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"""
SleekXMPP: The Sleek XMPP Library
Copyright (C) 2010 Nathanael C. Fritz
This file is part of SleekXMPP.
See the file LICENSE for copying permission.
"""
import time
import threading
import logging
try:
import queue
except ImportError:
import Queue as queue
log = logging.getLogger(__name__)
class Task(object):
"""
A scheduled task that will be executed by the scheduler
after a given time interval has passed.
Attributes:
name -- The name of the task.
seconds -- The number of seconds to wait before executing.
callback -- The function to execute.
args -- The arguments to pass to the callback.
kwargs -- The keyword arguments to pass to the callback.
repeat -- Indicates if the task should repeat.
Defaults to False.
qpointer -- A pointer to an event queue for queuing callback
execution instead of executing immediately.
Methods:
run -- Either queue or execute the callback.
reset -- Reset the task's timer.
"""
def __init__(self, name, seconds, callback, args=None,
kwargs=None, repeat=False, qpointer=None):
"""
Create a new task.
Arguments:
name -- The name of the task.
seconds -- The number of seconds to wait before executing.
callback -- The function to execute.
args -- The arguments to pass to the callback.
kwargs -- The keyword arguments to pass to the callback.
repeat -- Indicates if the task should repeat.
Defaults to False.
qpointer -- A pointer to an event queue for queuing callback
execution instead of executing immediately.
"""
self.name = name
self.seconds = seconds
self.callback = callback
self.args = args or tuple()
self.kwargs = kwargs or {}
self.repeat = repeat
self.next = time.time() + self.seconds
self.qpointer = qpointer
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.name))
else:
self.callback(*self.args, **self.kwargs)
self.reset()
return self.repeat
def reset(self):
"""
Reset the task's timer so that it will repeat.
"""
self.next = time.time() + self.seconds
class Scheduler(object):
"""
A threaded scheduler that allows for updates mid-execution unlike the
scheduler in the standard library.
http://docs.python.org/library/sched.html#module-sched
Attributes:
addq -- A queue storing added tasks.
schedule -- A list of tasks in order of execution times.
thread -- If threaded, the thread processing the schedule.
run -- Indicates if the scheduler is running.
stop -- Threading event indicating if the main process
has been stopped.
Methods:
add -- Add a new task to the schedule.
process -- Process and schedule tasks.
quit -- Stop the scheduler.
"""
def __init__(self, parentstop=None):
"""
Create a new scheduler.
Arguments:
parentstop -- A threading event indicating if the main process has
been stopped.
"""
self.addq = queue.Queue()
self.schedule = []
self.thread = None
self.run = False
self.stop = parentstop
self.schedule_lock = threading.RLock()
def process(self, threaded=True):
"""
Begin accepting and processing scheduled tasks.
Arguments:
threaded -- Indicates if the scheduler should execute in its own
thread. Defaults to True.
"""
if threaded:
self.thread = threading.Thread(name='sheduler_process',
target=self._process)
self.thread.start()
else:
self._process()
def _process(self):
"""Process scheduled tasks."""
self.run = True
try:
while self.run and not self.stop.isSet():
wait = 1
updated = False
if self.schedule:
wait = self.schedule[0].next - time.time()
try:
if wait <= 0.0:
newtask = self.addq.get(False)
else:
if wait >= 3.0:
wait = 3.0
newtask = self.addq.get(True, wait)
except queue.Empty:
cleanup = []
self.schedule_lock.acquire()
for task in self.schedule:
if time.time() >= task.next:
updated = True
if not task.run():
cleanup.append(task)
else:
break
for task in cleanup:
x = self.schedule.pop(self.schedule.index(task))
else:
updated = True
self.schedule_lock.acquire()
self.schedule.append(newtask)
finally:
if updated:
self.schedule = sorted(self.schedule,
key=lambda task: task.next)
self.schedule_lock.release()
except KeyboardInterrupt:
self.run = False
except SystemExit:
self.run = False
log.debug("Quitting Scheduler thread")
def add(self, name, seconds, callback, args=None,
kwargs=None, repeat=False, qpointer=None):
"""
Schedule a new task.
Arguments:
name -- The name of the task.
seconds -- The number of seconds to wait before executing.
callback -- The function to execute.
args -- The arguments to pass to the callback.
kwargs -- The keyword arguments to pass to the callback.
repeat -- Indicates if the task should repeat.
Defaults to False.
qpointer -- 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()
def remove(self, name):
"""
Remove a scheduled task ahead of schedule, and without
executing it.
Arguments:
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()
def quit(self):
"""Shutdown the scheduler."""
self.run = False
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