Fix the merge with txn_scope_guard() and put the necessary =cut in.
[dbsrgits/DBIx-Class-Historic.git] / lib / DBIx / Class / Storage.pm
CommitLineData
4012acd8 1package DBIx::Class::Storage;
a62cf8d4 2
3use strict;
4use warnings;
5
046ad905 6use base qw/DBIx::Class/;
7
8use Scalar::Util qw/weaken/;
aaba9524 9use Carp::Clan qw/^DBIx::Class/;
942cd0c1 10use IO::File;
1bc193ac 11use DBIx::Class::Storage::TxnScopeGuard;
046ad905 12
046ad905 13__PACKAGE__->mk_group_accessors('simple' => qw/debug debugobj schema/);
e4eb8ee1 14__PACKAGE__->mk_group_accessors('inherited' => 'cursor_class');
15
16__PACKAGE__->cursor_class('DBIx::Class::Cursor');
17
18sub cursor { shift->cursor_class(@_); }
046ad905 19
4012acd8 20package # Hide from PAUSE
21 DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION;
22
23use overload '"' => sub {
24 'DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION'
25};
26
27sub new {
28 my $class = shift;
29 my $self = {};
30 return bless $self, $class;
31}
32
33package DBIx::Class::Storage;
34
046ad905 35=head1 NAME
36
37DBIx::Class::Storage - Generic Storage Handler
38
39=head1 DESCRIPTION
40
41A base implementation of common Storage methods. For specific
42information about L<DBI>-based storage, see L<DBIx::Class::Storage::DBI>.
43
44=head1 METHODS
45
46=head2 new
47
48Arguments: $schema
49
50Instantiates the Storage object.
51
52=cut
53
54sub new {
55 my ($self, $schema) = @_;
56
57 $self = ref $self if ref $self;
58
59 my $new = {};
60 bless $new, $self;
61
62 $new->set_schema($schema);
63 $new->debugobj(new DBIx::Class::Storage::Statistics());
64
70f39278 65 #my $fh;
046ad905 66
67 my $debug_env = $ENV{DBIX_CLASS_STORAGE_DBI_DEBUG}
68 || $ENV{DBIC_TRACE};
69
046ad905 70 $new->debug(1) if $debug_env;
71
72 $new;
73}
74
75=head2 set_schema
76
77Used to reset the schema class or object which owns this
78storage object, such as during L<DBIx::Class::Schema/clone>.
79
80=cut
81
82sub set_schema {
83 my ($self, $schema) = @_;
84 $self->schema($schema);
85 weaken($self->{schema}) if ref $self->{schema};
86}
87
88=head2 connected
89
90Returns true if we have an open storage connection, false
91if it is not (yet) open.
92
93=cut
94
a62cf8d4 95sub connected { die "Virtual method!" }
046ad905 96
97=head2 disconnect
98
99Closes any open storage connection unconditionally.
100
101=cut
102
103sub disconnect { die "Virtual method!" }
104
105=head2 ensure_connected
106
107Initiate a connection to the storage if one isn't already open.
108
109=cut
110
a62cf8d4 111sub ensure_connected { die "Virtual method!" }
046ad905 112
113=head2 throw_exception
114
115Throws an exception - croaks.
116
117=cut
118
119sub throw_exception {
120 my $self = shift;
121
122 $self->schema->throw_exception(@_) if $self->schema;
123 croak @_;
124}
a62cf8d4 125
4012acd8 126=head2 txn_do
a62cf8d4 127
4012acd8 128=over 4
a62cf8d4 129
4012acd8 130=item Arguments: C<$coderef>, @coderef_args?
a62cf8d4 131
4012acd8 132=item Return Value: The return value of $coderef
133
134=back
135
136Executes C<$coderef> with (optional) arguments C<@coderef_args> atomically,
137returning its result (if any). If an exception is caught, a rollback is issued
138and the exception is rethrown. If the rollback fails, (i.e. throws an
139exception) an exception is thrown that includes a "Rollback failed" message.
