Improve network handling and implement time-based KeepAlive

adafruit_minimqtt.py

@@ -90,10 +90,12 @@ class MQTT:
     :param str client_id: Optional client identifier, defaults to a unique, generated string.
     :param bool is_ssl: Sets a secure or insecure connection with the broker.
     :param bool log: Attaches a logger to the MQTT client, defaults to logging level INFO.
+    :param int keep_alive: KeepAlive interval between the broker and the MiniMQTT client.
     """
     # pylint: disable=too-many-arguments,too-many-instance-attributes, not-callable, invalid-name, no-member
     def __init__(self, socket, broker, port=None, username=None,
-                 password=None, network_manager=None, client_id=None, is_ssl=True, log=False):
+                 password=None, network_manager=None, client_id=None,
+                 is_ssl=True, log=False, keep_alive=60):
         # network management
         self._socket = socket
         network_manager_type = str(type(network_manager))
@@ -137,9 +139,11 @@ def __init__(self, socket, broker, port=None, username=None,
         self._is_connected = False
         self._msg_size_lim = MQTT_MSG_SZ_LIM
         self.packet_id = 0
-        self._keep_alive = 60
+        self._keep_alive = keep_alive
         self._pid = 0
         self._user_data = None
+        self._timestamp = 0
+        # List of subscribed topics, used for tracking
         self._subscribed_topics = []
         # Server callbacks
         self.on_message = None
@@ -180,34 +184,6 @@ def last_will(self, topic=None, message=None, qos=0, retain=False):
         self._lw_msg = message
         self._lw_retain = retain
 
-    def reconnect(self, retries=30, resub_topics=True):
-        """Attempts to reconnect to the MQTT broker.
-        :param int retries: Amount of retries before resetting the network interface.
-        :param bool resub_topics: Resubscribe to previously subscribed topics.
-        """
-        retries = 0
-        while not self._is_connected:
-            if self._logger is not None:
-                self._logger.debug('Attempting to reconnect to broker')
-            try:
-                self.connect()
-                if self._logger is not None:
-                    self._logger.debug('Reconnected to broker')
-                if resub_topics:
-                    if self._logger is not None:
-                        self._logger.debug('Attempting to resubscribe to prv. subscribed topics.')
-                    while self._subscribed_topics:
-                        feed = self._subscribed_topics.pop()
-                        self.subscribe(feed)
-            except OSError as e:
-                if self._logger is not None:
-                    self._logger.debug('Lost connection, reconnecting and resubscribing...', e)
-                retries += 1
-                if retries >= 30:
-                    retries = 0
-                time.sleep(1)
-                continue
-
     # pylint: disable=too-many-branches, too-many-statements
     def connect(self, clean_session=True):
         """Initiates connection with the MQTT Broker.
@@ -564,29 +540,100 @@ def unsubscribe(self, topic):
                     self._subscribed_topics.remove(t)
                 return
 
+    @property
+    def is_wifi_connected(self):
+        """Returns if the ESP module is connected to
+        an access point, resets module if False"""
+        if self._wifi:
+            return self._wifi.esp.is_connected
+        raise MMQTTException("MiniMQTT Client does not use a WiFi NetworkManager.")
+
+    # pylint: disable=line-too-long, protected-access
+    @property
+    def is_sock_connected(self):
+        """Returns if the socket is connected."""
+        return self.is_wifi_connected and self._sock and self._wifi.esp.socket_connected(self._sock._socknum)
+
+    def reconnect_socket(self):
+        """Re-establishes the socket's connection with the MQTT broker.
+        """
+        try:
+            if self._logger is not None:
+                self._logger.debug("Attempting to reconnect with MQTT Broker...")
+            self.reconnect()
+        except RuntimeError as err:
+            if self._logger is not None:
+                self._logger.debug('Failed to reconnect with MQTT Broker, retrying...', err)
+            time.sleep(1)
+            self.reconnect_socket()
+
+    def reconnect_wifi(self):
+        """Reconnects to WiFi Access Point and socket, if disconnected.
+        """
+        while not self.is_wifi_connected:
+            try:
+                if self._logger is not None:
+                    self._logger.debug('Connecting to WiFi AP...')
+                self._wifi.connect()
+            except (RuntimeError, ValueError):
+                if self._logger is not None:
+                    self._logger.debug('Failed to reset WiFi module, retrying...')
+                time.sleep(1)
+        # we just reconnected, is the socket still connected?
+        if not self.is_sock_connected:
+            self.reconnect_socket()
+
+    def reconnect(self, resub_topics=True):
+        """Attempts to reconnect to the MQTT broker.
+        :param bool resub_topics: Resubscribe to previously subscribed topics.
+        """
+        if self._logger is not None:
+            self._logger.debug('Attempting to reconnect with MQTT broker')
+        self.connect()
+        if self._logger is not None:
+            self._logger.debug('Reconnected with broker')
+        if resub_topics:
+            if self._logger is not None:
+                self._logger.debug('Attempting to resubscribe to previously subscribed topics.')
+            while self._subscribed_topics:
+                feed = self._subscribed_topics.pop()
+                self.subscribe(feed)
+
     def loop_forever(self):
         """Starts a blocking message loop. Use this
         method if you want to run a program forever.
+        Code below a call to this method will NOT execute.
         Network reconnection is handled within this call.
-        Your code will not execute anything below this call.
+
         """
-        run = True
-        while run:
-            if self._is_connected:
-                self._wait_for_msg(0.0)
-            else:
-                if self._logger is not None:
-                    self._logger.debug('Lost connection, reconnecting and resubscribing...')
-                self.reconnect(resub_topics=True)
-                if self._logger is not None:
-                    self._logger.debug('Connection restored, continuing to loop forever...')
+        while True:
+            # Check WiFi and socket status
+            if self.is_sock_connected:
+                try:
+                    self.loop()
+                except (RuntimeError, ValueError):
+                    if self._wifi:
+                        # Reconnect the WiFi module and the socket
+                        self.reconnect_wifi()
+                    continue
 
     def loop(self):
         """Non-blocking message loop. Use this method to
-        check incoming subscription messages. Does not handle
-        network reconnection like loop_forever - reconnection must
-        be handled within your code.
+        check incoming subscription messages.
+
+        This method does NOT handle networking or
+        network hardware management, use loop_forever
+        or handle in code instead.
         """
+        if self._timestamp == 0:
+            self._timestamp = time.monotonic()
+        current_time = time.monotonic()
+        if current_time - self._timestamp >= self._keep_alive:
+            # Handle KeepAlive by expecting a PINGREQ/PINGRESP from the server
+            if self._logger is not None:
+                self._logger.debug('KeepAlive period elapsed - requesting a PINGRESP from the server...')
+            self.ping()
+            self._timestamp = 0
         self._sock.settimeout(0.1)
         return self._wait_for_msg()