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[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage / DBI / Replicated.pm
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2156bbdd 1package DBIx::Class::Storage::DBI::Replicated;
f5d3a5de 2
ecb65397 3BEGIN {
4 use Carp::Clan qw/^DBIx::Class/;
a34b0c89 5 use DBIx::Class;
6 croak('The following modules are required for Replication ' . DBIx::Class::Optional::Dependencies->req_missing_for ('replicated') )
7 unless DBIx::Class::Optional::Dependencies->req_ok_for ('replicated');
ecb65397 8}
9
b2e4d522 10use Moose;
26ab719a 11use DBIx::Class::Storage::DBI;
2bf79155 12use DBIx::Class::Storage::DBI::Replicated::Pool;
26ab719a 13use DBIx::Class::Storage::DBI::Replicated::Balancer;
6a151f58 14use DBIx::Class::Storage::DBI::Replicated::Types qw/BalancerClassNamePart DBICSchema DBICStorageDBI/;
41916570 15use MooseX::Types::Moose qw/ClassName HashRef Object/;
b2e4d522 16use Scalar::Util 'reftype';
e666c5fd 17use Hash::Merge;
3244fdcc 18use List::Util qw/min max/;
9901aad7 19
20use namespace::clean -except => 'meta';
2bf79155 21
22=head1 NAME
23
ecb65397 24DBIx::Class::Storage::DBI::Replicated - BETA Replicated database support
2bf79155 25
26=head1 SYNOPSIS
27
28The Following example shows how to change an existing $schema to a replicated
48580715 29storage type, add some replicated (read-only) databases, and perform reporting
955a6df6 30tasks.
2bf79155 31
3da4f736 32You should set the 'storage_type attribute to a replicated type. You should
d4daee7b 33also define your arguments, such as which balancer you want and any arguments
3da4f736 34that the Pool object should get.
35
ce854fd3 36 my $schema = Schema::Class->clone;
64cdad22 37 $schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
ce854fd3 38 $schema->connection(...);
d4daee7b 39
3da4f736 40Next, you need to add in the Replicants. Basically this is an array of
41arrayrefs, where each arrayref is database connect information. Think of these
42arguments as what you'd pass to the 'normal' $schema->connect method.
d4daee7b 43
64cdad22 44 $schema->storage->connect_replicants(
45 [$dsn1, $user, $pass, \%opts],
46 [$dsn2, $user, $pass, \%opts],
47 [$dsn3, $user, $pass, \%opts],
48 );
d4daee7b 49
3da4f736 50Now, just use the $schema as you normally would. Automatically all reads will
51be delegated to the replicants, while writes to the master.
52
7e38d850 53 $schema->resultset('Source')->search({name=>'etc'});
d4daee7b 54
3da4f736 55You can force a given query to use a particular storage using the search
56attribute 'force_pool'. For example:
d4daee7b 57
7e38d850 58 my $RS = $schema->resultset('Source')->search(undef, {force_pool=>'master'});
3da4f736 59
60Now $RS will force everything (both reads and writes) to use whatever was setup
61as the master storage. 'master' is hardcoded to always point to the Master,
62but you can also use any Replicant name. Please see:
212cc5c2 63L<DBIx::Class::Storage::DBI::Replicated::Pool> and the replicants attribute for more.
3da4f736 64
65Also see transactions and L</execute_reliably> for alternative ways to
66force read traffic to the master. In general, you should wrap your statements
67in a transaction when you are reading and writing to the same tables at the
68same time, since your replicants will often lag a bit behind the master.
212cc5c2 69
70See L<DBIx::Class::Storage::DBI::Replicated::Instructions> for more help and
71walkthroughs.
d4daee7b 72
2bf79155 73=head1 DESCRIPTION
74
7e38d850 75Warning: This class is marked BETA. This has been running a production
ccb3b897 76website using MySQL native replication as its backend and we have some decent
7e38d850 77test coverage but the code hasn't yet been stressed by a variety of databases.
48580715 78Individual DBs may have quirks we are not aware of. Please use this in first
7e38d850 79development and pass along your experiences/bug fixes.
2bf79155 80
81This class implements replicated data store for DBI. Currently you can define
82one master and numerous slave database connections. All write-type queries
83(INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master
84database, all read-type queries (SELECTs) go to the slave database.
