Remove locking related unused code

activerecord/lib/active_record/base.rb

@@ -1702,14 +1702,6 @@ def array_of_strings?(o)
           o.is_a?(Array) && o.all?{|obj| obj.is_a?(String)}
         end
 
-        # The optional scope argument is for the current <tt>:find</tt> scope.
-        # The <tt>:lock</tt> option has precedence over a scoped <tt>:lock</tt>.
-        def add_lock!(sql, options, scope = :auto)
-          scope = scope(:find) if :auto == scope
-          options = options.reverse_merge(:lock => scope[:lock]) if scope
-          connection.add_lock!(sql, options)
-        end
-
         def type_condition(table_alias=nil)
           quoted_table_alias = self.connection.quote_table_name(table_alias || table_name)
           quoted_inheritance_column = connection.quote_column_name(inheritance_column)

activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

@@ -181,18 +181,6 @@ def commit_db_transaction()   end
       # done if the transaction block raises an exception or returns false.
       def rollback_db_transaction() end
 
-      # Appends a locking clause to an SQL statement.
-      # This method *modifies* the +sql+ parameter.
-      #   # SELECT * FROM suppliers FOR UPDATE
-      #   add_lock! 'SELECT * FROM suppliers', :lock => true
-      #   add_lock! 'SELECT * FROM suppliers', :lock => ' FOR UPDATE'
-      def add_lock!(sql, options)
-        case lock = options[:lock]
-          when true;   sql << ' FOR UPDATE'
-          when String; sql << " #{lock}"
-        end
-      end
-
       def default_sequence_name(table, column)
         nil
       end

activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb

@@ -183,12 +183,6 @@ def rollback_db_transaction #:nodoc:
         catch_schema_changes { @connection.rollback }
       end
 
-      # SELECT ... FOR UPDATE is redundant since the table is locked.
-      def add_lock!(sql, options) #:nodoc:
-        sql
-      end
-
-
       # SCHEMA STATEMENTS ========================================
 
       def tables(name = nil) #:nodoc: