Mailman 3 December 2009 - Twisted

[Twisted-Python] deferred list behaviour
by Nathan 15 Dec '09

15 Dec '09

Are the results of a deferred list guaranteed to be in the same order as the list of deferreds that was given to it? i.e. if I pass [d1, d2, d3] to a deferred list and the results list in the call back has [(True, (something,)), (False, (something,)), (True, (something))] is it guaranteed that items 0, 1, and 2 in each list correspond to each other? ~ Nathan

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[Twisted-Python] subprocess.Popen
by Aníbal Pacheco 15 Dec '09

15 Dec '09

Hi list, Is it possible to attach a callback to a process launched using subprocess.Popen?, I want to receive a notification on process termination. many thanks! anibal.-

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[Twisted-Python] XMLRPC get IP address
by Landreville 14 Dec '09

14 Dec '09

Hello, I've looked through the mailing list and already found this reference to get the IP address when using xmlrpc: http://twistedmatrix.com/pipermail/twisted-python/2004-June/007987.html But it is not working. I have added this to my class that inherits from xmlrpc.XMLRPC def render(self, request): self.request = request xmlrpc.XMLRPC.render(self, request) Now when I call any function the log says: 2009-12-14 12:29:18-0500 [-] /usr/local/lib/python2.6/dist-packages/Twisted-9.0.0-py2.6-linux-x86_64.egg/twisted/web/xmlrpc.py:148: exceptions.UserWarning: Warning! request.finish called twice. I have two XMLRPC classes, and one of them is a subHandler, but the subhandler's render method never gets called as far as I've seen (so it shouldnt be causing request.finish to be called twice) and just to be sure I added this to only the parent XMLRPC class. Any ideas why this would cause request.finish to be called twice?

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[Twisted-Python] Twisted download issues
by Tuure Laurinolli 13 Dec '09

13 Dec '09

It appears that Twisted source and binary packages are currently distributed solely via tmrc.mit.edu, which seems to be down. I don't know what has happened to tmrc.mit.edu, but it would be nice if there were more mirrors even if this is just a minor glitch. I guess open source projects typically distribute their installabled via services like Sourceforge. Although Sourceforge immediately creeps me out with the slowness of the site itself, they certainly do have a sizable collection of mirrors and there usually aren't any problems in downloading files if the mirror link can be coaxed out of Sourceforge itself. Perhaps there is a way to get Twisted mirrored on these sites without going through Soruceforge? Also, my personal VPS has been sitting nigh unused for about a year now. It currently runs DNS and e-mail, but I wouldn't mind mirroring Twisted too :)

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 12 Dec '09

12 Dec '09

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[Twisted-Python] web vs web2 clarification
by Jared Gisin 11 Dec '09

11 Dec '09

I'm curious if anyone can shed some light on the following sentence which is taken from "http://twistedmatrix.com/trac/wiki/WebDevelopmentWithTwisted" "We decided this was a mistake and development focus has shifted to porting the best parts of Twisted Web 2 back to Twisted Web where existing applications will benefit from them." I'm curious as to why twisted web2 was a mistake what is the fundamental difference between web and web2? Thanks, -Jared

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Re: [Twisted-Python] A resizable cooperator class for queuing and dispatching jobs
by Terry Jones 11 Dec '09

11 Dec '09

>>>>> "Dave" == Dave Peticolas <dave(a)krondo.com> writes: Dave> Cool. What about being able to get the set of underway objects, in Dave> addition to the set of pending objects? Then you can get the whole Dave> state of the queue at that point. I added an underway() method that gets you a set of underway jobs, each with its job spec, deferred, and start time. I guess you could add callbacks or timeouts to the set of outstanding deferreds (e.g., for some reason you're about to pause and you know the currently outstanding jobs are going to fail or are somehow invalid and that you're going to have to redo them, so you could add a callback to each to put it back on the queue, and then call pause). Dave> I think: Dave> queue.resume(0) Dave> doesn't work the way you'd expect at the moment. OK, added an assert to make sure you can't do this. I'm not sure the details of all this are of interest to many people on the list. I'll find time to put the code up somewhere more useful. It would be nice to have a runnable demo/example too. Not sure I'll get there. Terry

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Re: [Twisted-Python] A resizable cooperator class for queuing and dispatching jobs
by Terry Jones 10 Dec '09

10 Dec '09

>>>>> "Dave" == Dave Peticolas <dave(a)krondo.com> writes: Dave> This is really nifty. I know I could use this. Great. Me too :-) >> There's also the issue about what to do when the dispatch function hits >> an error. An option could be added to re-queue the job, but it's >> perhaps better to let the dispatch function do that along with whatever >> else it needs. Dave> One reason to have a separate error handler is to support generic Dave> error-handling strategies, like 're-try N times and then send an Dave> email here', etc. Though maybe you could do that with decorators on Dave> the dispatch function. It does mean the dispatch function needs to Dave> know about the task queue, though. Yes. But I think that's fine, and appropriate. If you're doing something more sophisticated you can make a class that creates the dispatch queue, deals with errors, resubmission, etc. That's how I plan to use it. Dave> Having written something like this, though not as general or as Dave> elegant, several times, I've found that pause() and resume() is a Dave> very useful API. That's not the same as setting the width to 0 and Dave> then back again, as pause() and resume() don't require you to know or Dave> remember the current width of the queue. OK, I added pause/resume. You can change the width when it's paused (or on resume). Jobs can still be added to the queue when the thing is paused, they just don't get dispatched. The pause method returns a deferred that fires when all currently underway tasks have completed. There's also a new method 'size' which gets you a 2-tuple of the number of tasks currently underway and the length of the queue. And I made it so you can clear the queue (perhaps useful if you want to pause, get the pending jobs via pending(), and clear the queue before resuming, etc). I also got rid of narrow/widen, following Glyph's comments. I'll stick it somewhere more official / permanent soon (I guess into Launchpad, either in the Fluidinfo PPA or as a sub-project of the tx collection). For now you can grab the code & the tests at http://jon.es/other/rdq.tar.bz2 The tests feel funky to me - the ones that really do anything are all based on expected timings of jobs, queue sizes, etc. That's what I'm supposed to be testing, but perhaps my way of doing it is weird. Terry

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[Twisted-Python] Deferred on PyPI
by Jonathan Lange 10 Dec '09

10 Dec '09

Hello, A while ago at EuroPython, Mikeal Rogers and I talked about Deferreds and how they don't really depend on the rest of Twisted. Later, Mikeal made a branch that extracted Deferred out of the rest of Twisted, and I contributed a patch to make it more correct. You can find the latest release at: http://pypi.python.org/pypi/deferred/0.2 I've also made a project for it on Launchpad: https://launchpad.net/deferred So you can get the code with 'bzr branch lp:deferred'. Mikeal is maintaining the official trunk branch on Github. I haven't heard anything about it on this list, so I thought I'd mention to see what you all think and whether we should do anything about it. cheers, jml

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Re: [Twisted-Python] A resizable cooperator class for queuing and dispatching jobs
by Terry Jones 10 Dec '09

10 Dec '09

glyph> Heh. For something in a pastebin, that's all I got :). Stick it in glyph> version control somewhere! Will do. I'm just adding pause/resume, following the suggestion of Dave Peticolas (thanks Dave). Terry

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