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1 | package DBIx::Class::Storage::DBI::Replicated; |
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2 | |
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3 | use Moose; |
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4 | use DBIx::Class::Storage::DBI; |
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5 | use DBIx::Class::Storage::DBI::Replicated::Pool; |
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6 | use DBIx::Class::Storage::DBI::Replicated::Balancer; |
7 | use Scalar::Util qw(blessed); |
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8 | |
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9 | extends 'DBIx::Class::Storage::DBI', 'Moose::Object'; |
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10 | |
11 | =head1 NAME |
12 | |
13 | DBIx::Class::Storage::DBI::Replicated - ALPHA Replicated database support |
14 | |
15 | =head1 SYNOPSIS |
16 | |
17 | The Following example shows how to change an existing $schema to a replicated |
18 | storage type, add some replicated (readonly) databases, and perform reporting |
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19 | tasks. |
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20 | |
21 | ## Change storage_type in your schema class |
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22 | $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] ); |
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23 | |
24 | ## Add some slaves. Basically this is an array of arrayrefs, where each |
25 | ## arrayref is database connect information |
26 | |
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27 | $schema->storage->connect_replicants( |
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28 | [$dsn1, $user, $pass, \%opts], |
29 | [$dsn1, $user, $pass, \%opts], |
30 | [$dsn1, $user, $pass, \%opts], |
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31 | ); |
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32 | |
33 | =head1 DESCRIPTION |
34 | |
35 | Warning: This class is marked ALPHA. We are using this in development and have |
36 | some basic test coverage but the code hasn't yet been stressed by a variety |
37 | of databases. Individual DB's may have quirks we are not aware of. Please |
38 | use this in development and pass along your experiences/bug fixes. |
39 | |
40 | This class implements replicated data store for DBI. Currently you can define |
41 | one master and numerous slave database connections. All write-type queries |
42 | (INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master |
43 | database, all read-type queries (SELECTs) go to the slave database. |
44 | |
45 | Basically, any method request that L<DBIx::Class::Storage::DBI> would normally |
46 | handle gets delegated to one of the two attributes: L</master_storage> or to |
47 | L</current_replicant_storage>. Additionally, some methods need to be distributed |
48 | to all existing storages. This way our storage class is a drop in replacement |
49 | for L<DBIx::Class::Storage::DBI>. |
50 | |
51 | Read traffic is spread across the replicants (slaves) occuring to a user |
52 | selected algorithm. The default algorithm is random weighted. |
53 | |
54 | TODO more details about the algorithm. |
55 | |
56 | =head1 ATTRIBUTES |
57 | |
58 | This class defines the following attributes. |
59 | |
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60 | =head2 pool_type |
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61 | |
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62 | Contains the classname which will instantiate the L</pool> object. Defaults |
63 | to: L<DBIx::Class::Storage::DBI::Replicated::Pool>. |
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64 | |
65 | =cut |
66 | |
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67 | has 'pool_type' => ( |
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68 | is=>'ro', |
69 | isa=>'ClassName', |
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70 | lazy_build=>1, |
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71 | handles=>{ |
72 | 'create_pool' => 'new', |
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73 | }, |
74 | ); |
75 | |
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76 | =head2 pool_args |
77 | |
78 | Contains a hashref of initialized information to pass to the Pool object. See |
79 | L<DBIx::Class::Storage::Replicated::Pool> for available arguments. |
80 | |
81 | =cut |
82 | |
83 | has 'pool_args' => ( |
84 | is=>'ro', |
85 | isa=>'HashRef', |
86 | ); |
87 | |
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88 | =head2 balancer_type |
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89 | |
90 | The replication pool requires a balance class to provider the methods for |
91 | choose how to spread the query load across each replicant in the pool. |
92 | |
93 | =cut |
94 | |
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95 | has 'balancer_type' => ( |
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96 | is=>'ro', |
97 | isa=>'ClassName', |
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98 | lazy_build=>1, |
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99 | handles=>{ |
100 | 'create_balancer' => 'new', |
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101 | }, |
102 | ); |
103 | |
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104 | =head2 pool |
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105 | |
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106 | Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a |
