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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 balancer_type |
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77 | |
78 | The replication pool requires a balance class to provider the methods for |
79 | choose how to spread the query load across each replicant in the pool. |
80 | |
81 | =cut |
82 | |
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83 | has 'balancer_type' => ( |
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84 | is=>'ro', |
85 | isa=>'ClassName', |
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86 | lazy_build=>1, |
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87 | handles=>{ |
88 | 'create_balancer' => 'new', |
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89 | }, |
90 | ); |
91 | |
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92 | =head2 pool |
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93 | |
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94 | Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a |
95 | container class for one or more replicated databases. |
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96 | |
97 | =cut |
98 | |
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99 | has 'pool' => ( |
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100 | is=>'ro', |
101 | isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
102 | lazy_build=>1, |
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103 | handles=>[qw/ |
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104 | connect_replicants |
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105 | replicants |
106 | has_replicants |
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107 | num_replicants |
108 | delete_replicant |
109 | /], |
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110 | ); |
111 | |
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112 | =head2 balancer |
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113 | |
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114 | Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This |
115 | is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>) |
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116 | |
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117 | =cut |
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118 | |
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119 | has 'balancer' => ( |
120 | is=>'ro', |
121 | isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', |
122 | lazy_build=>1, |
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123 | ); |
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124 | |
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125 | =head2 master |
126 | |
127 | The master defines the canonical state for a pool of connected databases. All |
128 | the replicants are expected to match this databases state. Thus, in a classic |
129 | Master / Slaves distributed system, all the slaves are expected to replicate |
130 | the Master's state as quick as possible. This is the only database in the |
131 | pool of databases that is allowed to handle write traffic. |
132 | |
133 | =cut |
134 | |
135 | has 'master' => ( |
136 | is=> 'ro', |
137 | isa=>'DBIx::Class::Storage::DBI', |
138 | lazy_build=>1, |
139 | ); |
140 | |
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141 | =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE |
142 | |
143 | The following methods are delegated all the methods required for the |
144 | L<DBIx::Class::Storage::DBI> interface. |
145 | |
146 | =head2 read_handler |
147 | |
148 | Defines an object that implements the read side of L<BIx::Class::Storage::DBI>. |
149 | |
150 | =cut |
151 | |
152 | has 'read_handler' => ( |
153 | is=>'rw', |
154 | isa=>'Object', |
155 | lazy_build=>1, |
156 | handles=>[qw/ |
157 | select |
158 | select_single |
159 | columns_info_for |
160 | /], |
161 | ); |
162 | |
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163 | =head2 write_handler |
164 | |
165 | Defines an object that implements the write side of L<BIx::Class::Storage::DBI>. |
166 | |
167 | =cut |
168 | |
169 | has 'write_handler' => ( |
170 | is=>'ro', |
171 | isa=>'Object', |
172 | lazy_build=>1, |
173 | lazy_build=>1, |
174 | handles=>[qw/ |
175 | on_connect_do |
176 | on_disconnect_do |
177 | connect_info |
178 | throw_exception |
179 | sql_maker |
180 | sqlt_type |
181 | create_ddl_dir |
182 | deployment_statements |
183 | datetime_parser |
184 | datetime_parser_type |
185 | last_insert_id |
186 | insert |
187 | insert_bulk |
188 | update |
189 | delete |
190 | dbh |
191 | txn_do |
192 | txn_commit |
193 | txn_rollback |
194 | sth |
195 | deploy |
196 | schema |
197 | /], |
198 | ); |
199 | |
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200 | =head1 METHODS |
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201 | |
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202 | This class defines the following methods. |
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203 | |
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204 | =head2 new |
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205 | |
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206 | L<DBIx::Class::Schema> when instantiating it's storage passed itself as the |
207 | first argument. We need to invoke L</new> on the underlying parent class, make |
208 | sure we properly give it a L<Moose> meta class, and then correctly instantiate |
209 | our attributes. Basically we pass on whatever the schema has in it's class |
210 | data for 'storage_type_args' to our replicated storage type. |
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211 | |
212 | =cut |
213 | |
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214 | sub new { |
215 | my $class = shift @_; |
216 | my $schema = shift @_; |
217 | my $storage_type_args = shift @_; |
218 | my $obj = $class->SUPER::new($schema, $storage_type_args, @_); |
