From: Hugh Sasse <hgs@...>
Date: 2005-11-17T00:42:30+09:00
Subject: Re: DRb Crashing

On Thu, 17 Nov 2005, James Edward Gray II wrote:

> On Nov 15, 2005, at 6:50 PM, Hugh Sasse wrote:
> 
> > On Wed, 16 Nov 2005, James Edward Gray II wrote:
> > 
> > 
> > > If I launch this server:
> > > 
> >        [...]
> > 
> > > __END__
> > > 
> > > Then run this client:
> > > 
> > > #!/usr/local/bin/ruby -w
> > > 
> > > require "drb"
> > > require "rinda/tuplespace"
> > > 
> > > DRb.start_service
> > > tuplespace = Rinda::TupleSpaceProxy.new(
> > > DRbObject.new_with_uri("druby://localhost:61676")
> > > )
> > > 
> > > while problem = tuplespace.take(["Problem", %r{^\d+(?: [-+*/] \d+)+$}])
> > > tuplespace.write(["Result", "#{problem.last} = #{eval problem.last}"])
> > > end
> > > 
> > > __END__
> > > 
> > > The client crashes, generally within a few seconds.  Adding a sleep inside
> > > the
> > > server loop seems to resolve the issue.
> > > 
> > > Anyone know why?
> > > 
> > 
> > No, I don't. What happens if you match the old way? Like:
> >  while problem = tuplespace.take(["Problem", nil])
> 
> The Regexp is pretty critical in this case.  It validates the data before an
> otherwise dangerous call to eval().

  while problem = tuplespace.take(["Problem", nil])
    unless problem.last =~ %r{^\d+(?: [-+*/] \d+)+$}
      puts "Bogus input \'#{problem.last}\', Ted!" #:-)
    else
      tuplespace.write(["Result", "#{problem.last} = #{eval problem.last}"])
    end
  end
> 
> James Edward Gray II
> 
        Hugh