107 | container class for one or more replicated databases. |
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108 | |
109 | =cut |
110 | |
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111 | has 'pool' => ( |
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112 | is=>'ro', |
113 | isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
114 | lazy_build=>1, |
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115 | handles=>[qw/ |
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116 | connect_replicants |
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117 | replicants |
118 | has_replicants |
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119 | num_replicants |
120 | delete_replicant |
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121 | validate_replicants |
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122 | /], |
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123 | ); |
124 | |
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125 | =head2 balancer |
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126 | |
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127 | Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This |
128 | is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>) |
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129 | |
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130 | =cut |
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131 | |
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132 | has 'balancer' => ( |
133 | is=>'ro', |
134 | isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', |
135 | lazy_build=>1, |
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136 | ); |
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137 | |
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138 | =head2 master |
139 | |
140 | The master defines the canonical state for a pool of connected databases. All |
141 | the replicants are expected to match this databases state. Thus, in a classic |
142 | Master / Slaves distributed system, all the slaves are expected to replicate |
143 | the Master's state as quick as possible. This is the only database in the |
144 | pool of databases that is allowed to handle write traffic. |
145 | |
146 | =cut |
147 | |
148 | has 'master' => ( |
149 | is=> 'ro', |
150 | isa=>'DBIx::Class::Storage::DBI', |
151 | lazy_build=>1, |
152 | ); |
153 | |
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154 | =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE |
155 | |
156 | The following methods are delegated all the methods required for the |
157 | L<DBIx::Class::Storage::DBI> interface. |
158 | |
159 | =head2 read_handler |
160 | |
161 | Defines an object that implements the read side of L<BIx::Class::Storage::DBI>. |
162 | |
163 | =cut |
164 | |
165 | has 'read_handler' => ( |
166 | is=>'rw', |
167 | isa=>'Object', |
168 | lazy_build=>1, |
169 | handles=>[qw/ |
170 | select |
171 | select_single |
172 | columns_info_for |
173 | /], |
174 | ); |
175 | |
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176 | =head2 write_handler |
177 | |
178 | Defines an object that implements the write side of L<BIx::Class::Storage::DBI>. |
179 | |
180 | =cut |
181 | |
182 | has 'write_handler' => ( |
183 | is=>'ro', |
184 | isa=>'Object', |
185 | lazy_build=>1, |
186 | lazy_build=>1, |
187 | handles=>[qw/ |
188 | on_connect_do |
189 | on_disconnect_do |
190 | connect_info |
191 | throw_exception |
192 | sql_maker |
193 | sqlt_type |
194 | create_ddl_dir |
195 | deployment_statements |
196 | datetime_parser |
197 | datetime_parser_type |
198 | last_insert_id |
199 | insert |
200 | insert_bulk |
201 | update |
202 | delete |
203 | dbh |
204 | txn_do |
205 | txn_commit |
206 | txn_rollback |
207 | sth |
208 | deploy |
209 | schema |
210 | /], |
211 | ); |
212 | |
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213 | =head1 METHODS |
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214 | |
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215 | This class defines the following methods. |
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216 | |
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217 | =head2 new |
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218 | |
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219 | L<DBIx::Class::Schema> when instantiating it's storage passed itself as the |
220 | first argument. We need to invoke L</new> on the underlying parent class, make |
221 | sure we properly give it a L<Moose> meta class, and then correctly instantiate |
222 | our attributes. Basically we pass on whatever the schema has in it's class |
223 | data for 'storage_type_args' to our replicated storage type. |
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224 | |
225 | =cut |
226 | |
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227 | sub new { |
228 | my $class = shift @_; |
229 | my $schema = shift @_; |
230 | my $storage_type_args = shift @_; |
231 | my $obj = $class->SUPER::new($schema, $storage_type_args, @_); |
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232 | |
233 | ## Hate to do it this way, but can't seem to get advice on the attribute working right |
234 | ## maybe we can do a type and coercion for it. |
235 | if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) { |
236 | $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; |
237 | eval "require $storage_type_args->{balancer_type}"; |
238 | } |
239 | |
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240 | return $class->meta->new_object( |
241 | __INSTANCE__ => $obj, |
242 | %$storage_type_args, |
