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
   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 __cmp__(self, other):
  19                 return cmp(self.time, other.time)
  20
  21         def __call__(self):
  22                 f = self.func
  23                 self.func = None
  24                 if f:
  25                         return f()
  26
  27         def cancel(self):
  28                 assert self.func is not None
  29                 self.func = None
  30
  31 def schedule(delay, func, args=[], kwargs={}):
  32         task = Task(delay, func, args, kwargs)
  33         heapq.heappush(tasks, task)
  34         return task
  35
  36 def loop(timeout=30.0, use_poll=False):
  37         global running
  38         running = True
  39         oldhandler = signal.signal(signal.SIGTERM, exit)
  40
  41         while running:
  42                 now = time.time()
  43                 while tasks and tasks[0].time < now:
  44                         task = heapq.heappop(tasks)
  45                         task()
  46
  47                 t = timeout
  48                 if tasks:
  49                         t = max(min(t, tasks[0].time - now), 0)
  50
  51                 asyncore.loop(timeout=t, count=1, use_poll=use_poll)
  52
  53         signal.signal(signal.SIGTERM, oldhandler)
  54
  55 def exit(*args):
  56         global running
  57         running = False
  58
  59 __all__ = ("schedule", "loop", "exit")
  60