How to use the uwsgi.wait_fd_read function in uWSGI

def async_wait(conn):
    # conn can be a connection or a cursor
    if not hasattr(conn, 'poll'):
        conn = conn.connection

    # interesting part: suspend until ready
    while True:
        state = conn.poll()
        if state == psycopg2.extensions.POLL_OK:
            break
        elif state == psycopg2.extensions.POLL_READ:
            uwsgi.wait_fd_read(conn.fileno())
            uwsgi.suspend()
        elif state == psycopg2.extensions.POLL_WRITE:
            uwsgi.wait_fd_write(conn.fileno())
            uwsgi.suspend()
        else:
            raise Exception("Unexpected result from poll: %r", state)

def send_request(env, client):

    uwsgi.send(client, b"GET /intl/it_it/images/logo.gif HTTP/1.0\r\n")

    # test for suspend/resume
    uwsgi.suspend()

    uwsgi.send(client, b"Host: www.google.it\r\n\r\n")

    while 1:
        yield uwsgi.wait_fd_read(client, 2)
        if env['x-wsgiorg.fdevent.timeout']:
            return

        buf = uwsgi.recv(client, 4096)
        if buf:
            yield buf
        else:
            break

# call suspend 10 times and yield some value
    for i in range(0, 10):
        print i
        uwsgi.suspend()
        yield str(i)

    # connect to a memcached server
    fd = uwsgi.async_connect('127.0.0.1:11211')
    try:
        # start waiting for socket availability (4 seconds max)
        uwsgi.wait_fd_write(fd, 4)
        # suspend execution 'til event
        uwsgi.suspend()
        uwsgi.send(fd, "get /foobar\r\n")
        # now wait for memcached response
        uwsgi.wait_fd_read(fd, 4)
        uwsgi.suspend()
        # read the response
        data = uwsgi.recv(fd, 4096)
        # return to the client
        yield data
    finally:
        uwsgi.close(fd)

    print "sleeping for 3 seconds..."
    uwsgi.async_sleep(3)
    uwsgi.suspend()
    yield "done"

def recv(self, bufsize):
        if not self.closed:
            uwsgi.wait_fd_read(self.fileno(), 300)
            uwsgi.suspend()
        if not self.closed:
            return uwsgi.recv(self.fileno(), bufsize)

while cl > 0:
            bufsize = min(cl, 4096)
            yield uwsgi.wait_fd_read(input, 30)
            if env['x-wsgiorg.fdevent.timeout']:
                print "connection timed out !!!"
                uwsgi.close(fd)
                raise StopIteration
            body = uwsgi.recv(input, bufsize)
            if body:
                uwsgi.send(fd, body)
                cl = cl - len(body)
            else:
                break

    # wait for response (30s timeout)
    yield uwsgi.wait_fd_read(fd, 30)

    # has timed out ?
    if env['x-wsgiorg.fdevent.timeout']:
        print "connection timed out !!!"
        uwsgi.close(fd)
        raise StopIteration

    data = uwsgi.recv(fd)
    # recv the data, if it returns None the callable will end
    while data:
        yield data
        # wait for response
        yield uwsgi.wait_fd_read(fd, 30)
        if env['x-wsgiorg.fdevent.timeout']:
            print "connection timed out !!!"
            uwsgi.close(fd)

# connect to a memcached server
    fd = uwsgi.async_connect('127.0.0.1:11211')
    try:
        command = "get /foobar\r\n"
        remains = len(command)
        while remains > 0:
            # start waiting for socket availability (4 seconds max)
            uwsgi.wait_fd_write(fd, 4)
            # suspend execution 'til event
            uwsgi.suspend()
            pos = len(command) - remains
            written = uwsgi.send(fd, command[pos:])
            remains -= written

        # now wait for memcached response
        uwsgi.wait_fd_read(fd, 4)
        uwsgi.suspend()
        # read a chunk of data
        data = uwsgi.recv(fd, 4096)
        # .. and yield it
        yield data
    finally:
        # always ensure sockets are closed
        uwsgi.close(fd)

    print "sleeping for 3 seconds..."
    uwsgi.async_sleep(3)
    uwsgi.suspend()
    yield "done"

def recv(self, bufsize):
        if not self.closed:
            uwsgi.wait_fd_read(self.fileno(), -1)
            uwsgi.suspend()
        if not self.closed:
            return uwsgi.recv(self.fileno(), bufsize)