243 | @_, |
244 | ); |
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245 | } |
246 | |
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247 | =head2 _build_master |
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248 | |
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249 | Lazy builder for the L</master> attribute. |
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250 | |
251 | =cut |
252 | |
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253 | sub _build_master { |
254 | DBIx::Class::Storage::DBI->new; |
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255 | } |
256 | |
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257 | =head2 _build_pool_type |
258 | |
259 | Lazy builder for the L</pool_type> attribute. |
260 | |
261 | =cut |
262 | |
263 | sub _build_pool_type { |
264 | return 'DBIx::Class::Storage::DBI::Replicated::Pool'; |
265 | } |
266 | |
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267 | =head2 _build_pool |
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268 | |
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269 | Lazy builder for the L</pool> attribute. |
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270 | |
271 | =cut |
272 | |
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273 | sub _build_pool { |
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274 | my $self = shift @_; |
275 | $self->create_pool($self->pool_args); |
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276 | } |
277 | |
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278 | =head2 _build_balancer_type |
279 | |
280 | Lazy builder for the L</balancer_type> attribute. |
281 | |
282 | =cut |
283 | |
284 | sub _build_balancer_type { |
285 | return 'DBIx::Class::Storage::DBI::Replicated::Balancer'; |
286 | } |
287 | |
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288 | =head2 _build_balancer |
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289 | |
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290 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
291 | the balancer knows which pool it's balancing. |
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292 | |
293 | =cut |
294 | |
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295 | sub _build_balancer { |
296 | my $self = shift @_; |
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297 | $self->create_balancer( |
298 | pool=>$self->pool, |
299 | master=>$self->master); |
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300 | } |
301 | |
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302 | =head2 _build_write_handler |
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303 | |
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304 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
305 | the L</master>. |
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306 | |
307 | =cut |
308 | |
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309 | sub _build_write_handler { |
310 | return shift->master; |
311 | } |
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312 | |
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313 | =head2 _build_read_handler |
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314 | |
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315 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
316 | the L</balancer>. |
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317 | |
318 | =cut |
319 | |
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320 | sub _build_read_handler { |
321 | return shift->balancer; |
322 | } |
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323 | |
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324 | =head2 around: connect_replicants |
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325 | |
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326 | All calls to connect_replicants needs to have an existing $schema tacked onto |
327 | top of the args, since L<DBIx::Storage::DBI> needs it. |
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328 | |
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329 | =cut |
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330 | |
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331 | around 'connect_replicants' => sub { |
332 | my ($method, $self, @args) = @_; |
333 | $self->$method($self->schema, @args); |
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334 | }; |
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335 | |
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336 | =head2 all_storages |
337 | |
338 | Returns an array of of all the connected storage backends. The first element |
339 | in the returned array is the master, and the remainings are each of the |
340 | replicants. |
341 | |
342 | =cut |
343 | |
344 | sub all_storages { |
345 | my $self = shift @_; |
346 | |
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347 | return grep {defined $_ && blessed $_} ( |
348 | $self->master, |
349 | $self->replicants, |
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350 | ); |
351 | } |
352 | |
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353 | =head2 set_reliable_storage |
354 | |
355 | Sets the current $schema to be 'reliable', that is all queries, both read and |
356 | write are sent to the master |
357 | |
358 | =cut |
359 | |
360 | sub set_reliable_storage { |
361 | my $self = shift @_; |
362 | my $schema = $self->schema; |
363 | my $write_handler = $self->schema->storage->write_handler; |
364 | |
365 | $schema->storage->read_handler($write_handler); |
366 | } |
367 | |
