chat_archiver: Start a new client on RECONNECT

chat_archiver/chat_archiver/main.py

@@ -1,5 +1,4 @@
 
-from calendar import timegm
 import base64
 import hashlib
 import json
@@ -8,7 +7,9 @@ import os
 import signal
 import socket
 import time
+from calendar import timegm
 from datetime import datetime
+from itertools import count
 from uuid import uuid4
 
 import gevent.event
@@ -55,6 +56,7 @@ class Archiver(object):
 		self.path = os.path.join(base_dir, channel)
 		
 		self.stopping = gevent.event.Event()
+		self.got_reconnect = gevent.event.Event()
 		self.client = Client(
 			hostname='irc.chat.twitch.tv',
 			port=6697,
@@ -74,8 +76,17 @@ class Archiver(object):
 		@self.client.handler(command='ROOMSTATE', sync=True)
 		def register_real_handler(client, message):
 			self.client.handler(lambda c, m: self.messages.put(m), sync=True)
+			self.logger.info("Client started")
 			return True
 
+		# Twitch sends a RECONNECT shortly before terminating the connection from the server side.
+		# This gives us time to start up a new instance of the archiver while keeping this one
+		# running, so that we can be sure we don't miss anything. This will cause duplicate batches,
+		# but those will get merged later.
+		@self.client.handler(command='RECONNECT')
+		def handle_reconnect(client, message):
+			self.got_reconnect.set()
+
 		self.client.start()
 
 		last_server_time = None
@@ -83,7 +94,7 @@ class Archiver(object):
 		# {batch time: [messages]}
 		batches = {}
 
-		while not self.stopping.is_set():
+		while not (self.stopping.is_set() and self.messages.empty()):
 			# wait until we either have a message, are stopping, or a batch can be closed
 			if batches:
 				next_batch_close = min(batches.keys()) + BATCH_INTERVAL + MAX_SERVER_LAG
@@ -168,6 +179,7 @@ class Archiver(object):
 			write_batch(self.path, batch_time, messages)
 
 		self.client.wait_for_stop() # re-raise any errors
+		self.logger.info("Client stopped")
 
 	def stop(self):
 		self.client.stop()
@@ -376,12 +388,30 @@ def merge_messages(left, right):
 def main(channel, nick, oauth_token_path, base_dir='/mnt'):
 	with open(oauth_token_path) as f:
 		oauth_token = f.read()
-	name = socket.gethostname()
+	# To ensure uniqueness even if multiple instances are running on the same host,
+	# also include our pid
+	name = "{}.{}".format(socket.gethostname(), os.getpid())
 
-	archiver = Archiver(name, base_dir, channel, nick, oauth_token)
-
-	gevent.signal_handler(signal.SIGTERM, archiver.stop)
+	stopping = gevent.event.Event()
+	gevent.signal_handler(signal.SIGTERM, stopping.set)
 
 	logging.info("Starting")
-	archiver.run()
+	for index in count():
+		# To ensure uniqueness between clients, include a client number
+		archiver = Archiver("{}.{}".format(name, index), base_dir, channel, nick, oauth_token)
+		worker = gevent.spawn(archiver.run)
+		# wait for either graceful exit, error, or for a signal from the archiver that a reconnect was requested
+		gevent.wait([stopping, worker, archiver.got_reconnect], count=1)
+		if stopping.is_set():
+			archiver.stop()
+			worker.get()
+			break
+		# if got reconnect, discard the old archiver (we don't care even if it fails after this)
+		# and make a new one
+		if archiver.got_reconnect.is_set():
+			logging.info("Got RECONNECT, creating new client while waiting for old one to finish")
+			continue
+		# the only remaining case is that the worker failed, re-raise
+		worker.get()
+		assert False, "Not stopping, but worker exited successfully"
 	logging.info("Gracefully stopped")