package DBIx::Class::Storage::DBI::Replicated;
+BEGIN {
+ use Carp::Clan qw/^DBIx::Class/;
+
+ ## Modules required for Replication support not required for general DBIC
+ ## use, so we explicitly test for these.
+
+ my %replication_required = (
+ 'Moose' => '0.90',
+ 'MooseX::Types' => '0.16',
+ 'namespace::clean' => '0.11',
+ 'Hash::Merge' => '0.11'
+ );
+
+ my @didnt_load;
+
+ for my $module (keys %replication_required) {
+ eval "use $module $replication_required{$module}";
+ push @didnt_load, "$module $replication_required{$module}"
+ if $@;
+ }
+
+ croak("@{[ join ', ', @didnt_load ]} are missing and are required for Replication")
+ if @didnt_load;
+}
+
use Moose;
-use Class::MOP;
-use Moose::Util::TypeConstraints;
use DBIx::Class::Storage::DBI;
use DBIx::Class::Storage::DBI::Replicated::Pool;
use DBIx::Class::Storage::DBI::Replicated::Balancer;
+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 'merge';
+
+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
storage type, add some replicated (readonly) databases, and perform reporting
tasks.
- ## Change storage_type in your schema class
+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.
+
$schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
-
- ## Add some slaves. Basically this is an array of arrayrefs, where each
- ## arrayref is database connect information
-
+
+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<DBIx::Class::Storage::DBI::Replicated::Pool> and the replicants attribute for more.
+
+Also see transactions and L</execute_reliably> 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<DBIx::Class::Storage::DBI::Replicated::Instructions> 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 DB's 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
=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.
+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<DBIx::Class>
+
+ Moose => '0.90',
+ MooseX::Types => '0.16',
+ namespace::clean => '0.11',
+ Hash::Merge => '0.11'
+
+You will need to install these modules manually via CPAN or make them part of the
+Makefile for your distribution.
=head1 ATTRIBUTES
has 'schema' => (
is=>'rw',
- isa=>'DBIx::Class::Schema',
+ isa=>DBICSchema,
weak_ref=>1,
required=>1,
);
=cut
has 'pool_type' => (
- is=>'ro',
- isa=>'ClassName',
- required=>1,
+ 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<DBIx::Class::Storage::Replicated::Pool> for available arguments.
+See L<DBIx::Class::Storage::DBI::Replicated::Pool> for available arguments.
=cut
has 'pool_args' => (
- is=>'ro',
- isa=>'HashRef',
+ is=>'rw',
+ isa=>HashRef,
lazy=>1,
- required=>1,
default=>sub { {} },
);
=cut
-subtype 'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart',
- as 'ClassName';
-
-coerce 'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart',
- from 'Str',
- via {
- my $type = $_;
- if($type=~m/^::/) {
- $type = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$type;
- }
- Class::MOP::load_class($type);
- $type;
- };
-
has 'balancer_type' => (
- is=>'ro',
- isa=>'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart',
+ is=>'rw',
+ isa=>BalancerClassNamePart,
coerce=>1,
required=>1,
default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First',
=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.
+See L<DBIx::Class::Storage::DBI::Replicated::Balancer> for available arguments.
=cut
has 'balancer_args' => (
- is=>'ro',
- isa=>'HashRef',
+ is=>'rw',
+ isa=>HashRef,
lazy=>1,
required=>1,
default=>sub { {} },
isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
lazy_build=>1,
handles=>[qw/
- connect_replicants
+ connect_replicants
replicants
has_replicants
/],
=cut
has 'balancer' => (
- is=>'ro',
+ is=>'rw',
isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
lazy_build=>1,
handles=>[qw/auto_validate_every/],
has 'master' => (
is=> 'ro',
- isa=>'DBIx::Class::Storage::DBI',
+ isa=>DBICStorageDBI,
lazy_build=>1,
);
has 'read_handler' => (
is=>'rw',
- isa=>'Object',
+ isa=>Object,
lazy_build=>1,
handles=>[qw/
select
select_single
columns_info_for
- /],
+ /],
);
=head2 write_handler
has 'write_handler' => (
is=>'ro',
- isa=>'Object',
- lazy_build=>1,
+ isa=>Object,
lazy_build=>1,
- handles=>[qw/
+ handles=>[qw/
on_connect_do
- on_disconnect_do
+ on_disconnect_do
connect_info
throw_exception
sql_maker
create_ddl_dir
deployment_statements
datetime_parser
- datetime_parser_type
+ datetime_parser_type
+ build_datetime_parser
last_insert_id
insert
insert_bulk
txn_scope_guard
sth
deploy
-
+ with_deferred_fk_checks
+ dbh_do
reload_row
+ with_deferred_fk_checks
_prep_for_execute
- configure_sqlt
-
+
+ backup
+ is_datatype_numeric
+ _count_select
+ _subq_count_select
+ _subq_update_delete
+ svp_rollback
+ svp_begin
+ svp_release
/],
);
+has _master_connect_info_opts =>
+ (is => 'rw', isa => HashRef, default => sub { {} });
+
+=head2 around: connect_info
+
+Preserve master's C<connect_info> options (for merging with replicants.)
