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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, $pass, \%opts], |
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29 | [$dsn2, $user, $pass, \%opts], |
30 | [$dsn3, $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 |
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46 | handle gets delegated to one of the two attributes: L</read_handler> or to |
47 | L</write_handler>. Additionally, some methods need to be distributed |
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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 | |
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54 | =head1 NOTES |
55 | |
56 | The consistancy betweeen master and replicants is database specific. The Pool |
57 | gives you a method to validate it's replicants, removing and replacing them |
58 | when they fail/pass predefined criteria. It is recommened that your application |
59 | define two schemas, one using the replicated storage and another that just |
60 | connects to the master. |
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61 | |
62 | =head1 ATTRIBUTES |
63 | |
64 | This class defines the following attributes. |
65 | |
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66 | =head2 pool_type |
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67 | |
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68 | Contains the classname which will instantiate the L</pool> object. Defaults |
69 | to: L<DBIx::Class::Storage::DBI::Replicated::Pool>. |
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70 | |
71 | =cut |
72 | |
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73 | has 'pool_type' => ( |
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74 | is=>'ro', |
75 | isa=>'ClassName', |
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76 | lazy_build=>1, |
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77 | handles=>{ |
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78 | 'create_pool' => 'new', |
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79 | }, |
80 | ); |
81 | |
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82 | =head2 pool_args |
83 | |
84 | Contains a hashref of initialized information to pass to the Balancer object. |
85 | See L<DBIx::Class::Storage::Replicated::Pool> for available arguments. |
86 | |
87 | =cut |
88 | |
89 | has 'pool_args' => ( |
90 | is=>'ro', |
91 | isa=>'HashRef', |
92 | lazy=>1, |
93 | required=>1, |
94 | default=>sub { {} }, |
95 | ); |
96 | |
97 | |
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98 | =head2 balancer_type |
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99 | |
100 | The replication pool requires a balance class to provider the methods for |
101 | choose how to spread the query load across each replicant in the pool. |
102 | |
103 | =cut |
104 | |
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105 | has 'balancer_type' => ( |
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106 | is=>'ro', |
107 | isa=>'ClassName', |
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108 | lazy_build=>1, |
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109 | handles=>{ |
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110 | 'create_balancer' => 'new', |
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111 | }, |
112 | ); |
113 | |
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114 | =head2 balancer_args |
115 | |
116 | Contains a hashref of initialized information to pass to the Balancer object. |
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117 | See L<DBIx::Class::Storage::Replicated::Balancer> for available arguments. |
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118 | |
119 | =cut |
120 | |
121 | has 'balancer_args' => ( |
122 | is=>'ro', |
123 | isa=>'HashRef', |
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124 | lazy=>1, |
125 | required=>1, |
126 | default=>sub { {} }, |
17b05c13 |
127 | ); |
128 | |
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129 | =head2 pool |
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130 | |
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131 | Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a |
132 | container class for one or more replicated databases. |
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133 | |
134 | =cut |
135 | |
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136 | has 'pool' => ( |
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137 | is=>'ro', |
138 | isa=>'DBIx::Class::Storage::DBI::Replicated::Pool', |
139 | lazy_build=>1, |
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140 | handles=>[qw/ |
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141 | connect_replicants |
