75 lines
2.0 KiB
Python
75 lines
2.0 KiB
Python
import logging
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import json
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import time
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from kafka import KafkaConsumer, KafkaProducer
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from .. import Backend
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class KafkaBackend(Backend):
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_conn_retry_secs = 5
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def __init__(self, server, topic, **kwargs):
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super().__init__(**kwargs)
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self.server = server
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self.topic_prefix = topic
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self.topic = self._topic_by_device_id(self.device_id)
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self.producer = None
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def _on_record(self, record):
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if record.topic != self.topic: return
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try:
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msg = json.loads(record.value.decode('utf-8'))
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except Exception as e:
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logging.exception(e)
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logging.debug('Received message: {}'.format(msg))
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self.on_message(msg)
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def _init_producer(self):
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if not self.producer:
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self.producer = KafkaProducer(bootstrap_servers=self.server)
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def _topic_by_device_id(self, device_id):
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return '{}.{}'.format(self.topic_prefix, device_id)
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def send_message(self, msg):
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target = msg.target
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msg = str(msg).encode('utf-8')
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self._init_producer()
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self.producer.send(self._topic_by_device_id(target), msg)
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self.producer.flush()
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def on_stop(self):
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try:
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if self.producer:
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self.producer.flush()
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self.producer.close()
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if self.consumer:
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self.consumer.close()
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except: pass
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def run(self):
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super().run()
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self.consumer = KafkaConsumer(self.topic, bootstrap_servers=self.server)
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logging.info('Initialized kafka backend - server: {}, topic: {}'
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.format(self.server, self.topic))
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try:
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for msg in self.consumer:
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self._on_record(msg)
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if self.should_stop():
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break
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except ConnectionError:
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logging.warning('Kafka connection error, retrying in {} seconds'.
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format(self._conn_retry_secs))
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time.sleep(self._conn_retry_secs)
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# vim:sw=4:ts=4:et:
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