osm_policy_module/common/message_bus_client.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Copyright 2018 Whitestack, LLC
   4 # *************************************************************
   5
   6 # This file is part of OSM Monitoring module
   7 # All Rights Reserved to Whitestack, LLC
   8
   9 # Licensed under the Apache License, Version 2.0 (the "License"); you may
  10 # not use this file except in compliance with the License. You may obtain
  11 # a copy of the License at
  12
  13 #         http://www.apache.org/licenses/LICENSE-2.0
  14
  15 # Unless required by applicable law or agreed to in writing, software
  16 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  17 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  18 # License for the specific language governing permissions and limitations
  19 # under the License.
  20
  21 # For those usages not covered by the Apache License, Version 2.0 please
  22 # contact: bdiaz@whitestack.com or glavado@whitestack.com
  23 ##
  24 import asyncio
  25 from typing import List, Callable
  26
  27 from osm_common import msgkafka, msglocal
  28
  29 from osm_policy_module.core.config import Config
  30
  31
  32 class MessageBusClient:
  33     def __init__(self, config: Config, loop=None):
  34         if config.get('message', 'driver') == "local":
  35             self.msg_bus = msglocal.MsgLocal()
  36         elif config.get('message', 'driver') == "kafka":
  37             self.msg_bus = msgkafka.MsgKafka()
  38         else:
  39             raise Exception("Unknown message bug driver {}".format(config.get('section', 'driver')))
  40         self.msg_bus.connect(config.get('message'))
  41         if not loop:
  42             loop = asyncio.get_event_loop()
  43         self.loop = loop
  44
  45     async def aioread(self, topics: List[str], callback: Callable = None, **kwargs):
  46         """
  47         Retrieves messages continuously from bus and executes callback for each message consumed.
  48         :param topics: List of message bus topics to consume from.
  49         :param callback: Async callback function to be called for each message received.
  50         :param kwargs: Keyword arguments to be passed to callback function.
  51         :return: None
  52         """
  53         await self.msg_bus.aioread(topics, self.loop, aiocallback=callback, **kwargs)
  54
  55     async def aiowrite(self, topic: str, key: str, msg: dict):
  56         """
  57         Writes message to bus.
  58         :param topic: Topic to write to.
  59         :param key: Key to write to.
  60         :param msg: Dictionary containing message to be written.
  61         :return: None
  62         """
  63         await self.msg_bus.aiowrite(topic, key, msg, self.loop)
  64
  65     async def aioread_once(self, topic: str):
  66         """
  67         Retrieves last message from bus.
  68         :param topic: topic to retrieve message from.
  69         :return: tuple(topic, key, message)
  70         """
  71         result = await self.msg_bus.aioread(topic, self.loop)
  72         return result