chrome/test/pyautolib/timer_queue.py

   1 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import copy
   6 import threading
   7 import time
   8
   9 class TimerQueue(threading.Thread):
  10   """Executes timers at a given interval.
  11
  12   This class provides the ability to run methods at a given interval.  All
  13   methods are fired synchronously.  Only one method is running at a time.
  14
  15   Example of using TimerQueue:
  16     def _fooPrinter(word):
  17       print('foo : %s' % word)
  18
  19     timers = TimerQueue()
  20     timers.addTimer(self._fooPrinter, 15, args=('hello',))
  21     timers.start()
  22
  23   >> hello will be printed after 15 seconds
  24
  25   Note: TimerQueue is a subclass of threading.Thread, call start() to activate;
  26   do not call run() directly.
  27   """
  28
  29   def __init__(self):
  30     """Initializes a TimerQueue object."""
  31     threading.Thread.__init__(self, name='timer_thread')
  32     self.timer_queue_lock = threading.Lock()
  33     self.terminate = False
  34     self.wait_time = 1
  35     self.timers = []
  36
  37   def AddTimer(self, method, interval, args=()):
  38     """Adds a timer to the queue.
  39
  40     Args:
  41       method: the method to be called at the given interval
  42       interval: delay between method runs, in seconds
  43       args: arguments to be passed to the method
  44     """
  45     self.timer_queue_lock.acquire()
  46     next_time = time.time() + interval
  47     self.timers.append({'method': method, 'interval': interval,
  48                         'next time': next_time, 'args': copy.copy(args)})
  49     self.timer_queue_lock.release()
  50
  51   def SetResolution(self, resolution):
  52     """Sets the timer check frequency, in seconds."""
  53     self.wait_time = resolution
  54
  55   def RemoveTimer(self, method):
  56     """Removes a timer from the queue.
  57
  58     Args:
  59       method: the timer containing the given method to be removed
  60     """
  61     self.timer_queue_lock.acquire()
  62     for timer in self.timers:
  63       if timer['method'] == method:
  64         self.timers.remove(timer)
  65         break
  66     self.timer_queue_lock.release()
  67
  68   def Stop(self):
  69     """Stops the timer."""
  70     self.terminate = True
  71
  72   def run(self):
  73     """Primary run loop for the timer."""
  74     while True:
  75       now = time.time()
  76       self.timer_queue_lock.acquire()
  77       for timer in self.timers:
  78         if timer['next time'] <= now:
  79           # Use * to break the list into separate arguments
  80           timer['method'](*timer['args'])
  81           timer['next time'] += timer['interval']
  82       self.timer_queue_lock.release()
  83       if self.terminate:
  84         return
  85       time.sleep(self.wait_time)