85
86Basically, any method request that L<DBIx::Class::Storage::DBI> would normally
bca099a3 87handle gets delegated to one of the two attributes: L</read_handler> or to
88L</write_handler>. Additionally, some methods need to be distributed
2bf79155 89to all existing storages. This way our storage class is a drop in replacement
90for L<DBIx::Class::Storage::DBI>.
91
48580715 92Read traffic is spread across the replicants (slaves) occurring to a user
2bf79155 93selected algorithm. The default algorithm is random weighted.
94
bca099a3 95=head1 NOTES
96
48580715 97The consistency between master and replicants is database specific. The Pool
faaba25f 98gives you a method to validate its replicants, removing and replacing them
7e38d850 99when they fail/pass predefined criteria. Please make careful use of the ways
ecb65397 100to force a query to run against Master when needed.
101
102=head1 REQUIREMENTS
103
a34b0c89 104Replicated Storage has additional requirements not currently part of
aa8b2277 105L<DBIx::Class>. See L<DBIx::Class::Optional::Dependencies> for more details.
2bf79155 106
107=head1 ATTRIBUTES
108
109This class defines the following attributes.
110
2ce6e9a6 111=head2 schema
112
113The underlying L<DBIx::Class::Schema> object this storage is attaching
114
115=cut
116
117has 'schema' => (
118 is=>'rw',
6a151f58 119 isa=>DBICSchema,
2ce6e9a6 120 weak_ref=>1,
121 required=>1,
122);
123
26ab719a 124=head2 pool_type
2bf79155 125
26ab719a 126Contains the classname which will instantiate the L</pool> object. Defaults
127to: L<DBIx::Class::Storage::DBI::Replicated::Pool>.
2bf79155 128
129=cut
130
26ab719a 131has 'pool_type' => (
dcdf7b2c 132 is=>'rw',
41916570 133 isa=>ClassName,
2ce6e9a6 134 default=>'DBIx::Class::Storage::DBI::Replicated::Pool',
64cdad22 135 handles=>{
136 'create_pool' => 'new',
137 },
2bf79155 138);
139
f068a139 140=head2 pool_args
141
142Contains a hashref of initialized information to pass to the Balancer object.
212cc5c2 143See L<DBIx::Class::Storage::DBI::Replicated::Pool> for available arguments.
f068a139 144
145=cut
146
147has 'pool_args' => (
dcdf7b2c 148 is=>'rw',
41916570 149 isa=>HashRef,
64cdad22 150 lazy=>1,
64cdad22 151 default=>sub { {} },
f068a139 152);
153
154
26ab719a 155=head2 balancer_type
2bf79155 156
157The replication pool requires a balance class to provider the methods for
158choose how to spread the query load across each replicant in the pool.
159
160=cut
161
26ab719a 162has 'balancer_type' => (
dcdf7b2c 163 is=>'rw',
9901aad7 164 isa=>BalancerClassNamePart,
2ce6e9a6 165 coerce=>1,
166 required=>1,
167 default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First',
64cdad22 168 handles=>{
169 'create_balancer' => 'new',
170 },
2bf79155 171);
172
17b05c13 173=head2 balancer_args
174
175Contains a hashref of initialized information to pass to the Balancer object.
212cc5c2 176See L<DBIx::Class::Storage::DBI::Replicated::Balancer> for available arguments.
17b05c13 177
178=cut
179
180has 'balancer_args' => (
dcdf7b2c 181 is=>'rw',
41916570 182 isa=>HashRef,
64cdad22 183 lazy=>1,
184 required=>1,
185 default=>sub { {} },
17b05c13 186);
187
26ab719a 188=head2 pool
2bf79155 189
26ab719a 190Is a <DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a
191container class for one or more replicated databases.
2bf79155 192
193=cut
194
26ab719a 195has 'pool' => (
64cdad22 196 is=>'ro',
197 isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
198 lazy_build=>1,
199 handles=>[qw/
6f7344b8 200 connect_replicants
64cdad22 201 replicants
202 has_replicants
203 /],
2bf79155 204);
205
26ab719a 206=head2 balancer
2bf79155 207
26ab719a 208Is a <DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This
209is a class that takes a pool (<DBIx::Class::Storage::DBI::Replicated::Pool>)
2bf79155 210
26ab719a 211=cut
2bf79155 212
26ab719a 213has 'balancer' => (
dcdf7b2c 214 is=>'rw',
64cdad22 215 isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
216 lazy_build=>1,
217 handles=>[qw/auto_validate_every/],
26ab719a 218);
2bf79155 219
cb6ec758 220=head2 master
221
222The master defines the canonical state for a pool of connected databases. All
223the replicants are expected to match this databases state. Thus, in a classic
224Master / Slaves distributed system, all the slaves are expected to replicate
225the Master's state as quick as possible. This is the only database in the
226pool of databases that is allowed to handle write traffic.
