X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FReplicated.pm;h=03a3fcdfe192e3bc3127c592faa0f6d9c65314ca;hb=0c90fabe2d883d5a51ee47491b6c9af2c5f53e60;hp=6408cb4fd2f3ad7b6be77da13941c8c69b428f91;hpb=106d5f3b7e03a68fb2e125772e3f06a34115f22d;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Storage/DBI/Replicated.pm b/lib/DBIx/Class/Storage/DBI/Replicated.pm index 6408cb4..03a3fcd 100644 --- a/lib/DBIx/Class/Storage/DBI/Replicated.pm +++ b/lib/DBIx/Class/Storage/DBI/Replicated.pm @@ -43,15 +43,21 @@ one master and numerous slave database connections. All write-type queries database, all read-type queries (SELECTs) go to the slave database. Basically, any method request that L would normally -handle gets delegated to one of the two attributes: L or to -L. Additionally, some methods need to be distributed +handle gets delegated to one of the two attributes: L or to +L. Additionally, some methods need to be distributed to all existing storages. This way our storage class is a drop in replacement for L. Read traffic is spread across the replicants (slaves) occuring to a user selected algorithm. The default algorithm is random weighted. -TODO more details about the algorithm. +=head1 NOTES + +The consistancy betweeen master and replicants is database specific. The Pool +gives you a method to validate it's replicants, removing and replacing them +when they fail/pass predefined criteria. It is recommened that your application +define two schemas, one using the replicated storage and another that just +connects to the master. =head1 ATTRIBUTES @@ -69,10 +75,26 @@ has 'pool_type' => ( isa=>'ClassName', lazy_build=>1, handles=>{ - 'create_pool' => 'new', + 'create_pool' => 'new', }, ); +=head2 pool_args + +Contains a hashref of initialized information to pass to the Balancer object. +See L for available arguments. + +=cut + +has 'pool_args' => ( + is=>'ro', + isa=>'HashRef', + lazy=>1, + required=>1, + default=>sub { {} }, +); + + =head2 balancer_type The replication pool requires a balance class to provider the methods for @@ -85,10 +107,25 @@ has 'balancer_type' => ( isa=>'ClassName', lazy_build=>1, handles=>{ - 'create_balancer' => 'new', + 'create_balancer' => 'new', }, ); +=head2 balancer_args + +Contains a hashref of initialized information to pass to the Balancer object. +See L for available arguments. + +=cut + +has 'balancer_args' => ( + is=>'ro', + isa=>'HashRef', + lazy=>1, + required=>1, + default=>sub { {} }, +); + =head2 pool Is a or derived class. This is a @@ -104,8 +141,6 @@ has 'pool' => ( connect_replicants replicants has_replicants - num_replicants - delete_replicant /], ); @@ -120,6 +155,7 @@ has 'balancer' => ( is=>'ro', isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', lazy_build=>1, + handles=>[qw/auto_validate_every/], ); =head2 master @@ -194,6 +230,7 @@ has 'write_handler' => ( sth deploy schema + reload_row /], ); @@ -220,8 +257,8 @@ sub new { ## Hate to do it this way, but can't seem to get advice on the attribute working right ## maybe we can do a type and coercion for it. if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) { - $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; - eval "require $storage_type_args->{balancer_type}"; + $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; + eval "require $storage_type_args->{balancer_type}"; } return $class->meta->new_object( @@ -238,7 +275,7 @@ Lazy builder for the L attribute. =cut sub _build_master { - DBIx::Class::Storage::DBI->new; + DBIx::Class::Storage::DBI->new; } =head2 _build_pool_type @@ -258,7 +295,8 @@ Lazy builder for the L attribute. =cut sub _build_pool { - shift->create_pool; + my $self = shift @_; + $self->create_pool(%{$self->pool_args}); } =head2 _build_balancer_type @@ -268,7 +306,7 @@ Lazy builder for the L attribute. =cut sub _build_balancer_type { - return 'DBIx::Class::Storage::DBI::Replicated::Balancer'; + return 'DBIx::Class::Storage::DBI::Replicated::Balancer::First'; } =head2 _build_balancer @@ -282,7 +320,9 @@ sub _build_balancer { my $self = shift @_; $self->create_balancer( pool=>$self->pool, - master=>$self->master); + master=>$self->master, + %{$self->balancer_args}, + ); } =head2 _build_write_handler @@ -315,8 +355,8 @@ top of the args, since L needs it. =cut around 'connect_replicants' => sub { - my ($method, $self, @args) = @_; - $self->$method($self->schema, @args); + my ($method, $self, @args) = @_; + $self->$method($self->schema, @args); }; =head2 all_storages @@ -328,12 +368,78 @@ replicants. =cut sub all_storages { - my $self = shift @_; - - return grep {defined $_ && blessed $_} ( - $self->master, - $self->replicants, - ); + my $self = shift @_; + + return grep {defined $_ && blessed $_} ( + $self->master, + $self->replicants, + ); +} + +=head2 execute_reliably ($coderef, ?