Source code for volttron.platform.agent.sched

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'''VOLTTRON platform™ agent event scheduling classes.'''


import heapq
import time as time_mod


class Event(object):
    '''Base class for schedulable objects.'''

    __slots__ = ['function', 'args', 'kwargs', 'canceled', 'finished']

    def __init__(self, function, args=None, kwargs=None):
        self.function = function
        self.args = args or []
        self.kwargs = kwargs or {}
        self.canceled = False
        self.finished = False

    def cancel(self):
        '''Mark the timer as canceled to avoid a callback.'''
        self.canceled = True

    def __call__(self, deadline):
        if not self.canceled:
            self.function(*self.args, **self.kwargs)
        self.finished = True
        
class EventWithTime(Event): 
    '''Event that passes deadline to event handler.'''
    def __call__(self, deadline):
        if not self.canceled:
            self.function(deadline, *self.args, **self.kwargs)
        self.finished = True


class RecurringEvent(Event):
    __slots__ = ['period']

    def __init__(self, period, function, args=None, kwargs=None):
        super(RecurringEvent, self).__init__(function, args, kwargs)
        self.period = period

    def __call__(self, deadline):
        if not self.canceled:
            self.function(*self.args, **self.kwargs)
            if not self.canceled:
                return deadline + self.period
        self.finished = True


class Queue(object):
    def __init__(self):
        self._queue = []

    def schedule(self, time, event):
        heapq.heappush(self._queue, (time, event))

    def execute(self, time):
        if not self._queue:
            return
        deadline, callback = event = self._queue[0]
        if deadline > time:
            return
        assert heapq.heappop(self._queue) == event
        time = callback(deadline)
        if time is not None:
            if hasattr(time, 'timetuple'):
                time = time_mod.mktime(time.timetuple())
            heapq.heappush(self._queue, (time, callback))
        return True

    def delay(self, time):
        if not self._queue:
            return
        deadline, _ = self._queue[0]
        return deadline - time if deadline > time else 0

    def __bool__(self):
        return bool(self._queue)