Commit | Line | Data |
2156bbdd |
1 | package DBIx::Class::Storage::DBI::Replicated; |
f5d3a5de |
2 | |
ecb65397 |
3 | BEGIN { |
4 | use Carp::Clan qw/^DBIx::Class/; |
d4daee7b |
5 | |
ecb65397 |
6 | ## Modules required for Replication support not required for general DBIC |
7 | ## use, so we explicitly test for these. |
d4daee7b |
8 | |
ecb65397 |
9 | my %replication_required = ( |
c4d78acb |
10 | 'Moose' => '0.90', |
62eabf11 |
11 | 'MooseX::Types' => '0.16', |
bd5da369 |
12 | 'namespace::clean' => '0.11', |
13 | 'Hash::Merge' => '0.11' |
ecb65397 |
14 | ); |
d4daee7b |
15 | |
ecb65397 |
16 | my @didnt_load; |
d4daee7b |
17 | |
ecb65397 |
18 | for my $module (keys %replication_required) { |
1a58752c |
19 | eval "use $module $replication_required{$module}"; |
20 | push @didnt_load, "$module $replication_required{$module}" |
21 | if $@; |
ecb65397 |
22 | } |
d4daee7b |
23 | |
ecb65397 |
24 | croak("@{[ join ', ', @didnt_load ]} are missing and are required for Replication") |
d4daee7b |
25 | if @didnt_load; |
ecb65397 |
26 | } |
27 | |
b2e4d522 |
28 | use Moose; |
26ab719a |
29 | use DBIx::Class::Storage::DBI; |
2bf79155 |
30 | use DBIx::Class::Storage::DBI::Replicated::Pool; |
26ab719a |
31 | use DBIx::Class::Storage::DBI::Replicated::Balancer; |
6a151f58 |
32 | use DBIx::Class::Storage::DBI::Replicated::Types qw/BalancerClassNamePart DBICSchema DBICStorageDBI/; |
41916570 |
33 | use MooseX::Types::Moose qw/ClassName HashRef Object/; |
b2e4d522 |
34 | use Scalar::Util 'reftype'; |
b88b85e7 |
35 | use Hash::Merge 'merge'; |
9901aad7 |
36 | |
37 | use namespace::clean -except => 'meta'; |
2bf79155 |
38 | |
39 | =head1 NAME |
40 | |
ecb65397 |
41 | DBIx::Class::Storage::DBI::Replicated - BETA Replicated database support |
2bf79155 |
42 | |
43 | =head1 SYNOPSIS |
44 | |
45 | The Following example shows how to change an existing $schema to a replicated |
46 | storage type, add some replicated (readonly) databases, and perform reporting |
955a6df6 |
47 | tasks. |
2bf79155 |
48 | |
3da4f736 |
49 | You should set the 'storage_type attribute to a replicated type. You should |
d4daee7b |
50 | also define your arguments, such as which balancer you want and any arguments |
3da4f736 |
51 | that the Pool object should get. |
52 | |
64cdad22 |
53 | $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] ); |
d4daee7b |
54 | |
3da4f736 |
55 | Next, you need to add in the Replicants. Basically this is an array of |
56 | arrayrefs, where each arrayref is database connect information. Think of these |
57 | arguments as what you'd pass to the 'normal' $schema->connect method. |
d4daee7b |
58 | |
64cdad22 |
59 | $schema->storage->connect_replicants( |
60 | [$dsn1, $user, $pass, \%opts], |
61 | [$dsn2, $user, $pass, \%opts], |
62 | [$dsn3, $user, $pass, \%opts], |
63 | ); |
d4daee7b |
64 | |
3da4f736 |
65 | Now, just use the $schema as you normally would. Automatically all reads will |
66 | be delegated to the replicants, while writes to the master. |
67 | |
7e38d850 |
68 | $schema->resultset('Source')->search({name=>'etc'}); |
d4daee7b |
69 | |
3da4f736 |
70 | You can force a given query to use a particular storage using the search |
71 | attribute 'force_pool'. For example: |
d4daee7b |
72 | |
7e38d850 |
73 | my $RS = $schema->resultset('Source')->search(undef, {force_pool=>'master'}); |
3da4f736 |
74 | |
75 | Now $RS will force everything (both reads and writes) to use whatever was setup |
76 | as the master storage. 'master' is hardcoded to always point to the Master, |
77 | but you can also use any Replicant name. Please see: |
212cc5c2 |
78 | L<DBIx::Class::Storage::DBI::Replicated::Pool> and the replicants attribute for more. |
3da4f736 |
79 | |
80 | Also see transactions and L</execute_reliably> for alternative ways to |
