Jean-Paul Calderone wrote:
On Tue, 13 Jan 2009 16:34:29 +0100, Gabriel Rossetti
<gabriel.rosse...@arimaz.com> wrote:
Hello everyone,
I implemented a push-produce a while back and I though it works, but
it didn't. When the msgs where spaced out, it worked, but if several
msgs were sent one after the other, then things go bad (the msgs get
mixed up)...
I found this thread :
http://www.twistedmatrix.com/pipermail/twisted-python
/2007-March/014983.html
and I think I ave the same problem, my code looks a bit like his :
def pauseProducing(self):
"""
Pause the producer
"""
self.__paused = True
def resumeProducing(self):
"""
Resume the producer
"""
self.__paused = False
while(not self.__paused and self.__startLimit < self.__total):
data = self.__buf[self.__startLimit:self.__endLimit]
self.transport.write(data)
self.__startLimit = self.__endLimit
self.__endLimit += self.__burstSize
if(not self.__stream):
break
if(not self.__paused or self.__startLimit >= self.__total):
self.stopProducing()
def stopProducing(self):
"""
Stop the producer
"""
self.__paused = False
self.__startLimit = 0
self.__buf = None
self.__total = None
self.__endLimit = self.__burstSize
and when I send a msg I use this :
def sendMessage(self, msg):
if domish.IElement.providedBy(msg):
msg = msg.toXml()
if isinstance(msg, unicode):
msg = msg.encode('utf-8')
self.__buf = msg
self.__total = len(msg)
if(self.__stream):
self.resumeProducing()
I think what happens is that the code is re-entered, just like
Jean-Paul suggested in the other thread. The thing is I didn't
understand the solution, could somebody please explain it to me or
suggest something else?
It's extremely difficult to say without seeing a complete example and
without
knowing exactly how the code is failing. However, one thing I do see
is that
it is not safe to call your `sendMessage` a second time before all of the
data from the first call has been written. Since you are using
`__buf´ to
record the message to send, if you try to send another message, the first
buffer will be clobbered. Could this be the problem you're having?
Perhaps consider appending to `__buf´ instead of overwriting it.
There are
probably lots of other areas where this code could improve too, but not
corrupting the internal state of the producer is a good start. :)
Jean-Paul
Thanks for your answer Jean-Paul, yes, not currupting the internal state
of my producer is a good start :-). I re-wrote it like this and it seems
to work correctly now :
def pauseProducing(self):
"""
Pause the producer
"""
self.__paused = True
def resumeProducing(self):
"""
Resume the producer
"""
self.__paused = False
while(not self.__paused and self.__buf):
self.transport.write(self.__buf[:self.__burstSize])
self.__buf = self.__buf[self.__burstSize:]
if(not self.__stream):
break
if(not self.__paused or not self.__buf):
self.stopProducing()
def stopProducing(self):
"""
Stop the producer
"""
self.__paused = False
def sendMessage(self, msg):
if domish.IElement.providedBy(msg):
msg = msg.toXml()
if isinstance(msg, unicode):
msg = msg.encode('utf-8')
self.__buf += msg
if(self.__stream and not self.__paused):
self.resumeProducing()
Thanks again for pointing that out :-),
Gabriel
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