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 import util
  27
  28 from database import Database
  29 from errors import *
  30 from events import *
  31
  32 class Queue(Thread):
  33         heartbeat = 1.0
  34         maxitems = 10000
  35
  36         def __init__(self, log):
  37                 Thread.__init__(self)
  38
  39                 self.log = log
  40
  41                 self.__running = True
  42                 self.__queue = []
  43
  44                 self.db = Database(log)
  45                 self.lastgc = None
  46
  47         def __len__(self):
  48                 return self.length
  49
  50         def add(self, event):
  51                 if self.length > self.maxitems:
  52                         raise QueueFullError, "Cannot queue new event."
  53
  54                 self.__queue.append(event)
  55
  56         @property
  57         def length(self):
  58                 return len(self.__queue)
  59
  60         def run(self):
  61                 self.log.debug("Started event queue")
  62
  63                 util.setprocname("queue")
  64
  65                 self.db.open()
  66
  67                 while self.__running or self.__queue:
  68                         if not self.__queue:
  69                                 #self.log.debug("Queue sleeping for %s seconds" % self.heartbeat)
  70                                 time.sleep(self.heartbeat)
  71                                 continue
  72
  73                         self._checkGc()
  74
  75                         event = self.__queue.pop(0)
  76                         self.log.debug("Processing queue event: %s" % event)
  77                         try:
  78                                 event.run()
  79                         except EventException, e:
  80                                 self.log.error("Catched event exception: %s" % e)
  81
  82                 self.db.close()
  83
  84         def shutdown(self):
  85                 self.__running = False
  86                 self.log.debug("Shutting down queue")
  87                 self.log.debug("%d events in queue left" % len(self.__queue))
  88
  89                 # Wait until queue handled all events
  90                 self.join()
  91
  92         def _checkGc(self):
  93                 if not self.lastgc or self.lastgc <= (time.time() - DB_GC_INTERVAL):
  94                         self.add(EventGarbageCollector(self.db, self.log))
  95                         self.lastgc = time.time()