vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

   1 require 'benchmark'
   2 require 'date'
   3 require 'bigdecimal'
   4 require 'bigdecimal/util'
   5
   6 # TODO: Autoload these files
   7 require 'active_record/connection_adapters/abstract/schema_definitions'
   8 require 'active_record/connection_adapters/abstract/schema_statements'
   9 require 'active_record/connection_adapters/abstract/database_statements'
  10 require 'active_record/connection_adapters/abstract/quoting'
  11 require 'active_record/connection_adapters/abstract/connection_pool'
  12 require 'active_record/connection_adapters/abstract/connection_specification'
  13 require 'active_record/connection_adapters/abstract/query_cache'
  14
  15 module ActiveRecord
  16   module ConnectionAdapters # :nodoc:
  17     # ActiveRecord supports multiple database systems. AbstractAdapter and
  18     # related classes form the abstraction layer which makes this possible.
  19     # An AbstractAdapter represents a connection to a database, and provides an
  20     # abstract interface for database-specific functionality such as establishing
  21     # a connection, escaping values, building the right SQL fragments for ':offset'
  22     # and ':limit' options, etc.
  23     #
  24     # All the concrete database adapters follow the interface laid down in this class.
  25     # ActiveRecord::Base.connection returns an AbstractAdapter object, which
  26     # you can use.
  27     #
  28     # Most of the methods in the adapter are useful during migrations. Most
  29     # notably, the instance methods provided by SchemaStatement are very useful.
  30     class AbstractAdapter
  31       include Quoting, DatabaseStatements, SchemaStatements
  32       include QueryCache
  33       include ActiveSupport::Callbacks
  34       define_callbacks :checkout, :checkin
  35
  36       @@row_even = true
  37
  38       def initialize(connection, logger = nil) #:nodoc:
  39         @connection, @logger = connection, logger
  40         @runtime = 0
  41         @last_verification = 0
  42         @query_cache_enabled = false
  43       end
  44
  45       # Returns the human-readable name of the adapter.  Use mixed case - one
  46       # can always use downcase if needed.
  47       def adapter_name
  48         'Abstract'
  49       end
  50
  51       # Does this adapter support migrations?  Backend specific, as the
  52       # abstract adapter always returns +false+.
  53       def supports_migrations?
  54         false
  55       end
  56
  57       # Does this adapter support using DISTINCT within COUNT?  This is +true+
  58       # for all adapters except sqlite.
  59       def supports_count_distinct?
  60         true
  61       end
  62
  63       # Does this adapter support DDL rollbacks in transactions?  That is, would
  64       # CREATE TABLE or ALTER TABLE get rolled back by a transaction?  PostgreSQL,
  65       # SQL Server, and others support this.  MySQL and others do not.
  66       def supports_ddl_transactions?
  67         false
  68       end
  69
  70       # Does this adapter support savepoints? PostgreSQL and MySQL do, SQLite
  71       # does not.
  72       def supports_savepoints?
  73         false
  74       end
  75
  76       # Should primary key values be selected from their corresponding
  77       # sequence before the insert statement?  If true, next_sequence_value
  78       # is called before each insert to set the record's primary key.
  79       # This is false for all adapters but Firebird.
  80       def prefetch_primary_key?(table_name = nil)
  81         false
  82       end
  83
  84       def reset_runtime #:nodoc:
  85         rt, @runtime = @runtime, 0
  86         rt
  87       end
  88
  89       # QUOTING ==================================================
  90
  91       # Override to return the quoted table name. Defaults to column quoting.
  92       def quote_table_name(name)
  93         quote_column_name(name)
  94       end
  95
  96       # REFERENTIAL INTEGRITY ====================================
  97
  98       # Override to turn off referential integrity while executing <tt>&block</tt>.
  99       def disable_referential_integrity(&block)
 100         yield
 101       end
 102
 103       # CONNECTION MANAGEMENT ====================================
 104
 105       # Checks whether the connection to the database is still active. This includes
 106       # checking whether the database is actually capable of responding, i.e. whether
 107       # the connection isn't stale.
