    # File lib/sqlite3/driver/dl/driver.rb, line 113
        def busy_handler( db, data=nil, &block )
          @busy_handler = block

          unless @busy_handler_callback
            @busy_handler_callback = ::DL.callback( "IPI" ) do |cookie, timeout|
              @busy_handler.call( cookie, timeout ) || 0
            end
          end

          API.sqlite3_busy_handler( db, block&&@busy_handler_callback, data )
        end