From: Robert Klemme <bob.news@...>
Date: 2005-02-05T07:00:25+09:00
Subject: Re: robust socket reconnect?


"Martin Pirker" <crf@sbox.tu-graz.ac.at> schrieb im Newsbeitrag 
news:4203e766$0$8024$3b214f66@aconews.univie.ac.at...
> Imagine 2 servers, exchanging data every minute, so a good idea is
> to just leave a connection open.
> But sometimes the net goes strange ways, connection is lost and one
> has to reconnect.
>
> That would be done like...
>
>
> t = Thread.new(....) do |...|
>  begin
>    socket = TCPSocket::open(someip,someport)
>    loop do
>      ...
>      whatever
>      ...
>      break if done
>    end
>  rescue *ErrorsOnSocket => err        # socket errors, see 
> ruby-talk:127627
>    socket.close                       # cleanup
>    sleep 60                           # 1 min recovery
>    retry                              # reconnect
>  rescue Exception => ex               # general bug
>    puts "BUG in xyz!"
>    puts "#{ex.class}:  #{ex.message}\n\t#{ex.backtrace[0]}"
>    raise
>  ensure
>    socket.close
>  end
> end
>
>
> - Is the cleanup by just doing a socket.close the correct way? Are really
> all Ruby internal data structures cleaned up afterwards and we don't
> silently leak file descriptors and/or bet on the gc to clean up (soon)?
>
> - Anybody else had the same problem - any (more sophisticated) code to
> showcase? :-)

I'd structure the code a bit differently:

t = Thread.new(....) do |...|
  begin
    TCPSocket::open(someip,someport) do |socket|
      loop do
        ...
        whatever
        ...
        break if done
      end
    end
  rescue *ErrorsOnSocket => err        # socket errors, see ruby-talk:127627
# no close because that is done by the block already
    sleep 60                           # 1 min recovery
    retry                              # reconnect
# I'd put this general code at a much higher level as
# you rethrow anyway:
  rescue Exception => ex               # general bug
    puts "BUG in xyz!"
    puts "#{ex.class}:  #{ex.message}\n\t#{ex.backtrace[0]}"
    raise
  end
end

Now the code is significantly shorter and cleaner (when you remove my 
comments and the other code :-))

Kind regards

    robert