1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
|
# frozen_string_literal: true
require "active_record/connection_adapters/determine_if_preparable_visitor"
require "active_record/connection_adapters/schema_cache"
require "active_record/connection_adapters/sql_type_metadata"
require "active_record/connection_adapters/abstract/schema_dumper"
require "active_record/connection_adapters/abstract/schema_creation"
require "active_support/concurrency/load_interlock_aware_monitor"
require "active_support/deprecation"
require "arel/collectors/bind"
require "arel/collectors/composite"
require "arel/collectors/sql_string"
require "arel/collectors/substitute_binds"
module ActiveRecord
module ConnectionAdapters # :nodoc:
extend ActiveSupport::Autoload
autoload :Column
autoload :ConnectionSpecification
autoload_at "active_record/connection_adapters/abstract/schema_definitions" do
autoload :IndexDefinition
autoload :ColumnDefinition
autoload :ChangeColumnDefinition
autoload :ForeignKeyDefinition
autoload :TableDefinition
autoload :Table
autoload :AlterTable
autoload :ReferenceDefinition
end
autoload_at "active_record/connection_adapters/abstract/connection_pool" do
autoload :ConnectionHandler
end
autoload_under "abstract" do
autoload :SchemaStatements
autoload :DatabaseStatements
autoload :DatabaseLimits
autoload :Quoting
autoload :ConnectionPool
autoload :QueryCache
autoload :Savepoints
end
autoload_at "active_record/connection_adapters/abstract/transaction" do
autoload :TransactionManager
autoload :NullTransaction
autoload :RealTransaction
autoload :SavepointTransaction
autoload :TransactionState
end
# Active Record supports multiple database systems. AbstractAdapter and
# related classes form the abstraction layer which makes this possible.
# An AbstractAdapter represents a connection to a database, and provides an
# abstract interface for database-specific functionality such as establishing
# a connection, escaping values, building the right SQL fragments for +:offset+
# and +:limit+ options, etc.
#
# All the concrete database adapters follow the interface laid down in this class.
# {ActiveRecord::Base.connection}[rdoc-ref:ConnectionHandling#connection] returns an AbstractAdapter object, which
# you can use.
#
# Most of the methods in the adapter are useful during migrations. Most
# notably, the instance methods provided by SchemaStatements are very useful.
class AbstractAdapter
ADAPTER_NAME = "Abstract"
include ActiveSupport::Callbacks
define_callbacks :checkout, :checkin
include Quoting, DatabaseStatements, SchemaStatements
include DatabaseLimits
include QueryCache
include Savepoints
SIMPLE_INT = /\A\d+\z/
attr_accessor :pool
attr_reader :schema_cache, :visitor, :owner, :logger, :lock, :prepared_statements, :prevent_writes
alias :in_use? :owner
set_callback :checkin, :after, :enable_lazy_transactions!
def self.type_cast_config_to_integer(config)
if config.is_a?(Integer)
config
elsif SIMPLE_INT.match?(config)
config.to_i
else
config
end
end
def self.type_cast_config_to_boolean(config)
if config == "false"
false
else
config
end
end
def self.build_read_query_regexp(*parts) # :nodoc:
parts = parts.map { |part| /\A[\(\s]*#{part}/i }
Regexp.union(*parts)
end
def initialize(connection, logger = nil, config = {}) # :nodoc:
super()
@connection = connection
@owner = nil
@instrumenter = ActiveSupport::Notifications.instrumenter
@logger = logger
@config = config
@pool = nil
@idle_since = Concurrent.monotonic_time
@schema_cache = SchemaCache.new self
@quoted_column_names, @quoted_table_names = {}, {}
@prevent_writes = false
@visitor = arel_visitor
@statements = build_statement_pool
@lock = ActiveSupport::Concurrency::LoadInterlockAwareMonitor.new
if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
@prepared_statements = true
@visitor.extend(DetermineIfPreparableVisitor)
else
@prepared_statements = false
end
@advisory_locks_enabled = self.class.type_cast_config_to_boolean(
config.fetch(:advisory_locks, true)
)
end
def replica?
