Class: NeverBlock::DB::FiberedPostgresConnection

Inherits:
PGconn
  • Object
show all
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 Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ FiberedPostgresConnection

Creates a new postgresql connection, sets it to nonblocking and wraps the descriptor in an IO object.



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 21

def initialize(*args)
  super(*args)
  @fd = socket
  @io = IO.new(socket)
  setnonblocking(true)	
end

Instance Attribute Details

#fd ⇒ Object (readonly)

needed to access the sockect by the event loop



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 16

def fd
  @fd
end

#io ⇒ Object (readonly)

needed to access the sockect by the event loop



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 16

def io
  @io
end

Instance Method Details

#exec(sql) ⇒ Object

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 32

def exec(sql)
  if Fiber.respond_to? :current and Fiber.current[:neverblock]		      
    self.send_query sql
    @fiber = Fiber.current		      
    Fiber.yield 
  else		      
    super(sql)
  end		
end

#process_command ⇒ Object

The callback, this is called whenever there is data available at the socket



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 65

def process_command
  # make sure all commands are sent
  # before attempting to read
  return unless self.flush
  self.consume_input
  unless is_busy		
    res, data = 0, []
    while res != nil
      res = self.get_result
      data << res unless res.nil?
    end
    #let the fiber continue its work		      
    @fiber.resume(data.last)
  end
end

#register_with_event_loop(loop) ⇒ Object

Attaches the connection socket to an event loop. Currently only supports EM, but Rev support will be completed soon.



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# File 'lib/never_block/db/fibered_postgres_connection.rb', line 45

def register_with_event_loop(loop)
  if loop == :em
    unless EM.respond_to?(:attach)
      puts "invalide EM version, please download the modified gem from: (TBA) "
      exit
    end
    if EM.reactor_running?
      EM::attach(@io,EMConnectionHandler,self)
    else
      raise "REACTOR NOT RUNNING YA ZALAMA"
    end 
  elsif loop.class.name == "REV::Loop"
    loop.attach(RevConnectionHandler.new(socket))
  else
    raise "could not register with the event loop"
  end
end