src/robot/mqtt & mqtt_client.py #33

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1. KavinduMethpura

   assigned

   TharinduHimantha

   on Nov 5, 2025
2. KavinduMethpura

   changed the title [-]src/robot/mqtt[/-] [+]src/robot/mqtt & mqtt_client.py[/+] on Nov 5, 2025
3. KavinduMethpura

   assigned

   Rinali-P

   and unassigned

   TharinduHimantha

   on Nov 5, 2025
4. TharinduHimantha commented on Nov 13, 2025

   

   TharinduHimantha

   on Nov 13, 2025

   More actions

   Reviewed
5. Rinali-P commented on Nov 14, 2025

   

   Rinali-P

   on Nov 14, 2025

   More actions

   In src/robot/mqtt/init.py :
   Provides clear package exports, and requires no modifications.

   In src/robot/mqtt/mqtt_msg.py :
   MODIFICATION #1: Make _next_id thread-safe to prevent race conditions when multiple threads create messages simultaneously.

   import threading
   
   class MqttMsg:
       _next_id = 0
       _lock = threading.Lock()
   
       def __init__(self, topic: str, message: str, qos: int = 0):
           # Thread-safe ID increment
           with MqttMsg._lock:
               self.id = MqttMsg._next_id
               MqttMsg._next_id += 1
   
           self.topic = topic
           self.message = message
           self.topic_groups = topic.split("/")
           self.channel = self.topic_groups[0] if len(self.topic_groups) > 1 else ""
           self.qos = qos
   

   In src/robot/mqtt/robot_mqtt_client.py :

   Problem: Connection is not guaranteed yet. Should wait for _on_connect callback to confirm success.

   MODIFICATION #1: Set _connected = True only after successful connection in _on_connect(). (set _connected = True only in _on_connect())

   def _connect(self):
       try:
           if self.user_name:
               self._client.username_pw_set(self.user_name, self.password)
           self._client.connect(self.server, self.port, keepalive=60)
           self._client.loop_start()
           print("Connecting to MQTT broker...")
       except Exception as e:
           print(f"MQTT connection error: {e}")
   

   def _on_connect(self, client, userdata, flags, rc):
       if rc == 0:
           self._connected = True
       else:
           print(f"MQTT: Connection failed with code {rc}")
   

   MODIFICATION #2: Add automatic reconnect in _on_disconnect() to handle network drops.

   def _on_disconnect(self, client, userdata, rc):
       self._connected = False
       print("Connection lost, retrying...")
       while not self._connected:
           try:
               self._client.reconnect()
           except Exception:
               time.sleep(5)
   

   MODIFICATION #3: Validate QoS values in publish() or subscribe(). By validating the value before sending, the client prevents invalid QoS settings that would otherwise cause broker errors or message delivery failures.

   if qos not in [0, 1, 2]:
       raise ValueError("QoS must be 0, 1, or 2")
   
6. Rinali-P

   closed this as completedon Nov 15, 2025
7. TharinduHimantha commented on Nov 15, 2025

   

   TharinduHimantha

   on Nov 15, 2025

   More actions

   When a custom robot is created as an object, it fails with an exception since topic "v1/localization/update" doesn't exist during the very first instance. Therefore, initially a message had to be published to the mentioned topic before testing #my_test_robot.py in order to work as intended.