Mailman 3 January 2025 - Twisted

reactor.running False in (some) callback/errback
by Kirill Miazine Jan. 28, 2025

Jan. 28, 2025

This has been driving me crazy for a while -- for some reason reactor.stop() in the _error errback in example below raises error.ReactorNotRunning. In order to stop the reactor, I have to do reactor.callWhenRunning(reactor.stop) (or I did reactor.callLater(0, ...) until I discovered callWhenRunning). In the example, I bind to a low port to make sure error is triggered. #!/usr/local/bin/python3 from twisted.internet import reactor, defer, protocol from twisted.internet.protocol import Factory from twisted.internet.endpoints import TCP4ServerEndpoint def _port(port): print('got', port) def _error(err): print('got err', err) print('is reactor running?', reactor.running) print('is reactor running?', (lambda: reactor.running)()) reactor.stop() # reactor.callWhenRunning(reactor.stop) d = TCP4ServerEndpoint(reactor, 123).listen(Factory()) d.addCallback(_port) d.addErrback(_error) d.addErrback(print) reactor.run() OTOH, in the following example reactor.stop() is stoppig the reactor properly: #!/usr/local/bin/python3 from twisted.internet import reactor, defer def cb(res): print('running?', reactor.running) if res == 'bar': raise Exception() reactor.stop() def eb(err): print('running?', reactor.running) print(err) reactor.stop() d = defer.Deferred() d.addCallback(cb) d.addErrback(eb) #reactor.callWhenRunning(d.callback, 'foo') reactor.callWhenRunning(d.callback, 'bar') reactor.run() Any ideas?

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(tiny) twisted success story
by Kirill Miazine Jan. 22, 2025

Jan. 22, 2025

Hello, world! I'm very happy to be using Twisted again -- after a break of about 20 years! In ol' days I did mailing lists in Twisted, implemented Dovecot AUTH protocol in Twisted and a lot more. Mostly it was mail related. A lot have been forgotten and have to be re-discovered. A couple of words about use-case: I was curious about what could be achieved using the filtering facility in the OpenSMTPD MTA. The filters are programs which are executed by the daemon, and some data is exchanged on stdin/stdout using non-blocking fashion. More at https://man.openbsd.org/smtpd-filters I tried getting Python asyncio to work at first, even using aioconsole package, but I kept hitting something which made the thing break after handshake exchange. This evening I did a rewrite in Twisted, it took me a couple of hours, but the was running on the first try! Thanks for all the fish! -- Kirill

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time-sensitive code reviews
by Glyph Jan. 20, 2025

Jan. 20, 2025

As per this announcement <https://about.readthedocs.com/blog/2024/12/deprecate-config-files-without-s…>, several of our projects' readthedocs builds will stop working tomorrow. I have prepared 3 PRs to address this: https://github.com/twisted/twisted/pull/12420 https://github.com/twisted/treq/pull/406 https://github.com/twisted/towncrier/pull/681 The Twisted one also includes a version-specification fix for PyObjC on 3.8, because that will also make trunk fail right now if tests were to run on it. (We should really pin our deps, but I digress.) These should be very easy code reviews for anyone interested, and it would be great to get these done before all the builds start failing tomorrow. Thanks, -g

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PB: remote_* deferred return magic
by Kirill Miazine Jan. 11, 2025

Jan. 11, 2025

I'm playing with PB, and it's booth cool and somewhat confusing. So I have some remote_* methods, e.g. def remote_ping(self): return 'pong' def remote_run(self): d = Deferred() d.AddCallback(self.got_result) # return d # <- magic here when deferred is returned? def got_result(self, res) return res When I do callRemote('ping') and execute callback, I am getting 'pong' as a result. However, when I do callRemote('run'), it returns a deferred which returns None, which is expected, as remote_run() doesn't have any result yet. However, if I return deferred ("d") from remote_run, then callRemote('run') gives me the result. Is it some expected magic going on when remote_ method returns a deferred?

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