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1 | package DBIx::Class::Storage::DBI::Replicated; |
f5d3a5de |
2 | |
ecb65397 |
3 | BEGIN { |
4 | use Carp::Clan qw/^DBIx::Class/; |
5 | |
6 | ## Modules required for Replication support not required for general DBIC |
7 | ## use, so we explicitly test for these. |
8 | |
9 | my %replication_required = ( |
10 | Moose => '0.54', |
11 | MooseX::AttributeHelpers => '0.12', |
12 | Moose::Util::TypeConstraints => '0.54', |
13 | Class::MOP => '0.63', |
14 | ); |
15 | |
16 | my @didnt_load; |
17 | |
18 | for my $module (keys %replication_required) { |
19 | eval "use $module $replication_required{$module}"; |
20 | push @didnt_load, "$module $replication_required{$module}" |
21 | if $@; |
22 | } |
23 | |
24 | croak("@{[ join ', ', @didnt_load ]} are missing and are required for Replication") |
25 | if @didnt_load; |
26 | } |
27 | |
26ab719a |
28 | use DBIx::Class::Storage::DBI; |
2bf79155 |
29 | use DBIx::Class::Storage::DBI::Replicated::Pool; |
26ab719a |
30 | use DBIx::Class::Storage::DBI::Replicated::Balancer; |
2bf79155 |
31 | |
32 | =head1 NAME |
33 | |
ecb65397 |
34 | DBIx::Class::Storage::DBI::Replicated - BETA Replicated database support |
2bf79155 |
35 | |
36 | =head1 SYNOPSIS |
37 | |
38 | The Following example shows how to change an existing $schema to a replicated |
39 | storage type, add some replicated (readonly) databases, and perform reporting |
955a6df6 |
40 | tasks. |
2bf79155 |
41 | |
64cdad22 |
42 | ## Change storage_type in your schema class |
43 | $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] ); |
44 | |
45 | ## Add some slaves. Basically this is an array of arrayrefs, where each |
46 | ## arrayref is database connect information |
47 | |
48 | $schema->storage->connect_replicants( |
49 | [$dsn1, $user, $pass, \%opts], |
50 | [$dsn2, $user, $pass, \%opts], |
51 | [$dsn3, $user, $pass, \%opts], |
52 | ); |
53 | |
7e38d850 |
54 | ## Now, just use the $schema as normal |
55 | $schema->resultset('Source')->search({name=>'etc'}); |
56 | |
57 | ## You can force a given query to use a particular storage using the search |
58 | ### attribute 'force_pool'. For example: |
59 | |
60 | my $RS = $schema->resultset('Source')->search(undef, {force_pool=>'master'}); |
61 | |
62 | ## Now $RS will force everything (both reads and writes) to use whatever was |
63 | ## setup as the master storage. 'master' is hardcoded to always point to the |
64 | ## Master, but you can also use any Replicant name. Please see: |
65 | ## L<DBIx::Class::Storage::Replicated::Pool> and the replicants attribute for |
66 | ## More. Also see transactions and L</execute_reliably> for alternative ways |
67 | ## to force read traffic to the master. |
68 | |
2bf79155 |
69 | =head1 DESCRIPTION |
70 | |
7e38d850 |
71 | Warning: This class is marked BETA. This has been running a production |
ccb3b897 |
72 | website using MySQL native replication as its backend and we have some decent |
7e38d850 |
73 | test coverage but the code hasn't yet been stressed by a variety of databases. |
74 | Individual DB's may have quirks we are not aware of. Please use this in first |
75 | development and pass along your experiences/bug fixes. |
2bf79155 |
76 | |
77 | This class implements replicated data store for DBI. Currently you can define |
78 | one master and numerous slave database connections. All write-type queries |
79 | (INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master |
80 | database, all read-type queries (SELECTs) go to the slave database. |