@args) + +Given a coderef, saves the current state of the L, forces it to +use reliable storage (ie sets it to the master), executes a coderef and then +restores the original state. + +Example: + + my $reliably = sub { + my $name = shift @_; + $schema->resultset('User')->create({name=>$name}); + my $user_rs = $schema->resultset('User')->find({name=>$name}); + return $user_rs; + }; + + my $user_rs = $schema->storage->execute_reliably($reliably, 'John'); + +Use this when you must be certain of your database state, such as when you just +inserted something and need to get a resultset including it, etc. + +=cut + +sub execute_reliably { + my ($self, $coderef, @args) = @_; + + unless( ref $coderef eq 'CODE') { + $self->throw_exception('Second argument must be a coderef'); + } + + ##Get copy of master storage + my $master = $self->master; + + ##Get whatever the current read hander is + my $current = $self->read_handler; + + ##Set the read handler to master + $self->read_handler($master); + + ## do whatever the caller needs + my @result; + my $want_array = wantarray; + + eval { + if($want_array) { + @result = $coderef->(@args); + } + elsif(defined $want_array) { + ($result[0]) = ($coderef->(@args)); + } else { + $coderef->(@args); + } + }; + + ##Reset to the original state + $self->read_handler($current); + + ##Exception testing has to come last, otherwise you might leave the + ##read_handler set to master. + + if($@) { + $self->throw_exception("coderef returned an error: $@"); + } else { + return $want_array ? @result : $result[0]; + } } =head2 set_reliable_storage @@ -344,11 +450,11 @@ write are sent to the master =cut sub set_reliable_storage { - my $self = shift @_; - my $schema = $self->schema; - my $write_handler = $self->schema->storage->write_handler; - - $schema->storage->read_handler($write_handler); + my $self = shift @_; + my $schema = $self->schema; + my $write_handler = $self->schema->storage->write_handler; + + $schema->storage->read_handler($write_handler); } =head2 set_balanced_storage @@ -366,6 +472,33 @@ sub set_balanced_storage { $schema->storage->read_handler($write_handler); } +=head2 around: txn_do ($coderef) + +Overload to the txn_do method, which is delegated to whatever the +L is set to. We overload this in order to wrap in inside a +L method. + +=cut + +around 'txn_do' => sub { + my($txn_do, $self, $coderef, @args) = @_; + $self->execute_reliably(sub {$self->$txn_do($coderef, @args)}); +}; + +=head2 reload_row ($row) + +Overload to the reload_row method so that the reloading is always directed to +the master storage. + +=cut + +around 'reload_row' => sub { + my ($reload_row, $self, $row) = @_; + return $self->execute_reliably(sub { + return $self->$reload_row(shift); + }, $row); +}; + =head2 connected Check that the master and at least one of the replicants is connected. @@ -373,11 +506,11 @@ Check that the master and at least one of the replicants is connected. =cut sub connected { - my $self = shift @_; - - return - $self->master->connected && - $self->pool->connected_replicants; + my $self = shift @_; + + return + $self->master->connected && + $self->pool->connected_replicants; } =head2 ensure_connected @@ -439,10 +572,10 @@ Set the schema object for all existing storages =cut sub set_schema { - my $self = shift @_; - foreach my $source ($self->all_storages) { - $source->set_schema(@_); - } + my $self = shift @_; + foreach my $source ($self->all_storages) { + $source->set_schema(@_); + } } =head2 debug @@ -512,11 +645,12 @@ sub disconnect { =head1 AUTHOR -Norbert Csongrádi + John Napiorkowski -Peter Siklósi +Based on code originated by: -John Napiorkowski + Norbert Csongrádi + Peter Siklósi =head1 LICENSE