src/osm_ngsa/osm_mon/core/message_bus_client.py

   1 #######################################################################################
   2 # Copyright ETSI Contributors and Others.
   3 #
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7 #
   8 #    http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  13 # implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #######################################################################################
  17 import asyncio
  18 from typing import Callable, List
  19
  20 from osm_common import msgkafka, msglocal
  21 from osm_mon.core.config import Config
  22
  23
  24 class MessageBusClient:
  25     def __init__(self, config: Config, loop=None):
  26         if config.get("message", "driver") == "local":
  27             self.msg_bus = msglocal.MsgLocal()
  28         elif config.get("message", "driver") == "kafka":
  29             self.msg_bus = msgkafka.MsgKafka()
  30         else:
  31             raise Exception(
  32                 "Unknown message bug driver {}".format(config.get("section", "driver"))
  33             )
  34         self.msg_bus.connect(config.get("message"))
  35         if not loop:
  36             loop = asyncio.get_event_loop()
  37         self.loop = loop
  38
  39     async def aioread(self, topics: List[str], callback: Callable = None, **kwargs):
  40         """
  41         Retrieves messages continuously from bus and executes callback for each message consumed.
  42         :param topics: List of message bus topics to consume from.
  43         :param callback: Async callback function to be called for each message received.
  44         :param kwargs: Keyword arguments to be passed to callback function.
  45         :return: None
  46         """
  47         await self.msg_bus.aioread(topics, self.loop, aiocallback=callback, **kwargs)
  48
  49     async def aiowrite(self, topic: str, key: str, msg: dict):
  50         """
  51         Writes message to bus.
  52         :param topic: Topic to write to.
  53         :param key: Key to write to.
  54         :param msg: Dictionary containing message to be written.
  55         :return: None
  56         """
  57         await self.msg_bus.aiowrite(topic, key, msg, self.loop)
  58
  59     async def aioread_once(self, topic: str):
  60         """
  61         Retrieves last message from bus.
  62         :param topic: topic to retrieve message from.
  63         :return: tuple(topic, key, message)
  64         """
  65         result = await self.msg_bus.aioread(topic, self.loop)
  66         return result