Twisted MX

gistfile1.py

from operator import attrgetter, itemgetter
from itertools import groupby, chain
from random import shuffle

from twisted.names.client import Resolver
from twisted.internet import defer
from twisted.python import log

def init(config):
    R.resolver = Resolver(resolv='/etc/resolv.conf')

@defer.inlineCallbacks
def resolve(esp):
    answers = yield R.resolver.lookupMailExchange(esp)

    groups = []
    for preference, grouped in groupby(answers[0], attrgetter('payload.preference')):
        group = [str(r.payload.name) for r in grouped]
        shuffle(group)
        groups.append((preference, group))

    groups = sorted(groups, key=itemgetter(0))
    log.msg("Sorted records %s" %(groups,))    
    groups = [group for preference, group in groups]

    defer.returnValue(list(chain(*groups)))

class R(object):
    resolver = None