X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=dbsrgits%2FDBIx-Class.git;a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FReplicated.pm;h=447747514dd38272da3c17fa1c9e635944407822;hp=aca3ea774f1ad9819bff58b26743890816b9f8f0;hb=64ae166780d0cb2b9577e506da9b9b240c146d20;hpb=503363253e1fa2c35e3b5368dd7f453b9cfbc6a1 diff --git a/lib/DBIx/Class/Storage/DBI/Replicated.pm b/lib/DBIx/Class/Storage/DBI/Replicated.pm index aca3ea7..4477475 100644 --- a/lib/DBIx/Class/Storage/DBI/Replicated.pm +++ b/lib/DBIx/Class/Storage/DBI/Replicated.pm @@ -1,46 +1,84 @@ package DBIx::Class::Storage::DBI::Replicated; +BEGIN { + use Carp::Clan qw/^DBIx::Class/; + use DBIx::Class; + croak('The following modules are required for Replication ' . DBIx::Class::Optional::Dependencies->req_missing_for ('replicated') ) + unless DBIx::Class::Optional::Dependencies->req_ok_for ('replicated'); +} + use Moose; use DBIx::Class::Storage::DBI; use DBIx::Class::Storage::DBI::Replicated::Pool; use DBIx::Class::Storage::DBI::Replicated::Balancer; -use Scalar::Util qw(blessed); +use DBIx::Class::Storage::DBI::Replicated::Types qw/BalancerClassNamePart DBICSchema DBICStorageDBI/; +use MooseX::Types::Moose qw/ClassName HashRef Object/; +use Scalar::Util 'reftype'; +use Hash::Merge; +use List::Util qw/min max reduce/; +use Try::Tiny; +use namespace::clean; -extends 'DBIx::Class::Storage::DBI', 'Moose::Object'; +use namespace::clean -except => 'meta'; =head1 NAME -DBIx::Class::Storage::DBI::Replicated - ALPHA Replicated database support +DBIx::Class::Storage::DBI::Replicated - BETA Replicated database support =head1 SYNOPSIS The Following example shows how to change an existing $schema to a replicated -storage type, add some replicated (readonly) databases, and perform reporting -tasks - - ## Change storage_type in your schema class - $schema->storage_type( '::DBI::Replicated' ); - - ## Add some slaves. Basically this is an array of arrayrefs, where each - ## arrayref is database connect information - - $schema->storage->create_replicants( - [$dsn1, $user, $pass, \%opts], - [$dsn1, $user, $pass, \%opts], - [$dsn1, $user, $pass, \%opts], - ## This is just going to use the standard DBIC connect method, so it - ## supports everything that method supports, such as connecting to an - ## existing database handle. - [$dbh], - ); +storage type, add some replicated (read-only) databases, and perform reporting +tasks. + +You should set the 'storage_type attribute to a replicated type. You should +also define your arguments, such as which balancer you want and any arguments +that the Pool object should get. + + my $schema = Schema::Class->clone; + $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] ); + $schema->connection(...); + +Next, you need to add in the Replicants. Basically this is an array of +arrayrefs, where each arrayref is database connect information. Think of these +arguments as what you'd pass to the 'normal' $schema->connect method. + + $schema->storage->connect_replicants( + [$dsn1, $user, $pass, \%opts], + [$dsn2, $user, $pass, \%opts], + [$dsn3, $user, $pass, \%opts], + ); + +Now, just use the $schema as you normally would. Automatically all reads will +be delegated to the replicants, while writes to the master. + + $schema->resultset('Source')->search({name=>'etc'}); + +You can force a given query to use a particular storage using the search +attribute 'force_pool'. For example: + + my $RS = $schema->resultset('Source')->search(undef, {force_pool=>'master'}); + +Now $RS will force everything (both reads and writes) to use whatever was setup +as the master storage. 'master' is hardcoded to always point to the Master, +but you can also use any Replicant name. Please see: +L and the replicants attribute for more. + +Also see transactions and L for alternative ways to +force read traffic to the master. In general, you should wrap your statements +in a transaction when you are reading and writing to the same tables at the +same time, since your replicants will often lag a bit behind the master. + +See L for more help and +walkthroughs. - =head1 DESCRIPTION -Warning: This class is marked ALPHA. We are using this in development and have -some basic test coverage but the code hasn't yet been stressed by a variety -of databases. Individual DB's may have quirks we are not aware of. Please -use this in development and pass along your experiences/bug fixes. +Warning: This class is marked