cappie/queue.py

   1 #!/usr/bin/python
   2 ###############################################################################
   3 #                                                                             #
   4 # Cappie                                                                      #
   5 # Copyright (C) 2010 Michael Tremer                                           #
   6 #                                                                             #
   7 # This program is free software: you can redistribute it and/or modify        #
   8 # it under the terms of the GNU General Public License as published by        #
   9 # the Free Software Foundation, either version 3 of the License, or           #
  10 # (at your option) any later version.                                         #
  11 #                                                                             #
  12 # This program is distributed in the hope that it will be useful,             #
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  15 # GNU General Public License for more details.                                #
  16 #                                                                             #
  17 # You should have received a copy of the GNU General Public License           #
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  19 #                                                                             #
  20 ###############################################################################
  21
  22 import time
  23
  24 from threading import Thread
  25
  26 from errors import *
  27
  28 class Queue(Thread):
  29         heartbeat = 1.0
  30         maxitems = 100
  31
  32         def __init__(self, log):
  33                 Thread.__init__(self)
  34
  35                 self.log = log
  36
  37                 self.__running = True
  38                 self.__queue = []
  39
  40         def __len__(self):
  41                 return self.length
  42
  43         def add(self, event):
  44                 if self.length > self.maxitems:
  45                         raise QueueFullError, "Cannot queue new event."
  46
  47                 self.__queue.append(event)
  48
  49         @property
  50         def length(self):
  51                 return len(self.__queue)
  52
  53         def run(self):
  54                 self.log.debug("Started event queue")
  55
  56                 while self.__running or self.__queue:
  57                         if not self.__queue:
  58                                 #self.log.debug("Queue sleeping for %s seconds" % self.heartbeat)
  59                                 time.sleep(self.heartbeat)
  60                                 continue
  61
  62                         event = self.__queue.pop(0)
  63                         self.log.debug("Processing queue event: %s" % event)
  64                         try:
  65                                 event.run()
  66                         except EventException, e:
  67                                 self.log.error("Catched event exception: %s" % e)
  68
  69         def shutdown(self):
  70                 self.__running = False
  71                 self.log.debug("Shutting down queue")
  72                 self.log.debug("%d events in queue left" % len(self.__queue))
  73
  74                 # Wait until queue handled all events
  75                 self.join()