+Also set any Replicated related options from connect_info, such as
+C<pool_type>, C<pool_args>, C<balancer_type> and C<balancer_args>.
+
+=cut
+
+around connect_info => sub {
+ my ($next, $self, $info, @extra) = @_;
+
+ my $wantarray = wantarray;
+
+ my %opts;
+ for my $arg (@$info) {
+ next unless (reftype($arg)||'') eq 'HASH';
+ %opts = %{ merge($arg, \%opts) };
+ }
+ delete $opts{dsn};
+
+ if (@opts{qw/pool_type pool_args/}) {
+ $self->pool_type(delete $opts{pool_type})
+ if $opts{pool_type};
+
+ $self->pool_args(
+ merge((delete $opts{pool_args} || {}), $self->pool_args)
+ );
+
+ $self->pool($self->_build_pool)
+ if $self->pool;
+ }
+
+ if (@opts{qw/balancer_type balancer_args/}) {
+ $self->balancer_type(delete $opts{balancer_type})
+ if $opts{balancer_type};
+
+ $self->balancer_args(
+ merge((delete $opts{balancer_args} || {}), $self->balancer_args)
+ );
+
+ $self->balancer($self->_build_balancer)
+ if $self->balancer;
+ }
+
+ $self->_master_connect_info_opts(\%opts);
+
+ my (@res, $res);
+ if ($wantarray) {
+ @res = $self->$next($info, @extra);
+ } else {
+ $res = $self->$next($info, @extra);
+ }
+
+ # 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 $master);
+ DBIx::Class::Storage::DBI::Replicated::WithDSN->meta->apply($master);
+
+ $wantarray ? @res : $res;
+};
+
=head1 METHODS
This class defines the following methods.
-=head2 new
+=head2 BUILDARGS
-L<DBIx::Class::Schema> when instantiating it's storage passed itself as the
+L<DBIx::Class::Schema> when instantiating its storage passed itself as the
first argument. So we need to massage the arguments a bit so that all the
bits get put into the correct places.
=cut
-around 'new' => sub {
- my ($new, $self, $schema, $storage_type_args, @args) = @_;
- return $self->$new(schema=>$schema, %$storage_type_args, @args);
-};
+sub BUILDARGS {
+ my ($class, $schema, $storage_type_args, @args) = @_;
+
+ return {
+ schema=>$schema,
+ %$storage_type_args,
+ @args
+ }
+}
=head2 _build_master
sub _build_master {
my $self = shift @_;
- DBIx::Class::Storage::DBI->new($self->schema);
+ my $master = DBIx::Class::Storage::DBI->new($self->schema);
+ $master
}
=head2 _build_pool
sub _build_balancer {
my $self = shift @_;
$self->create_balancer(
- pool=>$self->pool,
+ pool=>$self->pool,
master=>$self->master,
%{$self->balancer_args},
);
=head2 around: connect_replicants
All calls to connect_replicants needs to have an existing $schema tacked onto
-top of the args, since L<DBIx::Storage::DBI> needs it.
+top of the args, since L<DBIx::Storage::DBI> needs it, and any C<connect_info>
+options merged with the master, with replicant opts having higher priority.