81 | |
82 | Basically, any method request that L<DBIx::Class::Storage::DBI> would normally |
bca099a3 |
83 | handle gets delegated to one of the two attributes: L</read_handler> or to |
84 | L</write_handler>. Additionally, some methods need to be distributed |
2bf79155 |
85 | to all existing storages. This way our storage class is a drop in replacement |
86 | for L<DBIx::Class::Storage::DBI>. |
87 | |
88 | Read traffic is spread across the replicants (slaves) occuring to a user |
89 | selected algorithm. The default algorithm is random weighted. |
90 | |
bca099a3 |
91 | =head1 NOTES |
92 | |
93 | The consistancy betweeen master and replicants is database specific. The Pool |
94 | gives you a method to validate it's replicants, removing and replacing them |
7e38d850 |
95 | when they fail/pass predefined criteria. Please make careful use of the ways |
ecb65397 |
96 | to force a query to run against Master when needed. |
97 | |
98 | =head1 REQUIREMENTS |
99 | |
100 | Replicated Storage has additional requirements not currently part of L<DBIx::Class> |
101 | |
e3c2b86d |
102 | Moose => 0.54 |
ecb65397 |
103 | MooseX::AttributeHelpers => 0.12 |
104 | Moose::Util::TypeConstraints => 0.54 |
105 | Class::MOP => 0.63 |
106 | |
107 | You will need to install these modules manually via CPAN or make them part of the |
108 | Makefile for your distribution. |
2bf79155 |
109 | |
110 | =head1 ATTRIBUTES |
111 | |
112 | This class defines the following attributes. |
113 | |
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114 | =head2 schema |
115 | |
116 | The underlying L<DBIx::Class::Schema> object this storage is attaching |
117 | |
118 | =cut |
119 | |
120 | has 'schema' => ( |
121 | is=>'rw', |
122 | isa=>'DBIx::Class::Schema', |
123 | weak_ref=>1, |
124 | required=>1, |
125 | ); |
126 | |
26ab719a |
127 | =head2 pool_type |
2bf79155 |
128 | |
26ab719a |
129 | Contains the classname which will instantiate the L</pool> object. Defaults |
130 | to: L<DBIx::Class::Storage::DBI::Replicated::Pool>. |
2bf79155 |
131 | |
132 | =cut |
133 | |
26ab719a |
134 | has 'pool_type' => ( |
64cdad22 |
135 | is=>'ro', |
136 | isa=>'ClassName', |
2ce6e9a6 |
137 | required=>1, |
138 | default=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
64cdad22 |
139 | handles=>{ |
140 | 'create_pool' => 'new', |
141 | }, |
2bf79155 |
142 | ); |
143 | |
f068a139 |
144 | =head2 pool_args |
145 | |
146 | Contains a hashref of initialized information to pass to the Balancer object. |
147 | See L<DBIx::Class::Storage::Replicated::Pool> for available arguments. |
148 | |
149 | =cut |
150 | |
151 | has 'pool_args' => ( |
64cdad22 |
152 | is=>'ro', |
153 | isa=>'HashRef', |
154 | lazy=>1, |
155 | required=>1, |
156 | default=>sub { {} }, |
f068a139 |
157 | ); |
158 | |
159 | |
26ab719a |
160 | =head2 balancer_type |
2bf79155 |
161 | |
162 | The replication pool requires a balance class to provider the methods for |
163 | choose how to spread the query load across each replicant in the pool. |
164 | |
165 | =cut |
166 | |
2ce6e9a6 |
167 | subtype 'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart', |
168 | as 'ClassName'; |
169 | |
170 | coerce 'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart', |
171 | from 'Str', |
172 | via { |
173 | my $type = $_; |
174 | if($type=~m/^::/) { |
175 | $type = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$type; |
176 | } |
177 | Class::MOP::load_class($type); |
178 | $type; |
179 | }; |
180 | |
26ab719a |
