1 package DBIx::Class::Storage::DBI::Replicated;
4 use DBIx::Class::Storage::DBI;
5 use DBIx::Class::Storage::DBI::Replicated::Pool;
6 use DBIx::Class::Storage::DBI::Replicated::Balancer;
7 use Scalar::Util qw(blessed);
9 extends 'DBIx::Class::Storage::DBI', 'Moose::Object';
13 DBIx::Class::Storage::DBI::Replicated - ALPHA Replicated database support
17 The Following example shows how to change an existing $schema to a replicated
18 storage type, add some replicated (readonly) databases, and perform reporting
21 ## Change storage_type in your schema class
22 $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
24 ## Add some slaves. Basically this is an array of arrayrefs, where each
25 ## arrayref is database connect information
27 $schema->storage->connect_replicants(
28 [$dsn1, $user, $pass, \%opts],
29 [$dsn1, $user, $pass, \%opts],
30 [$dsn1, $user, $pass, \%opts],
35 Warning: This class is marked ALPHA. We are using this in development and have
36 some basic test coverage but the code hasn't yet been stressed by a variety
37 of databases. Individual DB's may have quirks we are not aware of. Please
38 use this in development and pass along your experiences/bug fixes.
40 This class implements replicated data store for DBI. Currently you can define
41 one master and numerous slave database connections. All write-type queries
42 (INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master
43 database, all read-type queries (SELECTs) go to the slave database.
45 Basically, any method request that L<DBIx::Class::Storage::DBI> would normally
46 handle gets delegated to one of the two attributes: L</master_storage> or to
47 L</current_replicant_storage>. Additionally, some methods need to be distributed
48 to all existing storages. This way our storage class is a drop in replacement
49 for L<DBIx::Class::Storage::DBI>.
51 Read traffic is spread across the replicants (slaves) occuring to a user
52 selected algorithm. The default algorithm is random weighted.
54 TODO more details about the algorithm.
58 This class defines the following attributes.
62 Contains the classname which will instantiate the L</pool> object. Defaults
63 to: L<DBIx::Class::Storage::DBI::Replicated::Pool>.
72 'create_pool' => 'new',
78 Contains a hashref of initialized information to pass to the Pool object. See
79 L<DBIx::Class::Storage::Replicated::Pool> for available arguments.
90 The replication pool requires a balance class to provider the methods for
91 choose how to spread the query load across each replicant in the pool.
95 has 'balancer_type' => (
100 'create_balancer' => 'new',
106 Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a
107 container class for one or more replicated databases.
113 isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
127 Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This
128 is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>)
134 isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
140 The master defines the canonical state for a pool of connected databases. All
141 the replicants are expected to match this databases state. Thus, in a classic
142 Master / Slaves distributed system, all the slaves are expected to replicate
143 the Master's state as quick as possible. This is the only database in the
144 pool of databases that is allowed to handle write traffic.
150 isa=>'DBIx::Class::Storage::DBI',
154 =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE
156 The following methods are delegated all the methods required for the
157 L<DBIx::Class::Storage::DBI> interface.
161 Defines an object that implements the read side of L<BIx::Class::Storage::DBI>.
165 has 'read_handler' => (
178 Defines an object that implements the write side of L<BIx::Class::Storage::DBI>.
182 has 'write_handler' => (
195 deployment_statements
215 This class defines the following methods.
219 L<DBIx::Class::Schema> when instantiating it's storage passed itself as the
220 first argument. We need to invoke L</new> on the underlying parent class, make
221 sure we properly give it a L<Moose> meta class, and then correctly instantiate
222 our attributes. Basically we pass on whatever the schema has in it's class
223 data for 'storage_type_args' to our replicated storage type.
228 my $class = shift @_;
229 my $schema = shift @_;
230 my $storage_type_args = shift @_;
231 my $obj = $class->SUPER::new($schema, $storage_type_args, @_);
233 ## Hate to do it this way, but can't seem to get advice on the attribute working right
234 ## maybe we can do a type and coercion for it.
