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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 |
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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=>{ |
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=>{ |
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 { {} }, |
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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 |
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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_commit |
228 | txn_rollback |
229 | sth |
230 | deploy |
231 | schema |
232 | /], |
233 | ); |
234 | |
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235 | =head1 METHODS |
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236 | |
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237 | This class defines the following methods. |
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238 | |
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239 | =head2 new |
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240 | |
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241 | L<DBIx::Class::Schema> when instantiating it's storage passed itself as the |
242 | first argument. We need to invoke L</new> on the underlying parent class, make |
243 | sure we properly give it a L<Moose> meta class, and then correctly instantiate |
244 | our attributes. Basically we pass on whatever the schema has in it's class |
245 | data for 'storage_type_args' to our replicated storage type. |
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246 | |
247 | =cut |
248 | |
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249 | sub new { |
250 | my $class = shift @_; |
251 | my $schema = shift @_; |
252 | my $storage_type_args = shift @_; |
253 | my $obj = $class->SUPER::new($schema, $storage_type_args, @_); |
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254 | |
255 | ## Hate to do it this way, but can't seem to get advice on the attribute working right |
256 | ## maybe we can do a type and coercion for it. |
257 | if( $storage_type_args->{balancer_type} && $storage_type_args->{balancer_type}=~m/^::/) { |
258 | $storage_type_args->{balancer_type} = 'DBIx::Class::Storage::DBI::Replicated::Balancer'.$storage_type_args->{balancer_type}; |
259 | eval "require $storage_type_args->{balancer_type}"; |
260 | } |
261 | |
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262 | return $class->meta->new_object( |
263 | __INSTANCE__ => $obj, |
264 | %$storage_type_args, |
265 | @_, |
266 | ); |
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267 | } |
268 | |
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269 | =head2 _build_master |
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270 | |
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271 | Lazy builder for the L</master> attribute. |
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272 | |
273 | =cut |
274 | |
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275 | sub _build_master { |
276 | DBIx::Class::Storage::DBI->new; |
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277 | } |
278 | |
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279 | =head2 _build_pool_type |
280 | |
281 | Lazy builder for the L</pool_type> attribute. |
282 | |
283 | =cut |
284 | |
285 | sub _build_pool_type { |
286 | return 'DBIx::Class::Storage::DBI::Replicated::Pool'; |
287 | } |
288 | |
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289 | =head2 _build_pool |
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290 | |
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291 | Lazy builder for the L</pool> attribute. |
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292 | |
293 | =cut |
294 | |
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295 | sub _build_pool { |
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296 | my $self = shift @_; |
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297 | $self->create_pool(%{$self->pool_args}); |
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298 | } |
299 | |
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300 | =head2 _build_balancer_type |
301 | |
302 | Lazy builder for the L</balancer_type> attribute. |
303 | |
304 | =cut |
305 | |
306 | sub _build_balancer_type { |
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307 | return 'DBIx::Class::Storage::DBI::Replicated::Balancer::First'; |
106d5f3b |
308 | } |
309 | |
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310 | =head2 _build_balancer |
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311 | |
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312 | Lazy builder for the L</balancer> attribute. This takes a Pool object so that |
313 | the balancer knows which pool it's balancing. |
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314 | |
315 | =cut |
316 | |
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317 | sub _build_balancer { |
318 | my $self = shift @_; |
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319 | $self->create_balancer( |
