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 The replication pool requires a balance class to provider the methods for
79 choose how to spread the query load across each replicant in the pool.
83 has 'balancer_type' => (
88 'create_balancer' => 'new',
94 Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a
95 container class for one or more replicated databases.
101 isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
114 Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This
115 is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>)
121 isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
127 The master defines the canonical state for a pool of connected databases. All
128 the replicants are expected to match this databases state. Thus, in a classic
129 Master / Slaves distributed system, all the slaves are expected to replicate
130 the Master's state as quick as possible. This is the only database in the
131 pool of databases that is allowed to handle write traffic.
137 isa=>'DBIx::Class::Storage::DBI',
141 =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE
143 The following methods are delegated all the methods required for the
144 L<DBIx::Class::Storage::DBI> interface.
148 Defines an object that implements the read side of L<BIx::Class::Storage::DBI>.
152 has 'read_handler' => (
165 Defines an object that implements the write side of L<BIx::Class::Storage::DBI>.
169 has 'write_handler' => (
182 deployment_statements
202 This class defines the following methods.
206 L<DBIx::Class::Schema> when instantiating it's storage passed itself as the
207 first argument. We need to invoke L</new> on the underlying parent class, make
208 sure we properly give it a L<Moose> meta class, and then correctly instantiate
209 our attributes. Basically we pass on whatever the schema has in it's class
210 data for 'storage_type_args' to our replicated storage type.
215 my $class = shift @_;
216 my $schema = shift @_;
217 my $storage_type_args = shift @_;
218 my $obj = $class->SUPER::new($schema, $storage_type_args, @_);
220 ## Hate to do it this way, but can't seem to get advice on the attribute working right
221 ## maybe we can do a type and coercion for it.
222 if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) {
223 $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type};
224 eval "require $storage_type_args->{balancer_type}";
227 return $class->meta->new_object(
228 __INSTANCE__ => $obj,
236 Lazy builder for the L</master> attribute.
241 DBIx::Class::Storage::DBI->new;
244 =head2 _build_pool_type
246 Lazy builder for the L</pool_type> attribute.
250 sub _build_pool_type {
251 return 'DBIx::Class::Storage::DBI::Replicated::Pool';
256 Lazy builder for the L</pool> attribute.
264 =head2 _build_balancer_type
266 Lazy builder for the L</balancer_type> attribute.
270 sub _build_balancer_type {
271 return 'DBIx::Class::Storage::DBI::Replicated::Balancer';
274 =head2 _build_balancer
276 Lazy builder for the L</balancer> attribute. This takes a Pool object so that
277 the balancer knows which pool it's balancing.
281 sub _build_balancer {
283 $self->create_balancer(
285 master=>$self->master);
288 =head2 _build_write_handler
290 Lazy builder for the L</write_handler> attribute. The default is to set this to
295 sub _build_write_handler {
296 return shift->master;
299 =head2 _build_read_handler
301 Lazy builder for the L</read_handler> attribute. The default is to set this to
306 sub _build_read_handler {
307 return shift->balancer;
310 =head2 around: connect_replicants
312 All calls to connect_replicants needs to have an existing $schema tacked onto
313 top of the args, since L<DBIx::Storage::DBI> needs it.
317 around 'connect_replicants' => sub {
318 my ($method, $self, @args) = @_;
319 $self->$method($self->schema, @args);
324 Returns an array of of all the connected storage backends. The first element
325 in the returned array is the master, and the remainings are each of the
333 return grep {defined $_ && blessed $_} (
339 =head2 set_reliable_storage
341 Sets the current $schema to be 'reliable', that is all queries, both read and
342 write are sent to the master
346 sub set_reliable_storage {
348 my $schema = $self->schema;
349 my $write_handler = $self->schema->storage->write_handler;
351 $schema->storage->read_handler($write_handler);
354 =head2 set_balanced_storage
356 Sets the current $schema to be use the </balancer> for all reads, while all
357 writea are sent to the master only
361 sub set_balanced_storage {
363 my $schema = $self->schema;
364 my $write_handler = $self->schema->storage->balancer;
366 $schema->storage->read_handler($write_handler);
371 Check that the master and at least one of the replicants is connected.
379 $self->master->connected &&
380 $self->pool->connected_replicants;
383 =head2 ensure_connected
385 Make sure all the storages are connected.
389 sub ensure_connected {
391 foreach my $source ($self->all_storages) {
392 $source->ensure_connected(@_);
398 Set the limit_dialect for all existing storages
404 foreach my $source ($self->all_storages) {
405 $source->limit_dialect(@_);
411 Set the quote_char for all existing storages
417 foreach my $source ($self->all_storages) {
418 $source->quote_char(@_);
424 Set the name_sep for all existing storages
430 foreach my $source ($self->all_storages) {
431 $source->name_sep(@_);
437 Set the schema object for all existing storages
443 foreach my $source ($self->all_storages) {
444 $source->set_schema(@_);
450 set a debug flag across all storages
456 foreach my $source ($self->all_storages) {
463 set a debug object across all storages
469 foreach my $source ($self->all_storages) {
470 $source->debugobj(@_);
476 set a debugfh object across all storages
482 foreach my $source ($self->all_storages) {
483 $source->debugfh(@_);
489 set a debug callback across all storages
495 foreach my $source ($self->all_storages) {
496 $source->debugcb(@_);
502 disconnect everything
508 foreach my $source ($self->all_storages) {
509 $source->disconnect(@_);
515 Norbert Csongrádi <bert@cpan.org>
517 Peter Siklósi <einon@einon.hu>
519 John Napiorkowski <john.napiorkowski@takkle.com>
523 You may distribute this code under the same terms as Perl itself.