make shutdown cleaner

bot.py

@@ -9,7 +9,7 @@ import threading
 import traceback
 from datetime import datetime
 
-from twisted.internet import protocol
+from twisted.internet import protocol, reactor
 from twisted.words.protocols import irc
 
 import db
@@ -183,6 +183,11 @@ class Fulvia(irc.IRCClient):
 			self._user_joined.remove(func)
 
 
+	def add_shutdown(self, func):
+		"""Adds the given function to the reactor's shutdown sequence."""
+		reactor.addSystemEventTrigger('before','shutdown', func)
+
+
 	def stillConnected(self):
 		"""Returns true if the bot is still connected to the server."""
 		if self._heartbeat:

scheduler.py

@@ -2,11 +2,24 @@
 """
 Allows the bot to scheduler tasks to be performed later.
 """
-import time
 import pickle
 import threading
 from datetime import datetime
 
+stop = threading.Event()
+
+class CronThread(threading.Thread):
+	def __init__(self, scheduler):
+		super().__init__()
+		self.scheduler = scheduler
+
+	def run(self):
+		while not self.scheduler.bot.stillConnected():
+			stop.wait(1)
+		while not stop.is_set():
+			self.scheduler.run_tasks()
+			stop.wait(5)
+
 class Scheduler:
 	def __init__(self, bot):
 		self.bot = bot
@@ -14,13 +27,11 @@ class Scheduler:
 		self.lock = threading.Lock()
 		self.init_database()
 		self.load_database()
-		self._t = threading.Thread(target=self.loop)
-		self._t.start()
+		self.bot.add_shutdown(stop.set)
+		self.loop = CronThread(self)
+		self.loop.start()
 
-	def loop(self):
-		while not self.bot.stillConnected():
-			time.sleep(1)
-		while True:
+	def run_tasks(self):
 		self.lock.acquire()
 		tasks_due = [t for t in self.tasks if t[1] <= datetime.now()]
 		for task in tasks_due:
@@ -32,7 +43,7 @@ class Scheduler:
 				"DELETE FROM scheduled_task WHERE dt = ?",
 				(pickle.dumps(task[1]),))
 		self.lock.release()
-			time.sleep(5)
+
 
 	def add_task(self, func, dt, args):
 		"""