=cut
-around 'connect_replicants' => sub {
- my ($method, $self, @args) = @_;
- $self->$method($self->schema, @args);
+around connect_replicants => sub {
+ my ($next, $self, @args) = @_;
+
+ 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;
+
+ $self->throw_exception('too many hashrefs in connect_info')
+ if @hashes > 2;
+
+ my %opts = %{ merge(reverse @hashes) };
+
+# delete them
+ splice @$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(\%opts, \%master_opts) };
+
+# update
+ $r->[$i] = \%opts;
+ }
+
+ $self->$next($self->schema, @args);
};
=head2 all_storages
my $self = shift @_;
return grep {defined $_ && blessed $_} (
$self->master,
- $self->replicants,
+ values %{ $self->replicants },
);
}
sub execute_reliably {
my ($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 = $coderef->(@args);
($result[0]) = ($coderef->(@args));
} else {
$coderef->(@args);
- }
+ }
};
-
+
##Reset to the original state
- $self->read_handler($current);
-
+ $self->read_handler($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 {
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);
}
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);
-}
-
-=head2 around: txn_do ($coderef)
+ my $balanced_handler = $self->schema->storage->balancer;
-Overload to the txn_do method, which is delegated to whatever the
-L<write_handler> is set to. We overload this in order to wrap in inside a
-L</execute_reliably> method.
-
-=cut
-
-around 'txn_do' => sub {
- my($txn_do, $self, $coderef, @args) = @_;
- $self->execute_reliably(sub {$self->$txn_do($coderef, @args)});
-};
+ $schema->storage->read_handler($balanced_handler);
+}
=head2 connected
foreach my $source ($self->all_storages) {
$source->limit_dialect(@_);
}
+ return $self->master->quote_char;
}
=head2 quote_char
foreach my $source ($self->all_storages) {
$source->quote_char(@_);
}
+ return $self->master->quote_char;
}
=head2 name_sep
foreach my $source ($self->all_storages) {
$source->name_sep(@_);
}
+ return $self->master->name_sep;
}
=head2 set_schema
sub debug {
my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debug(@_);
+ if(@_) {
+ foreach my $source ($self->all_storages) {
+ $source->debug(@_);
+ }
}
+ return $self->master->debug;
}
=head2 debugobj
sub debugobj {
my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugobj(@_);
+ if(@_) {
+ foreach my $source ($self->all_storages) {
+ $source->debugobj(@_);
+ }
}
+ return $self->master->debugobj;
}
=head2 debugfh
sub debugfh {
my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugfh(@_);
+ if(@_) {
+ foreach my $source ($self->all_storages) {
+ $source->debugfh(@_);
+ }
}
+ return $self->master->debugfh;
}
=head2 debugcb
sub debugcb {
my $self = shift @_;
- foreach my $source ($self->all_storages) {
- $source->debugcb(@_);
+ if(@_) {
+ foreach my $source ($self->all_storages) {
+ $source->debugcb(@_);
+ }
}
+ return $self->master->debugcb;
}
=head2 disconnect
}
}
+=head2 cursor_class
+
+set cursor class on all storages, or return master's
+
+=cut
+
+sub cursor_class {
+ my ($self, $cursor_class) = @_;
+
+ if ($cursor_class) {
+ $_->cursor_class($cursor_class) for $self->all_storages;
+ }
+ $self->master->cursor_class;
+}
+
+=head1 GOTCHAS
+
+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.
+
+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.
+
+Otherwise, you can force a single query to use the master with the 'force_pool'
+attribute:
+
+ my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk);
+
+This attribute will safely be ignore by non replicated storages, so you can use
+the same code for both types of systems.
+
+Lastly, you can use the L</execute_reliably> method, which works very much like
+a transaction.
+
+For debugging, you can turn replication on/off with the methods L</set_reliable_storage>
+and L</set_balanced_storage>, 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.
+
+ my $new_schema = $schema->clone;
+ $new_schema->set_reliable_storage;
+
+ ## $new_schema will use only the Master storage for all reads/writes while
+ ## the $schema object will use replicated storage.
+
=head1 AUTHOR
John Napiorkowski <john.napiorkowski@takkle.com>
=cut
+__PACKAGE__->meta->make_immutable;
+
1;
projects / dbsrgits/DBIx-Class.git / blobdiff