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