181 | has 'balancer_type' => ( |
64cdad22 |
182 | is=>'ro', |
2ce6e9a6 |
183 | isa=>'DBIx::Class::Storage::DBI::Replicated::BalancerClassNamePart', |
184 | coerce=>1, |
185 | required=>1, |
186 | default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First', |
64cdad22 |
187 | handles=>{ |
188 | 'create_balancer' => 'new', |
189 | }, |
2bf79155 |
190 | ); |
191 | |
17b05c13 |
192 | =head2 balancer_args |
193 | |
194 | Contains a hashref of initialized information to pass to the Balancer object. |
f068a139 |
195 | See L<DBIx::Class::Storage::Replicated::Balancer> for available arguments. |
17b05c13 |
196 | |
197 | =cut |
198 | |
199 | has 'balancer_args' => ( |
64cdad22 |
200 | is=>'ro', |
201 | isa=>'HashRef', |
202 | lazy=>1, |
203 | required=>1, |
204 | default=>sub { {} }, |
17b05c13 |
205 | ); |
206 | |
26ab719a |
207 | =head2 pool |
2bf79155 |
208 | |
26ab719a |
209 | Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a |
210 | container class for one or more replicated databases. |
2bf79155 |
211 | |
212 | =cut |
213 | |
26ab719a |
214 | has 'pool' => ( |
64cdad22 |
215 | is=>'ro', |
216 | isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
217 | lazy_build=>1, |
218 | handles=>[qw/ |
219 | connect_replicants |
220 | replicants |
221 | has_replicants |
222 | /], |
2bf79155 |
223 | ); |
224 | |
26ab719a |
225 | =head2 balancer |
2bf79155 |
226 | |
26ab719a |
227 | Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This |
228 | is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>) |
2bf79155 |
229 | |
26ab719a |
230 | =cut |
2bf79155 |
231 | |
26ab719a |
232 | has 'balancer' => ( |
64cdad22 |
233 | is=>'ro', |
234 | isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', |
235 | lazy_build=>1, |
236 | handles=>[qw/auto_validate_every/], |
26ab719a |
237 | ); |
2bf79155 |
238 | |
cb6ec758 |
239 | =head2 master |
240 | |
241 | The master defines the canonical state for a pool of connected databases. All |
242 | the replicants are expected to match this databases state. Thus, in a classic |
243 | Master / Slaves distributed system, all the slaves are expected to replicate |
244 | the Master's state as quick as possible. This is the only database in the |
245 | pool of databases that is allowed to handle write traffic. |
246 | |
247 | =cut |
248 | |
249 | has 'master' => ( |
64cdad22 |
250 | is=> 'ro', |
251 | isa=>'DBIx::Class::Storage::DBI', |
252 | lazy_build=>1, |
cb6ec758 |
253 | ); |
254 | |
cb6ec758 |
255 | =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE |
256 | |
257 | The following methods are delegated all the methods required for the |
258 | L<DBIx::Class::Storage::DBI> interface. |
259 | |
260 | =head2 read_handler |
261 | |
262 | Defines an object that implements the read side of L<BIx::Class::Storage::DBI>. |
263 | |
264 | =cut |
265 | |
266 | has 'read_handler' => ( |
64cdad22 |
267 | is=>'rw', |
268 | isa=>'Object', |
269 | lazy_build=>1, |
270 | handles=>[qw/ |
271 | select |
272 | select_single |
273 | columns_info_for |
274 | /], |
cb6ec758 |
275 | ); |
276 | |
cb6ec758 |
277 | =head2 write_handler |
278 | |
279 | Defines an object that implements the write side of L<BIx::Class::Storage::DBI>. |
280 | |
281 | =cut |
282 | |
283 | has 'write_handler' => ( |
64cdad22 |
284 | is=>'ro', |
285 | isa=>'Object', |
286 | lazy_build=>1, |
287 | lazy_build=>1, |
288 | handles=>[qw/ |
289 | on_connect_do |
290 | on_disconnect_do |
291 | connect_info |
292 | throw_exception |
293 | sql_maker |
294 | sqlt_type |
295 | create_ddl_dir |
