osm_nbi/subscriptions.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #    http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  12 # implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16 """
  17 This module implements a thread that reads from kafka bus implementing all the subscriptions.
  18 It is based on asyncio.
  19 To avoid race conditions it uses same engine class as the main module for database changes
  20 For the moment this module only deletes NS instances when they are terminated with the autoremove flag
  21 """
  22
  23 import logging
  24 import threading
  25 import asyncio
  26 from http import HTTPStatus
  27 from osm_common import dbmongo, dbmemory, msglocal, msgkafka
  28 from osm_common.dbbase import DbException
  29 from osm_common.msgbase import MsgException
  30 from engine import EngineException
  31
  32 __author__ = "Alfonso Tierno <alfonso.tiernosepulveda@telefonica.com>"
  33
  34
  35 class SubscriptionException(Exception):
  36
  37     def __init__(self, message, http_code=HTTPStatus.BAD_REQUEST):
  38         self.http_code = http_code
  39         Exception.__init__(self, message)
  40
  41
  42 class SubscriptionThread(threading.Thread):
  43
  44     def __init__(self, config, engine):
  45         """
  46         Constructor of class
  47         :param config: configuration parameters of database and messaging
  48         :param engine: an instance of Engine class, used for deleting instances
  49         """
  50         threading.Thread.__init__(self)
  51
  52         self.config = config
  53         self.db = None
  54         self.msg = None
  55         self.engine = engine
  56         self.loop = None
  57         self.logger = logging.getLogger("nbi.subscriptions")
  58         self.aiomain_task = None  # asyncio task for receiving kafka bus
  59         self.internal_session = {  # used for a session to the engine methods
  60             "_id": "subscription",
  61             "id": "subscription",
  62             "project_id": "admin",
  63             "admin": True
  64         }
  65
  66     def run(self):
  67         """
  68         Start of the thread
  69         :return: None
  70         """
  71         self.loop = asyncio.new_event_loop()
  72         try:
  73             if not self.db:
  74                 if self.config["database"]["driver"] == "mongo":
  75                     self.db = dbmongo.DbMongo()
  76                     self.db.db_connect(self.config["database"])
  77                 elif self.config["database"]["driver"] == "memory":
  78                     self.db = dbmemory.DbMemory()
  79                     self.db.db_connect(self.config["database"])
  80                 else:
  81                     raise SubscriptionException("Invalid configuration param '{}' at '[database]':'driver'".format(
  82                         self.config["database"]["driver"]))
  83             if not self.msg:
  84                 config_msg = self.config["message"].copy()
  85                 config_msg["loop"] = self.loop
  86                 if config_msg["driver"] == "local":
  87                     self.msg = msglocal.MsgLocal()
  88                     self.msg.connect(config_msg)
  89                 elif config_msg["driver"] == "kafka":
  90                     self.msg = msgkafka.MsgKafka()
  91                     self.msg.connect(config_msg)
  92                 else:
  93                     raise SubscriptionException("Invalid configuration param '{}' at '[message]':'driver'".format(
  94                         config_msg["driver"]))
  95
  96         except (DbException, MsgException) as e:
  97             raise SubscriptionException(str(e), http_code=e.http_code)
  98
  99         self.logger.debug("Starting")
 100         while True:
 101             try:
 102                 self.aiomain_task = asyncio.ensure_future(self.msg.aioread("ns", loop=self.loop,
 103                                                                            callback=self._msg_callback),
 104                                                           loop=self.loop)
 105                 self.loop.run_until_complete(self.aiomain_task)
 106             except asyncio.CancelledError:
 107                 break  # if cancelled it should end, breaking loop
 108             except Exception as e:
 109                 self.logger.exception("Exception '{}' at messaging read loop".format(e), exc_info=True)
 110
 111         self.logger.debug("Finishing")
 112         self._stop()
 113         self.loop.close()
 114
 115     def _msg_callback(self, topic, command, params):
 116         """
 117         Callback to process a received message from kafka
 118         :param topic:  topic received
 119         :param command:  command received
 120         :param params: rest of parameters
 121         :return: None
 122         """
 123         try:
 124             if topic == "ns":
 125                 if command == "terminated":
 126                     self.logger.debug("received ns terminated {}".format(params))
 127                     if params.get("autoremove"):
 128                         self.engine.del_item(self.internal_session, "nsrs", _id=params["nsr_id"])
 129                         self.logger.debug("ns={} deleted from database".format(params["nsr_id"]))
 130                     return
 131         except (EngineException, DbException, MsgException) as e:
 132             self.logger.error("Error while processing topic={} command={}: {}".format(topic, command, e))
 133         except Exception as e:
 134             self.logger.exception("Exception while processing topic={} command={}: {}".format(topic, command, e),
 135                                   exc_info=True)
 136
 137     def _stop(self):
 138         """
 139         Close all connections
 140         :return: None
 141         """
 142         try:
 143             if self.db:
 144                 self.db.db_disconnect()
 145             if self.msg:
 146                 self.msg.disconnect()
 147         except (DbException, MsgException) as e:
 148             raise SubscriptionException(str(e), http_code=e.http_code)
 149
 150     def terminate(self):
 151         """
 152         This is a threading safe method to terminate this thread. Termination is done asynchronous afterwards,
 153         but not immediately.
 154         :return: None
 155         """
 156         self.loop.call_soon_threadsafe(self.aiomain_task.cancel)