1 package DBIx::Class::Storage;
6 use base qw/DBIx::Class/;
10 package # Hide from PAUSE
11 DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION;
12 use base 'DBIx::Class::Exception';
15 use DBIx::Class::Carp;
16 use DBIx::Class::Storage::BlockRunner;
17 use Scalar::Util qw/blessed weaken/;
18 use DBIx::Class::Storage::TxnScopeGuard;
22 __PACKAGE__->mk_group_accessors(simple => qw/debug schema transaction_depth auto_savepoint savepoints/);
23 __PACKAGE__->mk_group_accessors(component_class => 'cursor_class');
25 __PACKAGE__->cursor_class('DBIx::Class::Cursor');
27 sub cursor { shift->cursor_class(@_); }
31 DBIx::Class::Storage - Generic Storage Handler
35 A base implementation of common Storage methods. For specific
36 information about L<DBI>-based storage, see L<DBIx::Class::Storage::DBI>.
44 Instantiates the Storage object.
49 my ($self, $schema) = @_;
51 $self = ref $self if ref $self;
54 transaction_depth => 0,
58 $new->set_schema($schema);
60 if $ENV{DBIX_CLASS_STORAGE_DBI_DEBUG} || $ENV{DBIC_TRACE};
67 Used to reset the schema class or object which owns this
68 storage object, such as during L<DBIx::Class::Schema/clone>.
73 my ($self, $schema) = @_;
74 $self->schema($schema);
75 weaken $self->{schema} if ref $self->{schema};
80 Returns true if we have an open storage connection, false
81 if it is not (yet) open.
85 sub connected { die "Virtual method!" }
89 Closes any open storage connection unconditionally.
93 sub disconnect { die "Virtual method!" }
95 =head2 ensure_connected
97 Initiate a connection to the storage if one isn't already open.
101 sub ensure_connected { die "Virtual method!" }
103 =head2 throw_exception
105 Throws an exception - croaks.
109 sub throw_exception {
112 if (ref $self and $self->schema) {
113 $self->schema->throw_exception(@_);
116 DBIx::Class::Exception->throw(@_);
124 =item Arguments: C<$coderef>, @coderef_args?
126 =item Return Value: The return value of $coderef
130 Executes C<$coderef> with (optional) arguments C<@coderef_args> atomically,
131 returning its result (if any). If an exception is caught, a rollback is issued
132 and the exception is rethrown. If the rollback fails, (i.e. throws an
133 exception) an exception is thrown that includes a "Rollback failed" message.
137 my $author_rs = $schema->resultset('Author')->find(1);
138 my @titles = qw/Night Day It/;
141 # If any one of these fails, the entire transaction fails
142 $author_rs->create_related('books', {
144 }) foreach (@titles);
146 return $author->books;
151 $rs = $schema->txn_do($coderef);
155 die "something terrible has happened!"
156 if ($error =~ /Rollback failed/); # Rollback failed
158 deal_with_failed_transaction();
161 In a nested transaction (calling txn_do() from within a txn_do() coderef) only
162 the outermost transaction will issue a L</txn_commit>, and txn_do() can be
163 called in void, scalar and list context and it will behave as expected.
165 Please note that all of the code in your coderef, including non-DBIx::Class
166 code, is part of a transaction. This transaction may fail out halfway, or
167 it may get partially double-executed (in the case that our DB connection
168 failed halfway through the transaction, in which case we reconnect and
169 restart the txn). Therefore it is best that any side-effects in your coderef
170 are idempotent (that is, can be re-executed multiple times and get the
171 same result), and that you check up on your side-effects in the case of
179 DBIx::Class::Storage::BlockRunner->new(
182 retry_handler => sub {
183 $_[0]->failed_attempt_count == 1
185 ! $_[0]->storage->connected
192 Starts a transaction.
194 See the preferred L</txn_do> method, which allows for
195 an entire code block to be executed transactionally.
202 if($self->transaction_depth == 0) {
203 $self->debugobj->txn_begin()
205 $self->_exec_txn_begin;
207 elsif ($self->auto_savepoint) {
210 $self->{transaction_depth}++;
216 Issues a commit of the current transaction.
218 It does I<not> perform an actual storage commit unless there's a DBIx::Class
219 transaction currently in effect (i.e. you called L</txn_begin>).
226 if ($self->transaction_depth == 1) {
227 $self->debugobj->txn_commit() if $self->debug;
228 $self->_exec_txn_commit;
229 $self->{transaction_depth}--;
231 elsif($self->transaction_depth > 1) {
232 $self->{transaction_depth}--;
233 $self->svp_release if $self->auto_savepoint;
236 $self->throw_exception( 'Refusing to commit without a started transaction' );
242 Issues a rollback of the current transaction. A nested rollback will
243 throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
244 which allows the rollback to propagate to the outermost transaction.
