Example nonblocking read from a Named Pipe (created elsewhere)

nonblock-named-pipe-read-example-pseudo.rb

class Engine

    def initialize
      #...
      # elsewhere a named pipe has been created in filesys using:
      # system("mkfifo #{fpath}") unless File.exists? fpath
        
      # call named_pipe method which wraps IO.open( fpath, flag )
      @pipe_from_ui = named_pipe( Pipes[:engine_in], "r" )
      msg_ui = @pipe_from_ui.gets # blocks until ui writes in there:w
      #...
    end

    def main_loop
      # ...
      while _exec_state_int == 1
        if _tns <= Time.now.to_i
          p "***** #{__FILE__}: - #{Time.now} thread: #{Thread.current.to_s} - L/MIN: #{_loops}"
          _tns = Time.now.to_i + 60
          _loops = 0 
        end 

        # dummy_work(10) # delay in milliseconds

        # handle messages
        msg_ui = nil

        rwe = IO.select([@pipe_from_ui], [], [], 0)
        msg_ui = rwe[0][0].read(2) unless rwe == nil

        if msg_ui != nil
          msg_ui = msg_ui.strip
          p " ***** Engine got ui message: #{msg_ui}"
	      # do message related stuff
        end

        _loops+=1
      end
    end
    # other stuff...
end