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142 | replicants |
143 | has_replicants |
26ab719a |
144 | /], |
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145 | ); |
146 | |
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147 | =head2 balancer |
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148 | |
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149 | Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This |
150 | is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>) |
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151 | |
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152 | =cut |
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153 | |
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154 | has 'balancer' => ( |
155 | is=>'ro', |
156 | isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer', |
157 | lazy_build=>1, |
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158 | handles=>[qw/auto_validate_every/], |
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159 | ); |
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160 | |
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161 | =head2 master |
162 | |
163 | The master defines the canonical state for a pool of connected databases. All |
164 | the replicants are expected to match this databases state. Thus, in a classic |
165 | Master / Slaves distributed system, all the slaves are expected to replicate |
166 | the Master's state as quick as possible. This is the only database in the |
167 | pool of databases that is allowed to handle write traffic. |
168 | |
169 | =cut |
170 | |
171 | has 'master' => ( |
172 | is=> 'ro', |
173 | isa=>'DBIx::Class::Storage::DBI', |
174 | lazy_build=>1, |
175 | ); |
176 | |
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177 | =head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE |
178 | |
179 | The following methods are delegated all the methods required for the |
180 | L<DBIx::Class::Storage::DBI> interface. |
181 | |
182 | =head2 read_handler |
183 | |
184 | Defines an object that implements the read side of L<BIx::Class::Storage::DBI>. |
185 | |
186 | =cut |
187 | |
188 | has 'read_handler' => ( |
189 | is=>'rw', |
190 | isa=>'Object', |
191 | lazy_build=>1, |
192 | handles=>[qw/ |
193 | select |
194 | select_single |
195 | columns_info_for |
196 | /], |
197 | ); |
198 | |
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199 | =head2 write_handler |
200 | |
201 | Defines an object that implements the write side of L<BIx::Class::Storage::DBI>. |
202 | |
203 | =cut |
204 | |
205 | has 'write_handler' => ( |
206 | is=>'ro', |
207 | isa=>'Object', |
208 | lazy_build=>1, |
209 | lazy_build=>1, |
210 | handles=>[qw/ |
211 | on_connect_do |
212 | on_disconnect_do |
213 | connect_info |
214 | throw_exception |
215 | sql_maker |
216 | sqlt_type |
217 | create_ddl_dir |
218 | deployment_statements |
219 | datetime_parser |
220 | datetime_parser_type |
221 | last_insert_id |
222 | insert |
223 | insert_bulk |
224 | update |
225 | delete |
226 | dbh |
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227 | txn_do |
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228 | txn_commit |
229 | txn_rollback |
230 | sth |
231 | deploy |
232 | schema |
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233 | reload_row |
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234 | /], |
235 | ); |
236 | |
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237 | =head1 METHODS |
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238 | |
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239 | This class defines the following methods. |
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240 | |
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241 | =head2 new |
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242 | |
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243 | L<DBIx::Class::Schema> when instantiating it's storage passed itself as the |
244 | first argument. We need to invoke L</new> on the underlying parent class, make |
245 | sure we properly give it a L<Moose> meta class, and then correctly instantiate |
246 | our attributes. Basically we pass on whatever the schema has in it's class |
247 | data for 'storage_type_args' to our replicated storage type. |
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248 | |
249 | =cut |
250 | |
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251 | sub new { |
252 | my $class = shift @_; |
253 | my $schema = shift @_; |
254 | my $storage_type_args = shift @_; |
255 | my $obj = $class->SUPER::new($schema, $storage_type_args, @_); |
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256 | |
257 | ## Hate to do it this way, but can't seem to get advice on the attribute working right |
