storage type, add some replicated (readonly) databases, and perform reporting
tasks.
- ## Change storage_type in your schema class
- $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
-
- ## Add some slaves. Basically this is an array of arrayrefs, where each
- ## arrayref is database connect information
-
- $schema->storage->connect_replicants(
- [$dsn1, $user, $pass, \%opts],
- [$dsn1, $user, $pass, \%opts],
- [$dsn1, $user, $pass, \%opts],
- );
-
+ ## Change storage_type in your schema class
+ $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
+
+ ## Add some slaves. Basically this is an array of arrayrefs, where each
+ ## arrayref is database connect information
+
+ $schema->storage->connect_replicants(
+ [$dsn1, $user, $pass, \%opts],
+ [$dsn2, $user, $pass, \%opts],
+ [$dsn3, $user, $pass, \%opts],
+ );
+
=head1 DESCRIPTION
Warning: This class is marked ALPHA. We are using this in development and have
database, all read-type queries (SELECTs) go to the slave database.
Basically, any method request that L<DBIx::Class::Storage::DBI> would normally
-handle gets delegated to one of the two attributes: L</master_storage> or to
-L</current_replicant_storage>. Additionally, some methods need to be distributed
+handle gets delegated to one of the two attributes: L</read_handler> or to
+L</write_handler>. Additionally, some methods need to be distributed
to all existing storages. This way our storage class is a drop in replacement
for L<DBIx::Class::Storage::DBI>.
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
=cut
has 'pool_type' => (
- is=>'ro',
- isa=>'ClassName',
- lazy_build=>1,
- handles=>{
- 'create_pool' => 'new',
- },
+ is=>'ro',
+ isa=>'ClassName',
+ lazy_build=>1,
+ handles=>{
+ 'create_pool' => 'new',
+ },
);
=head2 pool_args
-Contains a hashref of initialized information to pass to the Pool object. See
-L<DBIx::Class::Storage::Replicated::Pool> for available arguments.
+Contains a hashref of initialized information to pass to the Balancer object.
+See L<DBIx::Class::Storage::Replicated::Pool> for available arguments.
=cut
has 'pool_args' => (
- is=>'ro',
- isa=>'HashRef',
+ 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
=cut
has 'balancer_type' => (
- is=>'ro',
- isa=>'ClassName',
- lazy_build=>1,
- handles=>{
- 'create_balancer' => 'new',
- },
+ is=>'ro',
+ isa=>'ClassName',
+ lazy_build=>1,
+ handles=>{
+ 'create_balancer' => 'new',
+ },
+);
+
+=head2 balancer_args
+
+Contains a hashref of initialized information to pass to the Balancer object.
+See L<DBIx::Class::Storage::Replicated::Balancer> for available arguments.
+
+=cut
+
+has 'balancer_args' => (
+ is=>'ro',
+ isa=>'HashRef',
+ lazy=>1,
+ required=>1,
+ default=>sub { {} },
);
=head2 pool
=cut
has 'pool' => (
- is=>'ro',
- isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
- lazy_build=>1,
- handles=>[qw/
- connect_replicants
- replicants
- has_replicants
- num_replicants
- delete_replicant
- validate_replicants
- /],
+ is=>'ro',
+ isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
+ lazy_build=>1,
+ handles=>[qw/
+ connect_replicants
+ replicants
+ has_replicants
+ /],
);
=head2 balancer
=cut
has 'balancer' => (
- is=>'ro',
- isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
- lazy_build=>1,
+ is=>'ro',
+ isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
+ lazy_build=>1,
+ handles=>[qw/auto_validate_every/],
);
=head2 master
=cut
has 'master' => (
- is=> 'ro',
- isa=>'DBIx::Class::Storage::DBI',
- lazy_build=>1,
+ is=> 'ro',
+ isa=>'DBIx::Class::Storage::DBI',
+ lazy_build=>1,
);
=head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE
=cut
has 'read_handler' => (
- is=>'rw',
- isa=>'Object',
- lazy_build=>1,
- handles=>[qw/
- select
- select_single
- columns_info_for
- /],
+ is=>'rw',
+ isa=>'Object',
+ lazy_build=>1,
+ handles=>[qw/
+ select
+ select_single
+ columns_info_for
+ /],
);
=head2 write_handler
=cut
has 'write_handler' => (
- is=>'ro',
- isa=>'Object',
- lazy_build=>1,
- lazy_build=>1,
- handles=>[qw/
- on_connect_do
- on_disconnect_do
- connect_info
- throw_exception
- sql_maker
- sqlt_type
- create_ddl_dir
- deployment_statements
- datetime_parser
- datetime_parser_type
- last_insert_id
- insert
- insert_bulk
- update
- delete
- dbh
- txn_do
- txn_commit
- txn_rollback
- sth
- deploy
- schema
- /],
+ is=>'ro',
+ isa=>'Object',
+ lazy_build=>1,
+ lazy_build=>1,
+ handles=>[qw/
+ on_connect_do
+ on_disconnect_do
+ connect_info
+ throw_exception
+ sql_maker
+ sqlt_type
+ create_ddl_dir
+ deployment_statements
+ datetime_parser
+ datetime_parser_type
+ last_insert_id
+ insert
+ insert_bulk
+ update
+ delete
+ dbh
+ txn_do
+ txn_commit
+ txn_rollback
+ sth
+ deploy
+ schema
+ reload_row
+ /],
);
=head1 METHODS
=cut
sub new {
- my $class = shift @_;
- my $schema = shift @_;
- my $storage_type_args = shift @_;
