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1 | package DBIx::Class::Storage; |
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2 | |
3 | use strict; |
4 | use warnings; |
5 | |
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6 | use base qw/DBIx::Class/; |
7 | |
8 | use Scalar::Util qw/weaken/; |
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9 | use Carp::Clan qw/^DBIx::Class/; |
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10 | use IO::File; |
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11 | use DBIx::Class::Storage::TxnScopeGuard; |
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12 | |
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13 | __PACKAGE__->mk_group_accessors('simple' => qw/debug debugobj schema/); |
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14 | __PACKAGE__->mk_group_accessors('inherited' => 'cursor_class'); |
15 | |
16 | __PACKAGE__->cursor_class('DBIx::Class::Cursor'); |
17 | |
18 | sub cursor { shift->cursor_class(@_); } |
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19 | |
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20 | package # Hide from PAUSE |
21 | DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION; |
22 | |
23 | use overload '"' => sub { |
24 | 'DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION' |
25 | }; |
26 | |
27 | sub new { |
28 | my $class = shift; |
29 | my $self = {}; |
30 | return bless $self, $class; |
31 | } |
32 | |
33 | package DBIx::Class::Storage; |
34 | |
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35 | =head1 NAME |
36 | |
37 | DBIx::Class::Storage - Generic Storage Handler |
38 | |
39 | =head1 DESCRIPTION |
40 | |
41 | A base implementation of common Storage methods. For specific |
42 | information about L<DBI>-based storage, see L<DBIx::Class::Storage::DBI>. |
43 | |
44 | =head1 METHODS |
45 | |
46 | =head2 new |
47 | |
48 | Arguments: $schema |
49 | |
50 | Instantiates the Storage object. |
51 | |
52 | =cut |
53 | |
54 | sub new { |
55 | my ($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 | |
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65 | #my $fh; |
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66 | |
67 | my $debug_env = $ENV{DBIX_CLASS_STORAGE_DBI_DEBUG} |
68 | || $ENV{DBIC_TRACE}; |
69 | |
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70 | $new->debug(1) if $debug_env; |
71 | |
72 | $new; |
73 | } |
74 | |
75 | =head2 set_schema |
76 | |
77 | Used to reset the schema class or object which owns this |
78 | storage object, such as during L<DBIx::Class::Schema/clone>. |
79 | |
80 | =cut |
81 | |
82 | sub set_schema { |
83 | my ($self, $schema) = @_; |
84 | $self->schema($schema); |
85 | weaken($self->{schema}) if ref $self->{schema}; |
86 | } |
87 | |
88 | =head2 connected |
89 | |
90 | Returns true if we have an open storage connection, false |
91 | if it is not (yet) open. |
92 | |
93 | =cut |
94 | |
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95 | sub connected { die "Virtual method!" } |
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96 | |
97 | =head2 disconnect |
98 | |
99 | Closes any open storage connection unconditionally. |
100 | |
101 | =cut |
102 | |
103 | sub disconnect { die "Virtual method!" } |
104 | |
105 | =head2 ensure_connected |
106 | |
107 | Initiate a connection to the storage if one isn't already open. |
108 | |
109 | =cut |
110 | |
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111 | sub ensure_connected { die "Virtual method!" } |
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112 | |
113 | =head2 throw_exception |
114 | |
115 | Throws an exception - croaks. |
116 | |
117 | =cut |
118 | |
119 | sub throw_exception { |
120 | my $self = shift; |
121 | |
122 | $self->schema->throw_exception(@_) if $self->schema; |
123 | croak @_; |
124 | } |
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125 | |
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126 | =head2 txn_do |
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127 | |
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128 | =over 4 |
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129 | |
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130 | =item Arguments: C<$coderef>, @coderef_args? |
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131 | |
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132 | =item Return Value: The return value of $coderef |
133 | |
134 | =back |
135 | |