368 | =head2 set_balanced_storage |
369 | |
370 | Sets the current $schema to be use the </balancer> for all reads, while all |
371 | writea are sent to the master only |
372 | |
373 | =cut |
374 | |
375 | sub set_balanced_storage { |
376 | my $self = shift @_; |
377 | my $schema = $self->schema; |
378 | my $write_handler = $self->schema->storage->balancer; |
379 | |
380 | $schema->storage->read_handler($write_handler); |
381 | } |
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382 | |
383 | =head2 connected |
384 | |
385 | Check that the master and at least one of the replicants is connected. |
386 | |
387 | =cut |
388 | |
389 | sub connected { |
390 | my $self = shift @_; |
391 | |
392 | return |
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393 | $self->master->connected && |
394 | $self->pool->connected_replicants; |
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395 | } |
396 | |
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397 | =head2 ensure_connected |
398 | |
399 | Make sure all the storages are connected. |
400 | |
401 | =cut |
402 | |
403 | sub ensure_connected { |
404 | my $self = shift @_; |
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405 | foreach my $source ($self->all_storages) { |
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406 | $source->ensure_connected(@_); |
407 | } |
408 | } |
409 | |
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410 | =head2 limit_dialect |
411 | |
412 | Set the limit_dialect for all existing storages |
413 | |
414 | =cut |
415 | |
416 | sub limit_dialect { |
417 | my $self = shift @_; |
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418 | foreach my $source ($self->all_storages) { |
419 | $source->limit_dialect(@_); |
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420 | } |
421 | } |
422 | |
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423 | =head2 quote_char |
424 | |
425 | Set the quote_char for all existing storages |
426 | |
427 | =cut |
428 | |
429 | sub quote_char { |
430 | my $self = shift @_; |
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431 | foreach my $source ($self->all_storages) { |
432 | $source->quote_char(@_); |
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433 | } |
434 | } |
435 | |
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436 | =head2 name_sep |
437 | |
438 | Set the name_sep for all existing storages |
439 | |
440 | =cut |
441 | |
442 | sub name_sep { |
443 | my $self = shift @_; |
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444 | foreach my $source ($self->all_storages) { |
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445 | $source->name_sep(@_); |
446 | } |
447 | } |
448 | |
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449 | =head2 set_schema |
450 | |
451 | Set the schema object for all existing storages |
452 | |
453 | =cut |
454 | |
455 | sub set_schema { |
456 | my $self = shift @_; |
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457 | foreach my $source ($self->all_storages) { |
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458 | $source->set_schema(@_); |
459 | } |
460 | } |
461 | |
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462 | =head2 debug |
463 | |
464 | set a debug flag across all storages |
465 | |
466 | =cut |
467 | |
468 | sub debug { |
469 | my $self = shift @_; |
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470 | foreach my $source ($self->all_storages) { |
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471 | $source->debug(@_); |
472 | } |
473 | } |
474 | |
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475 | =head2 debugobj |
476 | |
477 | set a debug object across all storages |
478 | |
479 | =cut |
480 | |
481 | sub debugobj { |
482 | my $self = shift @_; |
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483 | foreach my $source ($self->all_storages) { |
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484 | $source->debugobj(@_); |
485 | } |
486 | } |
487 | |
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488 | =head2 debugfh |
489 | |
490 | set a debugfh object across all storages |
491 | |
492 | =cut |
493 | |
494 | sub debugfh { |
495 | my $self = shift @_; |
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496 | foreach my $source ($self->all_storages) { |
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497 | $source->debugfh(@_); |
498 | } |
499 | } |
500 | |
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501 | =head2 debugcb |
502 | |
503 | set a debug callback across all storages |
504 | |
505 | =cut |
506 | |
507 | sub debugcb { |
508 | my $self = shift @_; |
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509 | foreach my $source ($self->all_storages) { |
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510 | $source->debugcb(@_); |
511 | } |
512 | } |
513 | |
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514 | =head2 disconnect |
515 | |
516 | disconnect everything |
517 | |
518 | =cut |
519 | |
520 | sub disconnect { |
521 | my $self = shift @_; |
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522 | foreach my $source ($self->all_storages) { |
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523 | $source->disconnect(@_); |
524 | } |
525 | } |
526 | |
f5d3a5de |
527 | =head1 AUTHOR |
528 | |
529 | Norbert Csongrádi <bert@cpan.org> |
530 | |
531 | Peter Siklósi <einon@einon.hu> |
532 | |
2156bbdd |
533 | John Napiorkowski <john.napiorkowski@takkle.com> |
534 | |
f5d3a5de |
535 | =head1 LICENSE |
536 | |
537 | You may distribute this code under the same terms as Perl itself. |
538 | |
539 | =cut |
540 | |
541 | 1; |