258 | ## maybe we can do a type and coercion for it. |
259 | if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) { |
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260 | $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; |
261 | eval "require $storage_type_args->{balancer_type}"; |
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262 | } |
263 | |
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264 | return $class->meta->new_object( |
265 | __INSTANCE__ => $obj, |
266 | %$storage_type_args, |
267 | @_, |
268 | ); |
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269 | } |
270 | |
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271 | =head2 _build_master |
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272 | |
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273 | Lazy builder for the L</master> attribute. |
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274 | |
275 | =cut |
276 | |
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277 | sub _build_master { |
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278 | DBIx::Class::Storage::DBI->new; |
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279 | } |
280 | |
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281 | =head2 _build_pool_type |
282 | |
283 | Lazy builder for the L</pool_type> attribute. |
284 | |
285 | =cut |
286 | |
287 | sub _build_pool_type { |
288 | return 'DBIx::Class::Storage::DBI::Replicated::Pool'; |
289 | } |
290 | |
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291 | =head2 _build_pool |
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292 | |
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293 | Lazy builder for the L</pool> attribute. |
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294 | |
295 | =cut |
296 | |
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297 | sub _build_pool { |
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298 | my $self = shift @_; |
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299 | $self->create_pool(%{$self->pool_args}); |
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300 | } |
301 | |
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302 | =head2 _build_balancer_type |
303 | |
304 | Lazy builder for the L</balancer_type> attribute. |
305 | |
306 | =cut |
307 | |
308 | sub _build_balancer_type { |
17b05c13 |
309 | return 'DBIx::Class::Storage::DBI::Replicated::Balancer::First'; |
106d5f3b |
310 | } |
311 | |
26ab719a |
312 | =head2 _build_balancer |
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313 | |
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314 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
315 | the balancer knows which pool it's balancing. |
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316 | |
317 | =cut |
318 | |
26ab719a |
319 | sub _build_balancer { |
320 | my $self = shift @_; |
106d5f3b |
321 | $self->create_balancer( |
322 | pool=>$self->pool, |
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323 | master=>$self->master, |
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324 | %{$self->balancer_args}, |
325 | ); |
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326 | } |
327 | |
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328 | =head2 _build_write_handler |
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329 | |
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330 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
331 | the L</master>. |
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332 | |
333 | =cut |
334 | |
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335 | sub _build_write_handler { |
336 | return shift->master; |
337 | } |
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338 | |
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339 | =head2 _build_read_handler |
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340 | |
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341 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
342 | the L</balancer>. |
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343 | |
344 | =cut |
345 | |
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346 | sub _build_read_handler { |
347 | return shift->balancer; |
348 | } |
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349 | |
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350 | =head2 around: connect_replicants |
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351 | |
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352 | All calls to connect_replicants needs to have an existing $schema tacked onto |
353 | top of the args, since L<DBIx::Storage::DBI> needs it. |
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354 | |
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355 | =cut |
955a6df6 |
