Frank Millman wrote:
I have been experimenting with using a socket client instead of Twisted, and I got something up and running quite quickly. When I take a step back and look at how I got it working, I feel that I should be able to apply the same technique to Twisted, but I cannot get it to work. I will show both methods, and perhaps someone can point me in the right direction.
No, of course you can't apply the same technique. A socket client is a blocking, synchronous bit of code. The ENTIRE POINT of Twisted is that all operations are non-blocking, and asynchronous. Basically you're going to find it hard going until that's clear (I know I did). And sadly you're using wx, which is REALLY BAD and does not interact well with Twisted until recent developments (see below).
The trick is that I have two threads running concurrently - a wxPython main loop, and a subthread that monitors the socket. The socket loop looks like this (simplified), subclassed from threading.Thread -
def run(self): readable = [s.fileno()] error = [] self.sendData = [] while 1: if self.sendData: writable = [s.fileno()] else: writable = [] r,w,e = select.select(readable,writable,error,0.01) if r: self.recvData = s.recv(1024) if w: s.send(self.sendData.pop(0))
def checkData(self,item,value): # this is called from the *wx* thread self.recvData = None self.sendData.append(cPickle.dumps((CHECK,item,value))) while self.recvData is None: sleep(0.01) return self.recvData
As you can see, checkData() blocks the wxPython thread until it receives a response from the socket thread.
Fine. Odd, but fine (I'd use a semaphore as opposed to while True: sleep but whatever floats your boat)
This is how I tried with Twisted -
def checkData(self,item,value): # this is called from the *wx* thread self.recvData = None self.callCheckData(item,value) while self.recvData is None: sleep(0.01) return self.recvData
Bzzt! Error. You cannot call twisted functions from a thread. See extensive (and repetitive) posts in the archives about "threadselectreactor AND wx" for about a million posts describing this. Other than that, and the fact you've got no locking around mutable data structures, that code would probably work.
def callCheckData(self,item,value):
self.avatar.callRemote('checkData',item,value).addCallback(self.dataChecked)
def dataChecked(self,answer): self.recvData = answer
It looks as if it should work, but the server method 'perspective_checkData' never gets called.
It should not and does not work for the reason above. I believe "threadselectreactor" is what you want for wx integation. Sadly, I've never used threadselectreactor or wx, so can't be more useful to you. See: http://bob.pythonmac.org/archives/2005/04/17/twisted-and-foreign-event-loops... http://twistedmatrix.com/pipermail/twisted-python/2005-April/thread.html#101...