296 | deployment_statements |
297 | datetime_parser |
298 | datetime_parser_type |
299 | last_insert_id |
300 | insert |
301 | insert_bulk |
302 | update |
303 | delete |
304 | dbh |
2ce6e9a6 |
305 | txn_begin |
64cdad22 |
306 | txn_do |
307 | txn_commit |
308 | txn_rollback |
2ce6e9a6 |
309 | txn_scope_guard |
64cdad22 |
310 | sth |
311 | deploy |
0180bef9 |
312 | with_deferred_fk_checks |
2ce6e9a6 |
313 | |
64cdad22 |
314 | reload_row |
2ce6e9a6 |
315 | _prep_for_execute |
2ce6e9a6 |
316 | |
64cdad22 |
317 | /], |
cb6ec758 |
318 | ); |
319 | |
26ab719a |
320 | =head1 METHODS |
2bf79155 |
321 | |
26ab719a |
322 | This class defines the following methods. |
2bf79155 |
323 | |
c354902c |
324 | =head2 BUILDARGS |
2bf79155 |
325 | |
cb6ec758 |
326 | L<DBIx::Class::Schema> when instantiating it's storage passed itself as the |
2ce6e9a6 |
327 | first argument. So we need to massage the arguments a bit so that all the |
328 | bits get put into the correct places. |
2bf79155 |
329 | |
330 | =cut |
331 | |
c354902c |
332 | sub BUILDARGS { |
333 | my ($class, $schema, $storage_type_args, @args) = @_; |
334 | |
335 | return { |
336 | schema=>$schema, |
337 | %$storage_type_args, |
338 | @args |
339 | } |
340 | } |
2bf79155 |
341 | |
cb6ec758 |
342 | =head2 _build_master |
2bf79155 |
343 | |
cb6ec758 |
344 | Lazy builder for the L</master> attribute. |
2bf79155 |
345 | |
346 | =cut |
347 | |
cb6ec758 |
348 | sub _build_master { |
2ce6e9a6 |
349 | my $self = shift @_; |
350 | DBIx::Class::Storage::DBI->new($self->schema); |
106d5f3b |
351 | } |
352 | |
26ab719a |
353 | =head2 _build_pool |
2bf79155 |
354 | |
26ab719a |
355 | Lazy builder for the L</pool> attribute. |
2bf79155 |
356 | |
357 | =cut |
358 | |
26ab719a |
359 | sub _build_pool { |
64cdad22 |
360 | my $self = shift @_; |
361 | $self->create_pool(%{$self->pool_args}); |
2bf79155 |
362 | } |
363 | |
26ab719a |
364 | =head2 _build_balancer |
2bf79155 |
365 | |
cb6ec758 |
366 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
367 | the balancer knows which pool it's balancing. |
2bf79155 |
368 | |
369 | =cut |
370 | |
26ab719a |
371 | sub _build_balancer { |
64cdad22 |
372 | my $self = shift @_; |
373 | $self->create_balancer( |
374 | pool=>$self->pool, |
375 | master=>$self->master, |
376 | %{$self->balancer_args}, |
377 | ); |
2bf79155 |
378 | } |
379 | |
cb6ec758 |
380 | =head2 _build_write_handler |
2bf79155 |
381 | |
cb6ec758 |
382 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
383 | the L</master>. |
50336325 |
384 | |
385 | =cut |
386 | |
cb6ec758 |
387 | sub _build_write_handler { |
64cdad22 |
388 | return shift->master; |
cb6ec758 |
389 | } |
50336325 |
390 | |
cb6ec758 |
391 | =head2 _build_read_handler |
2bf79155 |
392 | |
cb6ec758 |
393 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
394 | the L</balancer>. |
2bf79155 |
395 | |
396 | =cut |
397 | |
cb6ec758 |
398 | sub _build_read_handler { |
64cdad22 |
399 | return shift->balancer; |
cb6ec758 |
400 | } |
50336325 |
401 | |
cb6ec758 |
402 | =head2 around: connect_replicants |
2bf79155 |
403 | |
cb6ec758 |
404 | All calls to connect_replicants needs to have an existing $schema tacked onto |
405 | top of the args, since L<DBIx::Storage::DBI> needs it. |
955a6df6 |
406 | |
cb6ec758 |
407 | =cut |
955a6df6 |
408 | |
cb6ec758 |
409 | around 'connect_replicants' => sub { |
64cdad22 |
410 | my ($method, $self, @args) = @_; |
411 | $self->$method($self->schema, @args); |
955a6df6 |
412 | }; |
2bf79155 |
413 | |
2bf79155 |
414 | =head2 all_storages |