136 | Executes C<$coderef> with (optional) arguments C<@coderef_args> atomically, |
137 | returning its result (if any). If an exception is caught, a rollback is issued |
138 | and the exception is rethrown. If the rollback fails, (i.e. throws an |
139 | exception) an exception is thrown that includes a "Rollback failed" message. |
140 | |
141 | For 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 | |
167 | In a nested transaction (calling txn_do() from within a txn_do() coderef) only |
168 | the outermost transaction will issue a L</txn_commit>, and txn_do() can be |
169 | called in void, scalar and list context and it will behave as expected. |
170 | |
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171 | Unlike L</DBIx::Class::Storage/dbh_do>, the coderef will I<not> be |
172 | automatically retried on error. |
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173 | |
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174 | =cut |
175 | |
176 | sub txn_do { |
177 | my ($self, $coderef, @args) = @_; |
178 | |
179 | ref $coderef eq 'CODE' or $self->throw_exception |
180 | ('$coderef must be a CODE reference'); |
181 | |
182 | my (@return_values, $return_value); |
183 | |
184 | $self->txn_begin; # If this throws an exception, no rollback is needed |
185 | |
186 | my $wantarray = wantarray; # Need to save this since the context |
187 | # inside the eval{} block is independent |
188 | # of the context that called txn_do() |
189 | eval { |
190 | |
191 | # Need to differentiate between scalar/list context to allow for |
192 | # returning a list in scalar context to get the size of the list |
193 | if ($wantarray) { |
194 | # list context |
195 | @return_values = $coderef->(@args); |
196 | } elsif (defined $wantarray) { |
197 | # scalar context |
198 | $return_value = $coderef->(@args); |
199 | } else { |
200 | # void context |
201 | $coderef->(@args); |
202 | } |
203 | $self->txn_commit; |
204 | }; |
205 | |
206 | if ($@) { |
207 | my $error = $@; |
208 | |
209 | eval { |
210 | $self->txn_rollback; |
211 | }; |
212 | |
213 | if ($@) { |
214 | my $rollback_error = $@; |
215 | my $exception_class = "DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION"; |
216 | $self->throw_exception($error) # propagate nested rollback |
217 | if $rollback_error =~ /$exception_class/; |
218 | |
219 | $self->throw_exception( |
220 | "Transaction aborted: $error. Rollback failed: ${rollback_error}" |
221 | ); |
222 | } else { |
223 | $self->throw_exception($error); # txn failed but rollback succeeded |
224 | } |
225 | } |
226 | |
227 | return $wantarray ? @return_values : $return_value; |
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228 | } |
229 | |
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230 | =head2 txn_begin |
231 | |
232 | Starts a transaction. |
233 | |
234 | See the preferred L</txn_do> method, which allows for |
235 | an entire code block to be executed transactionally. |
236 | |
237 | =cut |
238 | |
239 | sub txn_begin { die "Virtual method!" } |
240 | |
241 | =head2 txn_commit |
242 | |
243 | Issues a commit of the current transaction. |
244 | |
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245 | It does I<not> perform an actual storage commit unless there's a DBIx::Class |
246 | transaction currently in effect (i.e. you called L</txn_begin>). |
247 | |
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248 | =cut |
249 | |
250 | sub txn_commit { die "Virtual method!" } |
251 | |
252 | =head2 txn_rollback |
253 | |
254 | Issues a rollback of the current transaction. A nested rollback will |
255 | throw a L<DBIx::Class::Storage::NESTED_ROLLBACK_EXCEPTION> exception, |
256 | which allows the rollback to propagate to the outermost transaction. |
257 | |
258 | =cut |
259 | |
260 | sub txn_rollback { die "Virtual method!" } |
261 | |
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262 | =head2 svp_begin |
263 | |
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264 | Arguments: $savepoint_name? |
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265 | |
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266 | Created a new savepoint using the name provided as argument. If no name |
267 | is provided, a random name will be used. |
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268 | |
269 | =cut |
270 | |
271 | sub svp_begin { die "Virtual method!" } |
272 | |
273 | =head2 svp_release |
274 | |
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275 | Arguments: $savepoint_name? |