227
228=cut
229
230has 'master' => (
64cdad22 231 is=> 'ro',
6a151f58 232 isa=>DBICStorageDBI,
64cdad22 233 lazy_build=>1,
cb6ec758 234);
235
cb6ec758 236=head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE
237
238The following methods are delegated all the methods required for the
239L<DBIx::Class::Storage::DBI> interface.
240
241=head2 read_handler
242
243Defines an object that implements the read side of L<BIx::Class::Storage::DBI>.
244
245=cut
246
247has 'read_handler' => (
64cdad22 248 is=>'rw',
41916570 249 isa=>Object,
64cdad22 250 lazy_build=>1,
251 handles=>[qw/
252 select
253 select_single
254 columns_info_for
3244fdcc 255 _dbh_columns_info_for
256 _select
6f7344b8 257 /],
cb6ec758 258);
259
cb6ec758 260=head2 write_handler
261
3244fdcc 262Defines an object that implements the write side of L<BIx::Class::Storage::DBI>,
263as well as methods that don't write or read that can be called on only one
264storage, methods that return a C<$dbh>, and any methods that don't make sense to
265run on a replicant.
cb6ec758 266
267=cut
268
269has 'write_handler' => (
64cdad22 270 is=>'ro',
41916570 271 isa=>Object,
64cdad22 272 lazy_build=>1,
6f7344b8 273 handles=>[qw/
64cdad22 274 on_connect_do
6f7344b8 275 on_disconnect_do
3244fdcc 276 on_connect_call
277 on_disconnect_call
64cdad22 278 connect_info
3244fdcc 279 _connect_info
64cdad22 280 throw_exception
281 sql_maker
282 sqlt_type
283 create_ddl_dir
284 deployment_statements
285 datetime_parser
6f7344b8 286 datetime_parser_type
287 build_datetime_parser
64cdad22 288 last_insert_id
289 insert
290 insert_bulk
291 update
292 delete
293 dbh
2ce6e9a6 294 txn_begin
64cdad22 295 txn_do
296 txn_commit
297 txn_rollback
2ce6e9a6 298 txn_scope_guard
64cdad22 299 sth
300 deploy
0180bef9 301 with_deferred_fk_checks
6f7344b8 302 dbh_do
64cdad22 303 reload_row
6f7344b8 304 with_deferred_fk_checks
2ce6e9a6 305 _prep_for_execute
7fb60fb1 306
6f7344b8 307 backup
308 is_datatype_numeric
227d8366 309 _supports_insert_returning
6f7344b8 310 _count_select
311 _subq_count_select
312 _subq_update_delete
313 svp_rollback
314 svp_begin
315 svp_release
e398f77e 316 relname_to_table_alias
317 _straight_join_to_node
3244fdcc 318 _dbh_last_insert_id
319 _fix_bind_params
320 _default_dbi_connect_attributes
321 _dbi_connect_info
322 auto_savepoint
323 _sqlt_version_ok
324 _query_end
325 bind_attribute_by_data_type
326 transaction_depth
327 _dbh
328 _select_args
329 _dbh_execute_array
330 _sql_maker_args
331 _sql_maker
332 _query_start
333 _sqlt_version_error
334 _per_row_update_delete
335 _dbh_begin_work
336 _dbh_execute_inserts_with_no_binds
337 _select_args_to_query
338 _svp_generate_name
339 _multipk_update_delete
340 source_bind_attributes
341 _normalize_connect_info
342 _parse_connect_do
343 _dbh_commit
344 _execute_array
345 _placeholders_supported
346 _verify_pid
347 savepoints
348 _sqlt_minimum_version
349 _sql_maker_opts
350 _conn_pid
351 _typeless_placeholders_supported
352 _conn_tid
353 _dbh_autocommit
354 _native_data_type
355 _get_dbh
356 sql_maker_class
357 _dbh_rollback
358 _adjust_select_args_for_complex_prefetch
359 _resolve_ident_sources
360 _resolve_column_info
361 _prune_unused_joins
362 _strip_cond_qualifiers
363 _parse_order_by
364 _resolve_aliastypes_from_select_args
365 _execute
366 _do_query
367 _dbh_sth
368 _dbh_execute
6ed1cd2e 369 _prefetch_insert_auto_nextvals
6d766626 370 /,
371
372 # TODO these need to be spread out to ALL servers not just the master
373 qw/
374 _get_server_version
375 _server_info
376 _server_info_hash
64cdad22 377 /],
cb6ec758 378);
379
6d766626 380
b2e4d522 381has _master_connect_info_opts =>
382 (is => 'rw', isa => HashRef, default => sub { {} });
383
384=head2 around: connect_info
385
48580715 386Preserves master's C<connect_info> options (for merging with replicants.)