 108       def active?
 109         @active != false
 110       end
 111
 112       # Disconnects from the database if already connected, and establishes a
 113       # new connection with the database.
 114       def reconnect!
 115         @active = true
 116       end
 117
 118       # Disconnects from the database if already connected. Otherwise, this
 119       # method does nothing.
 120       def disconnect!
 121         @active = false
 122       end
 123
 124       # Reset the state of this connection, directing the DBMS to clear
 125       # transactions and other connection-related server-side state. Usually a
 126       # database-dependent operation.
 127       #
 128       # The default implementation does nothing; the implementation should be
 129       # overridden by concrete adapters.
 130       def reset!
 131         # this should be overridden by concrete adapters
 132       end
 133
 134       # Returns true if its safe to reload the connection between requests for development mode.
 135       def requires_reloading?
 136         true
 137       end
 138
 139       # Checks whether the connection to the database is still active (i.e. not stale).
 140       # This is done under the hood by calling <tt>active?</tt>. If the connection
 141       # is no longer active, then this method will reconnect to the database.
 142       def verify!(*ignored)
 143         reconnect! unless active?
 144       end
 145
 146       # Provides access to the underlying database driver for this adapter. For
 147       # example, this method returns a Mysql object in case of MysqlAdapter,
 148       # and a PGconn object in case of PostgreSQLAdapter.
 149       #
 150       # This is useful for when you need to call a proprietary method such as
 151       # PostgreSQL's lo_* methods.
 152       def raw_connection
 153         @connection
 154       end
 155
 156       def open_transactions
 157         @open_transactions ||= 0
 158       end
 159
 160       def increment_open_transactions
 161         @open_transactions ||= 0
 162         @open_transactions += 1
 163       end
 164
 165       def decrement_open_transactions
 166         @open_transactions -= 1
 167       end
 168
 169       def transaction_joinable=(joinable)
 170         @transaction_joinable = joinable
 171       end
 172
 173       def create_savepoint
 174       end
 175
 176       def rollback_to_savepoint
 177       end
 178
 179       def release_savepoint
 180       end
 181
 182       def current_savepoint_name
 183         "active_record_#{open_transactions}"
 184       end
 185
 186       def log_info(sql, name, ms)
 187         if @logger && @logger.debug?
 188           name = '%s (%.1fms)' % [name || 'SQL', ms]
 189           @logger.debug(format_log_entry(name, sql.squeeze(' ')))
 190         end
 191       end
 192
 193       protected
 194         def log(sql, name)
 195           if block_given?
 196             result = nil
 197             ms = Benchmark.ms { result = yield }
 198             @runtime += ms
 199             log_info(sql, name, ms)
 200             result
 201           else
 202             log_info(sql, name, 0)
 203             nil
 204           end
 205         rescue Exception => e
 206           # Log message and raise exception.
 207           # Set last_verification to 0, so that connection gets verified
 208           # upon reentering the request loop
 209           @last_verification = 0
 210           message = "#{e.class.name}: #{e.message}: #{sql}"
 211           log_info(message, name, 0)
 212           raise ActiveRecord::StatementInvalid, message
 213         end
 214
 215         def format_log_entry(message, dump = nil)
 216           if ActiveRecord::Base.colorize_logging
 217             if @@row_even
 218               @@row_even = false
 219               message_color, dump_color = "4;36;1", "0;1"
 220             else
 221               @@row_even = true
 222               message_color, dump_color = "4;35;1", "0"
 223             end
 224
 225             log_entry = "  \e[#{message_color}m#{message}\e[0m   "
 226             log_entry << "\e[#{dump_color}m%#{String === dump ? 's' : 'p'}\e[0m" % dump if dump
 227             log_entry
 228           else
 229             "%s  %s" % [message, dump]
 230           end
 231         end
 232     end
 233   end
 234 end