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219 | |
220 | ## Hate to do it this way, but can't seem to get advice on the attribute working right |
221 | ## maybe we can do a type and coercion for it. |
222 | if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) { |
223 | $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; |
224 | eval "require $storage_type_args->{balancer_type}"; |
225 | } |
226 | |
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227 | return $class->meta->new_object( |
228 | __INSTANCE__ => $obj, |
229 | %$storage_type_args, |
230 | @_, |
231 | ); |
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232 | } |
233 | |
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234 | =head2 _build_master |
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235 | |
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236 | Lazy builder for the L</master> attribute. |
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237 | |
238 | =cut |
239 | |
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240 | sub _build_master { |
241 | DBIx::Class::Storage::DBI->new; |
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242 | } |
243 | |
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244 | =head2 _build_pool_type |
245 | |
246 | Lazy builder for the L</pool_type> attribute. |
247 | |
248 | =cut |
249 | |
250 | sub _build_pool_type { |
251 | return 'DBIx::Class::Storage::DBI::Replicated::Pool'; |
252 | } |
253 | |
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254 | =head2 _build_pool |
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255 | |
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256 | Lazy builder for the L</pool> attribute. |
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257 | |
258 | =cut |
259 | |
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260 | sub _build_pool { |
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261 | shift->create_pool; |
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262 | } |
263 | |
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264 | =head2 _build_balancer_type |
265 | |
266 | Lazy builder for the L</balancer_type> attribute. |
267 | |
268 | =cut |
269 | |
270 | sub _build_balancer_type { |
271 | return 'DBIx::Class::Storage::DBI::Replicated::Balancer'; |
272 | } |
273 | |
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274 | =head2 _build_balancer |
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275 | |
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276 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
277 | the balancer knows which pool it's balancing. |
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278 | |
279 | =cut |
280 | |
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281 | sub _build_balancer { |
282 | my $self = shift @_; |
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283 | $self->create_balancer( |
284 | pool=>$self->pool, |
285 | master=>$self->master); |
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286 | } |
287 | |
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288 | =head2 _build_write_handler |
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289 | |
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290 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
291 | the L</master>. |
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292 | |
293 | =cut |
294 | |
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295 | sub _build_write_handler { |
296 | return shift->master; |
297 | } |
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298 | |
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299 | =head2 _build_read_handler |
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300 | |
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301 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
302 | the L</balancer>. |
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303 | |
304 | =cut |
305 | |
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306 | sub _build_read_handler { |
307 | return shift->balancer; |
308 | } |
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309 | |
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310 | =head2 around: connect_replicants |
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311 | |
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312 | All calls to connect_replicants needs to have an existing $schema tacked onto |
313 | top of the args, since L<DBIx::Storage::DBI> needs it. |
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314 | |
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315 | =cut |
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316 | |
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317 | around 'connect_replicants' => sub { |
318 | my ($method, $self, @args) = @_; |
319 | $self->$method($self->schema, @args); |
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320 | }; |
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321 | |
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322 | =head2 all_storages |
323 | |
324 | Returns an array of of all the connected storage backends. The first element |
325 | in the returned array is the master, and the remainings are each of the |
326 | replicants. |
327 | |
328 | =cut |
329 | |
330 | sub all_storages { |
331 | my $self = shift @_; |
332 | |
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333 | return grep {defined $_ && blessed $_} ( |
334 | $self->master, |
335 | $self->replicants, |
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336 | ); |
337 | } |
338 | |
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339 | =head2 set_reliable_storage |
340 | |
341 | Sets the current $schema to be 'reliable', that is all queries, both read and |
342 | write are sent to the master |
343 | |
344 | =cut |
345 | |
346 | sub set_reliable_storage { |
347 | my $self = shift @_; |
