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tag: v3.2.8.rc2
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require 'date'
require 'bigdecimal'
require 'bigdecimal/util'
require 'active_support/core_ext/benchmark'
require 'active_support/deprecation'
require 'active_record/connection_adapters/schema_cache'
require 'monitor'
module ActiveRecord
module ConnectionAdapters # :nodoc:
extend ActiveSupport::Autoload
autoload :Column
autoload_under 'abstract' do
autoload :IndexDefinition, 'active_record/connection_adapters/abstract/schema_definitions'
autoload :ColumnDefinition, 'active_record/connection_adapters/abstract/schema_definitions'
autoload :TableDefinition, 'active_record/connection_adapters/abstract/schema_definitions'
autoload :Table, 'active_record/connection_adapters/abstract/schema_definitions'
autoload :SchemaStatements
autoload :DatabaseStatements
autoload :DatabaseLimits
autoload :Quoting
autoload :ConnectionPool
autoload :ConnectionHandler, 'active_record/connection_adapters/abstract/connection_pool'
autoload :ConnectionManagement, 'active_record/connection_adapters/abstract/connection_pool'
autoload :ConnectionSpecification
autoload :QueryCache
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 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 SchemaStatement are very useful.
class AbstractAdapter
include Quoting, DatabaseStatements, SchemaStatements
include DatabaseLimits
include QueryCache
include ActiveSupport::Callbacks
include MonitorMixin
define_callbacks :checkout, :checkin
attr_accessor :visitor, :pool
attr_reader :schema_cache, :last_use, :in_use, :logger
alias :in_use? :in_use
def initialize(connection, logger = nil, pool = nil) #:nodoc:
super()
@active = nil
@connection = connection
@in_use = false
@instrumenter = ActiveSupport::Notifications.instrumenter
@last_use = false
@logger = logger
@open_transactions = 0
@pool = pool
@query_cache = Hash.new { |h,sql| h[sql] = {} }
@query_cache_enabled = false
@schema_cache = SchemaCache.new self
@visitor = nil
end
def lease
synchronize do
unless in_use
@in_use = true
@last_use = Time.now
end
end
end
def expire
@in_use = false
end
# Returns the human-readable name of the adapter. Use mixed case - one
# can always use downcase if needed.
def adapter_name
'Abstract'
end
# Does this adapter support migrations? Backend specific, as the
# abstract adapter always returns +false+.
def supports_migrations?
false
end
# Can this adapter determine the primary key for tables not attached
# to an Active Record class, such as join tables? Backend specific, as
# the abstract adapter always returns +false+.
def supports_primary_key?
false
end
# Does this adapter support using DISTINCT within COUNT? This is +true+
# for all adapters except sqlite.
def supports_count_distinct?
true
end
# Does this adapter support DDL rollbacks in transactions? That is, would
# CREATE TABLE or ALTER TABLE get rolled back by a transaction? PostgreSQL,
# SQL Server, and others support this. MySQL and others do not.
def supports_ddl_transactions?
false
end
def supports_bulk_alter?
false
end
# Does this adapter support savepoints? PostgreSQL and MySQL do,
# SQLite < 3.6.8 does not.
def supports_savepoints?
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.
# This is false for all adapters but Firebird.
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 explain? As of this writing sqlite3,
# mysql2, and postgresql are the only ones that do.
def supports_explain?
false
end
# QUOTING ==================================================
# Override to return the quoted table name. Defaults to column quoting.
def quote_table_name(name)
quote_column_name(name)
end
# Returns a bind substitution value given a +column+ and list of current
# +binds+
def substitute_at(column, index)
Arel::Nodes::BindParam.new '?'
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?
@active != false
end
# Disconnects from the database if already connected, and establishes a
# new connection with the database.
def reconnect!
@active = true
end
# Disconnects from the database if already connected. Otherwise, this
# method does nothing.
def disconnect!
@active = 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.
#
# 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, for example
# clearing the prepared statement cache. This is database specific.
def clear_cache!
# this should be overridden by concrete adapters
end
# Returns true if its required to reload the connection between requests for development mode.
# This is not the case for Ruby/MySQL and it's not necessary for any adapters except SQLite.
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 <tt>active?</tt>. If the connection
# is no longer active, then this method will reconnect to the database.
def verify!(*ignored)
reconnect! unless active?
end
# Provides access to the underlying database driver for this adapter. For
# example, this method returns a Mysql object in case of MysqlAdapter,
# and a PGconn 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
@connection
end
attr_reader :open_transactions
def increment_open_transactions
@open_transactions += 1
end
def decrement_open_transactions
@open_transactions -= 1
end
def transaction_joinable=(joinable)
@transaction_joinable = joinable
end
def create_savepoint
end
def rollback_to_savepoint
end
def release_savepoint
end
def case_sensitive_modifier(node)
node
end
def case_insensitive_comparison(table, attribute, column, value)
table[attribute].lower.eq(table.lower(value))
end
def current_savepoint_name
"active_record_#{open_transactions}"
end
# Check the connection back in to the connection pool
def close
pool.checkin self
end
protected
def log(sql, name = "SQL", binds = [])
@instrumenter.instrument(
"sql.active_record",
:sql => sql,
:name => name,
:connection_id => object_id,
:binds => binds) { yield }
rescue Exception => e
message = "#{e.class.name}: #{e.message}: #{sql}"
@logger.debug message if @logger
exception = translate_exception(e, message)
exception.set_backtrace e.backtrace
raise exception
end
def translate_exception(e, message)
# override in derived class
ActiveRecord::StatementInvalid.new(message)
end
end
end
end
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