140
141For example,
142
143 my $author_rs = $schema->resultset('Author')->find(1);
144 my @titles = qw/Night Day It/;
145
146 my $coderef = sub {
147 # If any one of these fails, the entire transaction fails
148 $author_rs->create_related('books', {
149 title => $_
150 }) foreach (@titles);
151
152 return $author->books;
153 };
154
155 my $rs;
156 eval {
157 $rs = $schema->txn_do($coderef);
158 };
159
160 if ($@) { # Transaction failed
161 die "something terrible has happened!" #
162 if ($@ =~ /Rollback failed/); # Rollback failed
163
164 deal_with_failed_transaction();
165 }
166
167In a nested transaction (calling txn_do() from within a txn_do() coderef) only
168the outermost transaction will issue a L</txn_commit>, and txn_do() can be
169called in void, scalar and list context and it will behave as expected.
170
6500d50f 171Please note that all of the code in your coderef, including non-DBIx::Class
172code, is part of a transaction. This transaction may fail out halfway, or
173it may get partially double-executed (in the case that our DB connection
174failed halfway through the transaction, in which case we reconnect and
175restart the txn). Therefore it is best that any side-effects in your coderef
176are idempotent (that is, can be re-executed multiple times and get the
177same result), and that you check up on your side-effects in the case of
178transaction failure.
179
4012acd8 180=cut
181
182sub txn_do {
183 my ($self, $coderef, @args) = @_;
184
185 ref $coderef eq 'CODE' or $self->throw_exception
186 ('$coderef must be a CODE reference');
187
188 my (@return_values, $return_value);
189
190 $self->txn_begin; # If this throws an exception, no rollback is needed
191
192 my $wantarray = wantarray; # Need to save this since the context
193 # inside the eval{} block is independent
194 # of the context that called txn_do()
195 eval {
196
197 # Need to differentiate between scalar/list context to allow for
198 # returning a list in scalar context to get the size of the list
199 if ($wantarray) {
200 # list context
201 @return_values = $coderef->(@args);
202 } elsif (defined $wantarray) {
203 # scalar context
204 $return_value = $coderef->(@args);
205 } else {
206 # void context
207 $coderef->(@args);
208 }
209 $self->txn_commit;
210 };
211
212 if ($@) {
213 my $error = $@;
214
215 eval {
216 $self->txn_rollback;
217 };
218
219 if ($@) {
220 my $rollback_error = $@;
221 my $exception_class = "DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION";
222 $self->throw_exception($error) # propagate nested rollback
223 if $rollback_error =~ /$exception_class/;
224
225 $self->throw_exception(
226 "Transaction aborted: $error. Rollback failed: ${rollback_error}"
227 );
228 } else {
229 $self->throw_exception($error); # txn failed but rollback succeeded
230 }
231 }
232
233 return $wantarray ? @return_values : $return_value;
a62cf8d4 234}
235
046ad905 236=head2 txn_begin
237
238Starts a transaction.
239
240See the preferred L</txn_do> method, which allows for
241an entire code block to be executed transactionally.
242
243=cut
244
245sub txn_begin { die "Virtual method!" }
246
247=head2 txn_commit
248
249Issues a commit of the current transaction.
250
251=cut
252
253sub txn_commit { die "Virtual method!" }
254
255=head2 txn_rollback
256
257Issues a rollback of the current transaction. A nested rollback will
258throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception,
259which allows the rollback to propagate to the outermost transaction.
260
261=cut
262
263sub txn_rollback { die "Virtual method!" }
264
dd018f09 265=for comment
3b7f3eac 266
1bc193ac 267=head2 txn_scope_guard
268
269Return an object that does stuff.
270
271=cut
272
273sub txn_scope_guard {
274 return DBIx::Class::Storage::TxnScopeGuard->new($_[0]);
275}
276
046ad905 277=head2 sql_maker
278
279Returns a C<sql_maker> object - normally an object of class
280C<DBIC::SQL::Abstract>.
281
282=cut
283
284sub sql_maker { die "Virtual method!" }
285
286=head2 debug
287
288Causes trace information to be emitted on the C<debugobj> object.
289(or C<STDERR> if C<debugobj> has not specifically been set).
290
291This is the equivalent to setting L</DBIC_TRACE> in your
292shell environment.