320 | pool=>$self->pool, |
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321 | master=>$self->master, |
322 | %{$self->balancer_args},); |
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323 | } |
324 | |
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325 | =head2 _build_write_handler |
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326 | |
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327 | Lazy builder for the L</write_handler> attribute. The default is to set this to |
328 | the L</master>. |
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329 | |
330 | =cut |
331 | |
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332 | sub _build_write_handler { |
333 | return shift->master; |
334 | } |
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335 | |
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336 | =head2 _build_read_handler |
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337 | |
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338 | Lazy builder for the L</read_handler> attribute. The default is to set this to |
339 | the L</balancer>. |
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340 | |
341 | =cut |
342 | |
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343 | sub _build_read_handler { |
344 | return shift->balancer; |
345 | } |
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346 | |
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347 | =head2 around: connect_replicants |
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348 | |
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349 | All calls to connect_replicants needs to have an existing $schema tacked onto |
350 | top of the args, since L<DBIx::Storage::DBI> needs it. |
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351 | |
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352 | =cut |
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353 | |
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354 | around 'connect_replicants' => sub { |
355 | my ($method, $self, @args) = @_; |
356 | $self->$method($self->schema, @args); |
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357 | }; |
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358 | |
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359 | =head2 all_storages |
360 | |
361 | Returns an array of of all the connected storage backends. The first element |
362 | in the returned array is the master, and the remainings are each of the |
363 | replicants. |
364 | |
365 | =cut |
366 | |
367 | sub all_storages { |
368 | my $self = shift @_; |
369 | |
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370 | return grep {defined $_ && blessed $_} ( |
371 | $self->master, |
372 | $self->replicants, |
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373 | ); |
374 | } |
375 | |
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376 | =head2 execute_reliably ($coderef, ?@args) |
377 | |
378 | Given a coderef, saves the current state of the L</read_handler>, forces it to |
379 | use reliable storage (ie sets it to the master), executes a coderef and then |
380 | restores the original state. |
381 | |
382 | Example: |
383 | |
384 | my $reliably = sub { |
385 | my $name = shift @_; |
386 | $schema->resultset('User')->create({name=>$name}); |
387 | my $user_rs = $schema->resultset('User')->find({name=>$name}); |
388 | }; |
389 | |
390 | $schema->storage->execute_reliably($reliably, 'John'); |
391 | |
392 | Use this when you must be certain of your database state, such as when you just |
393 | inserted something and need to get a resultset including it, etc. |
394 | |
395 | =cut |
396 | |
397 | sub execute_reliably { |
398 | my ($self, $coderef, @args) = @_; |
399 | |
400 | unless( ref $coderef eq 'CODE') { |
401 | $self->throw_exception('Second argument must be a coderef'); |
402 | } |
403 | |
404 | ##Get copy of master storage |
405 | my $master = $self->master; |
406 | |
407 | ##Get whatever the current read hander is |
408 | my $current = $self->read_handler; |
409 | |
410 | ##Set the read handler to master |
411 | $self->read_handler($master); |
412 | |
413 | ## do whatever the caller needs |
414 | eval { |
415 | $coderef->(@args); |
416 | }; |
417 | |
418 | if($@) { |
419 | $self->throw_exception("coderef returned an error: $@"); |
420 | } |
421 | |
422 | ##Reset to the original state |
423 | $self->schema->storage->read_handler($current); |
424 | } |
425 | |
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426 | =head2 set_reliable_storage |
427 | |
428 | Sets the current $schema to be 'reliable', that is all queries, both read and |
429 | write are sent to the master |
430 | |
431 | =cut |
432 | |
433 | sub set_reliable_storage { |
434 | my $self = shift @_; |
435 | my $schema = $self->schema; |
436 | my $write_handler = $self->schema->storage->write_handler; |
437 | |
438 | $schema->storage->read_handler($write_handler); |
439 | } |
440 | |
441 | =head2 set_balanced_storage |
442 | |
443 | Sets the current $schema to be use the </balancer> for all reads, while all |
