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 database import Database
  27 from errors import *
  28
  29 class Queue(Thread):
  30         heartbeat = 1.0
  31         maxitems = 100
  32
  33         def __init__(self, log):
  34                 Thread.__init__(self)
  35
  36                 self.log = log
  37
  38                 self.__running = True
  39                 self.__queue = []
  40
  41                 self.db = Database(log)
  42
  43         def __len__(self):
  44                 return self.length
  45
  46         def add(self, event):
  47                 if self.length > self.maxitems:
  48                         raise QueueFullError, "Cannot queue new event."
  49
  50                 self.__queue.append(event)
  51
  52         @property
  53         def length(self):
  54                 return len(self.__queue)
  55
  56         def run(self):
  57                 self.log.debug("Started event queue")
  58
  59                 self.db.open()
  60
  61                 while self.__running or self.__queue:
  62                         if not self.__queue:
  63                                 #self.log.debug("Queue sleeping for %s seconds" % self.heartbeat)
  64                                 time.sleep(self.heartbeat)
  65                                 continue
  66
  67                         event = self.__queue.pop(0)
  68                         self.log.debug("Processing queue event: %s" % event)
  69                         try:
  70                                 event.run()
  71                         except EventException, e:
  72                                 self.log.error("Catched event exception: %s" % e)
  73
  74                 self.db.close()
  75
  76         def shutdown(self):
  77                 self.__running = False
  78                 self.log.debug("Shutting down queue")
  79                 self.log.debug("%d events in queue left" % len(self.__queue))
  80
  81                 # Wait until queue handled all events
  82                 self.join()