BETA. This has been running a production +website using MySQL native replication as its backend and we have some decent +test coverage but the code hasn't yet been stressed by a variety of databases. +Individual DBs may have quirks we are not aware of. Please use this in first +development and pass along your experiences/bug fixes. This class implements replicated data store for DBI. Currently you can define one master and numerous slave database connections. All write-type queries @@ -48,20 +86,139 @@ 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 +Read traffic is spread across the replicants (slaves) occurring to a user selected algorithm. The default algorithm is random weighted. -TODO more details about the algorithm. +=head1 NOTES + +The consistency between master and replicants is database specific. The Pool +gives you a method to validate its replicants, removing and replacing them +when they fail/pass predefined criteria. Please make careful use of the ways +to force a query to run against Master when needed. + +=head1 REQUIREMENTS + +Replicated Storage has additional requirements not currently part of +L. See L for more details. =head1 ATTRIBUTES This class defines the following attributes. +=head2 schema + +The underlying L object this storage is attaching + +=cut + +has 'schema' => ( + is=>'rw', + isa=>DBICSchema, + weak_ref=>1, + required=>1, +); + +=head2 pool_type + +Contains the classname which will instantiate the L object. Defaults +to: L. + +=cut + +has 'pool_type' => ( + is=>'rw', + isa=>ClassName, + default=>'DBIx::Class::Storage::DBI::Replicated::Pool', + handles=>{ + 'create_pool' => 'new', + }, +); + +=head2 pool_args + +Contains a hashref of initialized information to pass to the Balancer object. +See L for available arguments. + +=cut + +has 'pool_args' => ( + is=>'rw', + isa=>HashRef, + lazy=>1, + default=>sub { {} }, +); + + +=head2 balancer_type + +The replication pool requires a balance class to provider the methods for +choose how to spread the query load across each replicant in the pool. + +=cut + +has 'balancer_type' => ( + is=>'rw', + isa=>BalancerClassNamePart, + coerce=>1, + required=>1, + default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First', + handles=>{ + 'create_balancer' => 'new', + }, +); + +=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=>'rw', + isa=>HashRef, + lazy=>1, + required=>1, + default=>sub { {} }, +); + +=head2 pool + +Is a L or derived class. This is a +container class for one or more replicated databases. + +=cut + +has 'pool' => ( + is=>'ro', + isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', + lazy_build=>1, + handles=>[qw/ + connect_replicants + replicants + has_replicants + /], +); + +=head2 balancer + +Is a L or derived class. This +is a class that takes a pool (L) + +=cut + +has 'balancer' => ( + is=>'rw', + isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', + lazy_build=>1, + handles=>[qw/auto_validate_every/], +); + =head2 master The master defines the canonical state for a pool of connected databases. All @@ -73,181 +230,279 @@ pool of databases that is allowed to handle write traffic. =cut has 'master' => ( - is=> 'ro', - isa=>'DBIx::Class::Storage::DBI', - 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=>DBICStorageDBI, + lazy_build=>1, ); +=head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE -=head2 current_replicant +The following methods are delegated all the methods required for the +L interface. -Replicant storages (slaves) handle all read only traffic. The assumption is -that your database will become readbound well before it becomes write bound -and that being able to spread your read only traffic around to multiple -databases is going to help you to scale traffic. +=head2 read_handler -This attribute returns the next slave to handle a read request. Your L -attribute has methods to help you shuffle through all the available replicants -via it's balancer object. +Defines an object that implements the read side of L. -This attribute defines the following reader/writer methods +=cut -=over 4 +has 'read_handler' => ( + is=>'rw', + isa=>Object, + lazy_build=>1, + handles=>[qw/ + select + select_single + columns_info_for + _dbh_columns_info_for + _select + /], +); -=item get_current_replicant +=head2 write_handler -Returns the contained L replicant +Defines an object that implements the write side of L, +as well as methods that