b |
17 | |
cb6ec758 |
18 | =head1 DESCRIPTION |
19 | |
20 | Given a pool (L<DBIx::Class::Storage::DBI::Replicated::Pool>) of replicated |
21 | database's (L<DBIx::Class::Storage::DBI::Replicated::Replicant>), defines a |
22 | method by which query load can be spread out across each replicant in the pool. |
23 | |
24 | This Balancer uses L<List::Util> keyword 'shuffle' to randomly pick an active |
25 | replicant from the associated pool. This may or may not be random enough for |
26 | you, patches welcome. |
27 | |
28 | =head1 ATTRIBUTES |
29 | |
30 | This class defines the following attributes. |
31 | |
ee356d00 |
32 | =head2 master_read_weight |
33 | |
b88b85e7 |
34 | A number greater than 0 that specifies what weight to give the master when |
35 | choosing which backend to execute a read query on. A value of 0, which is the |
36 | default, does no reads from master, while a value of 1 gives it the same |
37 | priority as any single replicant. |
38 | |
39 | For example: if you have 2 replicants, and a L</master_read_weight> of C<0.5>, |
40 | the chance of reading from master will be C<20%>. |
41 | |
42 | You can set it to a value higher than 1, making master have higher weight than |
43 | any single replicant, if for example you have a very powerful master. |
ee356d00 |
44 | |
45 | =cut |
46 | |
80666849 |
47 | has master_read_weight => (is => 'rw', isa => PositiveNumber, default => sub { 0 }); |
ee356d00 |
48 | |
cb6ec758 |
49 | =head1 METHODS |
50 | |
51 | This class defines the following methods. |
52 | |
53 | =head2 next_storage |
54 | |
55 | Returns an active replicant at random. Please note that due to the nature of |
56 | the word 'random' this means it's possible for a particular active replicant to |
57 | be requested several times in a row. |
58 | |
59 | =cut |
60 | |
61 | sub next_storage { |
c354902c |
62 | my $self = shift @_; |
ee356d00 |
63 | |
64 | my @replicants = $self->pool->active_replicants; |
f404f53c |
65 | |
66 | if (not @replicants) { |
67 | # will fall back to master anyway |
68 | return; |
69 | } |
70 | |
ee356d00 |
71 | my $master = $self->master; |
72 | |
f404f53c |
73 | my $rnd = $self->_random_number(@replicants + $self->master_read_weight); |
ee356d00 |
74 | |
75 | return $rnd >= @replicants ? $master : $replicants[int $rnd]; |
76 | } |
77 | |
f404f53c |
78 | sub _random_number { |
ee356d00 |
79 | rand($_[1]) |
cb6ec758 |
80 | } |
81 | |
a2bd3796 |
82 | =head1 FURTHER QUESTIONS? |
cb6ec758 |
83 | |
a2bd3796 |
84 | Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>. |
cb6ec758 |
85 | |
a2bd3796 |
86 | =head1 COPYRIGHT AND LICENSE |
cb6ec758 |
87 | |
a2bd3796 |
88 | This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE> |
89 | by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can |
90 | redistribute it and/or modify it under the same terms as the |
91 | L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>. |
cb6ec758 |
92 | |
93 | =cut |
94 | |
41916570 |
95 | 1; |