415 | |
416 | Returns an array of of all the connected storage backends. The first element |
417 | in the returned array is the master, and the remainings are each of the |
418 | replicants. |
419 | |
420 | =cut |
421 | |
422 | sub all_storages { |
64cdad22 |
423 | my $self = shift @_; |
424 | return grep {defined $_ && blessed $_} ( |
425 | $self->master, |
426 | $self->replicants, |
427 | ); |
2bf79155 |
428 | } |
429 | |
c4d3fae2 |
430 | =head2 execute_reliably ($coderef, ?@args) |
431 | |
432 | Given a coderef, saves the current state of the L</read_handler>, forces it to |
433 | use reliable storage (ie sets it to the master), executes a coderef and then |
434 | restores the original state. |
435 | |
436 | Example: |
437 | |
64cdad22 |
438 | my $reliably = sub { |
439 | my $name = shift @_; |
440 | $schema->resultset('User')->create({name=>$name}); |
441 | my $user_rs = $schema->resultset('User')->find({name=>$name}); |
442 | return $user_rs; |
443 | }; |
c4d3fae2 |
444 | |
64cdad22 |
445 | my $user_rs = $schema->storage->execute_reliably($reliably, 'John'); |
c4d3fae2 |
446 | |
447 | Use this when you must be certain of your database state, such as when you just |
448 | inserted something and need to get a resultset including it, etc. |
449 | |
450 | =cut |
451 | |
452 | sub execute_reliably { |
64cdad22 |
453 | my ($self, $coderef, @args) = @_; |
454 | |
455 | unless( ref $coderef eq 'CODE') { |
456 | $self->throw_exception('Second argument must be a coderef'); |
457 | } |
458 | |
459 | ##Get copy of master storage |
460 | my $master = $self->master; |
461 | |
462 | ##Get whatever the current read hander is |
463 | my $current = $self->read_handler; |
464 | |
465 | ##Set the read handler to master |
466 | $self->read_handler($master); |
467 | |
468 | ## do whatever the caller needs |
469 | my @result; |
470 | my $want_array = wantarray; |
471 | |
472 | eval { |
473 | if($want_array) { |
474 | @result = $coderef->(@args); |
475 | } elsif(defined $want_array) { |
476 | ($result[0]) = ($coderef->(@args)); |
ed213e85 |
477 | } else { |
64cdad22 |
478 | $coderef->(@args); |
479 | } |
480 | }; |
481 | |
482 | ##Reset to the original state |
483 | $self->read_handler($current); |
484 | |
485 | ##Exception testing has to come last, otherwise you might leave the |
486 | ##read_handler set to master. |
487 | |
488 | if($@) { |
489 | $self->throw_exception("coderef returned an error: $@"); |
490 | } else { |
491 | return $want_array ? @result : $result[0]; |
492 | } |
c4d3fae2 |
493 | } |
494 | |
cb6ec758 |
495 | =head2 set_reliable_storage |
496 | |
497 | Sets the current $schema to be 'reliable', that is all queries, both read and |
498 | write are sent to the master |
64cdad22 |
499 | |
cb6ec758 |
500 | =cut |
501 | |
502 | sub set_reliable_storage { |
64cdad22 |
503 | my $self = shift @_; |
504 | my $schema = $self->schema; |
505 | my $write_handler = $self->schema->storage->write_handler; |
506 | |
507 | $schema->storage->read_handler($write_handler); |
cb6ec758 |
508 | } |
509 | |
510 | =head2 set_balanced_storage |
511 | |
512 | Sets the current $schema to be use the </balancer> for all reads, while all |
513 | writea are sent to the master only |
64cdad22 |
514 | |
cb6ec758 |
515 | =cut |
516 | |
517 | sub set_balanced_storage { |
64cdad22 |
518 | my $self = shift @_; |
519 | my $schema = $self->schema; |
520 | my $write_handler = $self->schema->storage->balancer; |
521 | |
522 | $schema->storage->read_handler($write_handler); |
cb6ec758 |
