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}--;
230 $self->savepoints([]);
232 elsif($self->transaction_depth > 1) {
233 $self->{transaction_depth}--;
234 $self->svp_release if $self->auto_savepoint;
237 $self->throw_exception( 'Refusing to commit without a started transaction' );
243 Issues a rollback of the current transaction. A nested rollback will
244 throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
245 which allows the rollback to propagate to the outermost transaction.
252 if ($self->transaction_depth == 1) {
253 $self->debugobj->txn_rollback() if $self->debug;
254 $self->_exec_txn_rollback;
255 $self->{transaction_depth}--;
256 $self->savepoints([]);
258 elsif ($self->transaction_depth > 1) {
259 $self->{transaction_depth}--;
261 if ($self->auto_savepoint) {
266 DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION->throw(
267 "A txn_rollback in nested transaction is ineffective! (depth $self->{transaction_depth})"
272 $self->throw_exception( 'Refusing to roll back without a started transaction' );
278 Arguments: $savepoint_name?
280 Created a new savepoint using the name provided as argument. If no name
281 is provided, a random name will be used.
286 my ($self, $name) = @_;
288 $self->throw_exception ("You can't use savepoints outside a transaction")
289 unless $self->transaction_depth;
291 my $exec = $self->can('_exec_svp_begin')
292 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
294 $name = $self->_svp_generate_name
295 unless defined $name;
297 push @{ $self->{savepoints} }, $name;
299 $self->debugobj->svp_begin($name) if $self->debug;
301 $exec->($self, $name);
304 sub _svp_generate_name {
306 return 'savepoint_'.scalar(@{ $self->{'savepoints'} });
312 Arguments: $savepoint_name?
314 Release the savepoint provided as argument. If none is provided,
315 release the savepoint created most recently. This will implicitly
316 release all savepoints created after the one explicitly released as well.
321 my ($self, $name) = @_;
323 $self->throw_exception ("You can't use savepoints outside a transaction")
324 unless $self->transaction_depth;
326 my $exec = $self->can('_exec_svp_release')
327 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
330 my @stack = @{ $self->savepoints };
333 while( $svp ne $name ) {
335 $self->throw_exception ("Savepoint '$name' does not exist")
341 $self->savepoints(\@stack); # put back what's left
344 $name = pop @{ $self->savepoints }
345 or $self->throw_exception('No savepoints to release');;
348 $self->debugobj->svp_release($name) if $self->debug;
350 $exec->($self, $name);
355 Arguments: $savepoint_name?
357 Rollback to the savepoint provided as argument. If none is provided,
358 rollback to the savepoint created most recently. This will implicitly
359 release all savepoints created after the savepoint we rollback to.
364 my ($self, $name) = @_;
366 $self->throw_exception ("You can't use savepoints outside a transaction")
367 unless $self->transaction_depth;
369 my $exec = $self->can('_exec_svp_rollback')
370 or $self->throw_exception ("Your Storage implementation doesn't support savepoints");
373 my @stack = @{ $self->savepoints };
376 # a rollback doesn't remove the named savepoint,
377 # only everything after it
378 while (@stack and $stack[-1] ne $name) {
382 $self->throw_exception ("Savepoint '$name' does not exist")
385 $self->savepoints(\@stack); # put back what's left
388 $name = $self->savepoints->[-1]
389 or $self->throw_exception('No savepoints to rollback');;
392 $self->debugobj->svp_rollback($name) if $self->debug;
394 $exec->($self, $name);
397 =head2 txn_scope_guard
399 An alternative way of transaction handling based on
400 L<DBIx::Class::Storage::TxnScopeGuard>:
402 my $txn_guard = $storage->txn_scope_guard;
404 $result->col1("val1");
409 If an exception occurs, or the guard object otherwise leaves the scope
410 before C<< $txn_guard->commit >> is called, the transaction will be rolled
411 back by an explicit L</txn_rollback> call. In essence this is akin to
412 using a L</txn_begin>/L</txn_commit> pair, without having to worry
413 about calling L</txn_rollback> at the right places. Note that since there
414 is no defined code closure, there will be no retries and other magic upon
415 database disconnection. If you need such functionality see L</txn_do>.
419 sub txn_scope_guard {
420 return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
425 Returns a C<sql_maker> object - normally an object of class
426 C<DBIx::Class::SQLMaker>.
430 sub sql_maker { die "Virtual method!" }
434 Causes trace information to be emitted on the L</debugobj> object.
435 (or C<STDERR> if L</debugobj> has not specifically been set).
