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
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<DBIx::Class::Storage::Replicated::Pool> 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
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<DBIx::Class::Storage::Replicated::Balancer> for available arguments.
+
+=cut
+
+has 'balancer_args' => (
+ is=>'ro',
+ isa=>'HashRef',
+ lazy=>1,
+ required=>1,
+ default=>sub { {} },
+);
+
=head2 pool
Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a
connect_replicants
replicants
has_replicants
- num_replicants
- delete_replicant
/],
);
is=>'ro',
isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
lazy_build=>1,
+ handles=>[qw/auto_validate_every/],
);
=head2 master
sth
deploy
schema
+ reload_row
/],
);
## 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(
=cut
sub _build_master {
- DBIx::Class::Storage::DBI->new;
+ DBIx::Class::Storage::DBI->new;
}
=head2 _build_pool_type
=cut
sub _build_pool {
- shift->create_pool;
+ 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
my $self = shift @_;
$self->create_balancer(
pool=>$self->pool,
- master=>$self->master);
+ master=>$self->master,
+ %{$self->balancer_args},
+ );
}
=head2 _build_write_handler
=cut
around 'connect_replicants' => sub {
- my ($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
=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
$schema->storage->read_handler($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 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
=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
projects / dbsrgits/DBIx-Class.git / blobdiff