Mailman 3 September 2003 - Twisted

[Twisted-Python] Patch to allow deferreds to be returned from resource.render
by James Y. Knight 15 Sep '03

15 Sep '03

Ooh lets try sending this mail one more time. Apparently the combined suckage of three different programs made my last mail not get through: 1) Apple Mail sucks and doesn't quote the "Full Name" automatically, so I end up with a non-RFC-conforming From: with a "." outside of quotes or the email address. 2) Exim sucks and doesn't fix it (OTOH, Sendmail does fix it, which is why i've never seen this problem before!) 3) Mailman sucks as well, and gets completely confused by this slightly non-conformant address format, and thinks my email address is "jamesy.knight". Anyways, on to the original message: === This patch lets you return a deferred from resource.render (the obvious thing to do) and have it work. As opposed to the current method where you need to return NOT_DONE_YET and restructure all your code to call request.write(...). That should still work too, though. I'd stick this on the bug tracker but I forgot my password. (anyone able to reset for me? :) James --- server.py~ Mon Jul 21 00:09:52 2003 +++ server.py Tue Sep 9 15:02:09 2003 @@ -160,56 +160,8 @@ except: self.processingFailed(failure.Failure()) - - def render(self, resrc): - try: - body = resrc.render(self) - except UnsupportedMethod, e: - allowedMethods = e.allowedMethods - if (self.method == "HEAD") and ("GET" in allowedMethods): - # We must support HEAD (RFC 2616, 5.1.1). If the - # resource doesn't, fake it by giving the resource - # a 'GET' request and then return only the headers, - # not the body. - log.msg("Using GET to fake a HEAD request for %s" % - (resrc,)) - self.method = "GET" - body = resrc.render(self) - - if body is NOT_DONE_YET: - log.msg("Tried to fake a HEAD request for %s, but " - "it got away from me." % resrc) - # Oh well, I guess we won't include the content length. - else: - self.setHeader('content-length', str(len(body))) - - self.write('') - self.finish() - return - - if self.method in (supportedMethods): - # We MUST include an Allow header - # (RFC 2616, 10.4.6 and 14.7) - self.setHeader('Allow', allowedMethods) - s = ('''Your browser approached me (at %(URI)s) with''' - ''' the method "%(method)s". I only allow''' - ''' the method%(plural)s %(allowed) here.''' % { - 'URI': self.uri, - 'method': self.method, - 'plural': ((len(allowedMethods) > 1) and 's') or '', - 'allowed': string.join(allowedMethods, ', ') - }) - epage = error.ErrorPage(http.NOT_ALLOWED, - "Method Not Allowed", s) - body = epage.render(self) - else: - epage = error.ErrorPage(http.NOT_IMPLEMENTED, "Huh?", - """I don't know how to treat a""" - """ %s request.""" - % (self.method)) - body = epage.render(self) - # end except UnsupportedMethod - + def _cbRender(self, body, resrc): + if body == NOT_DONE_YET: return if type(body) is not types.StringType: @@ -232,6 +184,58 @@ self.setHeader('content-length', str(len(body))) self.write(body) self.finish() + + def _ebRender(self, failure, resrc): + failure.trap(UnsupportedMethod) + e = failure.value + allowedMethods = e.allowedMethods + if (self.method == "HEAD") and ("GET" in allowedMethods): + # We must support HEAD (RFC 2616, 5.1.1). If the + # resource doesn't, fake it by giving the resource + # a 'GET' request and then return only the headers, + # not the body. + log.msg("Using GET to fake a HEAD request for %s" % + (resrc,)) + self.method = "GET" + body = resrc.render(self) + + if body is NOT_DONE_YET: + log.msg("Tried to fake a HEAD request for %s, but " + "it got away from me." % resrc) + # Oh well, I guess we won't include the content length. + else: + self.setHeader('content-length', str(len(body))) + + self.write('') + self.finish() + return + + if self.method in (supportedMethods): + # We MUST include an Allow header + # (RFC 2616, 10.4.6 and 14.7) + self.setHeader('Allow', allowedMethods) + s = ('''Your browser approached me (at %(URI)s) with''' + ''' the method "%(method)s". I only allow''' + ''' the method%(plural)s %(allowed) here.''' % { + 'URI': self.uri, + 'method': self.method, + 'plural': ((len(allowedMethods) > 1) and 's') or '', + 'allowed': string.join(allowedMethods, ', ') + }) + epage = error.ErrorPage(http.NOT_ALLOWED, + "Method Not Allowed", s) + body = epage.render(self) + else: + epage = error.ErrorPage(http.NOT_IMPLEMENTED, "Huh?", + """I don't know how to treat a""" + """ %s request.""" + % (self.method)) + body = epage.render(self) + + def render(self, resrc): + defer.maybeDeferred(resrc.render, self).addErrback(self._ebRender, resrc).addCallback(self._cbRender, resrc).addErrback(self.processingFailed) + + def processingFailed(self, reason): log.err(reason)

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[Twisted-Python] Re: Web server with Python
by Andrew Bennetts 14 Sep '03

14 Sep '03

[CC'ing the Twisted mailing list] On Fri, Sep 12, 2003 at 08:05:59PM +0200, Patrick Useldinger wrote: > On Fri, 12 Sep 2003 17:33:34 +1000, Andrew Bennetts > <andrew-pythonlist(a)puzzling.org> wrote: > > >> Does Twisted work well with Python 2.3? > > > >Yes, current versions support 2.3 without any problems. > > Version 1.0.6 refuses to install, though, complaining it requires Python > 2.2. Eek! Does 1.0.7 (just released) work any better? Also, what platform are you using, and are you installing from the source .tar.gz or something else? -Andrew.

