[Twisted-web] How to know if a LIveElement is alive :)

[Juanjo Conti]

Thanks! I'll try it.

So... what is detached for?

2009/6/26 Paul Reznicek <maillists at ivsn.com>:
> Juanjo Conti wrote:
>>
>> 2009/6/26 Juanjo Conti <jjconti at gmail.com>:
>>>
>>> Hi, I wonder know if my nevow.athena.LiveElement intances are alive.
>>> This means for example, the web browser was now closed.
>>>
>>> I've been checking the API documentation at
>>> http://buildbot.divmod.org/apidocs/nevow.athena.LiveElement.html but
>>> didn't fin any sutable method for asking this.
>>>
>>
>> I thought I could use the LiveElement detached method
>> http://buildbot.divmod.org/apidocs/nevow.athena._LiveMixin.html#detached
>> but it semms not to be called when I close the browser where a
>> LIveElement is living...
>
> Hello,
> 2 months back I've had same question - working solution from Werner
> is in attached message.
> Regards, Paul
>
>
> ---------- Mensaje reenviado ----------
> From: Werner Thie <wthie at thiengineering.ch>
> To: Twisted Web World <twisted-web at twistedmatrix.com>
> Date: Wed, 22 Apr 2009 16:44:17 +0200
> Subject: Re: [Twisted-web] Athena LiveElement: how to putChild under unique
> session URL?
> Paul Reznicek wrote:
>>
>> glyph at divmod.com wrote:
>>>
>>> On 21 Apr, 08:57 pm, maillists at ivsn.com wrote:
>>>>
>>>> Hello All,
>>>>
>>>> LiveElement is fantastic, but I'm too stupid to find out,
>>>> how to put temporary page under sessiop URL...
>>>> This work for js modules at start like:
>>>>   http://localhost:8080/user/<HASH clientID>/jsmodule/athena_test
>>>>
>>>> I'd like to add temporary during run time something like:
>>>>   http://localhost:8080/user/<HASH clientID>/your_data
>>>> page or staticFile, which should exists only few minutes.
>>
>> Caveat is, that instances of gone clients are keeping in memory. Is there
>> a way to find out, that a client is gone (closed browser or switched to
>> other site)?
>
> Welcome to the land of garbage collecting languages... What was the losing
> memory of the C++ ages is now the not releasing memory because of
> noncollectable garbage and server processes eating all the memory the
> machine has. I had to learn it the hard way but NEVER ever store a reference
> to something like sessions, mind or the the hierarchy of your LiveElements
> unless you're prepared to handle the breakup of the reference at cleanup
> time. Also keep in mind that the object hierarchy of client and server must
> be in sync or you're risking that the detach functionality does not work as
> advertised. Please see the detach/detached functionality in athena.py
>
> class thePage(athena.LivePage):
>
>  def beforeRender(self, ctx):
>           :
>    d = self.notifyOnDisconnect()
>    d.addErrback(self.disconn)
>
>  def disconn(self, reason):
>    """
>    we will be called back when the client disconnects, just iterate
>    over all children and call a disconnected func if available
>    """
>    for child in self.liveFragmentChildren:
>      if hasattr(child, 'disconnected'):
>        child.disconnected(reason);
>
> Werner
>
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>



-- 
Juanjo Conti