Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[Glyph Lefkowitz]

> On Oct 18, 2016, at 12:29 AM, John Aherne  wrote:
> 
> Having read the irc log a few times I'm still not clear what is meant to 
> happen.
> 
> I can't see under what circumstances notifyFinish will return a Failure.

The difference between firing with None and firing with a Failure is extremely 
subtle.  If the client connection terminates "before it's ready" then you'll 
get an Failure, but this is fairly fuzzily defined in terms of 
application-level semantics.  A connection that is "not ready" to terminate 
might be one that has outstanding data to send to the client which the client 
doesn't receive, or a connection which has only partially received a request.  
There are other low-level details of the socket which might also be relevant 
(for example, I think you might also get this if the client neglects to send a 
CLOSE_ALERT TLS message).

For most applications, the difference between "failure" and "success" in this 
case just isn't very interesting.

As Corey identified earlier in the thread though, _also_ a bug where it isn't 
being called all the time when we expect it.  As the ticket said though, you 
can try to work around this by just calling resumeProducing() unconditionally 
at the beginning of your request processing...

-glyph



___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[John Aherne]

Having read the irc log a few times I'm still not clear what is meant to
happen.

I can't see under what circumstances notifyFinish will return a Failure.

John Aherne


On Mon, Oct 17, 2016 at 5:48 PM, Cory Benfield  wrote:

>
> > On 17 Oct 2016, at 17:27, John Aherne  wrote:
> >
> > OK. Thanks for the link.
> >
> > That explains what is going on although I'm not too clear on the details.
> >
> > What I was looking to do was set up an http session and when the browser
> went away use that a the trigger to expire the session.
> >
> > I didn't just want to set some arbitrary time frame to expire the
> session but if they just exited the browser or browser tab I could use
> notifyFinish to pick up the lost connection and I could then expire the
> session.
> >
> > I have'nt  spotted any other info re sessions that would help with this.
>
> The biggest issue here is that “when the browser goes away” is not a
> well-defined condition that the server can observe. Browsers will attempt
> to keep connections open as long as they can, meaning that connection
> termination may not be observed until quite some time later.
>
> Is there any reason that standard cookies (ones that expire at the end of
> a browser session) + explicit log out aren’t a suitable approach here?
>
> Cory
>
>
> ___
> Twisted-Python mailing list
> Twisted-Python@twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
>



-- 
*John Aherne*




*www.rocs.co.uk *
020 7223 7567
___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[John Aherne]

Well since notifyFinish does not do what I was hoping, I'm back to using
the standard cookie expire mechanism.

I could use javascript to detect idle time, but that's just as arbitrary as
expiring cookies.

Thanks

John Aherne



On Mon, Oct 17, 2016 at 5:48 PM, Cory Benfield  wrote:

>
> > On 17 Oct 2016, at 17:27, John Aherne  wrote:
> >
> > OK. Thanks for the link.
> >
> > That explains what is going on although I'm not too clear on the details.
> >
> > What I was looking to do was set up an http session and when the browser
> went away use that a the trigger to expire the session.
> >
> > I didn't just want to set some arbitrary time frame to expire the
> session but if they just exited the browser or browser tab I could use
> notifyFinish to pick up the lost connection and I could then expire the
> session.
> >
> > I have'nt  spotted any other info re sessions that would help with this.
>
> The biggest issue here is that “when the browser goes away” is not a
> well-defined condition that the server can observe. Browsers will attempt
> to keep connections open as long as they can, meaning that connection
> termination may not be observed until quite some time later.
>
> Is there any reason that standard cookies (ones that expire at the end of
> a browser session) + explicit log out aren’t a suitable approach here?
>
> Cory
>
>
> ___
> Twisted-Python mailing list
> Twisted-Python@twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
>



-- 
*John Aherne*




*www.rocs.co.uk *
020 7223 7567
___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[Cory Benfield]

> On 17 Oct 2016, at 17:27, John Aherne  wrote:
> 
> OK. Thanks for the link.
> 
> That explains what is going on although I'm not too clear on the details.
> 
> What I was looking to do was set up an http session and when the browser went 
> away use that a the trigger to expire the session.
> 
> I didn't just want to set some arbitrary time frame to expire the session but 
> if they just exited the browser or browser tab I could use notifyFinish to 
> pick up the lost connection and I could then expire the session.
> 
> I have'nt  spotted any other info re sessions that would help with this.

The biggest issue here is that “when the browser goes away” is not a 
well-defined condition that the server can observe. Browsers will attempt to 
keep connections open as long as they can, meaning that connection termination 
may not be observed until quite some time later.

Is there any reason that standard cookies (ones that expire at the end of a 
browser session) + explicit log out aren’t a suitable approach here?

Cory


___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[John Aherne]

OK. Thanks for the link.

That explains what is going on although I'm not too clear on the details.

What I was looking to do was set up an http session and when the browser
went away use that a the trigger to expire the session.

I didn't just want to set some arbitrary time frame to expire the session
but if they just exited the browser or browser tab I could use notifyFinish
to pick up the lost connection and I could then expire the session.

I have'nt  spotted any other info re sessions that would help with this.

Thanks

John Aherne


On Mon, Oct 17, 2016 at 3:13 PM, Cory Benfield  wrote:

>
> > On 17 Oct 2016, at 08:46, John Aherne  wrote:
> >
> > I have been running some tests to check some issue and have seen that
> notifyFinish is not being called in 16.4.1
> >
> > This is on Windows 10 using python 2.7.12
> >
> > Checking back it  is not called 16.3.0 but is in 16.2.0
> >
> > The test uses some sample code from Twisted web in 60 seconds that sets
> a timer to allow the browser to halt the request by using Escape and make
> notifyFinish  get called.
> >
> > Before I did anything else I thought I would check and see if anyone
> else was seeing this behaviour.
>
> Yup, this looks like a known issue: https://twistedmatrix.com/
> trac/ticket/8692
>
> Cory
> ___
> Twisted-Python mailing list
> Twisted-Python@twistedmatrix.com
> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
>



-- 
*John Aherne*




*www.rocs.co.uk *
020 7223 7567
___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

Re: [Twisted-Python] notifyFinish not being called on Windows 10 Twisted 16.4.1

[Cory Benfield]

> On 17 Oct 2016, at 08:46, John Aherne  wrote:
> 
> I have been running some tests to check some issue and have seen that 
> notifyFinish is not being called in 16.4.1
> 
> This is on Windows 10 using python 2.7.12
> 
> Checking back it  is not called 16.3.0 but is in 16.2.0
> 
> The test uses some sample code from Twisted web in 60 seconds that sets a 
> timer to allow the browser to halt the request by using Escape and make 
> notifyFinish  get called.
> 
> Before I did anything else I thought I would check and see if anyone else was 
> seeing this behaviour.

Yup, this looks like a known issue: https://twistedmatrix.com/trac/ticket/8692

Cory
___
Twisted-Python mailing list
Twisted-Python@twistedmatrix.com
http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python