81 | force read traffic to the master. In general, you should wrap your statements |
82 | in a transaction when you are reading and writing to the same tables at the |
83 | same time, since your replicants will often lag a bit behind the master. |
212cc5c2 |
84 | |
85 | See L<DBIx::Class::Storage::DBI::Replicated::Instructions> for more help and |
86 | walkthroughs. |
d4daee7b |
87 | |
2bf79155 |
88 | =head1 DESCRIPTION |
89 | |
7e38d850 |
90 | Warning: This class is marked BETA. This has been running a production |
ccb3b897 |
91 | website using MySQL native replication as its backend and we have some decent |
7e38d850 |
92 | test coverage but the code hasn't yet been stressed by a variety of databases. |
93 | Individual DB's may have quirks we are not aware of. Please use this in first |
94 | development and pass along your experiences/bug fixes. |
2bf79155 |
95 | |
96 | This class implements replicated data store for DBI. Currently you can define |
97 | one master and numerous slave database connections. All write-type queries |
98 | (INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master |
99 | database, all read-type queries (SELECTs) go to the slave database. |
100 | |
101 | Basically, any method request that L<DBIx::Class::Storage::DBI> would normally |
bca099a3 |
102 | handle gets delegated to one of the two attributes: L</read_handler> or to |
103 | L</write_handler>. Additionally, some methods need to be distributed |
2bf79155 |
104 | to all existing storages. This way our storage class is a drop in replacement |
105 | for L<DBIx::Class::Storage::DBI>. |
106 | |
107 | Read traffic is spread across the replicants (slaves) occuring to a user |
108 | selected algorithm. The default algorithm is random weighted. |
109 | |
bca099a3 |
110 | =head1 NOTES |
111 | |
112 | The consistancy betweeen master and replicants is database specific. The Pool |
faaba25f |
113 | gives you a method to validate its replicants, removing and replacing them |
7e38d850 |
114 | when they fail/pass predefined criteria. Please make careful use of the ways |
ecb65397 |
115 | to force a query to run against Master when needed. |
116 | |
117 | =head1 REQUIREMENTS |
118 | |
119 | Replicated Storage has additional requirements not currently part of L<DBIx::Class> |
120 | |
c4d78acb |
121 | Moose => '0.90', |
62eabf11 |
122 | MooseX::Types => '0.16', |
123 | namespace::clean => '0.11', |
124 | Hash::Merge => '0.11' |
d4daee7b |
125 | |
ecb65397 |
126 | You will need to install these modules manually via CPAN or make them part of the |
127 | Makefile for your distribution. |
2bf79155 |
128 | |
129 | =head1 ATTRIBUTES |
130 | |
131 | This class defines the following attributes. |
132 | |
2ce6e9a6 |
133 | =head2 schema |
134 | |
135 | The underlying L<DBIx::Class::Schema> object this storage is attaching |
136 | |
137 | =cut |
138 | |
139 | has 'schema' => ( |
140 | is=>'rw', |
6a151f58 |
141 | isa=>DBICSchema, |
2ce6e9a6 |
142 | weak_ref=>1, |
143 | required=>1, |
144 | ); |
145 | |
26ab719a |
146 | =head2 pool_type |
2bf79155 |
147 | |
26ab719a |
148 | Contains the classname which will instantiate the L</pool> object. Defaults |
149 | to: L<DBIx::Class::Storage::DBI::Replicated::Pool>. |
2bf79155 |
150 | |
151 | =cut |
152 | |
26ab719a |
153 | has 'pool_type' => ( |
dcdf7b2c |
154 | is=>'rw', |
41916570 |
155 | isa=>ClassName, |
2ce6e9a6 |
156 | default=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
64cdad22 |
157 | handles=>{ |
158 | 'create_pool' => 'new', |
159 | }, |
2bf79155 |
160 | ); |
161 | |
f068a139 |
162 | =head2 pool_args |
163 | |
164 | Contains a hashref of initialized information to pass to the Balancer object. |
212cc5c2 |
165 | See L<DBIx::Class::Storage::DBI::Replicated::Pool> for available arguments. |
f068a139 |
166 | |
167 | =cut |
168 | |
169 | has 'pool_args' => ( |
dcdf7b2c |
170 | is=>'rw', |
41916570 |
171 | isa=>HashRef, |
64cdad22 |
172 | lazy=>1, |
64cdad22 |
173 | default=>sub { {} }, |
f068a139 |
174 | ); |
175 | |
176 | |
26ab719a |
177 | =head2 balancer_type |
2bf79155 |
178 | |
179 | The replication pool requires a balance class to provider the methods for |
180 | choose how to spread the query load across each replicant in the pool. |
181 | |
182 | =cut |
183 | |
26ab719a |
184 | has 'balancer_type' => ( |
dcdf7b2c |
185 | is=>'rw', |
9901aad7 |
186 | isa=>BalancerClassNamePart, |
2ce6e9a6 |
187 | coerce=>1, |
188 | required=>1, |
189 | default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First', |
64cdad22 |
190 | handles=>{ |
191 | 'create_balancer' => 'new', |
192 | }, |
2bf79155 |
193 | ); |
194 | |
17b05c13 |
195 | =head2 balancer_args |
196 | |
197 | Contains a hashref of initialized information to pass to the Balancer object. |
212cc5c2 |
198 | See L<DBIx::Class::Storage::DBI::Replicated::Balancer> for available arguments. |
17b05c13 |
199 | |
200 | =cut |
201 | |
202 | has 'balancer_args' => ( |
dcdf7b2c |
203 | is=>'rw', |
41916570 |
204 | isa=>HashRef, |
64cdad22 |
205 | lazy=>1, |
206 | required=>1, |
207 | default=>sub { {} }, |
17b05c13 |
208 | ); |
209 | |
26ab719a |
210 | =head2 pool |
2bf79155 |
211 | |
26ab719a |
212 | Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a |
213 | container class for one or more replicated databases. |
2bf79155 |
214 | |
215 | =cut |
216 | |
26ab719a |
217 | has 'pool' => ( |
64cdad22 |
218 | is=>'ro', |
219 | isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
220 | lazy_build=>1, |
221 | handles=>[qw/ |
6f7344b8 |
222 | connect_replicants |
64cdad22 |
223 | replicants |
224 | has_replicants |
225 | /], |
2bf79155 |
226 | ); |
227 | |
26ab719a |
228 | =head2 balancer |
2bf79155 |
229 | |
26ab719a |
230 | Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This |
231 | is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>) |
2bf79155 |
232 | |
26ab719a |
233 | =cut |
2bf79155 |
234 | |
26ab719a |
235 | has 'balancer' => ( |
dcdf7b2c |
236 | is=>'rw', |
64cdad22 |
237 | isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', |
238 | lazy_build=>1, |
239 | handles=>[qw/auto_validate_every/], |
26ab719a |
240 | ); |
2bf79155 |
241 | |
cb6ec758 |
242 | =head2 master |
243 | |
244 | The master defines the canonical state for a pool of connected databases. All |
245 | the replicants are expected to match this databases state. Thus, in a classic |
246 | Master / Slaves distributed system, all the slaves are expected to replicate |
247 | the Master's state as quick as possible. This is the only database in the |
248 | pool of databases that is allowed to handle write traffic. |
249 | |
250 | =cut |
251 | |
252 | has 'master' => ( |
64cdad22 |
253 | is=> 'ro', |
6a151f58 |
254 | isa=>DBICStorageDBI, |
64cdad22 |
255 | lazy_build=>1, |
cb6ec758 |
256 | ); |
257 | |
cb6ec758 |
258 | =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE |
259 | |
260 | The following methods are delegated all the methods required for the |
261 | L<DBIx::Class::Storage::DBI> interface. |
262 | |
263 | =head2 read_handler |
264 | |
265 | Defines an object that implements the read side of L<BIx::Class::Storage::DBI>. |
266 | |
267 | =cut |
268 | |
269 | has 'read_handler' => ( |
64cdad22 |
270 | is=>'rw', |
41916570 |
271 | isa=>Object, |
64cdad22 |
272 | lazy_build=>1, |
273 | handles=>[qw/ |
274 | select |
275 | select_single |
276 | columns_info_for |
6f7344b8 |
277 | /], |
cb6ec758 |
278 | ); |
279 | |
cb6ec758 |
280 | =head2 write_handler |
281 | |
282 | Defines an object that implements the write side of L<BIx::Class::Storage::DBI>. |
283 | |
284 | =cut |
285 | |
