# -*- coding: utf-8 -*-
"""
sleekxmpp.xmlstream.scheduler
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This module provides a task scheduler that works better
with SleekXMPP's threading usage than the stock version.
Part of SleekXMPP: The Sleek XMPP Library
:copyright: (c) 2011 Nathanael C. Fritz
:license: MIT, see LICENSE for more details
"""
import time
import threading
import logging
import itertools
from sleekxmpp.util import Queue, QueueEmpty
#: The time in seconds to wait for events from the event queue, and also the
#: time between checks for the process stop signal.
WAIT_TIMEOUT = 1.0
log = logging.getLogger(__name__)
[docs]class Task(object):
"""
A scheduled task that will be executed by the scheduler
after a given time interval has passed.
:param string name: The name of the task.
:param int seconds: The number of seconds to wait before executing.
:param callback: The function to execute.
:param tuple args: The arguments to pass to the callback.
:param dict kwargs: The keyword arguments to pass to the callback.
:param bool repeat: Indicates if the task should repeat.
Defaults to ``False``.
:param pointer: A pointer to an event queue for queuing callback
execution instead of executing immediately.
"""
def __init__(self, name, seconds, callback, args=None,
kwargs=None, repeat=False, qpointer=None):
#: The name of the task.
self.name = name
#: The number of seconds to wait before executing.
self.seconds = seconds
#: The function to execute once enough time has passed.
self.callback = callback
#: The arguments to pass to :attr:`callback`.
self.args = args or tuple()
#: The keyword arguments to pass to :attr:`callback`.
self.kwargs = kwargs or {}
#: Indicates if the task should repeat after executing,
#: using the same :attr:`seconds` delay.
self.repeat = repeat
#: The time when the task should execute next.
self.next = time.time() + self.seconds
#: The main event queue, which allows for callbacks to
#: be queued for execution instead of executing immediately.
self.qpointer = qpointer
[docs] def run(self):
"""Execute the task's callback.
If an event queue was supplied, place the callback in the queue;
otherwise, execute the callback immediately.
"""
if self.qpointer is not None:
self.qpointer.put(('schedule', self.callback,
self.args, self.kwargs, self.name))
else:
self.callback(*self.args, **self.kwargs)
self.reset()
return self.repeat
[docs] def reset(self):
"""Reset the task's timer so that it will repeat."""
self.next = time.time() + self.seconds
[docs]class Scheduler(object):
"""
A threaded scheduler that allows for updates mid-execution unlike the
scheduler in the standard library.
Based on: http://docs.python.org/library/sched.html#module-sched
:param parentstop: An :class:`~threading.Event` to signal stopping
the scheduler.
"""
def __init__(self, parentstop=None):
#: A queue for storing tasks
self.addq = Queue()
#: A list of tasks in order of execution time.
self.schedule = []
#: If running in threaded mode, this will be the thread processing
#: the schedule.
self.thread = None
#: A flag indicating that the scheduler is running.
self.run = False
#: An :class:`~threading.Event` instance for signalling to stop
#: the scheduler.
self.stop = parentstop
#: Lock for accessing the task queue.
self.schedule_lock = threading.RLock()
#: The time in seconds to wait for events from the event queue,
#: and also the time between checks for the process stop signal.
self.wait_timeout = WAIT_TIMEOUT
[docs] def process(self, threaded=True, daemon=False):
"""Begin accepting and processing scheduled tasks.
:param bool threaded: Indicates if the scheduler should execute
in its own thread. Defaults to ``True``.
"""
if threaded:
self.thread = threading.Thread(name='scheduler_process',
target=self._process)
self.thread.daemon = daemon
self.thread.start()
else:
self._process()
def _process(self):
"""Process scheduled tasks."""
self.run = True
try:
while self.run and not self.stop.is_set():
updated = False
if self.schedule:
wait = self.schedule[0].next - time.time()
else:
wait = self.wait_timeout
try:
if wait <= 0.0:
newtask = self.addq.get(False)
else:
newtask = None
while self.run and \
not self.stop.is_set() and \
newtask is None and \
wait > 0:
try:
newtask = self.addq.get(True, min(wait, self.wait_timeout))
except QueueEmpty: # Nothing to add, nothing to do. Check run flags and continue waiting.
wait -= self.wait_timeout
except QueueEmpty: # Time to run some tasks, and no new tasks to add.
self.schedule_lock.acquire()
# select only those tasks which are to be executed now
relevant = itertools.takewhile(
lambda task: time.time() >= task.next, self.schedule)
# run the tasks and keep the return value in a tuple
status = map(lambda task: (task, task.run()), relevant)
# remove non-repeating tasks
for task, doRepeat in status:
if not doRepeat:
try:
self.schedule.remove(task)
except ValueError:
pass
else:
# only need to resort tasks if a repeated task has
# been kept in the list.
updated = True
else: # Add new task
self.schedule_lock.acquire()
if newtask is not None:
self.schedule.append(newtask)
updated = True
finally:
if updated:
self.schedule.sort(key=lambda task: task.next)
self.schedule_lock.release()
except KeyboardInterrupt:
self.run = False
except SystemExit:
self.run = False
log.debug("Quitting Scheduler thread")
[docs] def add(self, name, seconds, callback, args=None,
kwargs=None, repeat=False, qpointer=None):
"""Schedule a new task.
:param string name: The name of the task.
:param int seconds: The number of seconds to wait before executing.
:param callback: The function to execute.
:param tuple args: The arguments to pass to the callback.
:param dict kwargs: The keyword arguments to pass to the callback.
:param bool repeat: Indicates if the task should repeat.
Defaults to ``False``.
:param pointer: A pointer to an event queue for queuing callback
execution instead of executing immediately.
"""
try:
self.schedule_lock.acquire()
for task in self.schedule:
if task.name == name:
raise ValueError("Key %s already exists" % name)
self.addq.put(Task(name, seconds, callback, args,
kwargs, repeat, qpointer))
except:
raise
finally:
self.schedule_lock.release()
[docs] def remove(self, name):
"""Remove a scheduled task ahead of schedule, and without
executing it.
:param string name: The name of the task to remove.
"""
try:
self.schedule_lock.acquire()
the_task = None
for task in self.schedule:
if task.name == name:
the_task = task
if the_task is not None:
self.schedule.remove(the_task)
except:
raise
finally:
self.schedule_lock.release()
[docs] def quit(self):
"""Shutdown the scheduler."""
self.run = False