Class: NeverBlock::DB::FiberedPostgresConnection

Inherits:
PGconn
  • Object
show all
Includes:
FiberedDBConnection
Defined in:
lib/never_block/db/fibered_postgres_connection.rb

Overview

A modified postgres connection driver builds on the original pg driver. This driver is able to register the socket at a certain backend (EM or Rev) and then whenever the query is executed within the scope of a friendly fiber it will be done in async mode and the fiber will yield

Instance Method Summary collapse

Methods included from FiberedDBConnection

#event_loop_connection_close, #register_with_event_loop, #remove_unregister_from_event_loop_callbacks, #resume_command, #unregister_from_event_loop

Instance Method Details

#exec(sql) ⇒ Object Also known as: query

Assuming the use of NeverBlock fiber extensions and that the exec is run in the context of a fiber. One that have the value :neverblock set to true. All neverblock IO classes check this value, setting it to false will force the execution in a blocking way.



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 23

def exec(sql)
  # TODO Still not "killing the query process"-proof
  # In some cases, the query is simply sent but the fiber never yields
  if NB.event_loop_available? && NB.neverblocking?
    begin
      send_query sql
      @fiber = Fiber.current
      Fiber.yield register_with_event_loop
      while is_busy
        consume_input
        Fiber.yield if is_busy
      end
      res, data = 0, []
      while res != nil
        res = self.get_result
        data << res unless res.nil?
      end
      data.last
    rescue Exception => e
      if error = ['not connected', 'gone away', 'Lost connection','no connection'].detect{|msg| e.message.include? msg}
        #event_loop_connection_close
        unregister_from_event_loop
        reset
      end
      raise e
    ensure
      unregister_from_event_loop
    end
  else
    super(sql)
  end
end