286 | has 'write_handler' => ( |
64cdad22 |
287 | is=>'ro', |
41916570 |
288 | isa=>Object, |
64cdad22 |
289 | lazy_build=>1, |
6f7344b8 |
290 | handles=>[qw/ |
64cdad22 |
291 | on_connect_do |
6f7344b8 |
292 | on_disconnect_do |
64cdad22 |
293 | connect_info |
294 | throw_exception |
295 | sql_maker |
296 | sqlt_type |
297 | create_ddl_dir |
298 | deployment_statements |
299 | datetime_parser |
6f7344b8 |
300 | datetime_parser_type |
301 | build_datetime_parser |
64cdad22 |
302 | last_insert_id |
303 | insert |
304 | insert_bulk |
305 | update |
306 | delete |
307 | dbh |
2ce6e9a6 |
308 | txn_begin |
64cdad22 |
309 | txn_do |
310 | txn_commit |
311 | txn_rollback |
2ce6e9a6 |
312 | txn_scope_guard |
64cdad22 |
313 | sth |
314 | deploy |
0180bef9 |
315 | with_deferred_fk_checks |
6f7344b8 |
316 | dbh_do |
64cdad22 |
317 | reload_row |
6f7344b8 |
318 | with_deferred_fk_checks |
2ce6e9a6 |
319 | _prep_for_execute |
7fb60fb1 |
320 | |
6f7344b8 |
321 | backup |
322 | is_datatype_numeric |
323 | _count_select |
324 | _subq_count_select |
325 | _subq_update_delete |
326 | svp_rollback |
327 | svp_begin |
328 | svp_release |
64cdad22 |
329 | /], |
cb6ec758 |
330 | ); |
331 | |
b2e4d522 |
332 | has _master_connect_info_opts => |
333 | (is => 'rw', isa => HashRef, default => sub { {} }); |
334 | |
335 | =head2 around: connect_info |
336 | |
337 | Preserve master's C<connect_info> options (for merging with replicants.) |
dcdf7b2c |
338 | Also set any Replicated related options from connect_info, such as |
339 | C<pool_type>, C<pool_args>, C<balancer_type> and C<balancer_args>. |
b2e4d522 |
340 | |
341 | =cut |
342 | |
343 | around connect_info => sub { |
344 | my ($next, $self, $info, @extra) = @_; |
345 | |
0ce2d0d5 |
346 | my $wantarray = wantarray; |
347 | |
b2e4d522 |
348 | my %opts; |
349 | for my $arg (@$info) { |
350 | next unless (reftype($arg)||'') eq 'HASH'; |
b88b85e7 |
351 | %opts = %{ merge($arg, \%opts) }; |
b2e4d522 |
352 | } |
b2e4d522 |
353 | delete $opts{dsn}; |
354 | |
dcdf7b2c |
355 | if (@opts{qw/pool_type pool_args/}) { |
356 | $self->pool_type(delete $opts{pool_type}) |
357 | if $opts{pool_type}; |
358 | |
b88b85e7 |
359 | $self->pool_args( |
360 | merge((delete $opts{pool_args} || {}), $self->pool_args) |
361 | ); |
dcdf7b2c |
362 | |
67c43863 |
363 | $self->pool($self->_build_pool) |
6f7344b8 |
364 | if $self->pool; |
dcdf7b2c |
365 | } |
366 | |
367 | if (@opts{qw/balancer_type balancer_args/}) { |
368 | $self->balancer_type(delete $opts{balancer_type}) |
369 | if $opts{balancer_type}; |
370 | |
b88b85e7 |
371 | $self->balancer_args( |
372 | merge((delete $opts{balancer_args} || {}), $self->balancer_args) |
373 | ); |
dcdf7b2c |
374 | |
67c43863 |
375 | $self->balancer($self->_build_balancer) |
6f7344b8 |
376 | if $self->balancer; |
dcdf7b2c |
377 | } |
378 | |
b2e4d522 |
379 | $self->_master_connect_info_opts(\%opts); |
380 | |
0ce2d0d5 |
381 | my (@res, $res); |
382 | if ($wantarray) { |
383 | @res = $self->$next($info, @extra); |
384 | } else { |
385 | $res = $self->$next($info, @extra); |
386 | } |
387 | |
fd4eb9c2 |
388 | # Make sure master is blessed into the correct class and apply role to it. |
389 | my $master = $self->master; |
390 | $master->_determine_driver; |
391 | Moose::Meta::Class->initialize(ref $master); |
392 | DBIx::Class::Storage::DBI::Replicated::WithDSN->meta->apply($master); |
0ce2d0d5 |
393 | |
394 | $wantarray ? @res : $res; |
b2e4d522 |
395 | }; |
396 | |
26ab719a |
397 | =head1 METHODS |
2bf79155 |
398 | |
26ab719a |
399 | This class defines the following methods. |
2bf79155 |
400 | |
c354902c |
401 | =head2 BUILDARGS |
2bf79155 |
402 | |
faaba25f |
403 | L<DBIx::Class::Schema> when instantiating its storage passed itself as the |
2ce6e9a6 |