@config[:replica] || false
end
# Determines whether writes are currently being prevents.
#
# Returns true if the connection is a replica, or if +prevent_writes+
# is set to true.
def preventing_writes?
replica? || prevent_writes
end
# Prevent writing to the database regardless of role.
#
# In some cases you may want to prevent writes to the database
# even if you are on a database that can write. `while_preventing_writes`
# will prevent writes to the database for the duration of the block.
def while_preventing_writes
original, @prevent_writes = @prevent_writes, true
yield
ensure
@prevent_writes = original
end
def migrations_paths # :nodoc:
@config[:migrations_paths] || Migrator.migrations_paths
end
def migration_context # :nodoc:
MigrationContext.new(migrations_paths)
end
class Version
include Comparable
attr_reader :full_version_string
def initialize(version_string, full_version_string = nil)
@version = version_string.split(".").map(&:to_i)
@full_version_string = full_version_string
end
def <=>(version_string)
@version <=> version_string.split(".").map(&:to_i)
end
def to_s
@version.join(".")
end
end
def valid_type?(type) # :nodoc:
!native_database_types[type].nil?
end
# this method must only be called while holding connection pool's mutex
def lease
if in_use?
msg = +"Cannot lease connection, "
if @owner == Thread.current
msg << "it is already leased by the current thread."
else
msg << "it is already in use by a different thread: #{@owner}. " \
"Current thread: #{Thread.current}."
end
raise ActiveRecordError, msg
end
@owner = Thread.current
end
def schema_cache=(cache)
cache.connection = self
@schema_cache = cache
end
# this method must only be called while holding connection pool's mutex
def expire
if in_use?
if @owner != Thread.current
raise ActiveRecordError, "Cannot expire connection, " \
"it is owned by a different thread: #{@owner}. " \
"Current thread: #{Thread.current}."
end
@idle_since = Concurrent.monotonic_time
@owner = nil
else
raise ActiveRecordError, "Cannot expire connection, it is not currently leased."
end
end
# this method must only be called while holding connection pool's mutex (and a desire for segfaults)
def steal! # :nodoc:
if in_use?
if @owner != Thread.current
pool.send :remove_connection_from_thread_cache, self, @owner
@owner = Thread.current
end
else
raise ActiveRecordError, "Cannot steal connection, it is not currently leased."
end
end
# Seconds since this connection was returned to the pool
def seconds_idle # :nodoc:
return 0 if in_use?
Concurrent.monotonic_time - @idle_since
end
def unprepared_statement
old_prepared_statements, @prepared_statements = @prepared_statements, false
yield
ensure
@prepared_statements = old_prepared_statements
end
# Returns the human-readable name of the adapter. Use mixed case - one
# can always use downcase if needed.
def adapter_name
self.class::ADAPTER_NAME
end
# Does this adapter support DDL rollbacks in transactions? That is, would
# CREATE TABLE or ALTER TABLE get rolled back by a transaction?
def supports_ddl_transactions?
false
end
def supports_bulk_alter?
false
end
# Does this adapter support savepoints?
def supports_savepoints?
false
end
# Does this adapter support application-enforced advisory locking?
def supports_advisory_locks?
false
end
# Should primary key values be selected from their corresponding
# sequence before the insert statement? If true, next_sequence_value
# is called before each insert to set the record's primary key.
def prefetch_primary_key?(table_name = nil)
false
end
# Does this adapter support index sort order?
def supports_index_sort_order?
false
end
# Does this adapter support partial indices?
def supports_partial_index?
false
end
# Does this adapter support expression indices?
def supports_expression_index?
false
end
# Does this adapter support explain?
def supports_explain?
false
end
# Does this adapter support setting the isolation level for a transaction?
def supports_transaction_isolation?
false
end
# Does this adapter support database extensions?
def supports_extensions?
false
end
# Does this adapter support creating indexes in the same statement as
# creating the table?
def supports_indexes_in_create?
false
end
# Does this adapter support creating foreign key constraints?
def supports_foreign_keys?
false
end
# Does this adapter support creating invalid constraints?
def supports_validate_constraints?
false
end
# Does this adapter support creating foreign key constraints
# in the same statement as creating the table?
def supports_foreign_keys_in_create?
supports_foreign_keys?
end
deprecate :supports_foreign_keys_in_create?
# Does this adapter support views?
def supports_views?
false
end
# Does this adapter support materialized views?
def supports_materialized_views?
false
end
# Does this adapter support datetime with precision?
def supports_datetime_with_precision?
false
end
# Does this adapter support json data type?
def supports_json?
false
end
# Does this adapter support metadata comments on database objects (tables, columns, indexes)?
def supports_comments?
false
end
# Can comments for tables, columns, and indexes be specified in create/alter table statements?
def supports_comments_in_create?
false
end
# Does this adapter support multi-value insert?
def supports_multi_insert?
true
end
deprecate :supports_multi_insert?