don't write or read that can be called on only one +storage, methods that return a C<$dbh>, and any methods that don't make sense to +run on a replicant. -=item set_current_replicant +=cut -Set the attribute to a given L (or subclass) object. +has 'write_handler' => ( + is=>'ro', + isa=>Object, + lazy_build=>1, + handles=>[qw/ + on_connect_do + on_disconnect_do + on_connect_call + on_disconnect_call + connect_info + _connect_info + throw_exception + sql_maker + sqlt_type + create_ddl_dir + deployment_statements + datetime_parser + datetime_parser_type + build_datetime_parser + last_insert_id + insert + insert_bulk + update + delete + dbh + txn_begin + txn_do + txn_commit + txn_rollback + txn_scope_guard + sth + deploy + with_deferred_fk_checks + dbh_do + reload_row + with_deferred_fk_checks + _prep_for_execute + + backup + is_datatype_numeric + _count_select + _subq_update_delete + svp_rollback + svp_begin + svp_release + relname_to_table_alias + _dbh_last_insert_id + _fix_bind_params + _default_dbi_connect_attributes + _dbi_connect_info + _dbic_connect_attributes + auto_savepoint + _sqlt_version_ok + _query_end + bind_attribute_by_data_type + transaction_depth + _dbh + _select_args + _dbh_execute_array + _sql_maker + _query_start + _sqlt_version_error + _per_row_update_delete + _dbh_begin_work + _dbh_execute_inserts_with_no_binds + _select_args_to_query + _svp_generate_name + _multipk_update_delete + source_bind_attributes + _normalize_connect_info + _parse_connect_do + _dbh_commit + _execute_array + savepoints + _sqlt_minimum_version + _sql_maker_opts + _conn_pid + _conn_tid + _dbh_autocommit + _native_data_type + _get_dbh + sql_maker_class + _dbh_rollback + _adjust_select_args_for_complex_prefetch + _resolve_ident_sources + _resolve_column_info + _prune_unused_joins + _strip_cond_qualifiers + _extract_order_columns + _resolve_aliastypes_from_select_args + _execute + _do_query + _dbh_sth + _dbh_execute + _prefetch_insert_auto_nextvals + /], +); -=back +my @unimplemented = qw( + _arm_global_destructor + _preserve_foreign_dbh + _verify_pid + _verify_tid -We split the reader/writer to make it easier to selectively override how the -replicant is altered. + get_use_dbms_capability + set_use_dbms_capability + get_dbms_capability + set_dbms_capability + _dbh_details -=cut + sql_limit_dialect -has 'current_replicant' => ( - is=> 'rw', - reader=>'get_current_replicant', - writer=>'set_current_replicant', - isa=>'DBIx::Class::Storage::DBI', - lazy_build=>1, - handles=>[qw/ - select - select_single - columns_info_for - /], - trigger=>sub {'xxxxxxxxxxxxxxxxxxxxxxxxxxx'}, + _inner_join_to_node + _group_over_selection ); +# the capability framework +# not sure if CMOP->initialize does evil things to DBIC::S::DBI, fix if a problem +push @unimplemented, ( grep + { $_ =~ /^ _ (?: use | supports | determine_supports ) _ /x } + ( Class::MOP::Class->initialize('DBIx::Class::Storage::DBI')->get_all_method_names ) +); -=head2 pool_type +for my $method (@unimplemented) { + __PACKAGE__->meta->add_method($method, sub { + croak "$method must not be called on ".(blessed shift).' objects'; + }); +} -Contains the classname which will instantiate the L object. Defaults -to: L. +has _master_connect_info_opts => + (is => 'rw', isa => HashRef, default => sub { {} }); + +=head2 around: connect_info + +Preserves master's C options (for merging with replicants.) +Also sets any Replicated-related options from connect_info, such as +C, C, C and C. =cut -has 'pool_type' => ( - is=>'ro', - isa=>'ClassName', - required=>1, - lazy=>1, - default=>'DBIx::Class::Storage::DBI::Replicated::Pool', - handles=>{ - 'create_pool' => 'new', - }, -); +around connect_info => sub { + my ($next, $self, $info, @extra) = @_; + my $wantarray = wantarray; -=head2 balancer_type + my $merge = Hash::Merge->new('LEFT_PRECEDENT'); -The replication pool requires a balance class to provider the methods for -choose how to spread the query load across each replicant in the pool. + my %opts; + for my $arg (@$info) { + next unless (reftype($arg)||'') eq 'HASH'; + %opts = %{ $merge->merge($arg, \%opts) }; + } + delete $opts{dsn}; -=cut + if (@opts{qw/pool_type pool_args/}) { + $self->pool_type(delete $opts{pool_type}) + if $opts{pool_type}; -has 'balancer_type' => ( - is=>'ro', - isa=>'ClassName', - required=>1, - lazy=>1, - default=>'DBIx::Class::Storage::DBI::Replicated::Balancer', - handles=>{ - 'create_balancer' => 