404 | first argument. So we need to massage the arguments a bit so that all the |
405 | bits get put into the correct places. |
2bf79155 |
406 | |
407 | =cut |
408 | |
c354902c |
409 | sub BUILDARGS { |
410 | my ($class, $schema, $storage_type_args, @args) = @_; |
d4daee7b |
411 | |
c354902c |
412 | return { |
6f7344b8 |
413 | schema=>$schema, |
414 | %$storage_type_args, |
415 | @args |
c354902c |
416 | } |
417 | } |
2bf79155 |
418 | |
cb6ec758 |
419 | =head2 _build_master |
2bf79155 |
420 | |
cb6ec758 |
421 | Lazy builder for the L</master> attribute. |
2bf79155 |
422 | |
423 | =cut |
424 | |
cb6ec758 |
425 | sub _build_master { |
2ce6e9a6 |
426 | my $self = shift @_; |
ee356d00 |
427 | my $master = DBIx::Class::Storage::DBI->new($self->schema); |
ee356d00 |
428 | $master |
106d5f3b |
429 | } |
430 | |
26ab719a |
431 | =head2 _build_pool |
2bf79155 |
432 | |
26ab719a |
433 | Lazy builder for the L</pool> attribute. |
2bf79155 |
434 | |
435 | =cut |
436 | |
26ab719a |
437 | sub _build_pool { |
64cdad22 |
438 | my $self = shift @_; |
439 | $self->create_pool(%{$self->pool_args}); |
2bf79155 |
440 | } |
441 | |
26ab719a |
442 | =head2 _build_balancer |
2bf79155 |
443 | |
cb6ec758 |
444 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
445 | the balancer knows which pool it's balancing. |
2bf79155 |
446 | |
447 | =cut |
448 | |
26ab719a |
449 | sub _build_balancer { |
64cdad22 |
450 | my $self = shift @_; |
451 | $self->create_balancer( |
6f7344b8 |
452 | pool=>$self->pool, |
64cdad22 |
453 | master=>$self->master, |
454 | %{$self->balancer_args}, |
455 | ); |
2bf79155 |
456 | } |
457 | |
cb6ec758 |
458 | =head2 _build_write_handler |
2bf79155 |
459 | |
cb6ec758 |
460 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
461 | the L</master>. |
50336325 |
462 | |
463 | =cut |
464 | |
cb6ec758 |
465 | sub _build_write_handler { |
64cdad22 |
466 | return shift->master; |
cb6ec758 |
467 | } |
50336325 |
468 | |
cb6ec758 |
469 | =head2 _build_read_handler |
2bf79155 |
470 | |
cb6ec758 |
471 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
472 | the L</balancer>. |
2bf79155 |
473 | |
474 | =cut |
475 | |
cb6ec758 |
476 | sub _build_read_handler { |
64cdad22 |
477 | return shift->balancer; |
cb6ec758 |
478 | } |
50336325 |
479 | |
cb6ec758 |
480 | =head2 around: connect_replicants |
2bf79155 |
481 | |
cb6ec758 |
482 | All calls to connect_replicants needs to have an existing $schema tacked onto |
b2e4d522 |
483 | top of the args, since L<DBIx::Storage::DBI> needs it, and any C<connect_info> |
484 | options merged with the master, with replicant opts having higher priority. |
955a6df6 |
485 | |
cb6ec758 |
486 | =cut |
955a6df6 |
487 | |
b2e4d522 |
488 | around connect_replicants => sub { |
489 | my ($next, $self, @args) = @_; |
490 | |
491 | for my $r (@args) { |
492 | $r = [ $r ] unless reftype $r eq 'ARRAY'; |
493 | |
1a58752c |
494 | $self->throw_exception('coderef replicant connect_info not supported') |
b2e4d522 |
495 | if ref $r->[0] && reftype $r->[0] eq 'CODE'; |
496 | |
497 | # any connect_info options? |
498 | my $i = 0; |
499 | $i++ while $i < @$r && (reftype($r->[$i])||'') ne 'HASH'; |
500 | |
6f7344b8 |
501 | # make one if none |
b2e4d522 |
502 | $r->[$i] = {} unless $r->[$i]; |
503 | |
504 | # merge if two hashes |
b88b85e7 |
505 | my @hashes = @$r[$i .. $#{$r}]; |
506 | |
1a58752c |
507 | $self->throw_exception('invalid connect_info options') |
b88b85e7 |
508 | if (grep { reftype($_) eq 'HASH' } @hashes) != @hashes; |
509 | |
1a58752c |
510 | $self->throw_exception('too many hashrefs in connect_info') |
b88b85e7 |
511 | if @hashes > 2; |
512 | |
513 | my %opts = %{ merge(reverse @hashes) }; |
514 | |
515 | # delete them |
b2e4d522 |
516 | splice @$r, $i+1, ($#{$r} - $i), (); |
517 | |
0bd8e058 |
518 | # make sure master/replicants opts don't clash |