387Also sets any Replicated-related options from connect_info, such as
dcdf7b2c 388C<pool_type>, C<pool_args>, C<balancer_type> and C<balancer_args>.
b2e4d522 389
390=cut
391
392around connect_info => sub {
393 my ($next, $self, $info, @extra) = @_;
394
0ce2d0d5 395 my $wantarray = wantarray;
396
282a9a4f 397 my $merge = Hash::Merge->new('LEFT_PRECEDENT');
e666c5fd 398
b2e4d522 399 my %opts;
400 for my $arg (@$info) {
401 next unless (reftype($arg)||'') eq 'HASH';
e666c5fd 402 %opts = %{ $merge->merge($arg, \%opts) };
b2e4d522 403 }
b2e4d522 404 delete $opts{dsn};
405
dcdf7b2c 406 if (@opts{qw/pool_type pool_args/}) {
407 $self->pool_type(delete $opts{pool_type})
408 if $opts{pool_type};
409
b88b85e7 410 $self->pool_args(
e666c5fd 411 $merge->merge((delete $opts{pool_args} || {}), $self->pool_args)
b88b85e7 412 );
dcdf7b2c 413
67c43863 414 $self->pool($self->_build_pool)
6f7344b8 415 if $self->pool;
dcdf7b2c 416 }
417
418 if (@opts{qw/balancer_type balancer_args/}) {
419 $self->balancer_type(delete $opts{balancer_type})
420 if $opts{balancer_type};
421
b88b85e7 422 $self->balancer_args(
e666c5fd 423 $merge->merge((delete $opts{balancer_args} || {}), $self->balancer_args)
b88b85e7 424 );
dcdf7b2c 425
67c43863 426 $self->balancer($self->_build_balancer)
6f7344b8 427 if $self->balancer;
dcdf7b2c 428 }
429
b2e4d522 430 $self->_master_connect_info_opts(\%opts);
431
0ce2d0d5 432 my (@res, $res);
433 if ($wantarray) {
434 @res = $self->$next($info, @extra);
435 } else {
436 $res = $self->$next($info, @extra);
437 }
438
fd4eb9c2 439 # Make sure master is blessed into the correct class and apply role to it.
440 my $master = $self->master;
441 $master->_determine_driver;
442 Moose::Meta::Class->initialize(ref $master);
cea43436 443
ec0946db 444 DBIx::Class::Storage::DBI::Replicated::WithDSN->meta->apply($master);
cea43436 445
446 # link pool back to master
447 $self->pool->master($master);
0ce2d0d5 448
449 $wantarray ? @res : $res;
b2e4d522 450};
451
26ab719a 452=head1 METHODS
2bf79155 453
26ab719a 454This class defines the following methods.
2bf79155 455
c354902c 456=head2 BUILDARGS
2bf79155 457
faaba25f 458L<DBIx::Class::Schema> when instantiating its storage passed itself as the
2ce6e9a6 459first argument. So we need to massage the arguments a bit so that all the
460bits get put into the correct places.
2bf79155 461
462=cut
463
c354902c 464sub BUILDARGS {
d7a58a29 465 my ($class, $schema, $storage_type_args, @args) = @_;
d4daee7b 466
c354902c 467 return {
6f7344b8 468 schema=>$schema,
469 %$storage_type_args,
470 @args
c354902c 471 }
472}
2bf79155 473
cb6ec758 474=head2 _build_master
2bf79155 475
cb6ec758 476Lazy builder for the L</master> attribute.