251 if ($self->transaction_depth == 1) {
252 $self->debugobj->txn_rollback() if $self->debug;
253 $self->_exec_txn_rollback;
254 $self->{transaction_depth}--;
256 elsif ($self->transaction_depth > 1) {
257 $self->{transaction_depth}--;
259 if ($self->auto_savepoint) {
264 DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION->throw(
265 "A txn_rollback in nested transaction is ineffective! (depth $self->{transaction_depth})"
270 $self->throw_exception( 'Refusing to roll back without a started transaction' );
276 Arguments: $savepoint_name?
278 Created a new savepoint using the name provided as argument. If no name
279 is provided, a random name will be used.
284 my ($self, $name) = @_;
286 $self->throw_exception ("You can't use savepoints outside a transaction")
287 unless $self->transaction_depth;
289 my $exec = $self->can('_exec_svp_begin')
290 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
292 $name = $self->_svp_generate_name
293 unless defined $name;
295 push @{ $self->{savepoints} }, $name;
297 $self->debugobj->svp_begin($name) if $self->debug;
299 $exec->($self, $name);
302 sub _svp_generate_name {
304 return 'savepoint_'.scalar(@{ $self->{'savepoints'} });
310 Arguments: $savepoint_name?
312 Release the savepoint provided as argument. If none is provided,
313 release the savepoint created most recently. This will implicitly
314 release all savepoints created after the one explicitly released as well.
319 my ($self, $name) = @_;
321 $self->throw_exception ("You can't use savepoints outside a transaction")
322 unless $self->transaction_depth;
324 my $exec = $self->can('_exec_svp_release')
325 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
328 my @stack = @{ $self->savepoints };
331 do { $svp = pop @stack } until $svp eq $name;
333 $self->throw_exception ("Savepoint '$name' does not exist")
336 $self->savepoints(\@stack); # put back what's left
339 $name = pop @{ $self->savepoints }
340 or $self->throw_exception('No savepoints to release');;
343 $self->debugobj->svp_release($name) if $self->debug;
345 $exec->($self, $name);
350 Arguments: $savepoint_name?
352 Rollback to the savepoint provided as argument. If none is provided,
353 rollback to the savepoint created most recently. This will implicitly
354 release all savepoints created after the savepoint we rollback to.
359 my ($self, $name) = @_;
361 $self->throw_exception ("You can't use savepoints outside a transaction")
362 unless $self->transaction_depth;
364 my $exec = $self->can('_exec_svp_rollback')
365 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
368 my @stack = @{ $self->savepoints };
371 # a rollback doesn't remove the named savepoint,
372 # only everything after it
373 while (@stack and $stack[-1] ne $name) {
377 $self->throw_exception ("Savepoint '$name' does not exist")
380 $self->savepoints(\@stack); # put back what's left
383 $name = $self->savepoints->[-1]
384 or $self->throw_exception('No savepoints to rollback');;
387 $self->debugobj->svp_rollback($name) if $self->debug;
389 $exec->($self, $name);
392 =head2 txn_scope_guard
394 An alternative way of transaction handling based on
395 L<DBIx::Class::Storage::TxnScopeGuard>:
397 my $txn_guard = $storage->txn_scope_guard;
399 $result->col1("val1");
404 If an exception occurs, or the guard object otherwise leaves the scope
405 before C<< $txn_guard->commit >> is called, the transaction will be rolled
406 back by an explicit L</txn_rollback> call. In essence this is akin to
407 using a L</txn_begin>/L</txn_commit> pair, without having to worry
408 about calling L</txn_rollback> at the right places. Note that since there
409 is no defined code closure, there will be no retries and other magic upon
410 database disconnection. If you need such functionality see L</txn_do>.
414 sub txn_scope_guard {
415 return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
420 Returns a C<sql_maker> object - normally an object of class
421 C<DBIx::Class::SQLMaker>.
425 sub sql_maker { die "Virtual method!" }
429 Causes trace information to be emitted on the L</debugobj> object.
430 (or C<STDERR> if L</debugobj> has not specifically been set).