235 if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) {
236 $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type};
237 eval "require $storage_type_args->{balancer_type}";
240 return $class->meta->new_object(
241 __INSTANCE__ => $obj,
249 Lazy builder for the L</master> attribute.
254 DBIx::Class::Storage::DBI->new;
257 =head2 _build_pool_type
259 Lazy builder for the L</pool_type> attribute.
263 sub _build_pool_type {
264 return 'DBIx::Class::Storage::DBI::Replicated::Pool';
269 Lazy builder for the L</pool> attribute.
275 $self->create_pool($self->pool_args);
278 =head2 _build_balancer_type
280 Lazy builder for the L</balancer_type> attribute.
284 sub _build_balancer_type {
285 return 'DBIx::Class::Storage::DBI::Replicated::Balancer';
288 =head2 _build_balancer
290 Lazy builder for the L</balancer> attribute. This takes a Pool object so that
291 the balancer knows which pool it's balancing.
295 sub _build_balancer {
297 $self->create_balancer(
299 master=>$self->master);
302 =head2 _build_write_handler
304 Lazy builder for the L</write_handler> attribute. The default is to set this to
309 sub _build_write_handler {
310 return shift->master;
313 =head2 _build_read_handler
315 Lazy builder for the L</read_handler> attribute. The default is to set this to
320 sub _build_read_handler {
321 return shift->balancer;
324 =head2 around: connect_replicants
326 All calls to connect_replicants needs to have an existing $schema tacked onto
327 top of the args, since L<DBIx::Storage::DBI> needs it.
331 around 'connect_replicants' => sub {
332 my ($method, $self, @args) = @_;
333 $self->$method($self->schema, @args);
338 Returns an array of of all the connected storage backends. The first element
339 in the returned array is the master, and the remainings are each of the
347 return grep {defined $_ && blessed $_} (
353 =head2 set_reliable_storage
355 Sets the current $schema to be 'reliable', that is all queries, both read and
356 write are sent to the master
360 sub set_reliable_storage {
362 my $schema = $self->schema;
363 my $write_handler = $self->schema->storage->write_handler;
365 $schema->storage->read_handler($write_handler);
368 =head2 set_balanced_storage
370 Sets the current $schema to be use the </balancer> for all reads, while all
371 writea are sent to the master only
375 sub set_balanced_storage {
377 my $schema = $self->schema;
378 my $write_handler = $self->schema->storage->balancer;
380 $schema->storage->read_handler($write_handler);
385 Check that the master and at least one of the replicants is connected.
393 $self->master->connected &&
394 $self->pool->connected_replicants;
397 =head2 ensure_connected
399 Make sure all the storages are connected.
403 sub ensure_connected {
405 foreach my $source ($self->all_storages) {
406 $source->ensure_connected(@_);
412 Set the limit_dialect for all existing storages
418 foreach my $source ($self->all_storages) {
419 $source->limit_dialect(@_);
425 Set the quote_char for all existing storages
431 foreach my $source ($self->all_storages) {
432 $source->quote_char(@_);
438 Set the name_sep for all existing storages
444 foreach my $source ($self->all_storages) {
445 $source->name_sep(@_);
451 Set the schema object for all existing storages
457 foreach my $source ($self->all_storages) {
458 $source->set_schema(@_);
464 set a debug flag across all storages
470 foreach my $source ($self->all_storages) {
477 set a debug object across all storages
483 foreach my $source ($self->all_storages) {
484 $source->debugobj(@_);
490 set a debugfh object across all storages
496 foreach my $source ($self->all_storages) {
497 $source->debugfh(@_);
503 set a debug callback across all storages
509 foreach my $source ($self->all_storages) {
510 $source->debugcb(@_);
516 disconnect everything
522 foreach my $source ($self->all_storages) {
523 $source->disconnect(@_);
529 Norbert Csongrádi <bert@cpan.org>
531 Peter Siklósi <einon@einon.hu>
533 John Napiorkowski <john.napiorkowski@takkle.com>
537 You may distribute this code under the same terms as Perl itself.