519 | my %master_opts = %{ $self->_master_connect_info_opts }; |
520 | if (exists $opts{dbh_maker}) { |
521 | delete @master_opts{qw/dsn user password/}; |
522 | } |
523 | delete $master_opts{dbh_maker}; |
524 | |
b2e4d522 |
525 | # merge with master |
0bd8e058 |
526 | %opts = %{ merge(\%opts, \%master_opts) }; |
b2e4d522 |
527 | |
528 | # update |
529 | $r->[$i] = \%opts; |
530 | } |
531 | |
532 | $self->$next($self->schema, @args); |
955a6df6 |
533 | }; |
2bf79155 |
534 | |
2bf79155 |
535 | =head2 all_storages |
536 | |
537 | Returns an array of of all the connected storage backends. The first element |
538 | in the returned array is the master, and the remainings are each of the |
539 | replicants. |
540 | |
541 | =cut |
542 | |
543 | sub all_storages { |
64cdad22 |
544 | my $self = shift @_; |
545 | return grep {defined $_ && blessed $_} ( |
546 | $self->master, |
6412a592 |
547 | values %{ $self->replicants }, |
64cdad22 |
548 | ); |
2bf79155 |
549 | } |
550 | |
c4d3fae2 |
551 | =head2 execute_reliably ($coderef, ?@args) |
552 | |
553 | Given a coderef, saves the current state of the L</read_handler>, forces it to |
554 | use reliable storage (ie sets it to the master), executes a coderef and then |
555 | restores the original state. |
556 | |
557 | Example: |
558 | |
64cdad22 |
559 | my $reliably = sub { |
560 | my $name = shift @_; |
561 | $schema->resultset('User')->create({name=>$name}); |
562 | my $user_rs = $schema->resultset('User')->find({name=>$name}); |
563 | return $user_rs; |
564 | }; |
c4d3fae2 |
565 | |
64cdad22 |
566 | my $user_rs = $schema->storage->execute_reliably($reliably, 'John'); |
c4d3fae2 |
567 | |
568 | Use this when you must be certain of your database state, such as when you just |
569 | inserted something and need to get a resultset including it, etc. |
570 | |
571 | =cut |
572 | |
573 | sub execute_reliably { |
64cdad22 |
574 | my ($self, $coderef, @args) = @_; |
d4daee7b |
575 | |
64cdad22 |
576 | unless( ref $coderef eq 'CODE') { |
577 | $self->throw_exception('Second argument must be a coderef'); |
578 | } |
d4daee7b |
579 | |
64cdad22 |
580 | ##Get copy of master storage |
581 | my $master = $self->master; |
d4daee7b |
582 | |
64cdad22 |
583 | ##Get whatever the current read hander is |
584 | my $current = $self->read_handler; |
d4daee7b |
585 | |
64cdad22 |
586 | ##Set the read handler to master |
587 | $self->read_handler($master); |
d4daee7b |
588 | |
64cdad22 |
589 | ## do whatever the caller needs |
590 | my @result; |
591 | my $want_array = wantarray; |
d4daee7b |
592 | |
64cdad22 |
593 | eval { |
594 | if($want_array) { |
595 | @result = $coderef->(@args); |
596 | } elsif(defined $want_array) { |
597 | ($result[0]) = ($coderef->(@args)); |
ed213e85 |
598 | } else { |
64cdad22 |
599 | $coderef->(@args); |
6f7344b8 |
600 | } |
64cdad22 |
601 | }; |
d4daee7b |
602 | |
64cdad22 |
603 | ##Reset to the original state |
6f7344b8 |
604 | $self->read_handler($current); |
d4daee7b |
605 | |
64cdad22 |
606 | ##Exception testing has to come last, otherwise you might leave the |
607 | ##read_handler set to master. |
d4daee7b |
608 | |
64cdad22 |
609 | if($@) { |
610 | $self->throw_exception("coderef returned an error: $@"); |
611 | } else { |
612 | return $want_array ? @result : $result[0]; |
613 | } |
c4d3fae2 |
614 | } |
615 | |
cb6ec758 |
616 | =head2 set_reliable_storage |
617 | |
618 | Sets the current $schema to be 'reliable', that is all queries, both read and |
619 | write are sent to the master |
d4daee7b |
620 | |
cb6ec758 |
621 | =cut |
622 | |
623 | sub set_reliable_storage { |
64cdad22 |
624 | my $self = shift @_; |
625 | my $schema = $self->schema; |
626 | my $write_handler = $self->schema->storage->write_handler; |
d4daee7b |
627 | |
64cdad22 |
