Re: [9fans] Design of webfs and webcookies

[erik quanstrom <quanstro@quanstro.net>]

On Mon Jan 25 15:15:42 EST 2010, eekee57@fastmail.fm wrote:
>
> On 13 Jan 2010, at 4:23 pm, Enrico Weigelt wrote:
>
> > * erik quanstrom <quanstro@quanstro.net> wrote:
> >
> >> i think you misunderstand the problem.  cookiefs' fs interface
> >> is not the issue.  cookiefs' robustness when storing the cookies
> >> on the fileserver in the face of multiple concurrently running
> >> cookiefs' is.
> >
> > ah, you're talking about the situation when multiple cookiefs
> > instances running on the same storage ? hmm, that's the classical
> > multi-access problem ;-O
> >
> > but how do you get into that situation in the first place ?
> > (more to the point: who starts these multiple instances ?)
>
> Wouldn't multiple instances of cookiefs neatly provide transaction
> isolation?

i don't see how you could get acid semantics without locking
the cookie file for the duration of each http exchange.  this is because
one can't predict the returned cookies or abort the request and try
again.  sending the same http request twice might end up charging
your credit card twice.

i'm not sure this level of inconsistency matters.

- erik