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[Twisted-Python] Please add changelog entry for all resolved issues in bug tracker
by Itamar Shtull-Trauring 14 Sep '03

14 Sep '03

This will make sure changelog is more up to date and allow people reading changelog to refer to issue tracker. -- Itamar Shtull-Trauring http://itamarst.org/ Available for Python & Twisted consulting

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[Twisted-Python] Examples and patterns for Twisted
by Dave Kuhlman 13 Sep '03

13 Sep '03

I've written a document that provides and explains a number of patterns and examples for Twisted Web applications. I'm hoping that it might be of help to beginning Twisted developers. I also wrote it to try to learn more about Twisted and also to straight out my own head. I'd like to post it at my Web site. But, before I make it public or announce it, it'd be helped by reviews from Twisted experts. Any comments and suggestions would be appreciated. You can find it at: http://www.rexx.com/~dkuhlman/twisted_patterns.html (I've placed it at my Web site, but have not yet made it visible on my main page.) Thanks in advance for criticism and suggestions. Dave -- Dave Kuhlman dkuhlman(a)rexx.com http://www.rexx.com/~dkuhlman

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[Twisted-Python] Suspending a result
by Uwe C. Schroeder 13 Sep '03

13 Sep '03

Hi, maybe I'm sitting on my brains here, but anyways: I have a (possibly) blocking function. The core work of it is handled in a separate thread, so the blocking is not a problem for Twisted. However - I need to get rid of the deferred callbacks. So basically what I'm trying to do is to have a class/method that wraps the blocking code WITHOUT returning a deferred. Instead I'd like to "suspend" the return, certainly without blocking twisted. So here is some "pseudocode" to clarify what I want to do: # the blocking function itself def possibly_blocking(params): do something blocking Normally I would call this by result=possibly_blocking("Blah") which may or may not block due to what's inside the function. In 99% of the time it will return a result quite quickly, so no blocking. BUT what if. So I want to make the result=xxx call "wait" for the result, without a deferred coming back. So I'd have to wrap that up somehow, so that the call seems to be waiting, but in what is called returning the result is delayed. I think one might be able to accomplish this with some kind of class that wraps the call and checks for the resultset once in a while, and when the result is there it returns the result. It's pretty similar to the way GUI's handle modal dialogs. The original modal dialog call will never return, until the dialog is closed, however the rest of the gui doesn't block, since internally scheduling still goes on. So can one wrap a "call / deferred / result" chain and block the caller, without blocking twisted completely ? Any help would be appreciated. (BTW: I don't want to use deferreds as the original resultset, since that would mean having to write tremendous state machines just to retain the order of the results depending on each other) UC -- Open Source Solutions 4U, LLC 2570 Fleetwood Drive Phone: +1 650 872 2425 San Bruno, CA 94066 Cell: +1 650 302 2405 United States Fax: +1 650 872 2417

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[Twisted-Python] and thanks to radix, hypatia, exarkun and glyph
by Itamar Shtull-Trauring 13 Sep '03

13 Sep '03

Mary Gardiner, for hosting our mail Chris Armstrong, who did lots of work on the move Jean-Paul Calderone, assembling and bringing server to hosting Glyph Lefkowitz, buying us a new server -- Itamar Shtull-Trauring http://itamarst.org/ Available for Python & Twisted consulting

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[Twisted-Python] A big thank you to Divmod and Tummy
by Itamar Shtull-Trauring 13 Sep '03

13 Sep '03

1. Tummy.com has donated CVS hosting on their wonderful virtual hosting setup (hosting.tummy.com). You should try them out, they are a great company. 2. Divmod (www.divmod.com) have donated rack space, bandwidth etc. for our main server's new home. You should all try out Quotient and send them patches and bug reports. -- Itamar Shtull-Trauring http://itamarst.org/ Available for Python & Twisted consulting

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[Twisted-Python] Who runs FreeBSD and Mac OS X buildbots?
by Itamar Shtull-Trauring 13 Sep '03

13 Sep '03

Warner has coded new bandwidth saving version of buildbot. Please don't switch to new CVS server until you've upgraded to using it. -- Itamar Shtull-Trauring http://itamarst.org/ Available for Python & Twisted consulting

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[Twisted-Python] executing .rpy in a thread
by stephan 13 Sep '03

13 Sep '03

Say I want to execute blocking code in a .rpy file. Can't I just execute all the code in a separate thread? I've found the following code to execute a function in a thread. How could I add a callback to that thread so I could get back the whole html page back from that "notthreadSafe" function and return it to the client (web browser)? from twisted.internet import reactor from twisted.python import threadable threadable.init(1) def notThreadSafe(x): """do something that isn't thread-safe""" # ... def threadSafeScheduler(): """Run in thread-safe manner.""" reactor.callFromThread(notThreadSafe, 3) # will run 'notThreadSafe(3)' # in the event loop _stephan

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[Twisted-Python] calling unix commands
by Konrad Rokicki 13 Sep '03

13 Sep '03

Hey everyone, I'm having a problem calling a unix comand from inside a twisted program.. I do os.popen(cmd).readlines() and I sporadically get: IOError: [Errno 4] Interrupted system call Sounds like it might be an async problem.. is there a preferred way to do this in twisted? Thanks, Konrad

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