444 | writea are sent to the master only |
445 | |
446 | =cut |
447 | |
448 | sub set_balanced_storage { |
449 | my $self = shift @_; |
450 | my $schema = $self->schema; |
451 | my $write_handler = $self->schema->storage->balancer; |
452 | |
453 | $schema->storage->read_handler($write_handler); |
454 | } |
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455 | |
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456 | =head2 txn_do ($coderef) |
457 | |
458 | Overload to the txn_do method, which is delegated to whatever the |
459 | L<write_handler> is set to. We overload this in order to wrap in inside a |
460 | L</execute_reliably> method. |
461 | |
462 | =cut |
463 | |
464 | sub txn_do { |
465 | my($self, $coderef, @args) = @_; |
466 | $self->execute_reliably($coderef, @args); |
467 | } |
468 | |
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469 | =head2 connected |
470 | |
471 | Check that the master and at least one of the replicants is connected. |
472 | |
473 | =cut |
474 | |
475 | sub connected { |
476 | my $self = shift @_; |
477 | |
478 | return |
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479 | $self->master->connected && |
480 | $self->pool->connected_replicants; |
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481 | } |
482 | |
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483 | =head2 ensure_connected |
484 | |
485 | Make sure all the storages are connected. |
486 | |
487 | =cut |
488 | |
489 | sub ensure_connected { |
490 | my $self = shift @_; |
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491 | foreach my $source ($self->all_storages) { |
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492 | $source->ensure_connected(@_); |
493 | } |
494 | } |
495 | |
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496 | =head2 limit_dialect |
497 | |
498 | Set the limit_dialect for all existing storages |
499 | |
500 | =cut |
501 | |
502 | sub limit_dialect { |
503 | my $self = shift @_; |
26ab719a |
504 | foreach my $source ($self->all_storages) { |
505 | $source->limit_dialect(@_); |
2bf79155 |
506 | } |
507 | } |
508 | |
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509 | =head2 quote_char |
510 | |
511 | Set the quote_char for all existing storages |
512 | |
513 | =cut |
514 | |
515 | sub quote_char { |
516 | my $self = shift @_; |
26ab719a |
517 | foreach my $source ($self->all_storages) { |
518 | $source->quote_char(@_); |
2bf79155 |
519 | } |
520 | } |
521 | |
2bf79155 |
522 | =head2 name_sep |
523 | |
524 | Set the name_sep for all existing storages |
525 | |
526 | =cut |
527 | |
528 | sub name_sep { |
529 | my $self = shift @_; |
26ab719a |
530 | foreach my $source ($self->all_storages) { |
2bf79155 |
531 | $source->name_sep(@_); |
532 | } |
533 | } |
534 | |
2bf79155 |
535 | =head2 set_schema |
536 | |
537 | Set the schema object for all existing storages |
538 | |
539 | =cut |
540 | |
541 | sub set_schema { |
542 | my $self = shift @_; |
26ab719a |
543 | foreach my $source ($self->all_storages) { |
2bf79155 |
544 | $source->set_schema(@_); |
545 | } |
546 | } |
547 | |
2bf79155 |
548 | =head2 debug |
549 | |
550 | set a debug flag across all storages |
551 | |
552 | =cut |
553 | |
554 | sub debug { |
555 | my $self = shift @_; |
26ab719a |
556 | foreach my $source ($self->all_storages) { |
2bf79155 |
557 | $source->debug(@_); |
558 | } |
559 | } |
560 | |
2bf79155 |
561 | =head2 debugobj |
562 | |
563 | set a debug object across all storages |
564 | |
565 | =cut |
566 | |
567 | sub debugobj { |
568 | my $self = shift @_; |
26ab719a |
569 | foreach my $source ($self->all_storages) { |
2bf79155 |
570 | $source->debugobj(@_); |
571 | } |
572 | } |
573 | |
2bf79155 |
574 | =head2 debugfh |
575 | |
576 | set a debugfh object across all storages |
577 | |
578 | =cut |
579 | |
580 | sub debugfh { |
581 | my $self = shift @_; |
26ab719a |
582 | foreach my $source ($self->all_storages) { |
2bf79155 |
583 | $source->debugfh(@_); |
584 | } |
585 | } |
586 | |
2bf79155 |
587 | =head2 debugcb |
588 | |
589 | set a debug callback across all storages |
590 | |
591 | =cut |
592 | |
593 | sub debugcb { |
594 | my $self = shift @_; |
26ab719a |
595 | foreach my $source ($self->all_storages) { |
2bf79155 |
596 | $source->debugcb(@_); |
597 | } |
598 | } |
599 | |
2bf79155 |
600 | =head2 disconnect |
601 | |
602 | disconnect everything |
603 | |
604 | =cut |
605 | |
606 | sub disconnect { |
607 | my $self = shift @_; |
26ab719a |
608 | foreach my $source ($self->all_storages) { |
2bf79155 |
609 | $source->disconnect(@_); |
610 | } |
611 | } |
612 | |
f5d3a5de |
613 | =head1 AUTHOR |
614 | |
c4d3fae2 |
615 | John Napiorkowski <john.napiorkowski@takkle.com> |
f5d3a5de |
616 | |
c4d3fae2 |
617 | Based on code originated by: |
f5d3a5de |
618 | |
c4d3fae2 |
619 | Norbert Csongrádi <bert@cpan.org> |
620 | Peter Siklósi <einon@einon.hu> |
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621 | |
f5d3a5de |
622 | =head1 LICENSE |
623 | |
624 | You may distribute this code under the same terms as Perl itself. |
625 | |
626 | =cut |
627 | |
628 | 1; |