txrequests

Asynchronous Python HTTP Requests for Humans

.. image:: https://travis-ci.org/tardyp/txrequests.png?branch=master :target: https://travis-ci.org/tardyp/txrequests

Small add-on for the python requests_ http library. Makes use twisted's ThreadPool, so that the requests'API returns deferred

The additional API and changes are minimal and strives to avoid surprises.

The following synchronous code:

.. code-block:: python

from requests import Session

session = Session()
# first requests starts and blocks until finished
response_one = session.get('http://httpbin.org/get')
# second request starts once first is finished
response_two = session.get('http://httpbin.org/get?foo=bar')
# both requests are complete
print('response one status: {0}'.format(response_one.status_code))
print(response_one.content)
print('response two status: {0}'.format(response_two.status_code))
print(response_two.content)

Can be translated to make use of futures, and thus be asynchronous by creating a FuturesSession and catching the returned Future in place of Response. The Response can be retrieved by calling the result method on the Future:

.. code-block:: python

from txrequests import Session
from twisted.internet import defer

@defer.inlineCallbacks
def main():
    # use with statement to cleanup session's threadpool, and connectionpool after use
    # you can also use session.close() if want to use session for long term use
    with Session() as session:
        # first request is started in background
        d1 = session.get('http://httpbin.org/get')
        # second requests is started immediately
        d2 = session.get('http://httpbin.org/get?foo=bar')
        # wait for the first request to complete, if it hasn't already
        response_one = yield d1
        print('response one status: {0}'.format(response_one.status_code))
        print(response_one.content)
        # wait for the second request to complete, if it hasn't already
        response_two = yield d2
        print('response two status: {0}'.format(response_two.status_code))
        print(response_two.content)

By default a ThreadPool is created with 4 max workers. If you would like to adjust that value or share a threadpool across multiple sessions you can provide one to the Session constructor.

.. code-block:: python

from twisted.python.threadpool import ThreadPool
from txrequests import Session

session = FuturesSession(pool=ThreadPool(maxthreads=10))
# ...

As a shortcut in case of just increasing workers number you can pass minthreads and/or maxthreads straight to the Session constructor:

.. code-block:: python

from txrequests import Session
session = Session(maxthreads=10)

That's it. The api of requests.Session is preserved without any modifications beyond returning a Deferred rather than Response. As with all futures exceptions are shifted to the deferred errback.

Working in the Background

There is one additional parameter to the various request functions, background_callback, which allows you to work with the Response objects in the background thread. This can be useful for shifting work out of the foreground, for a simple example take json parsing.

.. code-block:: python

from pprint import pprint
from txrequests import Session
from twisted.internet import defer

@defer.inlineCallbacks
def main():
    with Session() as session:

        def bg_cb(sess, resp):
            # parse the json storing the result on the response object
            resp.data = resp.json()
            return resp

        d = session.get('http://httpbin.org/get', background_callback=bg_cb)
        # do some other stuff, send some more requests while this one works
        response = yield d
        print('response status {0}'.format(response.status_code))
        # data will have been attached to the response object in the background
        pprint(response.data)

Installation

pip install txrequests

Credits

txrequests is based on requests_future_, from Ross McFarland

.. _requests: https://github.com/kennethreitz/requests .. _requests_future: https://github.com/ross/requests-futures