2bf79155 477
478=cut
479
cb6ec758 480sub _build_master {
2ce6e9a6 481 my $self = shift @_;
ee356d00 482 my $master = DBIx::Class::Storage::DBI->new($self->schema);
ee356d00 483 $master
106d5f3b 484}
485
26ab719a 486=head2 _build_pool
2bf79155 487
26ab719a 488Lazy builder for the L</pool> attribute.
2bf79155 489
490=cut
491
26ab719a 492sub _build_pool {
64cdad22 493 my $self = shift @_;
494 $self->create_pool(%{$self->pool_args});
2bf79155 495}
496
26ab719a 497=head2 _build_balancer
2bf79155 498
cb6ec758 499Lazy builder for the L</balancer> attribute. This takes a Pool object so that
500the balancer knows which pool it's balancing.
2bf79155 501
502=cut
503
26ab719a 504sub _build_balancer {
64cdad22 505 my $self = shift @_;
506 $self->create_balancer(
6f7344b8 507 pool=>$self->pool,
64cdad22 508 master=>$self->master,
509 %{$self->balancer_args},
510 );
2bf79155 511}
512
cb6ec758 513=head2 _build_write_handler
2bf79155 514
cb6ec758 515Lazy builder for the L</write_handler> attribute. The default is to set this to
516the L</master>.
50336325 517
518=cut
519
cb6ec758 520sub _build_write_handler {
64cdad22 521 return shift->master;
cb6ec758 522}
50336325 523
cb6ec758 524=head2 _build_read_handler
2bf79155 525
cb6ec758 526Lazy builder for the L</read_handler> attribute. The default is to set this to
527the L</balancer>.
2bf79155 528
529=cut
530
cb6ec758 531sub _build_read_handler {
64cdad22 532 return shift->balancer;
cb6ec758 533}
50336325 534
cb6ec758 535=head2 around: connect_replicants
2bf79155 536
cb6ec758 537All calls to connect_replicants needs to have an existing $schema tacked onto
b2e4d522 538top of the args, since L<DBIx::Storage::DBI> needs it, and any C<connect_info>
539options merged with the master, with replicant opts having higher priority.
955a6df6 540
cb6ec758 541=cut
955a6df6 542
b2e4d522 543around connect_replicants => sub {
544 my ($next, $self, @args) = @_;
545
546 for my $r (@args) {
547 $r = [ $r ] unless reftype $r eq 'ARRAY';
548
1a58752c 549 $self->throw_exception('coderef replicant connect_info not supported')
b2e4d522 550 if ref $r->[0] && reftype $r->[0] eq 'CODE';
551
552# any connect_info options?
553 my $i = 0;
554 $i++ while $i < @$r && (reftype($r->[$i])||'') ne 'HASH';
555
6f7344b8 556# make one if none
b2e4d522 557 $r->[$i] = {} unless $r->[$i];
558
559# merge if two hashes
b88b85e7 560 my @hashes = @$r[$i .. $#{$r}];
561
1a58752c 562 $self->throw_exception('invalid connect_info options')
b88b85e7 563 if (grep { reftype($_) eq 'HASH' } @hashes) != @hashes;
564
1a58752c 565 $self->throw_exception('too many hashrefs in connect_info')
b88b85e7 566 if @hashes > 2;
567
282a9a4f 568 my $merge = Hash::Merge->new('LEFT_PRECEDENT');
e666c5fd 569 my %opts = %{ $merge->merge(reverse @hashes) };
b88b85e7 570
571# delete them
b2e4d522 572 splice @$r, $i+1, ($#{$r} - $i), ();
573
0bd8e058 574# make sure master/replicants opts don't clash
575 my %master_opts = %{ $self->_master_connect_info_opts };
576 if (exists $opts{dbh_maker}) {
577 delete @master_opts{qw/dsn user password/};
578 }
579 delete $master_opts{dbh_maker};
580
b2e4d522 581# merge with master
e666c5fd 582 %opts = %{ $merge->merge(\%opts, \%master_opts) };
b2e4d522 583
584# update
585 $r->[$i] = \%opts;
586 }
587
588 $self->$next($self->schema, @args);
955a6df6 589};
2bf79155 590
2bf79155 591=head2 all_storages
592
593Returns an array of of all the connected storage backends. The first element
594in the returned array is the master, and the remainings are each of the
595replicants.
