osm_nbi/msgkafka.py

   1 import logging
   2 import asyncio
   3 import yaml
   4 from aiokafka import AIOKafkaConsumer
   5 from aiokafka import AIOKafkaProducer
   6 from aiokafka.errors import KafkaError
   7 from msgbase import MsgBase, MsgException
   8 #import json
   9
  10
  11 class MsgKafka(MsgBase):
  12     def __init__(self, logger_name='msg'):
  13         self.logger = logging.getLogger(logger_name)
  14         self.host = None
  15         self.port = None
  16         self.consumer = None
  17         self.producer = None
  18         # create a different file for each topic
  19         #self.files = {}
  20
  21     def connect(self, config):
  22         try:
  23             if "logger_name" in config:
  24                 self.logger = logging.getLogger(config["logger_name"])
  25             self.host = config["host"]
  26             self.port = config["port"]
  27             self.topic_lst = []
  28             self.loop = asyncio.get_event_loop()
  29             self.broker = str(self.host) + ":" + str(self.port)
  30
  31         except Exception as e:  # TODO refine
  32             raise MsgException(str(e))
  33
  34     def disconnect(self):
  35         try:
  36             self.loop.close()
  37         except Exception as e:  # TODO refine
  38             raise MsgException(str(e))
  39
  40     def write(self, topic, key, msg):
  41         try:
  42             self.loop.run_until_complete(self.aiowrite(topic=topic, key=key,
  43                                                        msg=yaml.safe_dump(msg, default_flow_style=True),
  44                                                        loop=self.loop))
  45
  46         except Exception as e:
  47             raise MsgException("Error writing {} topic: {}".format(topic, str(e)))
  48
  49     def read(self, topic):
  50         """
  51         Read from one or several topics. it is non blocking returning None if nothing is available
  52         :param topic: can be str: single topic; or str list: several topics
  53         :return: topic, key, message; or None
  54         """
  55         try:
  56             return self.loop.run_until_complete(self.aioread(topic, self.loop))
  57         except MsgException:
  58             raise
  59         except Exception as e:
  60             raise MsgException("Error reading {} topic: {}".format(topic, str(e)))
  61
  62     async def aiowrite(self, topic, key, msg, loop):
  63         try:
  64             self.producer = AIOKafkaProducer(loop=loop, key_serializer=str.encode, value_serializer=str.encode,
  65                                              bootstrap_servers=self.broker)
  66             await self.producer.start()
  67             await self.producer.send(topic=topic, key=key, value=msg)
  68         except Exception as e:
  69             raise MsgException("Error publishing to {} topic: {}".format(topic, str(e)))
  70         finally:
  71             await self.producer.stop()
  72
  73     async def aioread(self, topic, loop):
  74         """
  75         Asyncio read from one or several topics. It blocks
  76         :param topic: can be str: single topic; or str list: several topics
  77         :param loop: asyncio loop
  78         :return: topic, key, message
  79         """
  80         try:
  81             if isinstance(topic, (list, tuple)):
  82                 topic_list = topic
  83             else:
  84                 topic_list = (topic,)
  85
  86             self.consumer = AIOKafkaConsumer(loop=loop, bootstrap_servers=self.broker)
  87             await self.consumer.start()
  88             self.consumer.subscribe(topic_list)
  89             async for message in self.consumer:
  90                 return message.topic, yaml.load(message.key), yaml.load(message.value)
  91         except KafkaError as e:
  92             raise MsgException(str(e))
  93         finally:
  94             await self.consumer.stop()
  95
  96