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276 | |
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277 | Release the savepoint provided as argument. If none is provided, |
278 | release the savepoint created most recently. This will implicitly |
279 | release all savepoints created after the one explicitly released as well. |
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280 | |
281 | =cut |
282 | |
283 | sub svp_release { die "Virtual method!" } |
284 | |
285 | =head2 svp_rollback |
286 | |
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287 | Arguments: $savepoint_name? |
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288 | |
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289 | Rollback to the savepoint provided as argument. If none is provided, |
290 | rollback to the savepoint created most recently. This will implicitly |
291 | release all savepoints created after the savepoint we rollback to. |
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292 | |
293 | =cut |
294 | |
295 | sub svp_rollback { die "Virtual method!" } |
296 | |
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297 | =for comment |
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298 | |
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299 | =head2 txn_scope_guard |
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300 | |
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301 | An alternative way of transaction handling based on |
302 | L<DBIx::Class::Storage::TxnScopeGuard>: |
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303 | |
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304 | my $txn_guard = $storage->txn_scope_guard; |
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305 | |
306 | $row->col1("val1"); |
307 | $row->update; |
308 | |
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309 | $txn_guard->commit; |
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310 | |
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311 | If an exception occurs, or the guard object otherwise leaves the scope |
312 | before C<< $txn_guard->commit >> is called, the transaction will be rolled |
313 | back by an explicit L</txn_rollback> call. In essence this is akin to |
314 | using a L</txn_begin>/L</txn_commit> pair, without having to worry |
315 | about calling L</txn_rollback> at the right places. Note that since there |
316 | is no defined code closure, there will be no retries and other magic upon |
317 | database disconnection. If you need such functionality see L</txn_do>. |
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318 | |
319 | =cut |
320 | |
321 | sub txn_scope_guard { |
322 | return DBIx::Class::Storage::TxnScopeGuard->new($_[0]); |
323 | } |
324 | |
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325 | =head2 sql_maker |
326 | |
327 | Returns a C<sql_maker> object - normally an object of class |
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328 | C<DBIx::Class::SQLAHacks>. |
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329 | |
330 | =cut |
331 | |
332 | sub sql_maker { die "Virtual method!" } |
333 | |
334 | =head2 debug |
335 | |
336 | Causes trace information to be emitted on the C<debugobj> object. |
337 | (or C<STDERR> if C<debugobj> has not specifically been set). |
338 | |
339 | This is the equivalent to setting L</DBIC_TRACE> in your |
340 | shell environment. |
341 | |
342 | =head2 debugfh |
343 | |
344 | Set or retrieve the filehandle used for trace/debug output. This should be |
345 | an IO::Handle compatible ojbect (only the C<print> method is used. Initially |
346 | set to be STDERR - although see information on the |
347 | L<DBIC_TRACE> environment variable. |
348 | |
349 | =cut |
350 | |
351 | sub debugfh { |
352 | my $self = shift; |
353 | |
354 | if ($self->debugobj->can('debugfh')) { |
355 | return $self->debugobj->debugfh(@_); |
356 | } |
357 | } |
358 | |
359 | =head2 debugobj |
360 | |
361 | Sets or retrieves the object used for metric collection. Defaults to an instance |
362 | of L<DBIx::Class::Storage::Statistics> that is compatible with the original |
363 | method of using a coderef as a callback. See the aforementioned Statistics |
364 | class for more information. |
365 | |
366 | =head2 debugcb |
367 | |
368 | Sets a callback to be executed each time a statement is run; takes a sub |
369 | reference. Callback is executed as $sub->($op, $info) where $op is |
370 | SELECT/INSERT/UPDATE/DELETE and $info is what would normally be printed. |
371 | |
