X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FReplicated.pm;h=a21c413cf5547fbf4ab61c93c754bb2c9c940c5f;hb=6834cc1d0449dfc1f528a1b9ecaf4f1a98ae0794;hp=7323b42c9475c2d3dae9da894121028d11055125;hpb=7edf5f1cd3b097de79d262ed02d65128336f5893;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Storage/DBI/Replicated.pm b/lib/DBIx/Class/Storage/DBI/Replicated.pm index 7323b42..a21c413 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 @@ -75,16 +81,20 @@ has 'pool_type' => ( =head2 pool_args -Contains a hashref of initialized information to pass to the Pool object. See -L for available arguments. +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 @@ -101,6 +111,21 @@ has 'balancer_type' => ( }, ); +=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 @@ -116,9 +141,6 @@ has 'pool' => ( connect_replicants replicants has_replicants - num_replicants - delete_replicant - validate_replicants /], ); @@ -133,6 +155,7 @@ has 'balancer' => ( is=>'ro', isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', lazy_build=>1, + handles=>[qw/auto_validate_every/], ); =head2 master @@ -207,6 +230,7 @@ has 'write_handler' => ( sth deploy schema + reload_row /], ); @@ -272,7 +296,7 @@ Lazy builder for the L attribute. sub _build_pool { my $self = shift @_; - $self->create_pool($self->pool_args); + $self->create_pool(%{$self->pool_args}); } =head2 _build_balancer_type @@ -282,7 +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 @@ -296,7 +320,8 @@ sub _build_balancer { my $self = shift @_; $self->create_balancer( pool=>$self->pool, - master=>$self->master); + master=>$self->master, + %{$self->balancer_args},); } =head2 _build_write_handler @@ -350,6 +375,72 @@ sub all_storages { ); } +=head2 execute_reliably ($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 Sets the current $schema to be 'reliable', that is all queries, both read and @@ -380,6 +471,33 @@ 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. @@ -526,11 +644,12 @@ sub disconnect { =head1 AUTHOR -Norbert Csongrádi + John Napiorkowski -Peter Siklósi +Based on code originated by: -John Napiorkowski + Norbert Csongrádi + Peter Siklósi =head1 LICENSE