596
597=cut
598
599sub all_storages {
64cdad22 600 my $self = shift @_;
601 return grep {defined $_ && blessed $_} (
602 $self->master,
6412a592 603 values %{ $self->replicants },
64cdad22 604 );
2bf79155 605}
606
c4d3fae2 607=head2 execute_reliably ($coderef, ?@args)
608
609Given a coderef, saves the current state of the L</read_handler>, forces it to
48580715 610use reliable storage (e.g. sets it to the master), executes a coderef and then
c4d3fae2 611restores the original state.
612
613Example:
614
64cdad22 615 my $reliably = sub {
616 my $name = shift @_;
617 $schema->resultset('User')->create({name=>$name});
618 my $user_rs = $schema->resultset('User')->find({name=>$name});
619 return $user_rs;
620 };
c4d3fae2 621
64cdad22 622 my $user_rs = $schema->storage->execute_reliably($reliably, 'John');
c4d3fae2 623
624Use this when you must be certain of your database state, such as when you just
625inserted something and need to get a resultset including it, etc.
626
627=cut
628
629sub execute_reliably {
64cdad22 630 my ($self, $coderef, @args) = @_;
d4daee7b 631
64cdad22 632 unless( ref $coderef eq 'CODE') {
633 $self->throw_exception('Second argument must be a coderef');
634 }
d4daee7b 635
64cdad22 636 ##Get copy of master storage
637 my $master = $self->master;
d4daee7b 638
64cdad22 639 ##Get whatever the current read hander is
640 my $current = $self->read_handler;
d4daee7b 641
64cdad22 642 ##Set the read handler to master
643 $self->read_handler($master);
d4daee7b 644
64cdad22 645 ## do whatever the caller needs
646 my @result;
647 my $want_array = wantarray;
d4daee7b 648
64cdad22 649 eval {
650 if($want_array) {
651 @result = $coderef->(@args);
652 } elsif(defined $want_array) {
653 ($result[0]) = ($coderef->(@args));
ed213e85 654 } else {
64cdad22 655 $coderef->(@args);
6f7344b8 656 }
64cdad22 657 };
d4daee7b 658
64cdad22 659 ##Reset to the original state
6f7344b8 660 $self->read_handler($current);
d4daee7b 661
64cdad22 662 ##Exception testing has to come last, otherwise you might leave the
663 ##read_handler set to master.
d4daee7b 664
64cdad22 665 if($@) {
666 $self->throw_exception("coderef returned an error: $@");
667 } else {
668 return $want_array ? @result : $result[0];
669 }
c4d3fae2 670}
671
cb6ec758 672=head2 set_reliable_storage
673
674Sets the current $schema to be 'reliable', that is all queries, both read and
675write are sent to the master
d4daee7b 676
cb6ec758 677=cut
678
679sub set_reliable_storage {
64cdad22 680 my $self = shift @_;
681 my $schema = $self->schema;
682 my $write_handler = $self->schema->storage->write_handler;
d4daee7b 683
64cdad22 684 $schema->storage->read_handler($write_handler);
cb6ec758 685}
686
687=head2 set_balanced_storage
688
689Sets the current $schema to be use the </balancer> for all reads, while all
48580715 690writes are sent to the master only
d4daee7b 691
cb6ec758 692=cut
693
694sub set_balanced_storage {
64cdad22 695 my $self = shift @_;
696 my $schema = $self->schema;
bd5da369 697 my $balanced_handler = $self->schema->storage->balancer;
d4daee7b 698
bd5da369 699 $schema->storage->read_handler($balanced_handler);
cb6ec758 700}
2bf79155 701
702=head2 connected
703
704Check that the master and at least one of the replicants is connected.
705
706=cut
707
708sub connected {
64cdad22 709 my $self = shift @_;
710 return
711 $self->master->connected &&
712 $self->pool->connected_replicants;
2bf79155 713}
714
2bf79155 715=head2 ensure_connected
716
717Make sure all the storages are connected.
