From: Jason Wold <jason.wold@...>
Date: 2004-04-25T04:38:25+09:00
Subject: Re: Playing with sockets...

> 
> Very cool, Jason, thanks.
> 

You might find this interesting too.  That was actually part of my
attempt to generalize IO for taking commands from multiple sources. 
It is still not generalized enough (if FIFO checks) but work is still
in process.  This code starts a thread listening on three different
sources.  It currently only works on *nix but I hope to generalize the
FIFO listener to also work on windows:

    # start servers to listen for commands on FIFO, TCP PORT, and STDIO
    # FIXME make listen OS independant, use windows named pipe on windows
    def listen(*listeners)

      # if no arguments then  listen on STDIN
      listeners = ["STDIO"] if listeners.size == 0

      #capitalize list of listeners
      listeners.map!{ |l| l.upcase }

      mutex = Mutex.new

      #restart all threads if we aren't running the threads we think we are
      #FIXME
      #restart(@threads.keys) if @threads.values.sort != (Thread.list
- [Thread.main]).sort

      # TODO turn mkfifo into OS independant method that returns
correct IO object
      `mkfifo "#{FIFO_CONTROL}"` unless test(?p, FIFO_CONTROL)

      # set an IO object for each listener to be called later
      io = {}
      io["FIFO"] = Proc.new {
                     File.open(FIFO_CONTROL, File::NONBLOCK | File::RDONLY ) }
      io["STDIO"] = Proc.new { IO.new(1) }
      io["TCP"] = Proc.new{ TCPServer.new('localhost', PORT).accept }

      writeable=%w(STDIO TCP)

      # thread to aggregate cmd_buffer and process it
      #
      Thread.new do
        puts "Started Command Buffer processing thread" if $DEBUG
        cmd=""
        # run until we get a quit command
        #
        while ! cmd.match(/^(quit|q)$/i)
          # join buffers and zero them out
          mutex.synchronize do
            VALID_LISTENERS.each do |vl|
              @cmd_buffer["MAIN"] += @cmd_buffer[vl]
              @cmd_buffer[vl] = []
            end
          end

          # step through aggregate buffer, clean it, and run it
          while @cmd_buffer["MAIN"].size > 0
            puts "CMD BUFFER: " + @cmd_buffer["MAIN"].join(":")  if $DEBUG
            mutex.synchronize do
              cmd=@cmd_buffer["MAIN"].shift
            end
            # next if string is characters or numbers
            #FIXME (how do you internationalize untainting?)
            next if cmd.match(/[^A-Za-z0-9 ]/)
            cmd.untaint
            run_cmd(cmd)
          end
          sleep 1
        end
      end


      listeners.sort.each do |listener|
        # next unless we have a handler for this type
        next unless VALID_LISTENERS.include?(listener)
        # do we already have a thread listening?
        unless @threads[listener].respond_to?("alive") &&
               @threads[listener].alive?
          @threads[listener] = Thread.new do
            cmd = ""
            puts "Started #{listener} thread" if $DEBUG
            # call the proc object that creates the io object
            f = io[listener].call
            while ! cmd.match(/^quit|q/i)
              # Have to poll FIFO's and will get eof if nothing there
              (sleep(1);next) if listener == "FIFO" and f.eof
              # FIFO's are read only in server thread
              (f.print "HA>";f.flush) if writeable.include?(listener)
              cmd = f.readline.chomp
              next if cmd.empty?
              puts "Got command #{cmd} from #{listener}" if $DEBUG
              (f.close; next) if cmd.match(/^(quit|q)$/i)
              mutex.synchronize { @cmd_buffer[listener] << cmd }
            end
          end
        end
      end

      # prompt user or give focus to STDIO thread if it exists
      #
      if @threads["STDIO"].nil?
        puts "Listening on " + listeners.join(" and ")
        puts "Enter quit to exit."
        until gets.match(/^(quit|q)$/)
        end
      else
        @threads["STDIO"].join
      end
    end



> 
> Cheers,
> Hal
> 
>