628 | $schema->storage->read_handler($write_handler); |
cb6ec758 |
629 | } |
630 | |
631 | =head2 set_balanced_storage |
632 | |
633 | Sets the current $schema to be use the </balancer> for all reads, while all |
634 | writea are sent to the master only |
d4daee7b |
635 | |
cb6ec758 |
636 | =cut |
637 | |
638 | sub set_balanced_storage { |
64cdad22 |
639 | my $self = shift @_; |
640 | my $schema = $self->schema; |
bd5da369 |
641 | my $balanced_handler = $self->schema->storage->balancer; |
d4daee7b |
642 | |
bd5da369 |
643 | $schema->storage->read_handler($balanced_handler); |
cb6ec758 |
644 | } |
2bf79155 |
645 | |
646 | =head2 connected |
647 | |
648 | Check that the master and at least one of the replicants is connected. |
649 | |
650 | =cut |
651 | |
652 | sub connected { |
64cdad22 |
653 | my $self = shift @_; |
654 | return |
655 | $self->master->connected && |
656 | $self->pool->connected_replicants; |
2bf79155 |
657 | } |
658 | |
2bf79155 |
659 | =head2 ensure_connected |
660 | |
661 | Make sure all the storages are connected. |
662 | |
663 | =cut |
664 | |
665 | sub ensure_connected { |
64cdad22 |
666 | my $self = shift @_; |
667 | foreach my $source ($self->all_storages) { |
668 | $source->ensure_connected(@_); |
669 | } |
2bf79155 |
670 | } |
671 | |
2bf79155 |
672 | =head2 limit_dialect |
673 | |
674 | Set the limit_dialect for all existing storages |
675 | |
676 | =cut |
677 | |
678 | sub limit_dialect { |
64cdad22 |
679 | my $self = shift @_; |
680 | foreach my $source ($self->all_storages) { |
681 | $source->limit_dialect(@_); |
682 | } |
3fbe08e3 |
683 | return $self->master->quote_char; |
2bf79155 |
684 | } |
685 | |
2bf79155 |
686 | =head2 quote_char |
687 | |
688 | Set the quote_char for all existing storages |
689 | |
690 | =cut |
691 | |
692 | sub quote_char { |
64cdad22 |
693 | my $self = shift @_; |
694 | foreach my $source ($self->all_storages) { |
695 | $source->quote_char(@_); |
696 | } |
3fbe08e3 |
697 | return $self->master->quote_char; |
2bf79155 |
698 | } |
699 | |
2bf79155 |
700 | =head2 name_sep |
701 | |
702 | Set the name_sep for all existing storages |
703 | |
704 | =cut |
705 | |
706 | sub name_sep { |
64cdad22 |
707 | my $self = shift @_; |
708 | foreach my $source ($self->all_storages) { |
709 | $source->name_sep(@_); |
710 | } |
3fbe08e3 |
711 | return $self->master->name_sep; |
2bf79155 |
712 | } |
713 | |
2bf79155 |
714 | =head2 set_schema |
715 | |
716 | Set the schema object for all existing storages |
717 | |
718 | =cut |
719 | |
720 | sub set_schema { |
64cdad22 |
721 | my $self = shift @_; |
722 | foreach my $source ($self->all_storages) { |
723 | $source->set_schema(@_); |
724 | } |
2bf79155 |
725 | } |
726 | |
2bf79155 |
727 | =head2 debug |
728 | |
729 | set a debug flag across all storages |
730 | |
731 | =cut |
732 | |
733 | sub debug { |
64cdad22 |
734 | my $self = shift @_; |
3fbe08e3 |
735 | if(@_) { |
736 | foreach my $source ($self->all_storages) { |
737 | $source->debug(@_); |
6f7344b8 |
738 | } |
64cdad22 |
739 | } |
3fbe08e3 |
740 | return $self->master->debug; |
2bf79155 |
741 | } |
742 | |
2bf79155 |
743 | =head2 debugobj |
744 | |
745 | set a debug object across all storages |
746 | |
747 | =cut |
748 | |
749 | sub debugobj { |
64cdad22 |
750 | my $self = shift @_; |
3fbe08e3 |
751 | if(@_) { |
752 | foreach my $source ($self->all_storages) { |
753 | $source->debugobj(@_); |
6f7344b8 |
754 | } |
64cdad22 |
755 | } |
3fbe08e3 |
756 | return $self->master->debugobj; |
2bf79155 |
757 | } |
758 | |
2bf79155 |
759 | =head2 debugfh |
760 | |
761 | set a debugfh object across all storages |
762 | |
763 | =cut |
764 | |
765 | sub debugfh { |
64cdad22 |
766 | my $self = shift @_; |
3fbe08e3 |
767 | if(@_) { |
768 | foreach my $source ($self->all_storages) { |
