X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FReplicated%2FBalancer.pm;h=279ad51a6c556309edd26f8b9307c629cc4f63b5;hb=8592e2d12adc3061b28c17766b47bf802cba58cd;hp=3e4755d53b6dad94b25d61f6c669ff536beb1659;hpb=0c90fabe2d883d5a51ee47491b6c9af2c5f53e60;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Storage/DBI/Replicated/Balancer.pm b/lib/DBIx/Class/Storage/DBI/Replicated/Balancer.pm index 3e4755d..279ad51 100644 --- a/lib/DBIx/Class/Storage/DBI/Replicated/Balancer.pm +++ b/lib/DBIx/Class/Storage/DBI/Replicated/Balancer.pm @@ -2,15 +2,19 @@ package DBIx::Class::Storage::DBI::Replicated::Balancer; use Moose::Role; requires 'next_storage'; +use MooseX::Types::Moose qw/Int/; +use DBIx::Class::Storage::DBI::Replicated::Pool; +use DBIx::Class::Storage::DBI::Replicated::Types qw/DBICStorageDBI/; +use namespace::clean -except => 'meta'; =head1 NAME -DBIx::Class::Storage::DBI::Replicated::Balancer; A Software Load Balancer +DBIx::Class::Storage::DBI::Replicated::Balancer - A Software Load Balancer =head1 SYNOPSIS This role is used internally by L. - + =head1 DESCRIPTION Given a pool (L) of replicated @@ -30,9 +34,9 @@ validating every query. =cut has 'auto_validate_every' => ( - is=>'rw', - isa=>'Int', - predicate=>'has_auto_validate_every', + is=>'rw', + isa=>Int, + predicate=>'has_auto_validate_every', ); =head2 master @@ -44,9 +48,9 @@ ultimate fallback. =cut has 'master' => ( - is=>'ro', - isa=>'DBIx::Class::Storage::DBI', - required=>1, + is=>'ro', + isa=>DBICStorageDBI, + required=>1, ); =head2 pool @@ -57,9 +61,9 @@ balance. =cut has 'pool' => ( - is=>'ro', - isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', - required=>1, + is=>'ro', + isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', + required=>1, ); =head2 current_replicant @@ -71,19 +75,19 @@ databases is going to help you to scale traffic. This attribute returns the next slave to handle a read request. Your L attribute has methods to help you shuffle through all the available replicants -via it's balancer object. +via its balancer object. =cut has 'current_replicant' => ( - is=> 'rw', - isa=>'DBIx::Class::Storage::DBI', - lazy_build=>1, - handles=>[qw/ - select - select_single - columns_info_for - /], + is=> 'rw', + isa=>DBICStorageDBI, + lazy_build=>1, + handles=>[qw/ + select + select_single + columns_info_for + /], ); =head1 METHODS @@ -97,8 +101,8 @@ Lazy builder for the L attribute. =cut sub _build_current_replicant { - my $self = shift @_; - $self->next_storage; + my $self = shift @_; + $self->next_storage; } =head2 next_storage @@ -106,7 +110,7 @@ sub _build_current_replicant { This method should be defined in the class which consumes this role. Given a pool object, return the next replicant that will serve queries. The -default behavior is to grap the first replicant it finds but you can write +default behavior is to grab the first replicant it finds but you can write your own subclasses of L to support other balance systems. @@ -123,24 +127,46 @@ or just just forgot to create them :) =cut +my $on_master; + around 'next_storage' => sub { - my ($next_storage, $self, @args) = @_; - my $now = time; - - ## Do we need to validate the replicants? - if( - $self->has_auto_validate_every && - ($self->auto_validate_every + $self->pool->last_validated) <= $now - ) { - $self->pool->validate_replicants; - } - - ## Get a replicant, or the master if none - my $next = $self->$next_storage(@args); - return $next ? $next:$self->master; + my ($next_storage, $self, @args) = @_; + my $now = time; + + ## Do we need to validate the replicants? + if( + $self->has_auto_validate_every && + ($self->auto_validate_every + $self->pool->last_validated) <= $now + ) { + $self->pool->validate_replicants; + } + + ## Get a replicant, or the master if none + if(my $next = $self->$next_storage(@args)) { + $self->master->debugobj->print("Moved back to slave\n") if $on_master; + $on_master = 0; + return $next; + } else { + $self->master->debugobj->print("No Replicants validate, falling back to master reads.\n") + unless $on_master++; + + return $self->master; + } }; -=head2 before: select +=head2 increment_storage + +Rolls the Storage to whatever is next in the queue, as defined by the Balancer. + +=cut + +sub increment_storage { + my $self = shift @_; + my $next_replicant = $self->next_storage; + $self->current_replicant($next_replicant); +} + +=head2 around: select Advice on the select attribute. Each time we use a replicant we need to change it via the storage pool algorithm. That way we are spreading @@ -148,13 +174,21 @@ the load evenly (hopefully) across existing capacity. =cut -before 'select' => sub { - my $self = shift @_; - my $next_replicant = $self->next_storage; - $self->current_replicant($next_replicant); +around 'select' => sub { + my ($select, $self, @args) = @_; + + if (my $forced_pool = $args[-1]->{force_pool}) { + delete $args[-1]->{force_pool}; + return $self->_get_forced_pool($forced_pool)->select(@args); + } elsif($self->master->{transaction_depth}) { + return $self->master->select(@args); + } else { + $self->increment_storage; + return $self->$select(@args); + } }; -=head2 before: select_single +=head2 around: select_single Advice on the select_single attribute. Each time we use a replicant we need to change it via the storage pool algorithm. That way we are spreading @@ -162,10 +196,18 @@ the load evenly (hopefully) across existing capacity. =cut -before 'select_single' => sub { - my $self = shift @_; - my $next_replicant = $self->next_storage; - $self->current_replicant($next_replicant); +around 'select_single' => sub { + my ($select_single, $self, @args) = @_; + + if (my $forced_pool = $args[-1]->{force_pool}) { + delete $args[-1]->{force_pool}; + return $self->_get_forced_pool($forced_pool)->select_single(@args); + } elsif($self->master->{transaction_depth}) { + return $self->master->select_single(@args); + } else { + $self->increment_storage; + return $self->$select_single(@args); + } }; =head2 before: columns_info_for @@ -177,14 +219,32 @@ the load evenly (hopefully) across existing capacity. =cut before 'columns_info_for' => sub { - my $self = shift @_; - my $next_replicant = $self->next_storage; - $self->current_replicant($next_replicant); + my $self = shift @_; + $self->increment_storage; }; +=head2 _get_forced_pool ($name) + +Given an identifier, find the most correct storage object to handle the query. + +=cut + +sub _get_forced_pool { + my ($self, $forced_pool) = @_; + if(blessed $forced_pool) { + return $forced_pool; + } elsif($forced_pool eq 'master') { + return $self->master; + } elsif(my $replicant = $self->pool->replicants->{$forced_pool}) { + return $replicant; + } else { + $self->master->throw_exception("$forced_pool is not a named replicant."); + } +} + =head1 AUTHOR -John Napiorkowski +John Napiorkowski =head1 LICENSE