cis/cis_lb/load_balancer/base.py

   1 import threading
   2 import urllib
   3
   4 import config
   5 import logger
   6
   7 class LoadBalancer(threading.Thread):
   8
   9     def __init__(self, id, queue):
  10         """
  11         Initialize Load Balancer,
  12         """
  13
  14         threading.Thread.__init__(self, \
  15                 name = '%s%02d' % (self.__class__.__name__, id))
  16
  17         self.queue = queue
  18
  19     def run(self):
  20
  21         while True:
  22             (request, data) = self.queue.get()
  23             urls = config.CIS_URLS[:]
  24
  25             while len(urls) != 0:
  26                 cis = self.choose(urls)
  27
  28                 # Request is forwarded to the chosen CIS.
  29                 try:
  30                     urllib.urlopen(cis + request, data)
  31                 except IOError:
  32                     logger.log_msg('Failed to forward request to %s' % cis, \
  33                             logger.LOG_LEVEL_ERROR)
  34                     continue
  35
  36                 logger.log_msg('Request forwarded to %s' % cis, \
  37                         logger.LOG_LEVEL_INFO)
  38                 break
  39
  40             self.queue.task_done()
  41
  42     def choose(self, urls):
  43         """
  44         Implement load balancing policy in this method for child classes which
  45         choses a CIS from urls parameter. The chosen URL should be deleted from
  46         urls list.
  47         """
  48         pass