Thanks again for this. It's really useful. It turns out that the
delimiter is a plain old \n. Who knows how consistent this will be
between different policy daemons, I don't know!
I've modified it to manage a DeferredQueue which hopefully means I can
just keep throwing requests at it without every being bounced away. A
stripped down example (with even less error checking!) of what I've
managed to work your example in to is here:
class PostfixPolicyClient(LineReceiver):
delimiter = '\n'
def __init__(self):
self.resultQueue = DeferredQueue()
def lineReceived(self, line):
if '=' in line:
self.resultQueue.put(True if line.split('=')[1] == 'OK' else
False)
def sendPostfixPolicyClientRequest(self, request_dict):
for k, v in request_dict.items():
self.sendLine('{}={}'.format(k, v))
self.sendLine('')
return self.resultQueue.get()
Now, this isn't a working example, it's just the minimum that will
demonstrate my idea. I just wonder if what I've done with the
DeferredQueue is sane. If I return the .get() entry from the
DeferredQueue when doing the request, and then do a put() in
lineReceived, am I guaranteeing that I will get my results in the
correct order?
Thanks again for all your help!
Many thanks. Tom.
On 19/11/15 07:53, exvito here wrote:
>
> On Wed, Nov 18, 2015 at 9:28 AM, Tom Boland <t...@t0mb.net
> <mailto:t...@t0mb.net>> wrote:
>
> I think what you've provided me with is useful for me, but I think
> it's backwards for my purposes, as I need to be connecting to the
> policy daemon rather than being the policy daemon!
>
> I wanted to do this with deferred calls in case one of the policy
> daemons becomes unreachable and blocks my application. Do you
> think I should do something differently in that regard? My SQL
> lookups are done synchronously. If the database server goes away,
> I've got bigger problems anyway!
>
>
> So maybe something like this is more likely to be useful:
>
> #!/usr/bin/env python
>
> from __future__ import print_function
>
> from twisted.internet import reactor, protocol, endpoints, defer
> from twisted.protocols import basic
>
>
> class PostfixProtocol(basic.LineReceiver):
>
> # Assuming Postfix uses '\r\n' line breaks (does it?)
> delimiter = '\r\n'
>
> def __init__(self):
> self.action = None
> self.action_deferred = None
>
> def lineReceived(self, line):
> if '=' in line:
> self.action = line.split('=')[1]
> elif line == '':
> self.action_deferred.callback(self.action)
> self.action_deferred = None
> else:
> # oops, bad input
> pass
>
> def sendPostfixRequest(self, request_dict):
> if not self.action_deferred is None:
> raise Exception('transaction pending')
> for k, v in request_dict.items():
> self.sendLine('{}={}'.format(k,v))
> # Empty line signals we're done
> self.sendLine('')
> self.action_deferred = defer.Deferred()
> return self.action_deferred
>
> @defer.inlineCallbacks
> def checkPostfixPolicy(request_dict):
> ep = endpoints.clientFromString(reactor,
> 'tcp:host=127.0.0.1:port=10000')
> p = yield endpoints.connectProtocol(ep, PostfixProtocol())
> action = yield p.sendPostfixRequest(request_dict)
> print('got: {}'.format(action))
> reactor.stop()
>
>
> if __name__ == '__main__':
>
> request_dict = {
> 'recipient': 'em...@ddr.ess',
> 'sender': 'em...@ddr.ess',
> }
> reactor.callWhenRunning(checkPostfixPolicy, request_dict)
> reactor.run()
>
> Highlights:
> - This is not the same protocol as before, in particular it uses a
> different delimiter.
> - It assumes the response is also terminated with an empty line (does
> it?).
> - It more than one outstanding response: a different exception should
> be used.
> - The input processing is very rudimentary and failure-prone.
> - checkPostfixPolicy could, of course, return instead of printing. :)
>
> Cheers,
> --
> exvito
>
>
> _______________________________________________
> Twisted-Python mailing list
> Twisted-Python@twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
_______________________________________________
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