348 | my $schema = $self->schema; |
349 | my $write_handler = $self->schema->storage->write_handler; |
350 | |
351 | $schema->storage->read_handler($write_handler); |
352 | } |
353 | |
354 | =head2 set_balanced_storage |
355 | |
356 | Sets the current $schema to be use the </balancer> for all reads, while all |
357 | writea are sent to the master only |
358 | |
359 | =cut |
360 | |
361 | sub set_balanced_storage { |
362 | my $self = shift @_; |
363 | my $schema = $self->schema; |
364 | my $write_handler = $self->schema->storage->balancer; |
365 | |
366 | $schema->storage->read_handler($write_handler); |
367 | } |
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368 | |
369 | =head2 connected |
370 | |
371 | Check that the master and at least one of the replicants is connected. |
372 | |
373 | =cut |
374 | |
375 | sub connected { |
376 | my $self = shift @_; |
377 | |
378 | return |
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379 | $self->master->connected && |
380 | $self->pool->connected_replicants; |
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381 | } |
382 | |
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383 | =head2 ensure_connected |
384 | |
385 | Make sure all the storages are connected. |
386 | |
387 | =cut |
388 | |
389 | sub ensure_connected { |
390 | my $self = shift @_; |
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391 | foreach my $source ($self->all_storages) { |
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392 | $source->ensure_connected(@_); |
393 | } |
394 | } |
395 | |
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396 | =head2 limit_dialect |
397 | |
398 | Set the limit_dialect for all existing storages |
399 | |
400 | =cut |
401 | |
402 | sub limit_dialect { |
403 | my $self = shift @_; |
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404 | foreach my $source ($self->all_storages) { |
405 | $source->limit_dialect(@_); |
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406 | } |
407 | } |
408 | |
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409 | =head2 quote_char |
410 | |
411 | Set the quote_char for all existing storages |
412 | |
413 | =cut |
414 | |
415 | sub quote_char { |
416 | my $self = shift @_; |
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417 | foreach my $source ($self->all_storages) { |
418 | $source->quote_char(@_); |
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419 | } |
420 | } |
421 | |
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422 | =head2 name_sep |
423 | |
424 | Set the name_sep for all existing storages |
425 | |
426 | =cut |
427 | |
428 | sub name_sep { |
429 | my $self = shift @_; |
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430 | foreach my $source ($self->all_storages) { |
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431 | $source->name_sep(@_); |
432 | } |
433 | } |
434 | |
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435 | =head2 set_schema |
436 | |
437 | Set the schema object for all existing storages |
438 | |
439 | =cut |
440 | |
441 | sub set_schema { |
442 | my $self = shift @_; |
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443 | foreach my $source ($self->all_storages) { |
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444 | $source->set_schema(@_); |
445 | } |
446 | } |
447 | |
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448 | =head2 debug |
449 | |
450 | set a debug flag across all storages |
451 | |
452 | =cut |
453 | |
454 | sub debug { |
455 | my $self = shift @_; |
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456 | foreach my $source ($self->all_storages) { |
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457 | $source->debug(@_); |
458 | } |
459 | } |
460 | |
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461 | =head2 debugobj |
462 | |
463 | set a debug object across all storages |
464 | |
465 | =cut |
466 | |
467 | sub debugobj { |
468 | my $self = shift @_; |
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469 | foreach my $source ($self->all_storages) { |
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470 | $source->debugobj(@_); |
471 | } |
472 | } |
473 | |
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474 | =head2 debugfh |
475 | |
476 | set a debugfh object across all storages |
477 | |
478 | =cut |
479 | |
480 | sub debugfh { |
481 | my $self = shift @_; |
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482 | foreach my $source ($self->all_storages) { |
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483 | $source->debugfh(@_); |
484 | } |
485 | } |
486 | |
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487 | =head2 debugcb |
488 | |
489 | set a debug callback across all storages |
490 | |
491 | =cut |
492 | |
493 | sub debugcb { |
494 | my $self = shift @_; |
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495 | foreach my $source ($self->all_storages) { |
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496 | $source->debugcb(@_); |
497 | } |
498 | } |
499 | |
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500 | =head2 disconnect |
501 | |
502 | disconnect everything |
503 | |
504 | =cut |
505 | |
506 | sub disconnect { |
507 | my $self = shift @_; |
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508 | foreach my $source ($self->all_storages) { |
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509 | $source->disconnect(@_); |
510 | } |
511 | } |
512 | |
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513 | =head1 AUTHOR |
514 | |
515 | Norbert Csongrádi <bert@cpan.org> |
516 | |
517 | Peter Siklósi <einon@einon.hu> |
518 | |
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519 | John Napiorkowski <john.napiorkowski@takkle.com> |
520 | |
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521 | =head1 LICENSE |
522 | |
523 | You may distribute this code under the same terms as Perl itself. |
524 | |
525 | =cut |
526 | |
527 | 1; |