Implementation of wait_for_notify with PG and Celluloid::IO

wait_for_notify.rb

def wait_for_notify(&block)
  io = pg_connection.socket_io

  while @listening do
    Celluloid::IO.wait_readable(io) # blocks execution, but unblocks this actor
    pg_connection.consume_input # fetch any input on this connection

    # read the NOTIFY messages off the socket
    while notification = pg_connection.notifies do
      block.call(
        notification[:relname], # channel
        notification[:be_pid], # pid
        notification[:extra] # payload
      )
    end
  end
end