Twisted August 2002

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39 participants
61 discussions

[Twisted-Python] Concurrent data access with select() safe?
by Mukhsein Johari 14 Aug '02

14 Aug '02

Hello all, I've managed to get a working custom webserver thanks to Donovan. My next question is (perhaps more due to my ignorance of how select works) how do you control concurrent access to data? In a multi-thread system you'd normally use devices like locks on the data / resource but what about an event based one like twisted? Say my server does reads and writes on some file/files. How do I ensure data integrity? Do I need some kind of locking mechanism or does using SelectReactor make this point moot? -- Regards, Mukhsein Johari

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[Twisted-Python] Patch for tcp.py
by Martin Sjögren 13 Aug '02

13 Aug '02

Non-blocking connects seems to be handled wrong. In particular, EALREADY is handled like EISCONN, when it should be handled like e.g. EINPROGRESS. This is consistent for both unix and windows. Here's a patch: diff -u -r1.86 tcp.py --- tcp.py 6 Aug 2002 17:12:40 -0000 1.86 +++ tcp.py 13 Aug 2002 08:17:31 -0000 @@ -230,9 +230,9 @@ try: self.socket.connect(self.realAddress) except socket.error, se: - if se.args[0] in (EISCONN, EALREADY): + if se.args[0] == EISCONN: pass - elif se.args[0] in (EWOULDBLOCK, EINVAL, EINPROGRESS): + elif se.args[0] in (EWOULDBLOCK, EINVAL, EINPROGRESS, EALREADY): self.startReading() self.startWriting() return Regards, Martin -- Martin Sjögren martin(a)strakt.com ICQ : 41245059 Phone: +46 (0)31 7710870 Cell: +46 (0)739 169191 GPG key: http://www.strakt.com/~martin/gpg.html

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[Twisted-Python] Resource perplexity
by Steve Waterbury 12 Aug '02

12 Aug '02

Yet another newbie question: Firewall realities being what they are, I'd like to "multiplex" several things over a single web server/port (80 for production, but for now anything), so I've been hacking at the xmlrpc example, but no luck so far (see attached attempt -- it runs, but gives a "404" for /RPC2 or /RPC2/ ...). Two questions: (1) Is this an architecturally sound use of twisted? (Optimal?) (And if not, suggestions? :^) (2) If so, what am I doing blockheaded? Thanks again for your help and patience! -- Steve. Stephen C. Waterbury http://misspiggy.gsfc.nasa.gov/people/waterbug.html """ Derived from twisted xmlrpc example ... Adds a resource_mux resource to dispatch requests based on URL. ----------------------------------------------------------------- Hook up an object to XML-RPC. An example session: >>> s = xmlrpclib.Server('http://localhost:7080/RPC2/') >>> s.echo("lala") ['lala'] >>> s.echo("lala", 1) ['lala', 1] >>> s.echo("lala", 4) ['lala', 4] >>> s.echo("lala", 4, 3.4) ['lala', 4, 3.3999999999999999] >>> s.echo("lala", 4, [1, 2]) ['lala', 4, [1, 2]] """ from twisted.web import xmlrpc, resource from twisted.internet import defer import xmlrpclib class Echoer(xmlrpc.XMLRPC): """An example object to be published. Has five methods accessable by XML-RPC, 'echo', 'hello', 'defer's.echo('spam'), 'defer_fail' and 'fail. """ def xmlrpc_echo(self, *args): """Return all passed args.""" return args def xmlrpc_hello(self): """Return 'hello, world'.""" return 'hello, world!' def xmlrpc_defer(self): """Show how xmlrpc methods can return Deferred.""" return defer.succeed("hello") def xmlrpc_defer_fail(self): """Show how xmlrpc methods can return failed Deferred.""" return defer.fail(12) def xmlrpc_fail(self): """Show how we can return a failure code.""" return xmlrpclib.Fault(7, "Out of cheese.") def main(): from twisted.internet.app import Application from twisted.web import server # Resource multiplexer 'mux'; dispatches requests to Web, # XML-RPC, or SOAP handler, depending on base URL. Standard # base URLs: 'WWW', 'RPC2', 'SOAP' (probably should be # case-insensitive). mux = resource.Resource() mux.putChild('/RPC2/', Echoer()) # similarly for other handlers ... app = Application("thingy") app.listenTCP(7080, server.Site(mux)) app.run(0) if __name__ == '__main__': main()

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[Twisted-Python] [patch] mktap web --resource
by Sune Kirkeby 12 Aug '02

12 Aug '02

Hi, all! Attached is a short patch to add a --resource option to "mktap web", here is the --help for it: -r, --resource= <class> is the name (including module) of a subclass of twisted.web.resource.Resource to publish. So you can have any subclass of t.w.r.Resource be the 'root' of your web-server. I have also been working on a few other things: - an async Pytho-only PostgreSQL interface (not t.e.adbapi compatible, since I am not usre I like it's interface and need to play a bit before I figure out how I would like an async SQL-database interface to behave.) - a SQLResultWidget, very dull right now but I will probably hack some BoboDTML support into it. first-post-but-not-like-/.-ly yrs, -- Sune Kirkeby | /* we're still looking for the end of the | * server's header ... (does that make header | * parsing an "out of body experience" ? */ | -- jcc.c in junkex source-code

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[Twisted-Python] twisted.enterprise
by Jp Calderone 12 Aug '02

