trequests 0.9.5

A Tornado async HTTP/HTTPS client adaptor for python-requests

A Tornado async HTTP/HTTPS client adapter for python-requests.

The problem

You enjoy using Tornado to build fast non-blocking web applications, and you want to use a library from PyPI that makes a few HTTP requests, but pretty much every dev and their dog uses Requests to make HTTP requests (rightly so, because it’s awesome), but requests has no knowledge of the event loop nor can it yield when a socket blocks, which means any time you try to use a library like that it begins to block your request handling and grud-knows what other worlds of pain.

The solution

Luckily there are solutions, one such is to use the greenlet module to wrap blocking operations and swap Tornado coroutines at the right time, there is even the handy tornalet module which handles this for you.

To make life even easier, you lucky lucky people, I’ve created trequests, an async Requests adapter which uses greenlets (via tornalet) and the inbuilt non-blocking HTTP client methos in Tornado, to make any call to a library (utilizing Requests) non-blocking.

Installation

$ pip install trequests

Usage

# Assume bobs_big_data uses python-requests for HTTP requests
import bobs_big_data

from tornado.web import RequestHandler
from trequests import setup_session
from tornalet import tornalet

# Tell requests to use our AsyncHTTPadapter for the default
# session instance, you can also pass you own through
setup_session()

class WebHandler(RequestHandler):
    @tornalet
    def get(self):
        data = {'foo': 'bar'}
        # This will now unblock the current coroutine, like magic
        response = bobs_big_data.BigData(data).post()
        return self.write(response)

Caveats

trequests has been used in production in a large scale metrics application, and is a very small and quite simple module.

However I’ve released it as 0.9.x mainly because it’s missing 100% compatibility with the Requests adapter API, most noticeably cookie jar and session support, which I will improve (or please send me a pull request if you fancy adding support), and release as a 1.x branch when I have the time.

Also at the moment the setup_session utility actually monkey patches the session utility functions in Requests, as this was the only way I could see to override the mounts on “default” session instances (e.g. those created for every call when a session isn’t provided). I’m hoping to change this in the future.