356 | |
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357 | around 'connect_replicants' => sub { |
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358 | my ($method, $self, @args) = @_; |
359 | $self->$method($self->schema, @args); |
955a6df6 |
360 | }; |
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361 | |
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362 | =head2 all_storages |
363 | |
364 | Returns an array of of all the connected storage backends. The first element |
365 | in the returned array is the master, and the remainings are each of the |
366 | replicants. |
367 | |
368 | =cut |
369 | |
370 | sub all_storages { |
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371 | my $self = shift @_; |
372 | |
373 | return grep {defined $_ && blessed $_} ( |
374 | $self->master, |
375 | $self->replicants, |
376 | ); |
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377 | } |
378 | |
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379 | =head2 execute_reliably ($coderef, ?@args) |
380 | |
381 | Given a coderef, saves the current state of the L</read_handler>, forces it to |
382 | use reliable storage (ie sets it to the master), executes a coderef and then |
383 | restores the original state. |
384 | |
385 | Example: |
386 | |
387 | my $reliably = sub { |
388 | my $name = shift @_; |
389 | $schema->resultset('User')->create({name=>$name}); |
390 | my $user_rs = $schema->resultset('User')->find({name=>$name}); |
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391 | return $user_rs; |
c4d3fae2 |
392 | }; |
393 | |
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394 | my $user_rs = $schema->storage->execute_reliably($reliably, 'John'); |
c4d3fae2 |
395 | |
396 | Use this when you must be certain of your database state, such as when you just |
397 | inserted something and need to get a resultset including it, etc. |
398 | |
399 | =cut |
400 | |
401 | sub execute_reliably { |
402 | my ($self, $coderef, @args) = @_; |
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403 | |
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404 | unless( ref $coderef eq 'CODE') { |
405 | $self->throw_exception('Second argument must be a coderef'); |
406 | } |
407 | |
408 | ##Get copy of master storage |
409 | my $master = $self->master; |
410 | |
411 | ##Get whatever the current read hander is |
412 | my $current = $self->read_handler; |
413 | |
414 | ##Set the read handler to master |
415 | $self->read_handler($master); |
416 | |
417 | ## do whatever the caller needs |
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418 | my @result; |
419 | my $want_array = wantarray; |
420 | |
c4d3fae2 |
421 | eval { |
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422 | if($want_array) { |
423 | @result = $coderef->(@args); |
424 | } |
425 | elsif(defined $want_array) { |
426 | ($result[0]) = ($coderef->(@args)); |
427 | } else { |
428 | $coderef->(@args); |
429 | } |
c4d3fae2 |
430 | }; |
431 | |
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432 | ##Reset to the original state |
4fafa779 |
433 | $self->read_handler($current); |
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434 | |
435 | ##Exception testing has to come last, otherwise you might leave the |
436 | ##read_handler set to master. |
437 | |
c4d3fae2 |
438 | if($@) { |
439 | $self->throw_exception("coderef returned an error: $@"); |
ed213e85 |
440 | } else { |
0c90fabe |
441 | return $want_array ? @result : $result[0]; |
c4d3fae2 |
442 | } |
c4d3fae2 |
443 | } |
444 | |
cb6ec758 |
445 | =head2 set_reliable_storage |
446 | |
447 | Sets the current $schema to be 'reliable', that is all queries, both read and |
448 | write are sent to the master |
449 | |
450 | =cut |
451 | |
452 | sub set_reliable_storage { |
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453 | my $self = shift @_; |
454 | my $schema = $self->schema; |
455 | my $write_handler = $self->schema->storage->write_handler; |
456 | |
457 | $schema->storage->read_handler($write_handler); |
cb6ec758 |
458 | } |
459 | |
460 | =head2 set_balanced_storage |
461 | |
462 | Sets the current $schema to be use the </balancer> for all reads, while all |
463 | writea are sent to the master only |
464 | |
465 | =cut |
466 | |
467 | sub set_balanced_storage { |
468 | my $self = shift @_; |
469 | my $schema = $self->schema; |
470 | my $write_handler = $self->schema->storage->balancer; |
471 | |
472 | $schema->storage->read_handler($write_handler); |
473 | } |
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474 | |
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475 | =head2 around: txn_do ($coderef) |
c4d3fae2 |
476 | |
477 | Overload to the txn_do method, which is delegated to whatever the |
478 | L<write_handler> is set to. We overload this in order to wrap in inside a |
