class ActiveRecord::ConnectionAdapters::AbstractAdapter
Active Record Abstract Adapter
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.lease_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.
Inherits From
-
module
ActiveSupport::
Callbacks -
module
ActiveRecord::
ConnectionAdapters:: DatabaseLimits -
module
ActiveRecord::
ConnectionAdapters:: QueryCache -
module
ActiveRecord::
ConnectionAdapters:: Savepoints
Constants
Attributes
[RW] | allow_preconnect |
|
[R] | in_use? |
|
[R] | lock |
|
[R] | logger |
|
[R] | owner |
|
[R] | pool |
|
[R] | visitor |
Public class methods
Does the database for this adapter exist?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 388
def self.database_exists?(config)
new(config).database_exists?
end
Opens a database console session.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 122
def self.dbconsole(config, options = {})
raise NotImplementedError
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 93
def self.find_cmd_and_exec(commands, *args) # :doc:
commands = Array(commands)
dirs_on_path = ENV["PATH"].to_s.split(File::PATH_SEPARATOR)
unless (ext = RbConfig::CONFIG["EXEEXT"]).empty?
commands = commands.map { |cmd| "#{cmd}#{ext}" }
end
full_path_command = nil
found = commands.detect do |cmd|
dirs_on_path.detect do |path|
full_path_command = File.join(path, cmd)
begin
stat = File.stat(full_path_command)
rescue SystemCallError
else
stat.file? && stat.executable?
end
end
end
if found
exec full_path_command, *args
else
abort("Couldn't find database client: #{commands.join(', ')}. Check your $PATH and try again.")
end
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 66
def self.type_cast_config_to_boolean(config)
if config == "false"
false
else
config
end
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 56
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
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 74
def self.validate_default_timezone(config)
case config
when nil
when "utc", "local"
config.to_sym
else
raise ArgumentError, "default_timezone must be either 'utc' or 'local'"
end
end
Public instance methods
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.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 686
def active?
end
Returns the human-readable name of the adapter. Use mixed case - one can always use downcase if needed.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 383
def adapter_name
self.class::ADAPTER_NAME
end
Override to check all foreign key constraints in a database. The adapter should raise a ActiveRecord::StatementInvalid
if foreign key constraints are not met.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 671
def check_all_foreign_keys_valid!
end
Clear any caching the database adapter may be doing.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 773
def clear_cache!(new_connection: false)
if @statements
@lock.synchronize do
if new_connection
@statements.reset
else
@statements.clear
end
end
end
end
Check the connection back in to the connection pool
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 870
def close
pool.checkin self
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 814
def connect!
verify!
self
end
Checks whether the connection to the database was established. This doesn’t include checking whether the database is actually capable of responding, i.e. whether the connection is stale.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 679
def connected?
!@raw_connection.nil?
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 214
def connection_retries
(@config[:connection_retries] || 1).to_i
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 392
def database_exists?
connect!
true
rescue ActiveRecord::NoDatabaseError
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 230
def default_timezone
@default_timezone || ActiveRecord.default_timezone
end
This is meant to be implemented by the adapters that support extensions
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 598
def disable_extension(name, **)
end
Override to turn off referential integrity while executing &block
.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 664
def disable_referential_integrity
yield
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.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 748
def discard!
# This should be overridden by concrete adapters.
end
Disconnects from the database if already connected. Otherwise, this method does nothing.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 733
def disconnect!
@lock.synchronize do
clear_cache!(new_connection: true)
reset_transaction
@raw_connection_dirty = false
@connected_since = nil
end
end
This is meant to be implemented by the adapters that support extensions
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 602
def enable_extension(name, **)
end
A list of extensions, to be filled in by adapters that support them.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 652
def extensions
[]
end
A list of index algorithms, to be filled by adapters that support them.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 657
def index_algorithms
{}
end
this method must only be called while holding connection pool’s mutex
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 278
def lease
if in_use?
msg = +"Cannot lease connection, "
if @owner == ActiveSupport::IsolatedExecutionState.context
msg << "it is already leased by the current thread."