718
719=cut
720
721sub ensure_connected {
64cdad22 722 my $self = shift @_;
723 foreach my $source ($self->all_storages) {
724 $source->ensure_connected(@_);
725 }
2bf79155 726}
727
2bf79155 728=head2 limit_dialect
729
730Set the limit_dialect for all existing storages
731
732=cut
733
734sub limit_dialect {
64cdad22 735 my $self = shift @_;
736 foreach my $source ($self->all_storages) {
737 $source->limit_dialect(@_);
738 }
3fbe08e3 739 return $self->master->quote_char;
2bf79155 740}
741
2bf79155 742=head2 quote_char
743
744Set the quote_char for all existing storages
745
746=cut
747
748sub quote_char {
64cdad22 749 my $self = shift @_;
750 foreach my $source ($self->all_storages) {
751 $source->quote_char(@_);
752 }
3fbe08e3 753 return $self->master->quote_char;
2bf79155 754}
755
2bf79155 756=head2 name_sep
757
758Set the name_sep for all existing storages
759
760=cut
761
762sub name_sep {
64cdad22 763 my $self = shift @_;
764 foreach my $source ($self->all_storages) {
765 $source->name_sep(@_);
766 }
3fbe08e3 767 return $self->master->name_sep;
2bf79155 768}
769
2bf79155 770=head2 set_schema
771
772Set the schema object for all existing storages
773
774=cut
775
776sub set_schema {
64cdad22 777 my $self = shift @_;
778 foreach my $source ($self->all_storages) {
779 $source->set_schema(@_);
780 }
2bf79155 781}
782
2bf79155 783=head2 debug
784
785set a debug flag across all storages
786
787=cut
788
789sub debug {
64cdad22 790 my $self = shift @_;
3fbe08e3 791 if(@_) {
792 foreach my $source ($self->all_storages) {
793 $source->debug(@_);
6f7344b8 794 }
64cdad22 795 }
3fbe08e3 796 return $self->master->debug;
2bf79155 797}
798
2bf79155 799=head2 debugobj
800
cea43436 801set a debug object
2bf79155 802
803=cut
804
805sub debugobj {
64cdad22 806 my $self = shift @_;
cea43436 807 return $self->master->debugobj(@_);
2bf79155 808}
809
2bf79155 810=head2 debugfh
811
cea43436 812set a debugfh object
2bf79155 813
814=cut
815
816sub debugfh {
64cdad22 817 my $self = shift @_;
cea43436 818 return $self->master->debugfh(@_);
2bf79155 819}
820
2bf79155 821=head2 debugcb
822
cea43436 823set a debug callback
2bf79155 824
825=cut
826
827sub debugcb {
64cdad22 828 my $self = shift @_;
cea43436 829 return $self->master->debugcb(@_);
2bf79155 830}
831
2bf79155 832=head2 disconnect
833
834disconnect everything
835
836=cut
837
838sub disconnect {
64cdad22 839 my $self = shift @_;
840 foreach my $source ($self->all_storages) {
841 $source->disconnect(@_);
842 }
2bf79155 843}
844
b2e4d522 845=head2 cursor_class
846
847set cursor class on all storages, or return master's
848
849=cut
850
851sub cursor_class {
852 my ($self, $cursor_class) = @_;
853
854 if ($cursor_class) {
855 $_->cursor_class($cursor_class) for $self->all_storages;
856 }
857 $self->master->cursor_class;
858}
d4daee7b 859
3244fdcc 860=head2 cursor
861
862set cursor class on all storages, or return master's, alias for L</cursor_class>
863above.
864
865=cut
866
867sub cursor {
868 my ($self, $cursor_class) = @_;
869
870 if ($cursor_class) {
871 $_->cursor($cursor_class) for $self->all_storages;
872 }
873 $self->master->cursor;
874}
875
876=head2 unsafe
877
878sets the L<DBIx::Class::Storage::DBI/unsafe> option on all storages or returns
879master's current setting
880
881=cut
882
883sub unsafe {
884 my $self = shift;
885
886 if (@_) {
887 $_->unsafe(@_) for $self->all_storages;
888 }
889
890 return $self->master->unsafe;
891}
892
893=head2 disable_sth_caching
894
895sets the L<DBIx::Class::Storage::DBI/disable_sth_caching> option on all storages
896or returns master's current setting
897
898=cut
899
900sub disable_sth_caching {
901 my $self = shift;
902
903 if (@_) {
904 $_->disable_sth_caching(@_) for $self->all_storages;
905 }
906
907 return $self->master->disable_sth_caching;
908}
909
910=head2 lag_behind_master
911
912returns the highest Replicant L<DBIx::Class::Storage::DBI/lag_behind_master>
913setting
914
915=cut
916
917sub lag_behind_master {
918 my $self = shift;
919
920 return max map $_->lag_behind_master, $self->replicants;
921}
922
923=head2 is_replicating
924
925returns true if all replicants return true for
926L<DBIx::Class::Storage::DBI/is_replicating>