479 | L</execute_reliably> method. |
480 | |
481 | =cut |
482 | |
6834cc1d |
483 | around 'txn_do' => sub { |
484 | my($txn_do, $self, $coderef, @args) = @_; |
0c90fabe |
485 | $self->execute_reliably(sub {$self->$txn_do($coderef, @args)}); |
6834cc1d |
486 | }; |
c4d3fae2 |
487 | |
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488 | =head2 reload_row ($row) |
489 | |
490 | Overload to the reload_row method so that the reloading is always directed to |
491 | the master storage. |
492 | |
493 | =cut |
494 | |
495 | around 'reload_row' => sub { |
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496 | my ($reload_row, $self, $row) = @_; |
497 | return $self->execute_reliably(sub { |
498 | return $self->$reload_row(shift); |
499 | }, $row); |
ed213e85 |
500 | }; |
501 | |
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502 | =head2 connected |
503 | |
504 | Check that the master and at least one of the replicants is connected. |
505 | |
506 | =cut |
507 | |
508 | sub connected { |
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509 | my $self = shift @_; |
510 | |
511 | return |
512 | $self->master->connected && |
513 | $self->pool->connected_replicants; |
2bf79155 |
514 | } |
515 | |
2bf79155 |
516 | =head2 ensure_connected |
517 | |
518 | Make sure all the storages are connected. |
519 | |
520 | =cut |
521 | |
522 | sub ensure_connected { |
523 | my $self = shift @_; |
26ab719a |
524 | foreach my $source ($self->all_storages) { |
2bf79155 |
525 | $source->ensure_connected(@_); |
526 | } |
527 | } |
528 | |
2bf79155 |
529 | =head2 limit_dialect |
530 | |
531 | Set the limit_dialect for all existing storages |
532 | |
533 | =cut |
534 | |
535 | sub limit_dialect { |
536 | my $self = shift @_; |
26ab719a |
537 | foreach my $source ($self->all_storages) { |
538 | $source->limit_dialect(@_); |
2bf79155 |
539 | } |
540 | } |
541 | |
2bf79155 |
542 | =head2 quote_char |
543 | |
544 | Set the quote_char for all existing storages |
545 | |
546 | =cut |
547 | |
548 | sub quote_char { |
549 | my $self = shift @_; |
26ab719a |
550 | foreach my $source ($self->all_storages) { |
551 | $source->quote_char(@_); |
2bf79155 |
552 | } |
553 | } |
554 | |
2bf79155 |
555 | =head2 name_sep |
556 | |
557 | Set the name_sep for all existing storages |
558 | |
559 | =cut |
560 | |
561 | sub name_sep { |
562 | my $self = shift @_; |
26ab719a |
563 | foreach my $source ($self->all_storages) { |
2bf79155 |
564 | $source->name_sep(@_); |
565 | } |
566 | } |
567 | |
2bf79155 |
568 | =head2 set_schema |
569 | |
570 | Set the schema object for all existing storages |
571 | |
572 | =cut |
573 | |
574 | sub set_schema { |
0c90fabe |
575 | my $self = shift @_; |
576 | foreach my $source ($self->all_storages) { |
577 | $source->set_schema(@_); |
578 | } |
2bf79155 |
579 | } |
580 | |
2bf79155 |
581 | =head2 debug |
582 | |
583 | set a debug flag across all storages |
584 | |
585 | =cut |
586 | |
587 | sub debug { |
588 | my $self = shift @_; |
26ab719a |
589 | foreach my $source ($self->all_storages) { |
2bf79155 |
590 | $source->debug(@_); |
591 | } |
592 | } |
593 | |
2bf79155 |
594 | =head2 debugobj |
595 | |
596 | set a debug object across all storages |
597 | |
598 | =cut |
599 | |
600 | sub debugobj { |
601 | my $self = shift @_; |
26ab719a |
602 | foreach my $source ($self->all_storages) { |
2bf79155 |
603 | $source->debugobj(@_); |
604 | } |
605 | } |
606 | |
2bf79155 |
607 | =head2 debugfh |
608 | |
609 | set a debugfh object across all storages |
610 | |
611 | =cut |
612 | |
613 | sub debugfh { |
614 | my $self = shift @_; |
26ab719a |
615 | foreach my $source ($self->all_storages) { |
2bf79155 |
616 | $source->debugfh(@_); |
617 | } |
618 | } |
619 | |
2bf79155 |
620 | =head2 debugcb |
621 | |
622 | set a debug callback across all storages |
623 | |
624 | =cut |
625 | |
626 | sub debugcb { |
627 | my $self = shift @_; |
26ab719a |
628 | foreach my $source ($self->all_storages) { |
2bf79155 |
629 | $source->debugcb(@_); |
630 | } |
631 | } |
632 | |
2bf79155 |
633 | =head2 disconnect |
634 | |
635 | disconnect everything |
636 | |
637 | =cut |
638 | |
639 | sub disconnect { |
640 | my $self = shift @_; |
26ab719a |
641 | foreach my $source ($self->all_storages) { |
2bf79155 |
642 | $source->disconnect(@_); |
643 | } |
644 | } |
645 | |
f5d3a5de |
646 | =head1 AUTHOR |
647 | |
c4d3fae2 |
648 | John Napiorkowski <john.napiorkowski@takkle.com> |
f5d3a5de |
649 | |
c4d3fae2 |
650 | Based on code originated by: |
f5d3a5de |
651 | |
c4d3fae2 |
652 | Norbert Csongrádi <bert@cpan.org> |
653 | Peter Siklósi <einon@einon.hu> |
2156bbdd |
654 | |
f5d3a5de |
655 | =head1 LICENSE |
656 | |
657 | You may distribute this code under the same terms as Perl itself. |
658 | |
659 | =cut |
660 | |
661 | 1; |