437 This is the equivalent to setting L</DBIC_TRACE> in your
442 An opportunistic proxy to L<< ->debugobj->debugfh(@_)
443 |DBIx::Class::Storage::Statistics/debugfh >>
444 If the currently set L</debugobj> does not have a L</debugfh> method, caling
452 if ($self->debugobj->can('debugfh')) {
453 return $self->debugobj->debugfh(@_);
459 Sets or retrieves the object used for metric collection. Defaults to an instance
460 of L<DBIx::Class::Storage::Statistics> that is compatible with the original
461 method of using a coderef as a callback. See the aforementioned Statistics
462 class for more information.
470 return $self->{debugobj} = $_[0];
473 $self->{debugobj} ||= do {
474 if (my $profile = $ENV{DBIC_TRACE_PROFILE}) {
475 require DBIx::Class::Storage::Debug::PrettyPrint;
478 if ($profile =~ /^\.?\//) {
482 Config::Any->load_files({ files => [$profile], use_ext => 1 });
484 # sanitize the error message a bit
485 $_ =~ s/at \s+ .+ Storage\.pm \s line \s \d+ $//x;
486 $self->throw_exception("Failure processing \$ENV{DBIC_TRACE_PROFILE}: $_");
489 @pp_args = values %{$cfg->[0]};
492 @pp_args = { profile => $profile };
496 # Hash::Merge is a sorry piece of shit and tramples all over $@
497 # *without* throwing an exception
498 # This is a rather serious problem in the debug codepath
499 # Insulate the condition here with a try{} until a review of
500 # DBIx::Class::Storage::Debug::PrettyPrint takes place
501 # we do rethrow the error unconditionally, the only reason
502 # to try{} is to preserve the precise state of $@ (down
503 # to the scalar (if there is one) address level)
505 # Yes I am aware this is fragile and TxnScopeGuard needs
506 # a better fix. This is another yak to shave... :(
508 DBIx::Class::Storage::Debug::PrettyPrint->new(@pp_args);
510 $self->throw_exception($_);
514 require DBIx::Class::Storage::Statistics;
515 DBIx::Class::Storage::Statistics->new
522 Sets a callback to be executed each time a statement is run; takes a sub
523 reference. Callback is executed as $sub->($op, $info) where $op is
524 SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
526 See L</debugobj> for a better way.
533 if ($self->debugobj->can('callback')) {
534 return $self->debugobj->callback(@_);
540 The cursor class for this Storage object.
546 Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
547 Storage class). This would normally be called through
548 L<DBIx::Class::Schema/deploy>.
552 sub deploy { die "Virtual method!" }
556 The arguments of C<connect_info> are always a single array reference,
557 and are Storage-handler specific.
559 This is normally accessed via L<DBIx::Class::Schema/connection>, which
560 encapsulates its argument list in an arrayref before calling
561 C<connect_info> here.
565 sub connect_info { die "Virtual method!" }
569 Handle a select statement.
573 sub select { die "Virtual method!" }
577 Handle an insert statement.
581 sub insert { die "Virtual method!" }
585 Handle an update statement.
589 sub update { die "Virtual method!" }
593 Handle a delete statement.
597 sub delete { die "Virtual method!" }
601 Performs a select, fetch and return of data - handles a single row
606 sub select_single { die "Virtual method!" }
608 =head2 columns_info_for
610 Returns metadata for the given source's columns. This
611 is *deprecated*, and will be removed before 1.0. You should
612 be specifying the metadata yourself if you need it.
616 sub columns_info_for { die "Virtual method!" }
618 =head1 ENVIRONMENT VARIABLES
622 If C<DBIC_TRACE> is set then trace information
623 is produced (as when the L</debug> method is set).
625 If the value is of the form C<1=/path/name> then the trace output is
626 written to the file C</path/name>.
628 This environment variable is checked when the storage object is first
629 created (when you call connect on your schema). So, run-time changes
630 to this environment variable will not take effect unless you also
631 re-connect on your schema.
633 =head2 DBIC_TRACE_PROFILE
635 If C<DBIC_TRACE_PROFILE> is set, L<DBIx::Class::Storage::Debug::PrettyPrint>
636 will be used to format the output from C<DBIC_TRACE>. The value it
637 is set to is the C<profile> that it will be used. If the value is a
638 filename the file is read with L<Config::Any> and the results are
639 used as the configuration for tracing. See L<SQL::Abstract::Tree/new>
640 for what that structure should look like.
642 =head2 DBIX_CLASS_STORAGE_DBI_DEBUG
644 Old name for DBIC_TRACE
648 L<DBIx::Class::Storage::DBI> - reference storage implementation using
649 SQL::Abstract and DBI.
651 =head1 FURTHER QUESTIONS?
653 Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
655 =head1 COPYRIGHT AND LICENSE
657 This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
658 by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
659 redistribute it and/or modify it under the same terms as the
660 L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.