# Does this adapter support virtual columns?
def supports_virtual_columns?
false
end
# Does this adapter support foreign/external tables?
def supports_foreign_tables?
false
end
# Does this adapter support optimizer hints?
def supports_optimizer_hints?
false
end
def supports_lazy_transactions?
false
end
def supports_insert_returning?
false
end
def supports_insert_on_duplicate_skip?
false
end
def supports_insert_on_duplicate_update?
false
end
def supports_insert_conflict_target?
false
end
# This is meant to be implemented by the adapters that support extensions
def disable_extension(name)
end
# This is meant to be implemented by the adapters that support extensions
def enable_extension(name)
end
def advisory_locks_enabled? # :nodoc:
supports_advisory_locks? && @advisory_locks_enabled
end
# This is meant to be implemented by the adapters that support advisory
# locks
#
# Return true if we got the lock, otherwise false
def get_advisory_lock(lock_id) # :nodoc:
end
# This is meant to be implemented by the adapters that support advisory
# locks.
#
# Return true if we released the lock, otherwise false
def release_advisory_lock(lock_id) # :nodoc:
end
# A list of extensions, to be filled in by adapters that support them.
def extensions
[]
end
# A list of index algorithms, to be filled by adapters that support them.
def index_algorithms
{}
end
# REFERENTIAL INTEGRITY ====================================
# Override to turn off referential integrity while executing <tt>&block</tt>.
def disable_referential_integrity
yield
end
# CONNECTION MANAGEMENT ====================================
# Checks whether the connection to the database is still active. This includes
# checking whether the database is actually capable of responding, i.e. whether
# the connection isn't stale.
def active?
end
# Disconnects from the database if already connected, and establishes a
# new connection with the database. Implementors should call super if they
# override the default implementation.
def reconnect!
clear_cache!
reset_transaction
end
# Disconnects from the database if already connected. Otherwise, this
# method does nothing.
def disconnect!
clear_cache!
reset_transaction
end
# Immediately forget this connection ever existed. Unlike disconnect!,
# this will not communicate with the server.
#
# After calling this method, the behavior of all other methods becomes
# undefined. This is called internally just before a forked process gets
# rid of a connection that belonged to its parent.
def discard!
# This should be overridden by concrete adapters.
#
# Prevent @connection's finalizer from touching the socket, or
# otherwise communicating with its server, when it is collected.
end
# Reset the state of this connection, directing the DBMS to clear
# transactions and other connection-related server-side state. Usually a
# database-dependent operation.
#
# The default implementation does nothing; the implementation should be
# overridden by concrete adapters.
def reset!
# this should be overridden by concrete adapters
end
# Clear any caching the database adapter may be doing.
def clear_cache!
@lock.synchronize { @statements.clear } if @statements
end
# Returns true if its required to reload the connection between requests for development mode.
def requires_reloading?
false
end
# Checks whether the connection to the database is still active (i.e. not stale).
# This is done under the hood by calling #active?. If the connection
# is no longer active, then this method will reconnect to the database.
def verify!
reconnect! unless active?
end
# Provides access to the underlying database driver for this adapter. For
# example, this method returns a Mysql2::Client object in case of Mysql2Adapter,
# and a PG::Connection object in case of PostgreSQLAdapter.
#
# This is useful for when you need to call a proprietary method such as
# PostgreSQL's lo_* methods.
def raw_connection
disable_lazy_transactions!
@connection
end
def default_uniqueness_comparison(attribute, value, klass) # :nodoc:
attribute.eq(value)
end
def case_sensitive_comparison(attribute, value) # :nodoc:
attribute.eq(value)
end
def case_insensitive_comparison(attribute, value) # :nodoc:
column = column_for_attribute(attribute)
if can_perform_case_insensitive_comparison_for?(column)
attribute.lower.eq(attribute.relation.lower(value))
else
attribute.eq(value)
end
end
def can_perform_case_insensitive_comparison_for?(column)
true
end
private :can_perform_case_insensitive_comparison_for?