'new', - }, -); + $self->pool_args( + $merge->merge((delete $opts{pool_args} || {}), $self->pool_args) + ); + ## Since we possibly changed the pool_args, we need to clear the current + ## pool object so that next time it is used it will be rebuilt. + $self->clear_pool; + } -=head2 pool + if (@opts{qw/balancer_type balancer_args/}) { + $self->balancer_type(delete $opts{balancer_type}) + if $opts{balancer_type}; -Is a or derived class. This is a -container class for one or more replicated databases. + $self->balancer_args( + $merge->merge((delete $opts{balancer_args} || {}), $self->balancer_args) + ); -=cut + $self->balancer($self->_build_balancer) + if $self->balancer; + } -has 'pool' => ( - is=>'ro', - isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', - lazy_build=>1, - handles=>[qw/ - replicants - has_replicants - create_replicants - num_replicants - delete_replicant - /], -); + $self->_master_connect_info_opts(\%opts); + my (@res, $res); + if ($wantarray) { + @res = $self->$next($info, @extra); + } else { + $res = $self->$next($info, @extra); + } -=head2 balancer + # Make sure master is blessed into the correct class and apply role to it. + my $master = $self->master; + $master->_determine_driver; + Moose::Meta::Class->initialize(ref $master); -Is a or derived class. This -is a class that takes a pool () + DBIx::Class::Storage::DBI::Replicated::WithDSN->meta->apply($master); -=cut + # link pool back to master + $self->pool->master($master); -has 'balancer' => ( - is=>'ro', - isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', - lazy_build=>1, - handles=>[qw/next_storage/], -); + $wantarray ? @res : $res; +}; =head1 METHODS This class defines the following methods. -=head2 _build_master +=head2 BUILDARGS -Lazy builder for the L attribute. +L when instantiating its storage passed itself as the +first argument. So we need to massage the arguments a bit so that all the +bits get put into the correct places. =cut -sub _build_master { - DBIx::Class::Storage::DBI->new; -} +sub BUILDARGS { + my ($class, $schema, $storage_type_args, @args) = @_; + return { + schema=>$schema, + %$storage_type_args, + @args + } +} -=head2 _build_current_replicant +=head2 _build_master -Lazy builder for the L attribute. +Lazy builder for the L attribute. =cut -sub _build_current_replicant { - my $self = shift @_; - $self->next_storage($self->pool); +sub _build_master { + my $self = shift @_; + my $master = DBIx::Class::Storage::DBI->new($self->schema); + $master } - =head2 _build_pool Lazy builder for the L attribute. @@ -255,52 +510,103 @@ Lazy builder for the L attribute. =cut sub _build_pool { - my $self = shift @_; - $self->create_pool; + my $self = shift @_; + $self->create_pool(%{$self->pool_args}); } - =head2 _build_balancer -Lazy builder for the L attribute. +Lazy builder for the L attribute. This takes a Pool object so that +the balancer knows which pool it's balancing. =cut sub _build_balancer { - my $self = shift @_; - $self->create_balancer; + my $self = shift @_; + $self->create_balancer( + pool=>$self->pool, + master=>$self->master, + %{$self->balancer_args}, + ); } +=head2 _build_write_handler -=head2 around: create_replicants - -All calls to create_replicants needs to have an existing $schema tacked onto -top of the args +Lazy builder for the L attribute. The default is to set this to +the L. =cut -around 'create_replicants' => sub { - my ($method, $self, @args) = @_; - $self->$method($self->schema, @args); -}; +sub _build_write_handler { + return shift->master; +} +=head2 _build_read_handler -=head2 after: get_current_replicant_storage +Lazy builder for the L attribute. The default is to set this to +the L. -Advice on the current_replicant_storage attribute. Each time we use a replicant -we need to change it via the storage pool algorithm. That way we are spreading -the load evenly (hopefully) across existing capacity. +=cut + +sub _build_read_handler { + return shift->balancer; +} + +=head2 around: connect_replicants + +All calls to connect_replicants needs to have an existing $schema tacked onto +top of the args, since L needs it, and any C +options merged with the master, with replicant opts having higher priority. =cut -after 'current_replicant' => sub { - my $self = shift @_; - my $next_replicant = $self->next_storage($self->pool); +around connect_replicants => sub { + my ($next, $self, @args) = @_; -warn '......................'; - $self->set_current_replicant($next_replicant); -}; + for my $r (@args) { + $r = [ $r ] unless reftype $r eq 'ARRAY'; + + $self->throw_exception('coderef replicant connect_info not supported') + if ref $r->[0] && reftype $r->[0] eq 'CODE'; + +# any connect_info options? + my $i = 0; + $i++ while $i < @$r && (reftype($r->[$i])||'') ne 'HASH'; + +# make one if none + $r->[$i] = {} unless $r->[$i]; + +# merge if two hashes + my @hashes = @$r[$i .. $#{$r}]; + + $self->throw_exception('invalid connect_info options') + if (grep { reftype($_) eq 'HASH' } @hashes) != @hashes; + + $self->throw_exception('too many hashrefs in connect_info') + if @hashes > 2; + + my $merge = Hash::Merge->new('LEFT_PRECEDENT'); + my %opts = %{ $merge->merge(reverse @hashes) }; + +# delete them + splice @$r, $i+1, ($#{$r} - $i), (); + +# make sure master/replicants opts don't clash + my %master_opts = %{ $self->_master_connect_info_opts }; + if (exists $opts{dbh_maker}) { + delete @master_opts{qw/dsn user password/}; + } + delete $master_opts{dbh_maker}; +# merge with master + %opts = %{ $merge->merge(\%opts, \%master_opts) }; + +# update + $r->[$i] = \%opts; + } + + $self->$next($self->schema, @args); +}; =head2 all_storages @@ -311,14 +617,102 @@ replicants. =cut sub all_storages { - my $self = shift @_; - - return grep {defined $_ && blessed $_} ( - $self->master, - $self->replicants, - ); + my $self = shift @_; + return grep {defined $_ && blessed $_} ( + $self->master, + values %{ $self->replicants }, + ); +} + +=head2 execute_reliably ($coderef, ?@args) + +Given a coderef, saves the current state of the L, forces it to +use reliable storage (e.g. 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 $want_array = wantarray; + + try { + if($want_array) { + @result = $coderef->(@args); + } elsif(defined $want_array) { + ($result[0]) = ($coderef->(@args)); + } else { + $coderef->(@args); + } + } catch { + $self->throw_exception("coderef returned an error: $_"); + } finally { + ##Reset to the original state + $self->read_handler($current); + }; + + 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); +} + +=head2 set_balanced_storage + +Sets the current $schema to be use the for all reads, while all +writes are sent to the master only + +=cut + +sub set_balanced_storage { + my $self = shift @_; + my $schema = $self->schema; + my $balanced_handler = $self->schema->storage->balancer; + + $schema->storage->read_handler($balanced_handler); +} =head2 connected @@ -327,14 +721,12 @@ 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 Make sure all the storages are connected. @@ -342,13 +734,12 @@ Make sure all the storages are 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 Set the limit_dialect for all existing storages @@ -356,13 +747,13 @@ Set the limit_dialect for all existing storages =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(@_); + } + return $self->master->limit_dialect; } - =head2 quote_char Set the quote_char for all existing storages @@ -370,13 +761,13 @@ Set the quote_char for all existing storages =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(@_); + } + return $self->master->quote_char; } - =head2 name_sep Set the name_sep for all existing storages @@ -384,13 +775,13 @@ Set the name_sep for all existing storages =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(@_); + } + return $self->master->name_sep; } - =head2 set_schema Set the schema object for all existing storages @@ -398,13 +789,12 @@ Set the schema object for all existing storages =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 set a debug flag across all storages @@ -412,55 +802,48 @@ set a debug flag across all storages =cut sub debug { - my $self = shift @_; + my $self = shift @_; + if(@_) { foreach my $source ($self->all_storages) { - $source->debug(@_); + $source->debug(@_); } + } + return $self->master->debug; } - =head2 debugobj -set a debug object across all storages +set a debug object =cut sub debugobj { - my $self = shift @_; - foreach my $source ($self->all_storages) { - $source->debugobj(@_); - } + my $self = shift @_; + return $self->master->debugobj(@_); } - =head2 debugfh -set a debugfh object across all storages +set a debugfh object =cut sub debugfh { - my $self = shift @_; - foreach my $source ($self->all_storages) { - $source->debugfh(@_); - } + my $self = shift @_; + return $self->master->debugfh(@_); } - =head2 debugcb -set a debug callback across all storages +set a debug callback =cut sub debugcb { - my $self = shift @_; - foreach my $source ($self->all_storages) { - $source->debugcb(@_); - } + my $self = shift @_; + return $self->master->debugcb(@_); } - =head2 disconnect disconnect everything @@ -468,312 +851,260 @@ disconnect everything =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(@_); + } } +=head2 cursor_class -=head2 DESTROY - -Make sure we pass destroy events down to the storage handlers +set cursor class on all storages, or return master's =cut -sub DESTROY { - my $self = shift; - ## TODO, maybe we can just leave this alone ??? +sub cursor_class { + my ($self, $cursor_class) = @_; + + if ($cursor_class) { + $_->cursor_class($cursor_class) for $self->all_storages; + } + $self->master->cursor_class; } +=head2 cursor -=head1 AUTHOR +set cursor class on all storages, or return master's, alias for L +above. -Norbert Csongrádi +=cut -Peter Siklósi +sub cursor { + my ($self, $cursor_class) = @_; -John Napiorkowski + if ($cursor_class) { + $_->cursor($cursor_class) for $self->all_storages; + } + $self->master->cursor; +} -=head1 LICENSE +=head2 unsafe -You may distribute this code under the same terms as Perl itself. +sets the L option on all storages or returns +master's current setting =cut -1; +sub unsafe { + my $self = shift; -__END__ + if (@_) { + $_->unsafe(@_) for $self->all_storages; + } -use strict; -use warnings; + return $self->master->unsafe; +} -use DBIx::Class::Storage::DBI; -use DBD::Multi; +=head2 disable_sth_caching -use base qw/Class::Accessor::Fast/; +sets the L option on all storages +or returns master's current setting -__PACKAGE__->mk_accessors( qw/read_source write_source/ ); +=cut -=head1 NAME +sub disable_sth_caching { + my $self = shift; -DBIx::Class::Storage::DBI::Replicated - ALPHA Replicated database support + if (@_) { + $_->disable_sth_caching(@_) for $self->all_storages; + } -=head1 SYNOPSIS + return $self->master->disable_sth_caching; +} -The Following example shows how to change an existing $schema to a replicated -storage type and update it's connection information to contain a master DSN and -an array of slaves. - - ## Change storage_type in your schema class - $schema->storage_type( '::DBI::Replicated' ); - - ## Set your connection. - $schema->connect( - $dsn, $user, $password, { - AutoCommit => 1, - ## Other standard DBI connection or DBD custom attributes added as - ## usual. Additionally, we have two custom attributes for defining - ## slave information and controlling how the underlying DBD::Multi - slaves_connect_info => [ - ## Define each slave like a 'normal' DBI connection, but you add - ## in a DBD::Multi custom attribute to define how the slave is - ## prioritized. Please see DBD::Multi for more. - [$slave1dsn, $user, $password, {%slave1opts, priority=>10}], - [$slave2dsn, $user, $password, {%slave2opts, priority=>10}], - [$slave3dsn, $user, $password, {%slave3opts, priority=>20}], - ## add in a preexisting database handle - [$dbh, '','', {priority=>30}], - ## DBD::Multi will call this coderef for connects - [sub { DBI->connect(< DSN info >) }, '', '', {priority=>40}], - ## If the last item is hashref, we use that for DBD::Multi's - ## configuration information. Again, see DBD::Multi for more. - {timeout=>25, failed_max=>2}, - ], - }, - ); - - ## Now, just use the schema as normal - $schema->resultset('Table')->find(< unique >); ## Reads will use slaves - $schema->resultset('Table')->create(\%info); ## Writes will use master +=head2 lag_behind_master -=head1 DESCRIPTION +returns the highest Replicant L +setting -Warning: This class is marked ALPHA. We are using this in development and have -some basic test coverage but the code hasn't yet been stressed by a variety -of databases. Individual DB's may have quirks we are not aware of. Please -use this in development and pass along your experiences/bug fixes. +=cut -This class implements replicated data store for DBI. Currently you can define -one master and numerous slave database connections. All write-type queries -(INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master -database, all read-type queries (SELECTs) go to the slave database. +sub lag_behind_master { + my $self = shift; -For every slave database you can define a priority value, which controls data -source usage pattern. It uses L, so first the lower priority data -sources used (if they have the same priority, the are used randomized), than -if all low priority data sources fail, higher ones tried in order. + return max map $_->lag_behind_master, $self->replicants; +} -=head1 CONFIGURATION +=head2 is_replicating -Please see L for most configuration information. +returns true if all replicants return true for +L =cut -sub new { - my $proto = shift; - my $class = ref( $proto ) || $proto; - my $self = {}; +sub is_replicating { + my $self = shift; - bless( $self, $class ); + return (grep $_->is_replicating, $self->replicants) == ($self->replicants); +} - $self->write_source( DBIx::Class::Storage::DBI->new ); - $self->read_source( DBIx::Class::Storage::DBI->new ); +=head2 connect_call_datetime_setup - return $self; -} +calls L for all storages -sub all_sources { - my $self = shift; +=cut - my @sources = ($self->read_source, $self->write_source); +sub connect_call_datetime_setup { + my $self = shift; + $_->connect_call_datetime_setup for $self->all_storages; +} - return wantarray ? @sources : \@sources; +sub _populate_dbh { + my $self = shift; + $_->_populate_dbh for $self->all_storages; } -sub _connect_info { - my $self = shift; - my $master = $self->write_source->_connect_info; - $master->[-1]->{slave_connect_info} = $self->read_source->_connect_info; - return $master; +sub _connect { + my $self = shift; + $_->_connect for $self->all_storages; } -sub connect_info { - my ($self, $source_info) = @_; +sub _rebless { + my $self = shift; + $_->_rebless for $self->all_storages; +} - ## if there is no $source_info, treat this sub like an accessor - return $self->_connect_info - if !$source_info; - - ## Alright, let's conect the master - $self->write_source->connect_info($source_info); - - ## Now, build and then connect the Slaves - my @slaves_connect_info = @{$source_info->[-1]->{slaves_connect_info}}; - my $dbd_multi_config = ref $slaves_connect_info[-1] eq 'HASH' - ? pop @slaves_connect_info : {}; +sub _determine_driver { + my $self = shift; + $_->_determine_driver for $self->all_storages; +} - ## We need to do this since SQL::Abstract::Limit can't guess what DBD::Multi is - $dbd_multi_config->{limit_dialect} = $self->write_source->sql_maker->limit_dialect - unless defined $dbd_multi_config->{limit_dialect}; +sub _driver_determined { + my $self = shift; - @slaves_connect_info = map { - ## if the first element in the arrayhash is a ref, make that the value - my $db = ref $_->[0] ? $_->[0] : $_; - my $priority = $_->[-1]->{priority} || 10; ## default priority is 10 - $priority => $db; - } @slaves_connect_info; - - $self->read_source->connect_info([ - 'dbi:Multi:', undef, undef, { - dsns => [@slaves_connect_info], - %$dbd_multi_config, - }, - ]); - - ## Return the formated connection information - return $self->_connect_info; -} + if (@_) { + $_->_driver_determined(@_) for $self->all_storages; + } -sub select { - shift->read_source->select( @_ ); + return $self->master->_driver_determined; } -sub select_single { - shift->read_source->select_single( @_ ); -} -sub throw_exception { - shift->read_source->throw_exception( @_ ); + +sub _init { + my $self = shift; + + $_->_init for $self->all_storages; } -sub sql_maker { - shift->read_source->sql_maker( @_ ); + +sub _run_connection_actions { + my $self = shift; + + $_->_run_connection_actions for $self->all_storages; } -sub columns_info_for { - shift->read_source->columns_info_for( @_ ); + +sub _do_connection_actions { + my $self = shift; + + if (@_) { + $_->_do_connection_actions(@_) for $self->all_storages; + } } -sub sqlt_type { - shift->read_source->sqlt_type( @_ ); + +sub connect_call_do_sql { + my $self = shift; + $_->connect_call_do_sql(@_) for $self->all_storages; } -sub create_ddl_dir { - shift->read_source->create_ddl_dir( @_ ); + +sub disconnect_call_do_sql { + my $self = shift; + $_->disconnect_call_do_sql(@_) for $self->all_storages; } -sub deployment_statements { - shift->read_source->deployment_statements( @_ ); + +sub _seems_connected { + my $self = shift; + + return min map $_->_seems_connected, $self->all_storages; } -sub datetime_parser { - shift->read_source->datetime_parser( @_ ); + +sub _ping { + my $self = shift; + + return min map $_->_ping, $self->all_storages; } -sub datetime_parser_type { - shift->read_source->datetime_parser_type( @_ ); + +# not using the normalized_version, because we want to preserve +# version numbers much longer than the conventional xxx.yyyzzz +my $numify_ver = sub { + my $ver = shift; + my @numparts = split /\D+/, $ver; + my $format = '%d.' . (join '', ('%06d') x (@numparts - 1)); + + return sprintf $format, @numparts; +}; +sub _server_info { + my $self = shift; + + if (not $self->_dbh_details->{info}) { + $self->_dbh_details->{info} = ( + reduce { $a->[0] < $b->[0] ? $a : $b } + map [ $numify_ver->($_->{dbms_version}), $_ ], + map $_->_server_info, $self->all_storages + )->[1]; + } + + return $self->next::method; } -sub build_datetime_parser { - shift->read_source->build_datetime_parser( @_ ); + +sub _get_server_version { + my $self = shift; + + return $self->_server_info->{dbms_version}; } -sub limit_dialect { $_->limit_dialect( @_ ) for( shift->all_sources ) } -sub quote_char { $_->quote_char( @_ ) for( shift->all_sources ) } -sub name_sep { $_->quote_char( @_ ) for( shift->all_sources ) } -sub disconnect { $_->disconnect( @_ ) for( shift->all_sources ) } -sub set_schema { $_->set_schema( @_ ) for( shift->all_sources ) } +=head1 GOTCHAS -sub DESTROY { - my $self = shift; +Due to the fact that replicants can lag behind a master, you must take care to +make sure you use one of the methods to force read queries to a master should +you need realtime data integrity. For example, if you insert a row, and then +immediately re-read it from the database (say, by doing $row->discard_changes) +or you insert a row and then immediately build a query that expects that row +to be an item, you should force the master to handle reads. Otherwise, due to +the lag, there is no certainty your data will be in the expected state. - undef $self->{write_source}; - undef $self->{read_sources}; -} +For data integrity, all transactions automatically use the master storage for +all read and write queries. Using a transaction is the preferred and recommended +method to force the master to handle all read queries. -sub last_insert_id { - shift->write_source->last_insert_id( @_ ); -} -sub insert { - shift->write_source->insert( @_ ); -} -sub update { - shift->write_source->update( @_ ); -} -sub update_all { - shift->write_source->update_all( @_ ); -} -sub delete { - shift->write_source->delete( @_ ); -} -sub delete_all { - shift->write_source->delete_all( @_ ); -} -sub create { - shift->write_source->create( @_ ); -} -sub find_or_create { - shift->write_source->find_or_create( @_ ); -} -sub update_or_create { - shift->write_source->update_or_create( @_ ); -} -sub connected { - shift->write_source->connected( @_ ); -} -sub ensure_connected { - shift->write_source->ensure_connected( @_ ); -} -sub dbh { - shift->write_source->dbh( @_ ); -} -sub txn_do { - shift->write_source->txn_do( @_ ); -} -sub txn_commit { - shift->write_source->txn_commit( @_ ); -} -sub txn_rollback { - shift->write_source->txn_rollback( @_ ); -} -sub sth { - shift->write_source->sth( @_ ); -} -sub deploy { - shift->write_source->deploy( @_ ); -} -sub _prep_for_execute { - shift->write_source->_prep_for_execute(@_); -} +Otherwise, you can force a single query to use the master with the 'force_pool' +attribute: -sub debugobj { - shift->write_source->debugobj(@_); -} -sub debug { - shift->write_source->debug(@_); -} + my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk); -sub debugfh { shift->_not_supported( 'debugfh' ) }; -sub debugcb { shift->_not_supported( 'debugcb' ) }; +This attribute will safely be ignore by non replicated storages, so you can use +the same code for both types of systems. -sub _not_supported { - my( $self, $method ) = @_; +Lastly, you can use the L method, which works very much like +a transaction. - die "This Storage does not support $method method."; -} +For debugging, you can turn replication on/off with the methods L +and L, however this operates at a global level and is not +suitable if you have a shared Schema object being used by multiple processes, +such as on a web application server. You can get around this limitation by +using the Schema clone method. -=head1 SEE ALSO + my $new_schema = $schema->clone; + $new_schema->set_reliable_storage; -L, L, L + ## $new_schema will use only the Master storage for all reads/writes while + ## the $schema object will use replicated storage. =head1 AUTHOR -Norbert Csongrádi + John Napiorkowski -Peter Siklósi +Based on code originated by: -John Napiorkowski + Norbert Csongrádi + Peter Siklósi =head1 LICENSE @@ -781,4 +1112,6 @@ You may distribute this code under the same terms as Perl itself. =cut +__PACKAGE__->meta->make_immutable; + 1;