micropython
umqtt.robust: check_msg() blocks after reconnect
By testing the issue described in #186 I found that check_msg() did not work as expected in case of reconnection. This isssue may be related to #102 ...
I can reproduce it with the ESP8266 and unix port. Broker is mosquitto 1.3.4 with persistence true.
import utime as time
from umqtt.robust import MQTTClient
def sub_cb(topic, msg):
print((topic, msg))
c = MQTTClient("umqtt_client", SERVER)
c.DEBUG = True
c.set_callback(sub_cb)
c.connect(clean_session=False)
c.subscribe(b"foo_topic")
Now you can call c.check_msg() multiple times and see the non-blocking behaviour and if you publish a message then sub_cb() is called, as expected.
But if you restart the broker and call c.check_msg() again, you get:
>>> c.check_msg()
mqtt: OSError(-1,)
and check_msg() blocks until a new message is published.
This behaviour is obviously, because during reconnect, connect() creates a new socket and do not set non-blocking mode.
IMHO blocking during reconnection is fine, since delay() can be overriden, but check_msg() should not block, without pending message.
You found a solution? Is it fixed? What is the solution to a robust connection??
