import weakref
from twisted.internet import reactor
from twisted.internet.endpoints import TCP4ServerEndpoint
from twisted.python.sendmsg import getsockfam
from twisted.internet.protocol import Factory, Protocol
import twisted.internet.abstract

class EchoProtocol(Protocol):
    def dataReceived(self, data):
        self.transport.write(data)

class EchoFactory(Factory):
    protocol = EchoProtocol

class TransferProtocol(Protocol):
    def dataReceived(self, data):
        self.transport.write('main process still listening!: %s' % (data))

    def connectionMade(self):
        self.transport.write('this message should make it to the subprocess\n')

        # attempt 1: do nothing
        #    everything works fine in the adopt (including receiving the written message), but old protocol still exists (though isn't doing anything)

        # attempt 1: try calling loseConnection
        #    we lose connection before the adopt opens the socket (presumably TCP disconnect message was sent)
        #
        # self.transport.loseConnection()

        # attempt 2: try calling abortConnection
        #    result is same as loseConnection
        #
        # self.transport.abortConnection()

        # attempt 3: try monkey patching the socket close out and calling loseConnection
        #    result: same as doing nothing-- adopt works (including receiving the written message), old protocol still exists
        #
        # def ignored(*args, **kwargs):
        #       print 'ignored :D'
        #
        # self.transport._closeSocket = ignored
        # self.transport.loseConnection()

        reactor.callLater(0, adopt, self.transport.fileno())

class ServerFactory(Factory):
    def buildProtocol(self, addr):
        p = TransferProtocol()
        self.ref = weakref.ref(p)
        return p

f = ServerFactory()

def adopt(fileno):
    print "does old protocol still exist?: %r" % (f.ref())
    reactor.adoptStreamConnection(fileno, getsockfam(fileno), EchoFactory())

port = 1337
endpoint = TCP4ServerEndpoint(reactor, port)
d = endpoint.listen(f)
reactor.run()