Responding To Client Disconnects Using Bottle And Gevent.wsgi?

I have a small asynchronous server implemented using bottle and gevent.wsgi. There is a routine used to implement long poll that looks pretty much like the 'Event Callbacks' examp

Solution 1:

Aha! The wsgi.input variable, at least under gevent.wsgi, has an rfile member that is a file-like object. This doesn't appear to be required by the WSGI spec, so it might not work with other servers.

With this I was able to modify my code to look something like:

def worker(body, rfile):
  poll = zmq.Poller()
  poll.register(msgbus)
  poll.register(rfile, zmq.POLLIN)

  while True:
    events = dict(poll.poll())

    if rfile.fileno() in events:
      # client disconnect!
      break

    if msgbus in events:
      msg = msgbus.recv()
      body.put(msg)
      break

    body.put(StopIteration)

@route('/poll')
def poll():
  rfile = bottle.request.environ['wsgi.input'].rfile
  body = gevent.queue.Queue()
  worker = gevent.spawn(worker, body, rfile)
  return body

And this works great...

...except on OpenShift, where you will have to use the alternate frontend on port 8000 with websockets support.