[Twisted-Python] Fwd: [Twisted-commits] r11032 - Made LineReceiver about 3x as fast, and clarified some of the docstrings.

Jp Calderone exarkun at divmod.com
Sun Jun 19 20:57:19 EDT 2005

On Sun, 19 Jun 2005 19:51:35 -0400, James Y Knight <foom at fuhm.net> wrote:
>On Jun 18, 2005, at 2:58 PM, Jp Calderone wrote:
>>This changes dataReceived to call down into user code while the 
>>LineReceiver's instance attributes are in an inconsistent state.   This can 
>>lead to duplicate data delivery if dataReceived is called  into from 
>>lineReceived.  Normally this sounds like a ridiculous  thing to do, but 
>>notice the implementation of resumeProducing():
>>     def resumeProducing(self):
>>         self.paused = False
>>         self.dataReceived('')
>>         self.transport.resumeProducing()
>>Since resumeProducing is called immediately when a producer is  registered, 
>>this means LineReceivers can no longer register  themselves as producers 
>>for their transports from lineReceived,  which is a much more reasonable 
>>thing to do.
>>Demonstration of the bug in action attached.
>Two things about that:
>1) resumeProducing actually now says:
>     def resumeProducing(self):
>         self.paused = False
>         self.transport.resumeProducing()
>         self.dataReceived('')
>This was changed because of <http://twistedmatrix.com/pipermail/ twisted- 
>python/2005-February/009626.html> also <http:// 
>However, if resumeProducing is allowed to immediately produce data,  this is 
>somewhat bogus, as it could reverse the order of the data. In  reality, a 
>TCP transport's resumeProducing will not immediately  produce data, but I 
>think that's a fragile API to both have  resumeProducing immediately produce 
>data, and depend on a call to  someone else resumeProducing not immediately 
>producing data. I think  there's an issue here.
>2) dataReceived can be easily fixed to handle this by using a local  -- 
>patch coming separately.

[Patch received out of band]

I've created an issue for this and attached a slightly modified version of the patch.  See <http://twistedmatrix.com/bugs/issue1087>.


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