else
msg << "it is already in use by a different thread: #{@owner}. " \
"Current thread: #{ActiveSupport::IsolatedExecutionState.context}."
end
raise ActiveRecordError, msg
end
@owner = ActiveSupport::IsolatedExecutionState.context
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 206
def max_jitter
(@config[:pool_jitter] || 0.2).to_f.clamp(MAX_JITTER)
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 48
def pool=(value)
return if value.eql?(@pool)
@schema_cache = nil
@pool = value
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 313
def pool_jitter(duration)
duration * (1.0 - @pool_jitter)
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.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 432
def prefetch_primary_key?(table_name = nil)
false
end
Alias for:
prepared_statements?
.
Also aliased as:
prepared_statements
.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 245
def prepared_statements?
@prepared_statements && !prepared_statements_disabled_cache.include?(object_id)
end
Determines whether writes are currently being prevented.
Returns true if the connection is a replica or returns the value of current_preventing_writes
.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 238
def preventing_writes?
return true if replica?
return false if connection_descriptor.nil?
connection_descriptor.current_preventing_writes
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.
Active Record cannot track if the database is getting modified using this client. If that is the case, generally you’ll want to invalidate the query cache using ActiveRecord::Base.clear_query_cache
.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 838
def raw_connection
with_raw_connection do |conn|
disable_lazy_transactions!
@raw_connection_dirty = true
conn
end
end
Disconnects from the database if already connected, and establishes a new connection with the database. Implementors should define private reconnect instead.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 692
def reconnect!(restore_transactions: false)
retries_available = connection_retries
deadline = retry_deadline && Process.clock_gettime(Process::CLOCK_MONOTONIC) + retry_deadline
@lock.synchronize do
@allow_preconnect = false
reconnect
enable_lazy_transactions!
@raw_connection_dirty = false
@last_activity = @connected_since = Process.clock_gettime(Process::CLOCK_MONOTONIC)
@verified = true
@allow_preconnect = true
reset_transaction(restore: restore_transactions) do
clear_cache!(new_connection: true)
configure_connection
end
rescue => original_exception
translated_exception = translate_exception_class(original_exception, nil, nil)
retry_deadline_exceeded = deadline && deadline < Process.clock_gettime(Process::CLOCK_MONOTONIC)
if !retry_deadline_exceeded && retries_available > 0
retries_available -= 1
if retryable_connection_error?(translated_exception)
backoff(connection_retries - retries_available)
retry
end
end
@last_activity = nil
@verified = false
raise translated_exception
end
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 210
def replica?
@config[:replica] || false
end
Returns true if its required to reload the connection between requests for development mode.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 786
def requires_reloading?
false
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.
If a database driver or protocol does not support such a feature, implementors may alias this to reconnect!
. Otherwise, implementors should call super immediately after resetting the connection (and while still holding @lock).
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 760
def reset!
clear_cache!(new_connection: true)
reset_transaction
configure_connection
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 222
def retry_deadline
if @config[:retry_deadline]
@config[:retry_deadline].to_f
else
nil
end
end
The role (e.g. :writing
) for the current connection. In a non-multi role application, :writing
is returned.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 299
def role
@pool.role
end
Do TransactionRollbackErrors on savepoints affect the parent transaction?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 416
def savepoint_errors_invalidate_transactions?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 309
def schema_cache
@pool.schema_cache || (@schema_cache ||= BoundSchemaReflection.for_lone_connection(@pool.schema_reflection, self))
end
Returns the version identifier of the schema currently available in the database. This is generally equal to the number of the highest- numbered migration that has been executed, or 0 if no schema information is present / the database is empty.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 905
def schema_version
pool.migration_context.current_version
end
The shard (e.g. :default
) for the current connection. In a non-sharded application, :default
is returned.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 305
def shard
@pool.shard
end
Does this adapter support application-enforced advisory locking?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 425
def supports_advisory_locks?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 405
def supports_bulk_alter?
false
end
Does this adapter support creating check constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 497
def supports_check_constraints?
false
end
Does this adapter support metadata comments on database objects (tables, columns, indexes)?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 532
def supports_comments?
