python.d/python_modules/base.py

   1 # Description: base for netdata python.d plugins
   2 # Author: Pawel Krupa (paulfantom)
   3
   4 from time import time
   5 import sys
   6
   7
   8 class BaseService(object):
   9     """
  10     Prototype of Service class.
  11     Implemented basic functionality to run jobs by `python.d.plugin`
  12     """
  13     def __init__(self, configuration=None, name=None):
  14         """
  15         This needs to be initialized in child classes
  16         :param configuration: dict
  17         :param name: str
  18         """
  19         if configuration is None:
  20             self.error("BaseService: no configuration parameters supplied. Cannot create Service.")
  21             raise RuntimeError
  22         else:
  23             self._extract_base_config(configuration)
  24             self.timetable = {}
  25             self.create_timetable()
  26             self.execution_name = ""
  27
  28     def _extract_base_config(self, config):
  29         """
  30         Get basic parameters to run service
  31         Minimum config:
  32             config = {'update_every':1,
  33                       'priority':100000,
  34                       'retries':0}
  35         :param config: dict
  36         """
  37         self.update_every = int(config['update_every'])
  38         self.priority = int(config['priority'])
  39         self.retries = int(config['retries'])
  40         self.retries_left = self.retries
  41
  42     def create_timetable(self, freq=None):
  43         """
  44         Create service timetable.
  45         `freq` is optional
  46         Example:
  47             timetable = {'last': 1466370091.3767564,
  48                          'next': 1466370092,
  49                          'freq': 1}
  50         :param freq: int
  51         """
  52         if freq is None:
  53             freq = self.update_every
  54         now = time()
  55         self.timetable = {'last': now,
  56                           'next': now - (now % freq) + freq,
  57                           'freq': freq}
  58
  59     @staticmethod
  60     def error(msg, exception=""):
  61         if exception != "":
  62             exception = " " + str(exception).replace("\n"," ")
  63         sys.stderr.write(str(msg)+exception+"\n")
  64         sys.stderr.flush()
  65
  66     def check(self):
  67         """
  68         check() prototype
  69         :return: boolean
  70         """
  71         self.error("Service " + str(self.__name__) + "doesn't implement check() function")
  72         return False
  73
  74     def create(self):
  75         """
  76         create() prototype
  77         :return: boolean
  78         """
  79         self.error("Service " + str(self.__name__) + "doesn't implement create() function?")
  80         return False
  81
  82     def update(self):
  83         """
  84         update() prototype
  85         :return: boolean
  86         """
  87         self.error("Service " + str(self.__name__) + "doesn't implement update() function")
  88         return False