- my $obj = $class->SUPER::new($schema, $storage_type_args, @_);
-
- ## 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}";
- }
-
- return $class->meta->new_object(
- __INSTANCE__ => $obj,
- %$storage_type_args,
- @_,
- );
+ my $class = shift @_;
+ my $schema = shift @_;
+ my $storage_type_args = shift @_;
+ my $obj = $class->SUPER::new($schema, $storage_type_args, @_);
+
+ ## 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}";
+ }
+
+ return $class->meta->new_object(
+ __INSTANCE__ => $obj,
+ %$storage_type_args,
+ @_,
+ );
}
=head2 _build_master
=cut
sub _build_master {
- DBIx::Class::Storage::DBI->new;
+ DBIx::Class::Storage::DBI->new;
}
=head2 _build_pool_type
=cut
sub _build_pool_type {
- return 'DBIx::Class::Storage::DBI::Replicated::Pool';
+ return 'DBIx::Class::Storage::DBI::Replicated::Pool';
}
=head2 _build_pool
=cut
sub _build_pool {
- my $self = shift @_;
- $self->create_pool($self->pool_args);
+ my $self = shift @_;
+ $self->create_pool(%{$self->pool_args});
}
=head2 _build_balancer_type
=cut
sub _build_balancer_type {
- return 'DBIx::Class::Storage::DBI::Replicated::Balancer';
+ return 'DBIx::Class::Storage::DBI::Replicated::Balancer::First';
}
=head2 _build_balancer
=cut
sub _build_balancer {
- my $self = shift @_;
- $self->create_balancer(
- pool=>$self->pool,
- master=>$self->master);
+ my $self = shift @_;
+ $self->create_balancer(
+ pool=>$self->pool,
+ master=>$self->master,
+ %{$self->balancer_args},
+ );
}
=head2 _build_write_handler
=cut
sub _build_write_handler {
- return shift->master;
+ return shift->master;
}
=head2 _build_read_handler
=cut
sub _build_read_handler {
- return shift->balancer;
+ return shift->balancer;
}
=head2 around: connect_replicants
=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
=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</read_handler>, 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
Sets the current $schema to be 'reliable', that is all queries, both read and
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
Sets the current $schema to be use the </balancer> for all reads, while all
writea are sent to the master only
-
+
=cut
sub set_balanced_storage {
- my $self = shift @_;
- my $schema = $self->schema;
- my $write_handler = $self->schema->storage->balancer;
-
- $schema->storage->read_handler($write_handler);
+ my $self = shift @_;
+ my $schema = $self->schema;
+ my $write_handler = $self->schema->storage->balancer;
+
+ $schema->storage->read_handler($write_handler);
}
+=head2 around: txn_do ($coderef)
+
+Overload to the txn_do method, which is delegated to whatever the
+L<write_handler> is set to. We overload this in order to wrap in inside a
+L</execute_reliably> method.
+
+=cut
+
+around 'txn_do' => sub {
+ my($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.
=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
=cut
sub ensure_connected {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->ensure_connected(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->ensure_connected(@_);
+ }
}
=head2 limit_dialect
=cut
sub limit_dialect {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->limit_dialect(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->limit_dialect(@_);
+ }
}
=head2 quote_char
=cut
sub quote_char {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->quote_char(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->quote_char(@_);
+ }
}
=head2 name_sep
=cut
sub name_sep {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->name_sep(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->name_sep(@_);
+ }
}
=head2 set_schema
=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
=cut
sub debug {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debug(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->debug(@_);
+ }
}
=head2 debugobj
=cut
sub debugobj {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugobj(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->debugobj(@_);
+ }
}
=head2 debugfh
=cut
sub debugfh {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugfh(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->debugfh(@_);
+ }
}
=head2 debugcb
=cut
sub debugcb {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugcb(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->debugcb(@_);
+ }
}
=head2 disconnect
=cut
sub disconnect {
- my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->disconnect(@_);
- }
+ my $self = shift @_;
+ foreach my $source ($self->all_storages) {
+ $source->disconnect(@_);
+ }
}
=head1 AUTHOR
-Norbert Csongrádi <bert@cpan.org>
+ John Napiorkowski <john.napiorkowski@takkle.com>
-Peter Siklósi <einon@einon.hu>
+Based on code originated by:
-John Napiorkowski <john.napiorkowski@takkle.com>
+ Norbert Csongrádi <bert@cpan.org>
+ Peter Siklósi <einon@einon.hu>
=head1 LICENSE