false
end
Can comments for tables, columns, and indexes be specified in create/alter table statements?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 537
def supports_comments_in_create?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 556
def supports_common_table_expressions?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 580
def supports_concurrent_connections?
true
end
Does this adapter support datetime with precision?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 522
def supports_datetime_with_precision?
false
end
Does this adapter support DDL rollbacks in transactions? That is, would CREATE TABLE or ALTER TABLE get rolled back by a transaction?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 401
def supports_ddl_transactions?
false
end
Does this adapter support creating deferrable constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 492
def supports_deferrable_constraints?
false
end
Does this adapter support creating exclusion constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 502
def supports_exclusion_constraints?
false
end
Does this adapter support explain?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 461
def supports_explain?
false
end
Does this adapter support expression indices?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 456
def supports_expression_index?
false
end
Does this adapter support database extensions?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 471
def supports_extensions?
false
end
Does this adapter support creating foreign key constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 482
def supports_foreign_keys?
false
end
Does this adapter support foreign/external tables?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 547
def supports_foreign_tables?
false
end
Does this adapter support including non-key columns?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 451
def supports_index_include?
false
end
Does this adapter support index sort order?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 441
def supports_index_sort_order?
false
end
Does this adapter support creating indexes in the same statement as creating the table?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 477
def supports_indexes_in_create?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 576
def supports_insert_conflict_target?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 568
def supports_insert_on_duplicate_skip?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 572
def supports_insert_on_duplicate_update?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 564
def supports_insert_returning?
false
end
Does this adapter support JSON data type?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 527
def supports_json?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 560
def supports_lazy_transactions?
false
end
Does this adapter support materialized views?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 517
def supports_materialized_views?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 584
def supports_nulls_not_distinct?
false
end
Does this adapter support optimizer hints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 552
def supports_optimizer_hints?
false
end
Does this adapter support partial indices?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 446
def supports_partial_index?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 436
def supports_partitioned_indexes?
false
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 420
def supports_restart_db_transaction?
false
end
Does this adapter support savepoints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 410
def supports_savepoints?
false
end
Does this adapter support setting the isolation level for a transaction?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 466
def supports_transaction_isolation?
false
end
Does this adapter support creating unique constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 507
def supports_unique_constraints?
false
end
Does this adapter support creating invalid constraints?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 487
def supports_validate_constraints?
false
end
Does this adapter support views?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 512
def supports_views?
false
end
Does this adapter support virtual columns?
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 542
def supports_virtual_columns?
false
end
Removes the connection from the pool and disconnect it.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 767
def throw_away!
pool.remove self
disconnect!
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 374
def unprepared_statement
cache = prepared_statements_disabled_cache.add?(object_id) if @prepared_statements
yield
ensure
cache&.delete(object_id)
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.
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 793
def verify!
unless active?
@lock.synchronize do
if @unconfigured_connection
@raw_connection = @unconfigured_connection
@unconfigured_connection = nil
configure_connection
@last_activity = Process.clock_gettime(Process::CLOCK_MONOTONIC)
@verified = true
@allow_preconnect = true
return
end
reconnect!(restore_transactions: true)
end
end
@last_activity = Process.clock_gettime(Process::CLOCK_MONOTONIC)
@verified = true
end
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 218
def verify_timeout
(@config[:verify_timeout] || 2).to_i
end
Private instance methods
log(sql, name = "SQL", binds = [], type_casted_binds = [], async: false, allow_retry: false, &block)
Source code GitHub
# File activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 1174
def log(sql, name = "SQL", binds = [], type_casted_binds = [], async: false, allow_retry: false, &block) # :doc:
instrumenter.instrument(
"sql.active_record",
sql: sql,
name: name,
binds: binds,
type_casted_binds: type_casted_binds,
async: async,
allow_retry: allow_retry,
connection: self,
transaction: current_transaction.user_transaction.presence,
affected_rows: 0,
row_count: 0,
&block
)
rescue ActiveRecord::StatementInvalid => ex
raise ex.set_query(sql, binds)
end