From: Nwallins <rick.hull@...>
Date: 2007-07-13T02:55:04+09:00
Subject: Re: DRb object mutation issues

On Jul 12, 1:50 pm, Nwallins <rick.h...@gmail.com> wrote:
> On Jul 12, 1:46 pm, Nwallins <rick.h...@gmail.com> wrote:
>
>
>
> > On Jul 11, 3:02 pm, Joel VanderWerf <v...@path.berkeley.edu> wrote:
>
> > > Nwallins wrote:
> > > > # file 1
> > > > require 'drb/drb'
> > > > require 'thread'
> > > > DRb.start_service("druby://:1234", Hash.new.extend(DRbUndumped))
> > > > DRb.thread.join
> > > > # EOF
>
> > > > # file 2
> > > > require 'drb/drb'
> > > > d = DRbObject.new_with_uri("druby://:1234")
> > > > d[0] = 'zero'
> > > > d[0] #=> "zero"
> > > > d[0].slice!(0, 1)
> > > > d[0] #=> "zero"
>
> > > > # file 3
> > > > h = Hash.new
> > > > h[0] = 'zero'
> > > > h[0].slice!(0, 1)
> > > > h[0] #=> "ero"
>
> > > > # how can I change the state of the distributed hash's values?
>
> > > Some options:
>
> > > 1. make the values DRbUndumped, too.
>
> > > 2. use non-destructive methods on the values:
>
> > >    d[0] = d[0].slice(0, 1)
>
> > > 3. define a method on your front object that handles everything at
> > > server side, so the client says this:
>
> > >    idx = 0
> > >    d.slice_at_index(idx,0,1)
>
> > > --
> > >        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407
>
> > Joel,
>
> > thanks for the response.
>
> > (1) is not viable, as you cannot make objects or classes undumpable
> > from the client
> > (2) does not address the issue -- to mutate the value
> > (3) is interesting, but violates the architecture that my simplified
> > example is distilled from
>
> > I'm still wondering if the demonstrated behavior is a bug or a
> > feature.  I'm leaning towards the former ;)
>
> > - Rick
>
> Regarding my comment for (1), I presume you mean something like this:
>
> # file 2
> require 'drb/drb'
> d = DRbObject.new_with_uri("druby://:1234")
> d[0] = 'zero'.extend(DRbUndumped)
>
> # DRb::DRbConnError: DRb::DRbServerNotFound
> #        from /usr/lib/ruby/1.8/drb/drb.rb:1650:in `current_server'
>
> - Rick

There is also this approach, but it still fails:

>> d[0].extend(DRbUndumped)
=> "zero"
>> d[0].slice!(0,1)
=> "z"
>> d[0]
=> "zero"

- Rick