From: Zundra Daniel <zundra.daniel@...>
Date: 2010-05-30T02:39:03+09:00
Subject: Non blocking IO during an AJAX request

--0016361e7b446a9a3f0487bf19d3
Content-Type: text/plain; charset=ISO-8859-1

I realize this is a Ruby mailing list but I have a Ruby/Rails question that
seems to fall more on the Ruby side of the fence.  I have a library file
that creates a named pipe and writes the results of ping to the pipe.  This
method is called via a get AJAX request to kick off the process.

  def self.run(address)
    Fifo.open(PINGFIFO)

    Thread.new  {
      IO.popen "ping -c 10 localhost" do |f|
        until f.eof?
          Fifo.write(f.gets, PINGFIFO)
        end
      end
    }
    end


Then in a 2nd AJAX request I simply attempt to read the named pipe and
return the string to the browser:

  def results
    if File.exists?(PINGFIFO) && File.pipe?(PINGFIFO)
      File.open(PINGFIFO, "r") do |f|
        render :text => f.readlines
      end
    end
  end


The problem is the 2nd AJAX request simply hangs indefinitely.  If I tail
the pipe I can see data being written to it.  Does anyone have any insight
into why this is happening?  It seemed like a simple enough problem but this
one is throwing me for a loop (har!).

--0016361e7b446a9a3f0487bf19d3--