opcua-with-python/opcua2mqtt/MqttPublish.py

from threading import Event
from loguru import logger
from MqttBase import AbstractMqttPublisher
from queue import Empty
import json
import datetime

LOOP_SLICE = 0.1  # seconds

class MqttPublish(AbstractMqttPublisher):
    def __init__(self, config, queue):
        super().__init__(config)
        self.queue = queue
        self.topicPre = self.config["publishTopicPrefix"]
        self.statusTopic = self.config["statusTopic"]
        self.statusThreshold = self.config["statusThreshold"]

    def localLoop(self):
        cnt = 0
        startTime = datetime.datetime.now()
        while not self.killBill:
            try:
                dataObject = self.queue.get(timeout=LOOP_SLICE)
                if not dataObject.isValid():
                    logger.error("invalid dataObject received: drop it")
                else:
                    topic = self.topicPre + '/' + dataObject.getTopicPost()
                    payload = dataObject.getPayload()
                    self.client.publish(topic, payload)
                    cnt += 1
                    logger.debug("mqtt message sent: {} -> {}".format(topic, payload))
                    if cnt % 100 == 1:
                        currentTime = datetime.datetime.now()
                        uptime = int((currentTime - startTime).total_seconds())
                        payload = { "count": cnt, "uptime": uptime }
                        self.client.publish(self.statusTopic, json.dumps(payload), retain=True)
            except Empty:
                # just evaluate the killBill at the top of the loop again
                pass
            except Exception as e:
                logger.error(f"Exception {type(e)} received in MQTT local loop: {e}")