927
928=cut
929
930sub is_replicating {
931 my $self = shift;
932
933 return (grep $_->is_replicating, $self->replicants) == ($self->replicants);
934}
935
936=head2 connect_call_datetime_setup
937
938calls L<DBIx::Class::Storage::DBI/connect_call_datetime_setup> for all storages
939
940=cut
941
942sub connect_call_datetime_setup {
943 my $self = shift;
944 $_->connect_call_datetime_setup for $self->all_storages;
945}
946
947sub _populate_dbh {
948 my $self = shift;
949 $_->_populate_dbh for $self->all_storages;
950}
951
952sub _connect {
953 my $self = shift;
954 $_->_connect for $self->all_storages;
955}
956
957sub _rebless {
958 my $self = shift;
959 $_->_rebless for $self->all_storages;
960}
961
962sub _determine_driver {
963 my $self = shift;
964 $_->_determine_driver for $self->all_storages;
965}
966
967sub _driver_determined {
968 my $self = shift;
969
970 if (@_) {
971 $_->_driver_determined(@_) for $self->all_storages;
972 }
973
974 return $self->master->_driver_determined;
975}
976
977sub _init {
978 my $self = shift;
979
980 $_->_init for $self->all_storages;
981}
982
983sub _run_connection_actions {
984 my $self = shift;
985
986 $_->_run_connection_actions for $self->all_storages;
987}
988
989sub _do_connection_actions {
990 my $self = shift;
991
992 if (@_) {
993 $_->_do_connection_actions(@_) for $self->all_storages;
994 }
995}
996
997sub connect_call_do_sql {
998 my $self = shift;
999 $_->connect_call_do_sql(@_) for $self->all_storages;
1000}
1001
1002sub disconnect_call_do_sql {
1003 my $self = shift;
1004 $_->disconnect_call_do_sql(@_) for $self->all_storages;
1005}
1006
1007sub _seems_connected {
1008 my $self = shift;
1009
1010 return min map $_->_seems_connected, $self->all_storages;
1011}
1012
1013sub _ping {
1014 my $self = shift;
1015
1016 return min map $_->_ping, $self->all_storages;
1017}
1018
7e38d850 1019=head1 GOTCHAS
1020
1021Due to the fact that replicants can lag behind a master, you must take care to
1022make sure you use one of the methods to force read queries to a master should
1023you need realtime data integrity. For example, if you insert a row, and then
1024immediately re-read it from the database (say, by doing $row->discard_changes)
1025or you insert a row and then immediately build a query that expects that row
1026to be an item, you should force the master to handle reads. Otherwise, due to
1027the lag, there is no certainty your data will be in the expected state.
1028
1029For data integrity, all transactions automatically use the master storage for
1030all read and write queries. Using a transaction is the preferred and recommended
1031method to force the master to handle all read queries.
1032
1033Otherwise, you can force a single query to use the master with the 'force_pool'
1034attribute:
1035
1036 my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk);
1037
1038This attribute will safely be ignore by non replicated storages, so you can use
1039the same code for both types of systems.
1040
1041Lastly, you can use the L</execute_reliably> method, which works very much like
1042a transaction.
1043
1044For debugging, you can turn replication on/off with the methods L</set_reliable_storage>
1045and L</set_balanced_storage>, however this operates at a global level and is not
1046suitable if you have a shared Schema object being used by multiple processes,
1047such as on a web application server. You can get around this limitation by
1048using the Schema clone method.
1049
1050 my $new_schema = $schema->clone;
1051 $new_schema->set_reliable_storage;
d4daee7b 1052
7e38d850 1053 ## $new_schema will use only the Master storage for all reads/writes while
1054 ## the $schema object will use replicated storage.
1055
f5d3a5de 1056=head1 AUTHOR
1057
64cdad22 1058 John Napiorkowski <john.napiorkowski@takkle.com>
f5d3a5de 1059
c4d3fae2 1060Based on code originated by:
f5d3a5de 1061
64cdad22 1062 Norbert Csongrádi <bert@cpan.org>
1063 Peter Siklósi <einon@einon.hu>
2156bbdd 1064
f5d3a5de 1065=head1 LICENSE
1066
1067You may distribute this code under the same terms as Perl itself.
1068
1069=cut
1070
c354902c 1071__PACKAGE__->meta->make_immutable;
1072
f5d3a5de 10731;