services/nodemanager/arvnodeman/clientactor.py

   1 #!/usr/bin/env python
   2
   3 from __future__ import absolute_import, print_function
   4
   5 import logging
   6 import time
   7
   8 import pykka
   9
  10 from .config import actor_class
  11
  12 def _notify_subscribers(response, subscribers):
  13     """Send the response to all the subscriber methods.
  14
  15     If any of the subscriber actors have stopped, remove them from the
  16     subscriber set.
  17     """
  18     dead_subscribers = set()
  19     for subscriber in subscribers:
  20         try:
  21             subscriber(response)
  22         except pykka.ActorDeadError:
  23             dead_subscribers.add(subscriber)
  24     subscribers.difference_update(dead_subscribers)
  25
  26 class RemotePollLoopActor(actor_class):
  27     """Abstract actor class to regularly poll a remote service.
  28
  29     This actor sends regular requests to a remote service, and sends each
  30     response to subscribers.  It takes care of error handling, and retrying
  31     requests with exponential backoff.
  32
  33     To use this actor, define CLIENT_ERRORS and the _send_request method.
  34     If you also define an _item_key method, this class will support
  35     subscribing to a specific item by key in responses.
  36     """
  37     def __init__(self, client, timer_actor, poll_wait=60, max_poll_wait=180):
  38         super(RemotePollLoopActor, self).__init__()
  39         self._client = client
  40         self._timer = timer_actor
  41         self._logger = logging.getLogger(self.LOGGER_NAME)
  42         self._later = self.actor_ref.proxy()
  43         self.min_poll_wait = poll_wait
  44         self.max_poll_wait = max_poll_wait
  45         self.poll_wait = self.min_poll_wait
  46         self.last_poll_time = None
  47         self.all_subscribers = set()
  48         self.key_subscribers = {}
  49         if hasattr(self, '_item_key'):
  50             self.subscribe_to = self._subscribe_to
  51
  52     def _start_polling(self):
  53         if self.last_poll_time is None:
  54             self.last_poll_time = time.time()
  55             self._later.poll()
  56
  57     def subscribe(self, subscriber):
  58         self.all_subscribers.add(subscriber)
  59         self._logger.debug("%r subscribed to all events", subscriber)
  60         self._start_polling()
  61
  62     # __init__ exposes this method to the proxy if the subclass defines
  63     # _item_key.
  64     def _subscribe_to(self, key, subscriber):
  65         self.key_subscribers.setdefault(key, set()).add(subscriber)
  66         self._logger.debug("%r subscribed to events for '%s'", subscriber, key)
  67         self._start_polling()
  68
  69     def _send_request(self):
  70         raise NotImplementedError("subclasses must implement request method")
  71
  72     def _got_response(self, response):
  73         self.poll_wait = self.min_poll_wait
  74         _notify_subscribers(response, self.all_subscribers)
  75         if hasattr(self, '_item_key'):
  76             items = {self._item_key(x): x for x in response}
  77             for key, subscribers in self.key_subscribers.iteritems():
  78                 _notify_subscribers(items.get(key), subscribers)
  79
  80     def _got_error(self, error):
  81         self.poll_wait = min(self.poll_wait * 2, self.max_poll_wait)
  82         self._logger.warning("Client error: %s - waiting %s seconds",
  83                              error, self.poll_wait)
  84
  85     def poll(self):
  86         start_time = time.time()
  87         try:
  88             response = self._send_request()
  89         except self.CLIENT_ERRORS as error:
  90             self.last_poll_time = start_time
  91             self._got_error(error)
  92         else:
  93             self.last_poll_time += self.poll_wait
  94             self._got_response(response)
  95         self._timer.schedule(self.last_poll_time + self.poll_wait,
  96                              self._later.poll)