Using uWSGI's asyncio engine & Redis for generic websocket communication

[ggold6]

Following issue #27, i've been trying to implement a send/receive asyncio listener coroutine as follows:

websock = WebSocket(app)
@websock.route('/websocket')
def echo(ws):
    r = redis_conn.pubsub()
    r.subscribe("test_channel")
    asyncio.Task(listen(ws,r))

With the coroutine (called as a task, temporary: to edit to something sensible when bugs clear):

@asyncio.coroutine
def listen(ws,r):
    for msg in r.listen():
        ws.send(str(msg['data']))
    
    while True:
        msg=ws.receive()
        if msg is not None:
            print(msg)
        else:
            yield from asyncio.wait(1)

The server (namely, main flask app) should be able to send a message from anywhere using e.g.,redis_conn.publish('test_channel','hello @'+str(time.time()))

Using uwsgi (compiled with asyncio support) v2.0.10 and greenlet v0.4.7.

It seems uwsgi/websockets using uwsgi's asyncio event loop are is not supported in this configuration; asyncio is not in the supported concurrency models list (here

The error i'm getting when trying to connect is (browser to websocket route):

[BUG] current_wsgi_req NOT FOUND !!!
Task exception was never retrieved
future:  exception=SystemError('you can call uwsgi api function only from the main callable',)>
Traceback (most recent call last):
  File "/usr/lib/python3.4/asyncio/tasks.py", line 237, in _step
    result = next(coro)
  File "./api/__init__.py", line 80, in try_listen
    msg = ws.receive()
  File "./api/apivenv3/lib/python3.4/site-packages/flask_uwsgi_websocket/websocket.py", line 21, in receive
    return self.recv()
  File "./api/apivenv3/lib/python3.4/site-packages/flask_uwsgi_websocket/websocket.py", line 25, in recv
    return uwsgi.websocket_recv()
SystemError: you can call uwsgi api function only from the main callable

Any way around this error from within flask? [BUG] suggests uWSGI can't tell where the request is from (thread/process issue?)