523 | } |
2bf79155 |
524 | |
6834cc1d |
525 | =head2 around: txn_do ($coderef) |
c4d3fae2 |
526 | |
527 | Overload to the txn_do method, which is delegated to whatever the |
528 | L<write_handler> is set to. We overload this in order to wrap in inside a |
529 | L</execute_reliably> method. |
530 | |
531 | =cut |
532 | |
6834cc1d |
533 | around 'txn_do' => sub { |
64cdad22 |
534 | my($txn_do, $self, $coderef, @args) = @_; |
535 | $self->execute_reliably(sub {$self->$txn_do($coderef, @args)}); |
6834cc1d |
536 | }; |
c4d3fae2 |
537 | |
2bf79155 |
538 | =head2 connected |
539 | |
540 | Check that the master and at least one of the replicants is connected. |
541 | |
542 | =cut |
543 | |
544 | sub connected { |
64cdad22 |
545 | my $self = shift @_; |
546 | return |
547 | $self->master->connected && |
548 | $self->pool->connected_replicants; |
2bf79155 |
549 | } |
550 | |
2bf79155 |
551 | =head2 ensure_connected |
552 | |
553 | Make sure all the storages are connected. |
554 | |
555 | =cut |
556 | |
557 | sub ensure_connected { |
64cdad22 |
558 | my $self = shift @_; |
559 | foreach my $source ($self->all_storages) { |
560 | $source->ensure_connected(@_); |
561 | } |
2bf79155 |
562 | } |
563 | |
2bf79155 |
564 | =head2 limit_dialect |
565 | |
566 | Set the limit_dialect for all existing storages |
567 | |
568 | =cut |
569 | |
570 | sub limit_dialect { |
64cdad22 |
571 | my $self = shift @_; |
572 | foreach my $source ($self->all_storages) { |
573 | $source->limit_dialect(@_); |
574 | } |
3fbe08e3 |
575 | return $self->master->quote_char; |
2bf79155 |
576 | } |
577 | |
2bf79155 |
578 | =head2 quote_char |
579 | |
580 | Set the quote_char for all existing storages |
581 | |
582 | =cut |
583 | |
584 | sub quote_char { |
64cdad22 |
585 | my $self = shift @_; |
586 | foreach my $source ($self->all_storages) { |
587 | $source->quote_char(@_); |
588 | } |
3fbe08e3 |
589 | return $self->master->quote_char; |
2bf79155 |
590 | } |
591 | |
2bf79155 |
592 | =head2 name_sep |
593 | |
594 | Set the name_sep for all existing storages |
595 | |
596 | =cut |
597 | |
598 | sub name_sep { |
64cdad22 |
599 | my $self = shift @_; |
600 | foreach my $source ($self->all_storages) { |
601 | $source->name_sep(@_); |
602 | } |
3fbe08e3 |
603 | return $self->master->name_sep; |
2bf79155 |
604 | } |
605 | |
2bf79155 |
606 | =head2 set_schema |
607 | |
608 | Set the schema object for all existing storages |
609 | |
610 | =cut |
611 | |
612 | sub set_schema { |
64cdad22 |
613 | my $self = shift @_; |
614 | foreach my $source ($self->all_storages) { |
615 | $source->set_schema(@_); |
616 | } |
2bf79155 |
617 | } |
618 | |
2bf79155 |
619 | =head2 debug |
620 | |
621 | set a debug flag across all storages |
622 | |
623 | =cut |
624 | |
625 | sub debug { |
64cdad22 |
626 | my $self = shift @_; |
3fbe08e3 |
627 | if(@_) { |
628 | foreach my $source ($self->all_storages) { |
629 | $source->debug(@_); |
630 | } |
64cdad22 |
631 | } |
3fbe08e3 |
632 | return $self->master->debug; |
2bf79155 |
633 | } |
634 | |
2bf79155 |
635 | =head2 debugobj |
636 | |
637 | set a debug object across all storages |
638 | |
639 | =cut |
640 | |
641 | sub debugobj { |
64cdad22 |
642 | my $self = shift @_; |
3fbe08e3 |
643 | if(@_) { |
644 | foreach my $source ($self->all_storages) { |
645 | $source->debugobj(@_); |
646 | } |
64cdad22 |
647 | } |
3fbe08e3 |
648 | return $self->master->debugobj; |
2bf79155 |
649 | } |
650 | |
2bf79155 |
651 | =head2 debugfh |
652 | |
653 | set a debugfh object across all storages |
654 | |
