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 require 'active_record/connection_adapters/abstract/schema_definitions'
   7 require 'active_record/connection_adapters/abstract/schema_statements'
   8 require 'active_record/connection_adapters/abstract/database_statements'
   9 require 'active_record/connection_adapters/abstract/quoting'
  10 require 'active_record/connection_adapters/abstract/connection_pool'
  11 require 'active_record/connection_adapters/abstract/connection_specification'
  12 require 'active_record/connection_adapters/abstract/query_cache'
  13
  14 module ActiveRecord
  15   module ConnectionAdapters # :nodoc:
  16     # ActiveRecord supports multiple database systems. AbstractAdapter and
  17     # related classes form the abstraction layer which makes this possible.
  18     # An AbstractAdapter represents a connection to a database, and provides an
  19     # abstract interface for database-specific functionality such as establishing
  20     # a connection, escaping values, building the right SQL fragments for ':offset'
  21     # and ':limit' options, etc.
  22     #
  23     # All the concrete database adapters follow the interface laid down in this class.
  24     # ActiveRecord::Base.connection returns an AbstractAdapter object, which
  25     # you can use.
  26     #
  27     # Most of the methods in the adapter are useful during migrations. Most
  28     # notably, the instance methods provided by SchemaStatement are very useful.
  29     class AbstractAdapter
  30       include Quoting, DatabaseStatements, SchemaStatements
  31       include QueryCache
  32       include ActiveSupport::Callbacks
  33       define_callbacks :checkout, :checkin
  34
  35       @@row_even = true
  36
  37       def initialize(connection, logger = nil) #:nodoc:
  38         @connection, @logger = connection, logger
  39         @runtime = 0
  40         @last_verification = 0
  41         @query_cache_enabled = false
  42       end
  43
  44       # Returns the human-readable name of the adapter.  Use mixed case - one
  45       # can always use downcase if needed.
  46       def adapter_name
  47         'Abstract'
  48       end
  49
  50       # Does this adapter support migrations?  Backend specific, as the
  51       # abstract adapter always returns +false+.
  52       def supports_migrations?
  53         false
  54       end
  55
  56       # Does this adapter support using DISTINCT within COUNT?  This is +true+
  57       # for all adapters except sqlite.
  58       def supports_count_distinct?
  59         true
  60       end
  61
  62       # Does this adapter support DDL rollbacks in transactions?  That is, would
  63       # CREATE TABLE or ALTER TABLE get rolled back by a transaction?  PostgreSQL,
  64       # SQL Server, and others support this.  MySQL and others do not.
  65       def supports_ddl_transactions?
  66         false
  67       end
  68
  69       # Should primary key values be selected from their corresponding
  70       # sequence before the insert statement?  If true, next_sequence_value
  71       # is called before each insert to set the record's primary key.
  72       # This is false for all adapters but Firebird.
  73       def prefetch_primary_key?(table_name = nil)
  74         false
  75       end
  76
  77       def reset_runtime #:nodoc:
  78         rt, @runtime = @runtime, 0
  79         rt
  80       end
  81
  82       # QUOTING ==================================================
  83
  84       # Override to return the quoted table name. Defaults to column quoting.
  85       def quote_table_name(name)
  86         quote_column_name(name)
  87       end
  88
  89       # REFERENTIAL INTEGRITY ====================================
  90
  91       # Override to turn off referential integrity while executing <tt>&block</tt>.
  92       def disable_referential_integrity(&block)
  93         yield
  94       end
  95
  96       # CONNECTION MANAGEMENT ====================================
  97
  98       # Checks whether the connection to the database is still active. This includes
  99       # checking whether the database is actually capable of responding, i.e. whether
 100       # the connection isn't stale.
 101       def active?
 102         @active != false
 103       end
 104
 105       # Disconnects from the database if already connected, and establishes a
 106       # new connection with the database.
 107       def reconnect!
 108         @active = true
 109       end
 110
 111       # Disconnects from the database if already connected. Otherwise, this
 112       # method does nothing.
 113       def disconnect!
 114         @active = false
 115       end
 116
 117       # Reset the state of this connection, directing the DBMS to clear
 118       # transactions and other connection-related server-side state. Usually a
 119       # database-dependent operation.
 120       #
 121       # The default implementation does nothing; the implementation should be
 122       # overridden by concrete adapters.
 123       def reset!
 124         # this should be overridden by concrete adapters
 125       end
 126
 127       # Returns true if its safe to reload the connection between requests for development mode.
 128       def requires_reloading?
 129         true
 130       end
 131
 132       # Checks whether the connection to the database is still active (i.e. not stale).
 133       # This is done under the hood by calling <tt>active?</tt>. If the connection
 134       # is no longer active, then this method will reconnect to the database.
 135       def verify!(*ignored)
 136         reconnect! unless active?
 137       end
 138
 139       # Provides access to the underlying database driver for this adapter. For
 140       # example, this method returns a Mysql object in case of MysqlAdapter,
 141       # and a PGconn object in case of PostgreSQLAdapter.
 142       #
 143       # This is useful for when you need to call a proprietary method such as
 144       # PostgreSQL's lo_* methods.
 145       def raw_connection
 146         @connection
 147       end
 148
 149       def open_transactions
 150         @open_transactions ||= 0
 151       end
 152
 153       def increment_open_transactions
 154         @open_transactions ||= 0
 155         @open_transactions += 1
 156       end
 157
 158       def decrement_open_transactions
 159         @open_transactions -= 1
 160       end
 161
 162       def log_info(sql, name, seconds)
 163         if @logger && @logger.debug?
 164           name = "#{name.nil? ? "SQL" : name} (#{sprintf("%.1f", seconds * 1000)}ms)"
 165           @logger.debug(format_log_entry(name, sql.squeeze(' ')))
 166         end
 167       end
 168
 169       protected
 170         def log(sql, name)
 171           if block_given?
 172             result = nil
 173             seconds = Benchmark.realtime { result = yield }
 174             @runtime += seconds
 175             log_info(sql, name, seconds)
 176             result
 177           else
 178             log_info(sql, name, 0)
 179             nil
 180           end
 181         rescue Exception => e
 182           # Log message and raise exception.
 183           # Set last_verification to 0, so that connection gets verified
 184           # upon reentering the request loop
 185           @last_verification = 0
 186           message = "#{e.class.name}: #{e.message}: #{sql}"
 187           log_info(message, name, 0)
 188           raise ActiveRecord::StatementInvalid, message
 189         end
 190
 191         def format_log_entry(message, dump = nil)
 192           if ActiveRecord::Base.colorize_logging
 193             if @@row_even
 194               @@row_even = false
 195               message_color, dump_color = "4;36;1", "0;1"
 196             else
 197               @@row_even = true
 198               message_color, dump_color = "4;35;1", "0"
 199             end
 200
 201             log_entry = "  \e[#{message_color}m#{message}\e[0m   "
 202             log_entry << "\e[#{dump_color}m%#{String === dump ? 's' : 'p'}\e[0m" % dump if dump
 203             log_entry
 204           else
 205             "%s  %s" % [message, dump]
 206           end
 207         end
 208     end
 209   end
 210 end