769 | $source->debugfh(@_); |
6f7344b8 |
770 | } |
64cdad22 |
771 | } |
3fbe08e3 |
772 | return $self->master->debugfh; |
2bf79155 |
773 | } |
774 | |
2bf79155 |
775 | =head2 debugcb |
776 | |
777 | set a debug callback across all storages |
778 | |
779 | =cut |
780 | |
781 | sub debugcb { |
64cdad22 |
782 | my $self = shift @_; |
3fbe08e3 |
783 | if(@_) { |
784 | foreach my $source ($self->all_storages) { |
785 | $source->debugcb(@_); |
6f7344b8 |
786 | } |
64cdad22 |
787 | } |
3fbe08e3 |
788 | return $self->master->debugcb; |
2bf79155 |
789 | } |
790 | |
2bf79155 |
791 | =head2 disconnect |
792 | |
793 | disconnect everything |
794 | |
795 | =cut |
796 | |
797 | sub disconnect { |
64cdad22 |
798 | my $self = shift @_; |
799 | foreach my $source ($self->all_storages) { |
800 | $source->disconnect(@_); |
801 | } |
2bf79155 |
802 | } |
803 | |
b2e4d522 |
804 | =head2 cursor_class |
805 | |
806 | set cursor class on all storages, or return master's |
807 | |
808 | =cut |
809 | |
810 | sub cursor_class { |
811 | my ($self, $cursor_class) = @_; |
812 | |
813 | if ($cursor_class) { |
814 | $_->cursor_class($cursor_class) for $self->all_storages; |
815 | } |
816 | $self->master->cursor_class; |
817 | } |
d4daee7b |
818 | |
7e38d850 |
819 | =head1 GOTCHAS |
820 | |
821 | Due to the fact that replicants can lag behind a master, you must take care to |
822 | make sure you use one of the methods to force read queries to a master should |
823 | you need realtime data integrity. For example, if you insert a row, and then |
824 | immediately re-read it from the database (say, by doing $row->discard_changes) |
825 | or you insert a row and then immediately build a query that expects that row |
826 | to be an item, you should force the master to handle reads. Otherwise, due to |
827 | the lag, there is no certainty your data will be in the expected state. |
828 | |
829 | For data integrity, all transactions automatically use the master storage for |
830 | all read and write queries. Using a transaction is the preferred and recommended |
831 | method to force the master to handle all read queries. |
832 | |
833 | Otherwise, you can force a single query to use the master with the 'force_pool' |
834 | attribute: |
835 | |
836 | my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk); |
837 | |
838 | This attribute will safely be ignore by non replicated storages, so you can use |
839 | the same code for both types of systems. |
840 | |
841 | Lastly, you can use the L</execute_reliably> method, which works very much like |
842 | a transaction. |
843 | |
844 | For debugging, you can turn replication on/off with the methods L</set_reliable_storage> |
845 | and L</set_balanced_storage>, however this operates at a global level and is not |
846 | suitable if you have a shared Schema object being used by multiple processes, |
847 | such as on a web application server. You can get around this limitation by |
848 | using the Schema clone method. |
849 | |
850 | my $new_schema = $schema->clone; |
851 | $new_schema->set_reliable_storage; |
d4daee7b |
852 | |
7e38d850 |
853 | ## $new_schema will use only the Master storage for all reads/writes while |
854 | ## the $schema object will use replicated storage. |
855 | |
f5d3a5de |
856 | =head1 AUTHOR |
857 | |
64cdad22 |
858 | John Napiorkowski <john.napiorkowski@takkle.com> |
f5d3a5de |
859 | |
c4d3fae2 |
860 | Based on code originated by: |
f5d3a5de |
861 | |
64cdad22 |
862 | Norbert Csongrádi <bert@cpan.org> |
863 | Peter Siklósi <einon@einon.hu> |
2156bbdd |
864 | |
f5d3a5de |
865 | =head1 LICENSE |
866 | |
867 | You may distribute this code under the same terms as Perl itself. |
868 | |
869 | =cut |
870 | |
c354902c |
871 | __PACKAGE__->meta->make_immutable; |
872 | |
f5d3a5de |
873 | 1; |