432 This is the equivalent to setting L</DBIC_TRACE> in your
437 Set or retrieve the filehandle used for trace/debug output. This should be
438 an IO::Handle compatible object (only the C<print> method is used). Initially
439 set to be STDERR - although see information on the
440 L<DBIC_TRACE> environment variable.
447 if ($self->debugobj->can('debugfh')) {
448 return $self->debugobj->debugfh(@_);
454 Sets or retrieves the object used for metric collection. Defaults to an instance
455 of L<DBIx::Class::Storage::Statistics> that is compatible with the original
456 method of using a coderef as a callback. See the aforementioned Statistics
457 class for more information.
465 return $self->{debugobj} = $_[0];
468 $self->{debugobj} ||= do {
469 if (my $profile = $ENV{DBIC_TRACE_PROFILE}) {
470 require DBIx::Class::Storage::Debug::PrettyPrint;
473 if ($profile =~ /^\.?\//) {
477 Config::Any->load_files({ files => [$profile], use_ext => 1 });
479 # sanitize the error message a bit
480 $_ =~ s/at \s+ .+ Storage\.pm \s line \s \d+ $//x;
481 $self->throw_exception("Failure processing \$ENV{DBIC_TRACE_PROFILE}: $_");
484 @pp_args = values %{$cfg->[0]};
487 @pp_args = { profile => $profile };
491 # Hash::Merge is a sorry piece of shit and tramples all over $@
492 # *without* throwing an exception
493 # This is a rather serious problem in the debug codepath
494 # Insulate the condition here with a try{} until a review of
495 # DBIx::Class::Storage::Debug::PrettyPrint takes place
496 # we do rethrow the error unconditionally, the only reason
497 # to try{} is to preserve the precise state of $@ (down
498 # to the scalar (if there is one) address level)
500 # Yes I am aware this is fragile and TxnScopeGuard needs
501 # a better fix. This is another yak to shave... :(
503 DBIx::Class::Storage::Debug::PrettyPrint->new(@pp_args);
505 $self->throw_exception($_);
509 require DBIx::Class::Storage::Statistics;
510 DBIx::Class::Storage::Statistics->new
517 Sets a callback to be executed each time a statement is run; takes a sub
518 reference. Callback is executed as $sub->($op, $info) where $op is
519 SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
521 See L</debugobj> for a better way.
528 if ($self->debugobj->can('callback')) {
529 return $self->debugobj->callback(@_);
535 The cursor class for this Storage object.
541 Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
542 Storage class). This would normally be called through
543 L<DBIx::Class::Schema/deploy>.
547 sub deploy { die "Virtual method!" }
551 The arguments of C<connect_info> are always a single array reference,
552 and are Storage-handler specific.
554 This is normally accessed via L<DBIx::Class::Schema/connection>, which
555 encapsulates its argument list in an arrayref before calling
556 C<connect_info> here.
560 sub connect_info { die "Virtual method!" }
564 Handle a select statement.
568 sub select { die "Virtual method!" }
572 Handle an insert statement.
576 sub insert { die "Virtual method!" }
580 Handle an update statement.
584 sub update { die "Virtual method!" }
588 Handle a delete statement.
592 sub delete { die "Virtual method!" }
596 Performs a select, fetch and return of data - handles a single row
601 sub select_single { die "Virtual method!" }
603 =head2 columns_info_for
605 Returns metadata for the given source's columns. This
606 is *deprecated*, and will be removed before 1.0. You should
607 be specifying the metadata yourself if you need it.
611 sub columns_info_for { die "Virtual method!" }
613 =head1 ENVIRONMENT VARIABLES
617 If C<DBIC_TRACE> is set then trace information
618 is produced (as when the L</debug> method is set).
620 If the value is of the form C<1=/path/name> then the trace output is
621 written to the file C</path/name>.
623 This environment variable is checked when the storage object is first
624 created (when you call connect on your schema). So, run-time changes
625 to this environment variable will not take effect unless you also
626 re-connect on your schema.
628 =head2 DBIC_TRACE_PROFILE
630 If C<DBIC_TRACE_PROFILE> is set, L<DBIx::Class::Storage::Debug::PrettyPrint>
631 will be used to format the output from C<DBIC_TRACE>. The value it
632 is set to is the C<profile> that it will be used. If the value is a
633 filename the file is read with L<Config::Any> and the results are
634 used as the configuration for tracing. See L<SQL::Abstract::Tree/new>
635 for what that structure should look like.
638 =head2 DBIX_CLASS_STORAGE_DBI_DEBUG
640 Old name for DBIC_TRACE
644 L<DBIx::Class::Storage::DBI> - reference storage implementation using
645 SQL::Abstract and DBI.
647 =head1 AUTHOR AND CONTRIBUTORS
649 See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class
653 You may distribute this code under the same terms as Perl itself.