Thanks, Hynek and Jean-Paul! Crochet looks like exactly what I'm looking
for.
-Ameya
On Sun, Feb 23, 2014 at 5:11 AM, <exar...@twistedmatrix.com> wrote:
> On 02:17 am, lokare.am...@gmail.com wrote:
>
>> Hi everyone,
>>
>> I'm writing a client library that makes (potentially long running) HTTP
>> requests. Since the library will be used within non-Twisted code, I was
>> thinking of running the reactor in a separate thread. The library code
>> looks roughly like this:
>>
>> def start():
>> Thread(target=reactor.run, args=(False,)).start()
>>
>> def shutdown():
>> reactor.callFromThread(lambda x: reactor.stop(), None)
>>
>> def make_request(url):
>> agent = Agent(reactor)
>> d = agent.request(
>> 'GET',
>> url,
>> Headers({
>> 'User-Agent': ['Twisted SSE Client'],
>> 'Cache-Control': ['no-cache'],
>> }),
>> None)
>> d.addCallback(self.cbRequest)
>>
>> Then I make requests from the application like so:
>>
>> start()
>> make_request("http://localhost:12000";)
>> ....
>> make_request("http://localhost:12000";)
>> ...
>> shutdown()
>>
>> However, it looks like the 'd' deferred never gets fired. From a little
>> playing around, it looks like this is because the reactor is started
>> before
>> the call(s) to agent.request are made. All examples in the twisted docs
>> create the request before running the reactor. I'm sure I'm missing
>> something very obvious here. Also, is there a better way to design such a
>> library?
>>
>
> It sounds like you want to use Crochet (which Hynek already linked you to).
>
> The reason your code doesn't work, though, is that Twisted APIs are not
> thread safe. You may *only* call them in the thread the reactor is running
> in.
>
> Your `start` function runs the reactor in a new thread. Then the code
> proceeds to try to use `Agent` from the original thread. This is
> unsupported.
>
> Jean-Paul
>
>
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>
--
-Ameya
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