code.delx.au - bg-scripts/blob - asyncsched.py

   1 # Copyright 2008 James Bunton <jamesbunton@fastmail.fm>
   2 # Licensed for distribution under the GPL version 2, check COPYING for details
   3 # asyncore.loop() with delayed function calls
   4
   5 import asyncore, select
   6 import heapq
   7 import signal
   8 import time
   9
  10 tasks = []
  11 running = False
  12
  13 class Task(object):
  14     def __init__(self, delay, func, args=[], kwargs={}):
  15         self.time = time.time() + delay
  16         self.func = lambda: func(*args, **kwargs)
  17
  18     def __lt__(self, other):
  19         return self.time < other.time
  20
  21     def __eq__(self, other):
  22         return self.time == other.time
  23
  24     def __call__(self):
  25         f = self.func
  26         self.func = None
  27         if f:
  28             return f()
  29
  30     def cancel(self):
  31         assert self.func is not None
  32         self.func = None
  33
  34 def schedule(delay, func, args=[], kwargs={}):
  35     task = Task(delay, func, args, kwargs)
  36     heapq.heappush(tasks, task)
  37     return task
  38
  39 def loop(timeout=30.0, use_poll=False):
  40     global running
  41     running = True
  42     oldhandler = signal.signal(signal.SIGTERM, exit)
  43
  44     while running:
  45         now = time.time()
  46         while tasks and tasks[0].time < now:
  47             task = heapq.heappop(tasks)
  48             task()
  49
  50         t = timeout
  51         if tasks:
  52             t = max(min(t, tasks[0].time - now), 0)
  53
  54         asyncore.poll2(timeout=t)
  55
  56     signal.signal(signal.SIGTERM, oldhandler)
  57
  58 def exit(*args):
  59     global running
  60     running = False
  61
  62 __all__ = ("schedule", "loop", "exit")
  63