From: ts <decoux@...>
Date: 2003-12-13T03:17:35+09:00
Subject: Re: Bug with fifos in Linux?

>>>>> "D" == Derek Lewis <lewisd@f00f.net> writes:

D> Should that be File::NONBLOCK and File::RDONLY?  I just changed my code to

 IO:: is just fine

D> use those, but it's still behaving strangly.

D> Some more sample code based on the previous:

D> FIFO_FILE='/tmp/rubyfifo'
D> `mkfifo "#{FIFO_FILE}"` unless test(?e, FIFO_FILE)

add this

   Thread.abort_on_exception = true

 and you'll see the error

D> thread = Thread.new {
D>    puts "Opening fifo for writing"
D>    File.open(FIFO_FILE, File::NONBLOCK | File::WRONLY) { |file|
D>       puts "Starting write loop"
D>       while true
D>          puts "Thread is running"
D>          sleep 1
D>          file.puts "Thread is running"
D>       end
D>    }
D> }



svg% cat b.rb
#!/usr/bin/ruby
FIFO_FILE='/tmp/rubyfifo'
`mkfifo "#{FIFO_FILE}"` unless test(?e, FIFO_FILE)

Thread.abort_on_exception = true
thread = Thread.new {
   begin
      puts "Opening fifo for writing"
      File.open(FIFO_FILE, IO::NONBLOCK | IO::WRONLY) { |file|
         puts "Starting write loop"
         while true
            puts "Thread is running"
            sleep 1
            file.puts "Thread is running"
            file.flush
         end
      }
   rescue
      p $!
      sleep 1
      retry
   end
}

puts "Opening fifo for reading"
File.open(FIFO_FILE, IO::NONBLOCK | IO::RDONLY) { |file|
   puts "Reading from fifo"
   sleep 2
   while !file.eof
      line = file.gets("\n")
      puts "Read from fifo: #{line}"
   end
   puts "exited read loop"
}
svg% 

svg% b.rb
Opening fifo for writing
#<Errno::ENXIO: No such device or address - /tmp/rubyfifo>
Opening fifo for reading
Reading from fifo
Opening fifo for writing
Starting write loop
Thread is running
Thread is running
Read from fifo: Thread is running
Thread is running
Read from fifo: Thread is running
Thread is running
Read from fifo: Thread is running
Thread is running
Read from fifo: Thread is running
^Z
[4]+  Stopped                 b.rb
svg% 




Guy Decoux