293
294=head2 debugfh
295
296Set or retrieve the filehandle used for trace/debug output. This should be
297an IO::Handle compatible ojbect (only the C<print> method is used. Initially
298set to be STDERR - although see information on the
299L<DBIC_TRACE> environment variable.
300
301=cut
302
303sub debugfh {
304 my $self = shift;
305
306 if ($self->debugobj->can('debugfh')) {
307 return $self->debugobj->debugfh(@_);
308 }
309}
310
311=head2 debugobj
312
313Sets or retrieves the object used for metric collection. Defaults to an instance
314of L<DBIx::Class::Storage::Statistics> that is compatible with the original
315method of using a coderef as a callback. See the aforementioned Statistics
316class for more information.
317
318=head2 debugcb
319
320Sets a callback to be executed each time a statement is run; takes a sub
321reference. Callback is executed as $sub->($op, $info) where $op is
322SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed.
323
324See L<debugobj> for a better way.
325
326=cut
327
328sub debugcb {
329 my $self = shift;
330
331 if ($self->debugobj->can('callback')) {
332 return $self->debugobj->callback(@_);
333 }
334}
335
e4eb8ee1 336=head2 cursor_class
046ad905 337
338The cursor class for this Storage object.
339
340=cut
341
046ad905 342=head2 deploy
343
344Deploy the tables to storage (CREATE TABLE and friends in a SQL-based
345Storage class). This would normally be called through
346L<DBIx::Class::Schema/deploy>.
347
348=cut
349
350sub deploy { die "Virtual method!" }
351
a3eaff0e 352=head2 connect_info
353
354The arguments of C<connect_info> are always a single array reference,
355and are Storage-handler specific.
356
357This is normally accessed via L<DBIx::Class::Schema/connection>, which
358encapsulates its argument list in an arrayref before calling
359C<connect_info> here.
360
361=cut
362
046ad905 363sub connect_info { die "Virtual method!" }
a3eaff0e 364
365=head2 select
366
367Handle a select statement.
368
369=cut
370
371sub select { die "Virtual method!" }
372
373=head2 insert
374
375Handle an insert statement.
376
377=cut
378
046ad905 379sub insert { die "Virtual method!" }
a3eaff0e 380
381=head2 update
382
383Handle an update statement.
384
385=cut
386
046ad905 387sub update { die "Virtual method!" }
a3eaff0e 388
389=head2 delete
390
391Handle a delete statement.
392
393=cut
394
046ad905 395sub delete { die "Virtual method!" }
a3eaff0e 396
397=head2 select_single
398
399Performs a select, fetch and return of data - handles a single row
400only.
401
402=cut
403
046ad905 404sub select_single { die "Virtual method!" }
a3eaff0e 405
406=head2 columns_info_for
407
c22c7625 408Returns metadata for the given source's columns. This
409is *deprecated*, and will be removed before 1.0. You should
410be specifying the metadata yourself if you need it.
a3eaff0e 411
412=cut
413
046ad905 414sub columns_info_for { die "Virtual method!" }
415
416=head1 ENVIRONMENT VARIABLES
417
418=head2 DBIC_TRACE
419
420If C<DBIC_TRACE> is set then trace information
421is produced (as when the L<debug> method is set).
422
423If the value is of the form C<1=/path/name> then the trace output is
424written to the file C</path/name>.
425
426This environment variable is checked when the storage object is first
427created (when you call connect on your schema). So, run-time changes
428to this environment variable will not take effect unless you also
429re-connect on your schema.
430
431=head2 DBIX_CLASS_STORAGE_DBI_DEBUG
432
433Old name for DBIC_TRACE
434
ace385bd 435=head1 SEE ALSO
436
437L<DBIx::Class::Storage::DBI> - reference storage inplementation using SQL::Abstract and DBI.
438
046ad905 439=head1 AUTHORS
440
441Matt S. Trout <mst@shadowcatsystems.co.uk>
442
443Andy Grundman <andy@hybridized.org>
444
445=head1 LICENSE
446
447You may distribute this code under the same terms as Perl itself.
448
449=cut
450
a62cf8d4 4511;