network programming without goto

[Josiah Carlson]

kent sin <kentsin at yahoo.com> wrote:
> 
> But that will make too many uncessary connection:
> 
>    one connection can do a number of search before it
> got timeout, so I want to do as many search as
> possible before it got timeout. I think the connection
> cost is high here, and it also got some load on the
> remote servers which I do not want.
> 
> Thanks for the suggestion.

Indeed it will do many connections, but you weren't terribly specific
with what you wanted.

In any case, if you want a total of 3 failures under any situation, try
the following.

queries = [buildquery(t) for t in targets]

tries = 3
for host in hostlist:
    q = iter(queries)
    try:
        cq = q.next()
    except StopIteration:
        continue
    for i in xrange(tries):
        conn = zoom.Connecton(host.ip, host.port)
        fail = 0
        while 1:
            try:
                r = conn.query(cq)
                #deal with r
                cq = q.next()
            except StopIteration:
                break
            except:
                fail = 1
                break
        if not fail:
            break
    try:
        conn.close()
    except:
        pass


 - Josiah


> 
> --- Josiah Carlson <jcarlson at uci.edu> wrote:
> 
> > 
> > kent sin <kentsin at yahoo.com> wrote:
> > > 
> > > Please help:
> > > 
> > > I was really blocked here. without goto I really
> > do
> > > not known how to do it.
> > > 
> > > The problem is to use PyZ3950 to consult a lists
> > of
> > > hosts and for each of them to search for a list of
> > > targets. Since the network is undetermined, there
> > were
> > > always some exceptions: I would like to allow it
> > to
> > > retry for 3 times. Moreover, during the query
> > process,
> > > the conn will timeout (set by the remote server).
> > > Reconnect is preferred before fail the current
> > search,
> > > but the reconnect may fail even if the first try
> > is
> > > succeed.
> > 
> > The trick with getting it to do what you want it to
> > do is to understand
> > what you want it to do.
> > 
> > Being that I can't understand what you want it to
> > do, the following is
> > just an interpretation of what I think you want it
> > to do.  If you want
> > it to do something different, then be clearer with
> > what you want it to
> > do and ask again.  Note that depending on the
> > semantics of your
> > connection, this could probably be made more
> > efficient.
> > 
> > 
> > queries = [buildquery(t) for t in targets]
> > 
> > for host in hostlist:
> >     tries_remaining = 3 #tunable parameter
> >     for q in queries:
> >         for i in xrange(tries_remaining+1):
> >             if i == tries_remaining:
> >                 break
> >             try:
> >                 conn = zoom.Connecton(host.ip,
> > host.port)
> >                 r = conn.search(q)
> >                 conn.close()
> >                 break
> >             except:
> >                 continue
> >             
> >             #handle result r
> >             break
> >             
> >         tries_remaining -= i
> >         
> >         if tries_remaining == 0:
> >             break
> > 
> >  - Josiah
> > 
> >