Python3 passing a queue to a multi-threaded HTTP server class

Question

I will be the first to admit that I am still relatively new to Python. This board has been a lot of help...

I am working on a project where I am using a multi-threaded HTTP server and i need to send a signal back to the main loop. I am trying to base this off of this: Passing a Queue to ThreadedHTTPServer

Here is the extract of what I am currently doing (in Python 3.4):

if __name__ == '__main__':
    ...
    q1 = Queue(maxsize=0)

    ...
    remote_http_thread = threading.Thread(target=remote_threader, args=(q1))
    remote_http_thread.daemon = True
    remote_http_thread.start()
    ...


    while 1:
        time.sleep(1)
        try:
            my_message = q1.get_nowait()
            message_flag = 1
            print("GOT THE FOLLOWING QUEUE MESSAGE :", my_message)
        except:
            message flag = 0
        ...

The following is in a different file (my HTTP server code):

def remote_threader(qit):
    remote_Server = ThreadedHTTPServer(("", 35677), P_Server)
    remote_Server.qu = qit
    remote_Server.serve_forever()

class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
    """Handle requests in a separate thread."""

class P_Server(BaseHTTPRequestHandler):
    def __init__(self, request, client_address, server):
    BaseHTTPRequestHandler.__init__(self, request, client_address, server)
    self.qu = server.qu # save the queue here.

    def go_GET(self):
        ...
        #  We have an event that we want to signal back to the main loop
        self.qu.put("Event")

The HTTP server works fine and I am now trying to pass the message back to the main loop so that certain events cause things to occur. running the above code results in an exception that P_Server has not attribute 'qu'

It appears from testing that any attribute I create in the init step (even a hard coded number or string) is not available in the "do_GET" section.

Can anyone let me know what i am doing wrong here and I can change it so that the main section will get the message put into the queue in the HTTP server class?

Answer 1

Try setting the attribute before the call to

BaseHTTPRequestHandler.__init__()

so the code becomes...

def remote_threader(qit):
    remote_Server = ThreadedHTTPServer(("", 35677), P_Server)
    remote_Server.qu = qit
    remote_Server.serve_forever()

class ThreadedHTTPServer(ThreadingMixIn, HTTPServer):
    """Handle requests in a separate thread."""

class P_Server(BaseHTTPRequestHandler):
    def __init__(self, request, client_address, server):
        # THE ATTRIBUTE IS SET HERE
        self.qu = server.qu # save the queue here.
        # super's init called after setting attribute
        BaseHTTPRequestHandler.__init__(self, request, client_address, server)

    def go_GET(self):
        ...
        #  Accessed in GET
        self.qu.put("Event")

Worked for me when i set the attribute before the call to BaseHttpRequestHandler's init