Very primitive simulation of a caching cdn like cloudfront.

tornadofront.py

# -*- coding: utf-8 -*-
"""
Very primitive simulation of a caching cdn like cloudfront.
"""
import logging
import requests
import sys
from concurrent.futures import ThreadPoolExecutor
from functools import partial
from urlparse import urlunparse

import tornado.ioloop
import tornado.web
from cachecontrol import CacheControlAdapter


logging.basicConfig(
    stream=sys.stdout,
    level=logging.DEBUG,
    format='%(asctime)s %(levelname)s %(name)s %(funcName)s(%(lineno)d): %(message)s'
)

log = logging.getLogger(__name__)


ORIGIN_HOST = 'localhost:8000'
CACHE_PORT = 9000
THREADS = 32


class MainHandler(tornado.web.RequestHandler):
    def initialize(self, session=None):
        self.session = session

    def fetch_origin(self, callback=None):
        thread_pool.submit(
            self.session.get,
            urlunparse(('http', ORIGIN_HOST, self.request.uri, '', '', ''))
        ).add_done_callback(
            lambda future: tornado.ioloop.IOLoop.instance().add_callback(
                partial(callback, future)
            )
        )

    @tornado.web.asynchronous
    def get(self):
        def callback(future):
            response = future.result()
            self.set_header("Content-Type", response.headers['content-type'])
            self.write(response.content)
            self.finish()
        self.fetch_origin(callback)


thread_pool = ThreadPoolExecutor(THREADS)
session = requests.Session()
session.mount('http://', CacheControlAdapter(
    pool_connections=THREADS, pool_maxsize=THREADS
))
application = tornado.web.Application([
    (r".*", MainHandler, dict(session=session)),
])


if __name__ == "__main__":
    application.listen(CACHE_PORT)
    tornado.ioloop.IOLoop.current().start()