655 | =cut |
656 | |
657 | sub debugfh { |
64cdad22 |
658 | my $self = shift @_; |
3fbe08e3 |
659 | if(@_) { |
660 | foreach my $source ($self->all_storages) { |
661 | $source->debugfh(@_); |
662 | } |
64cdad22 |
663 | } |
3fbe08e3 |
664 | return $self->master->debugfh; |
2bf79155 |
665 | } |
666 | |
2bf79155 |
667 | =head2 debugcb |
668 | |
669 | set a debug callback across all storages |
670 | |
671 | =cut |
672 | |
673 | sub debugcb { |
64cdad22 |
674 | my $self = shift @_; |
3fbe08e3 |
675 | if(@_) { |
676 | foreach my $source ($self->all_storages) { |
677 | $source->debugcb(@_); |
678 | } |
64cdad22 |
679 | } |
3fbe08e3 |
680 | return $self->master->debugcb; |
2bf79155 |
681 | } |
682 | |
2bf79155 |
683 | =head2 disconnect |
684 | |
685 | disconnect everything |
686 | |
687 | =cut |
688 | |
689 | sub disconnect { |
64cdad22 |
690 | my $self = shift @_; |
691 | foreach my $source ($self->all_storages) { |
692 | $source->disconnect(@_); |
693 | } |
2bf79155 |
694 | } |
695 | |
7e38d850 |
696 | =head1 GOTCHAS |
697 | |
698 | Due to the fact that replicants can lag behind a master, you must take care to |
699 | make sure you use one of the methods to force read queries to a master should |
700 | you need realtime data integrity. For example, if you insert a row, and then |
701 | immediately re-read it from the database (say, by doing $row->discard_changes) |
702 | or you insert a row and then immediately build a query that expects that row |
703 | to be an item, you should force the master to handle reads. Otherwise, due to |
704 | the lag, there is no certainty your data will be in the expected state. |
705 | |
706 | For data integrity, all transactions automatically use the master storage for |
707 | all read and write queries. Using a transaction is the preferred and recommended |
708 | method to force the master to handle all read queries. |
709 | |
710 | Otherwise, you can force a single query to use the master with the 'force_pool' |
711 | attribute: |
712 | |
713 | my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk); |
714 | |
715 | This attribute will safely be ignore by non replicated storages, so you can use |
716 | the same code for both types of systems. |
717 | |
718 | Lastly, you can use the L</execute_reliably> method, which works very much like |
719 | a transaction. |
720 | |
721 | For debugging, you can turn replication on/off with the methods L</set_reliable_storage> |
722 | and L</set_balanced_storage>, however this operates at a global level and is not |
723 | suitable if you have a shared Schema object being used by multiple processes, |
724 | such as on a web application server. You can get around this limitation by |
725 | using the Schema clone method. |
726 | |
727 | my $new_schema = $schema->clone; |
728 | $new_schema->set_reliable_storage; |
729 | |
730 | ## $new_schema will use only the Master storage for all reads/writes while |
731 | ## the $schema object will use replicated storage. |
732 | |
f5d3a5de |
733 | =head1 AUTHOR |
734 | |
64cdad22 |
735 | John Napiorkowski <john.napiorkowski@takkle.com> |
f5d3a5de |
736 | |
c4d3fae2 |
737 | Based on code originated by: |
f5d3a5de |
738 | |
64cdad22 |
739 | Norbert Csongrádi <bert@cpan.org> |
740 | Peter Siklósi <einon@einon.hu> |
2156bbdd |
741 | |
f5d3a5de |
742 | =head1 LICENSE |
743 | |
744 | You may distribute this code under the same terms as Perl itself. |
745 | |
746 | =cut |
747 | |
c354902c |
748 | __PACKAGE__->meta->make_immutable; |
749 | |
f5d3a5de |
750 | 1; |