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