12 Aug '02

Quick query. I'm using twisted.enterprise.adbapi.Augmentation in my latest project and I've just moved the createSchema() call into the mktap phase. This seems like a decent place to put it, as the schema need only be created once for each server application. However, 'mktap' no longer exits now. The .tap is created, but then it looks like a thread is left running somewhere. What's the right way to release connections acquired indirectly from the ConnectionPool? With the .close() method, or ... ? Jp -- "I quite agree with you," said the Duchess; "and the moral of that is -- Be what you would seem to be' -- or, if you'd like it put more simply -- Never imagine yourself not to be otherwise than what it might appear to others that what you were or might have been was not otherwise than what you had been would have appeared to them to be otherwise.'" -- Lewis Carrol, "Alice in Wonderland" -- 9:35pm up 82 days, 22:23, 5 users, load average: 0.03, 0.07, 0.01

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[Twisted-Python] PB over unix socket ... how?
by Steve Waterbury 11 Aug '02

11 Aug '02

twisted gurus ... help! I want to use PB down in the guts of my application, but only later on will I actually be using the pb protocol over the network, so in the meantime I'd like to play it safe and have PB talk to other components over unix domain sockets. I know from wandering around in the internet module that there's lots of support for unix sockets and even an IReactorUNIX, but it's late and I'm a little dizzy and I figured someone could probably point me in the right direction with about 5 lines anyway ... if there's an example, I musta missed it ... 8^P TIA! -- Steve. Stephen C. Waterbury http://misspiggy.gsfc.nasa.gov/people/waterbug.html

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Re: [Twisted-Python] Twisted.web/DOMTemplate
by Donovan Preston 11 Aug '02

11 Aug '02

On Saturday, August 10, 2002, at 05:54 AM, Stephen Thorne wrote: > Okay, I've been doing some hacking trying to make a small application > using > twisted.web and the .rpy stuff, using DOMTemplate. Awesome. I really appreciate people using it and providing feedback; designing in a vacuum is tough. [ snip ] > This (when twistd --nodaemon is used) prints 1 twice (instead of the > once > expected). [ snip ] > This is *bad*. viewMethod in this instance is > response.factory_getBody, and in > order to figure out if factory_getBody returns a widget as opposed to > an > instance of xml.dom.minidom.Element it actually calls the function to > have a > look. If it doesn't return a widget it *throws the result away*. > viewMethod > is then returned and used elsewhere, where its actually intended to be > used. Indeed it is bad. The fix was to return the result up if the result was *not* a widget, and not bother calling viewMethod again. Since I always program DOMTemplate using domwidgets nowadays, I never encountered this. Patch committed, which you already know since you committed the patch ;-) > Considering that rendering a template node could have program logic in > it that > only should be evaluated once per pageview. It could also carry some > expensive database transactions. Just fyi,it is possible to do this sort of setup by overriding the setUp method. However, there are often cases where doing a monolithic "setUp" doesn't make sense, and leaving each node to gather it's own data is lazier and therefore more efficient. Thanks for the bug report. Donovan

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[Twisted-Python] Twisted.web/DOMTemplate
by Stephen Thorne 10 Aug '02

10 Aug '02

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Okay, I've been doing some hacking trying to make a small application using twisted.web and the .rpy stuff, using DOMTemplate. Ordinarily I'd chat about something like this on the irc channel, but it was dead quiet. Apart from me talking to myself of course. in the template: <P view='getBody'> in the response object def factory_getBody(self, request, node): print 1 return node This (when twistd --nodaemon is used) prints 1 twice (instead of the once expected). This is because of the following section of code: def getNodeView(self, request, node): <snip> maybeWidget = viewMethod(request, node) if isinstance(maybeWidget, domwidgets.Widget): view = maybeWidget viewMethod = view.generateDOM This is *bad*. viewMethod in this instance is response.factory_getBody, and in order to figure out if factory_getBody returns a widget as opposed to an instance of xml.dom.minidom.Element it actually calls the function to have a look. If it doesn't return a widget it *throws the result away*. viewMethod is then returned and used elsewhere, where its actually intended to be used. Considering that rendering a template node could have program logic in it that only should be evaluated once per pageview. It could also carry some expensive database transactions. Anyhow. I can't figure out how to refactor without breaking Widget functionality, and the way 'controller' works. Anyhow. I think I'd call the above a bug report. Maybe with elements of rant thrown in. Stephen Thorne. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) iD8DBQE9VQ0HRqaMcfqEy/YRAoOPAJ0WJiLcPvftgjna6tgiD1ifAbQkGACdEDWN 7psWJh0/77eiCaEai/xVnaU= =BNcB -----END PGP SIGNATURE-----

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[Twisted-Python] usage appears to be broke in cvs ...
by Steve Waterbury 09 Aug '02

09 Aug '02

usage fails test_checkFlags and test_checkParameters -- Steve. Stephen C. Waterbury http://misspiggy.gsfc.nasa.gov/people/waterbug.html

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[Twisted-Python] sturdy
by Paul Boehm 07 Aug '02

07 Aug '02

compare Twisted-0.19 behaviour to current cvs behaviour for this: --- from twisted.spread import sturdy from twisted.internet import reactor sturdy.PerspectiveConnector("localhost", 8787, "update", \ "secret", "sam", "update", 1).callRemote("moo") reactor.run() --- current cvs doesn't do reconnect attempts... this has to have broken in the last few days, but i don't know exactly where or when. paul

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Twisted August 2002