[Twisted-Python] How to dispatch message to different servers

[Benjamin BERTRAND]

Le 2 mars 2013 à 10:08, Laurens Van Houtven <_ at lvh.cc> a écrit :

> Yes, that looks okay, but that wasn't in your original sample ;-)
> 
> 

Yep, sorry about that.
I was more focused on the ServerFactory and Protocol.
The pcap in a thread comes from the link I mentioned in my first post: http://dound.com/2009/09/integrating-twisted-with-a-pcap-based-python-packet-sniffer/
But I know, it's better to put everything in one post. People shouldn't have to click links.

> I'm on my phone at the moment which isn't great for code review, but it looks like you only fire one deferred per line?
> 
> 

There is a specific deferred by line.
I re-arm it in the messageToSend method (that wasn't in the sample either).
In the Oldimon class, I have:

    def messageToSend(self, message):
        self.sendMessage(message)
        # Re-arm the deferred
        self.factory.deferred[self.line] = defer.Deferred()
        self.factory.deferred[self.line].addCallback(self.messageToSend)


> On Mar 2, 2013 9:50 AM, "Benjamin BERTRAND" <beenje at gmail.com> wrote:
> 
> Le 2 mars 2013 à 04:34, exarkun at twistedmatrix.com a écrit :
> 
> > On 1 Mar, 09:52 pm, beenje at gmail.com wrote:
> >> Thanks for the answer!
> >>
> >> I was hoping to avoid having to put something like AMP in place,
> >> because it looked a bit overkill for my case.
> >> I think I actually found a way :-)
> >
> > Unfortunately, it looks like the code that you shared will only work
> > accidentally (if at all).  You cannot use Twisted APIs except in the
> > reactor thread.  You will at least need to add in some code to send data
> > back to the reactor thread before you use Twisted APIs (such as
> > `Deferred.callback`).
> 
> 
> In run_pcap, I call reactor.callFromThread(callback, x25_data, line_id). See below.
> That seems to work with the tests I did.
> Am I missing something?
> 
> /Benjamin
> 
> def run_pcap(device, pcap_filter, callback):
> 
>     def analyse_packet(hdr, data):
>         # check the data
>         reactor.callFromThread(callback, x25_data, line_id)
> 
>     p = pcapy.open_live(device, 65535, 1, 100)
>     p.setfilter(pcap_filter)
>     p.loop(-1, analyse_packet)
> 
> 
> class Oldimon(Protocol):
> 
>     def __init__(self, factory):
>         self.factory = factory
>         self.line = None
> 
>     def connectionMade(self):
>         # Check the server port to get the line
>         # associated to this protocol
>         port = self.transport.getHost().port
>         self.line = LINES_PORT[port]
>         # Add the callback for this line
>         self.factory.deferred[self.line] = defer.Deferred()
>         self.factory.deferred[self.line].addCallback(self.messageToSend)
> 
> 
> class OldimonFactory(ServerFactory):
> 
>     def __init__(self, device, pcap_filter):
>         # pcapDataReceived callback is called everytime a message
>         # is received
>         reactor.callInThread(run_pcap, device, pcap_filter, self.pcapDataReceived)
>         # Dict with a deferred for each line
>         self.deferred = dict(zip(LINES_PORT.values(), [None] * len(LINES_PORT)))
> 
>     def buildProtocol(self, addr):
>         return Oldimon(self)
> 
>     def pcapDataReceived(self, data, line):
>         if self.deferred[line] is not None:
>             # Fire the callback for line
>             d, self.deferred[line] = self.deferred[line], None
>             d.callback(data)
> 
> oldimon_factory = OldimonFactory(device, pcap_filter)
> for port in LINES_PORT.keys():
>     reactor.listenTCP(port, oldimon_factory)
> reactor.run()
> 
> 
> >
> > Jean-Paul
> >
> > _______________________________________________
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> > Twisted-Python at twistedmatrix.com
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> 
> 
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