# Check the connection back in to the connection pool
def close
pool.checkin self
end
def column_name_for_operation(operation, node) # :nodoc:
visitor.compile(node)
end
def default_index_type?(index) # :nodoc:
index.using.nil?
end
# Called by ActiveRecord::InsertAll,
# Passed an instance of ActiveRecord::InsertAll::Builder,
# This method implements standard bulk inserts for all databases, but
# should be overridden by adapters to implement common features with
# non-standard syntax like handling duplicates or returning values.
def build_insert_sql(insert) # :nodoc:
if insert.skip_duplicates? || insert.update_duplicates?
raise NotImplementedError, "#{self.class} should define `build_insert_sql` to implement adapter-specific logic for handling duplicates during INSERT"
end
"INSERT #{insert.into} #{insert.values_list}"
end
def get_database_version # :nodoc:
end
def database_version # :nodoc:
schema_cache.database_version
end
def check_version # :nodoc:
end
private
def type_map
@type_map ||= Type::TypeMap.new.tap do |mapping|
initialize_type_map(mapping)
end
end
def initialize_type_map(m = type_map)
register_class_with_limit m, %r(boolean)i, Type::Boolean
register_class_with_limit m, %r(char)i, Type::String
register_class_with_limit m, %r(binary)i, Type::Binary
register_class_with_limit m, %r(text)i, Type::Text
register_class_with_precision m, %r(date)i, Type::Date
register_class_with_precision m, %r(time)i, Type::Time
register_class_with_precision m, %r(datetime)i, Type::DateTime
register_class_with_limit m, %r(float)i, Type::Float
register_class_with_limit m, %r(int)i, Type::Integer
m.alias_type %r(blob)i, "binary"
m.alias_type %r(clob)i, "text"
m.alias_type %r(timestamp)i, "datetime"
m.alias_type %r(numeric)i, "decimal"
m.alias_type %r(number)i, "decimal"
m.alias_type %r(double)i, "float"
m.register_type %r(^json)i, Type::Json.new
m.register_type(%r(decimal)i) do |sql_type|
scale = extract_scale(sql_type)
precision = extract_precision(sql_type)
if scale == 0
# FIXME: Remove this class as well
Type::DecimalWithoutScale.new(precision: precision)
else
Type::Decimal.new(precision: precision, scale: scale)
end
end
end
def reload_type_map
type_map.clear
initialize_type_map
end
def register_class_with_limit(mapping, key, klass)
mapping.register_type(key) do |*args|
limit = extract_limit(args.last)
klass.new(limit: limit)
end
end
def register_class_with_precision(mapping, key, klass)
mapping.register_type(key) do |*args|
precision = extract_precision(args.last)
klass.new(precision: precision)
end
end
def extract_scale(sql_type)
case sql_type
when /\((\d+)\)/ then 0
when /\((\d+)(,(\d+))\)/ then $3.to_i
end
end
def extract_precision(sql_type)
$1.to_i if sql_type =~ /\((\d+)(,\d+)?\)/
end
def extract_limit(sql_type)
$1.to_i if sql_type =~ /\((.*)\)/
end
def translate_exception_class(e, sql, binds)
message = "#{e.class.name}: #{e.message}"
exception = translate_exception(
e, message: message, sql: sql, binds: binds
)
exception.set_backtrace e.backtrace
exception
end
def log(sql, name = "SQL", binds = [], type_casted_binds = [], statement_name = nil) # :doc:
@instrumenter.instrument(
"sql.active_record",
sql: sql,
name: name,
binds: binds,
type_casted_binds: type_casted_binds,
statement_name: statement_name,
connection_id: object_id,
connection: self) do
@lock.synchronize do
yield
end
rescue => e
raise translate_exception_class(e, sql, binds)
end
end
def translate_exception(exception, message:, sql:, binds:)
# override in derived class
case exception
when RuntimeError
exception
else
ActiveRecord::StatementInvalid.new(message, sql: sql, binds: binds)
end
end
def without_prepared_statement?(binds)
!prepared_statements || binds.empty?
end
def column_for(table_name, column_name)
column_name = column_name.to_s
columns(table_name).detect { |c| c.name == column_name } ||
raise(ActiveRecordError, "No such column: #{table_name}.#{column_name}")
end
def column_for_attribute(attribute)
table_name = attribute.relation.name
schema_cache.columns_hash(table_name)[attribute.name.to_s]
end
def collector
if prepared_statements
Arel::Collectors::Composite.new(
Arel::Collectors::SQLString.new,
Arel::Collectors::Bind.new,
)
else
Arel::Collectors::SubstituteBinds.new(
self,
Arel::Collectors::SQLString.new,
)
end
end
def arel_visitor
Arel::Visitors::ToSql.new(self)
end
def build_statement_pool
end
end
end
end
|