372 | See L<debugobj> for a better way. |
373 | |
374 | =cut |
375 | |
376 | sub debugcb { |
377 | my $self = shift; |
378 | |
379 | if ($self->debugobj->can('callback')) { |
380 | return $self->debugobj->callback(@_); |
381 | } |
382 | } |
383 | |
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384 | =head2 cursor_class |
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385 | |
386 | The cursor class for this Storage object. |
387 | |
388 | =cut |
389 | |
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390 | =head2 deploy |
391 | |
392 | Deploy the tables to storage (CREATE TABLE and friends in a SQL-based |
393 | Storage class). This would normally be called through |
394 | L<DBIx::Class::Schema/deploy>. |
395 | |
396 | =cut |
397 | |
398 | sub deploy { die "Virtual method!" } |
399 | |
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400 | =head2 connect_info |
401 | |
402 | The arguments of C<connect_info> are always a single array reference, |
403 | and are Storage-handler specific. |
404 | |
405 | This is normally accessed via L<DBIx::Class::Schema/connection>, which |
406 | encapsulates its argument list in an arrayref before calling |
407 | C<connect_info> here. |
408 | |
409 | =cut |
410 | |
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411 | sub connect_info { die "Virtual method!" } |
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412 | |
413 | =head2 select |
414 | |
415 | Handle a select statement. |
416 | |
417 | =cut |
418 | |
419 | sub select { die "Virtual method!" } |
420 | |
421 | =head2 insert |
422 | |
423 | Handle an insert statement. |
424 | |
425 | =cut |
426 | |
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427 | sub insert { die "Virtual method!" } |
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428 | |
429 | =head2 update |
430 | |
431 | Handle an update statement. |
432 | |
433 | =cut |
434 | |
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435 | sub update { die "Virtual method!" } |
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436 | |
437 | =head2 delete |
438 | |
439 | Handle a delete statement. |
440 | |
441 | =cut |
442 | |
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443 | sub delete { die "Virtual method!" } |
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444 | |
445 | =head2 select_single |
446 | |
447 | Performs a select, fetch and return of data - handles a single row |
448 | only. |
449 | |
450 | =cut |
451 | |
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452 | sub select_single { die "Virtual method!" } |
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453 | |
454 | =head2 columns_info_for |
455 | |
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456 | Returns metadata for the given source's columns. This |
457 | is *deprecated*, and will be removed before 1.0. You should |
458 | be specifying the metadata yourself if you need it. |
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459 | |
460 | =cut |
461 | |
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462 | sub columns_info_for { die "Virtual method!" } |
463 | |
464 | =head1 ENVIRONMENT VARIABLES |
465 | |
466 | =head2 DBIC_TRACE |
467 | |
468 | If C<DBIC_TRACE> is set then trace information |
469 | is produced (as when the L<debug> method is set). |
470 | |
471 | If the value is of the form C<1=/path/name> then the trace output is |
472 | written to the file C</path/name>. |
473 | |
474 | This environment variable is checked when the storage object is first |
475 | created (when you call connect on your schema). So, run-time changes |
476 | to this environment variable will not take effect unless you also |
477 | re-connect on your schema. |
478 | |
479 | =head2 DBIX_CLASS_STORAGE_DBI_DEBUG |
480 | |
481 | Old name for DBIC_TRACE |
482 | |
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483 | =head1 SEE ALSO |
484 | |
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485 | L<DBIx::Class::Storage::DBI> - reference storage implementation using |
486 | SQL::Abstract and DBI. |
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487 | |
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488 | =head1 AUTHORS |
489 | |
490 | Matt S. Trout <mst@shadowcatsystems.co.uk> |
491 | |
492 | Andy Grundman <andy@hybridized.org> |
493 | |
494 | =head1 LICENSE |
495 | |
496 | You may distribute this code under the same terms as Perl itself. |
497 | |
498 | =cut |
499 | |
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500 | 1; |