Make event queues persistent across Tornado restarts using cPickle

(imported from commit 1434d1e9d394d725827b1740c0c07249d5e716ed)

zephyr/lib/event_queue.py

@@ -1,11 +1,16 @@
 from django.conf import settings
 from collections import deque
 from tornado.ioloop import PeriodicCallback
+import os
 import time
 import socket
 import logging
 import simplejson
 import requests
+import cPickle as pickle
+import atexit
+import sys
+import signal
 
 IDLE_EVENT_QUEUE_TIMEOUT_SECS = 60 * 10
 
@@ -54,7 +59,6 @@ class ClientDescriptor(object):
 class EventQueue(object):
     def __init__(self, id):
         self.queue = deque()
-        self.connected_handler = None
         self.next_event_id = 0
         self.id = id
 
@@ -116,7 +120,47 @@ def gc_event_queues():
                  % (len(to_remove), len(affected_users), time.time() - start,
                     len(clients)))
 
-def setup_event_queue_gc(io_loop):
+PERSISTENT_QUEUE_FILENAME = os.path.join(os.path.dirname(__file__),
+                                         "..", "event_queues.pickle")
+
+def dump_event_queues():
+    start = time.time()
+    # Remove unpickle-able attributes
+    for client in clients.itervalues():
+        client.current_handler = None
+
+    with file(PERSISTENT_QUEUE_FILENAME, "w") as stored_queues:
+        pickle.dump(clients, stored_queues)
+
+    logging.info('Tornado dumped %d event queues in %.3fs'
+                 % (len(clients), time.time() - start))
+
+def setup_event_queue(io_loop):
+    global clients
+    start = time.time()
+    # Read in existing event queues
+    try:
+        with file(PERSISTENT_QUEUE_FILENAME, "r") as stored_queues:
+            clients = pickle.load(stored_queues)
+    except (IOError, EOFError):
+        pass
+
+    for client in clients.itervalues():
+        user_clients.setdefault(client.user_profile_id, []).append(client)
+
+    logging.info('Tornado loaded %d event queues in %.3fs'
+                 % (len(clients), time.time() - start))
+
+    atexit.register(dump_event_queues)
+    # Make sure we dump event queues even if we exit via signal
+    signal.signal(signal.SIGTERM, lambda signum, stack: sys.exit(1))
+
+    try:
+        os.remove(PERSISTENT_QUEUE_FILENAME)
+    except OSError:
+        pass
+
+    # Set up event queue garbage collection
     pc = PeriodicCallback(gc_event_queues, EVENT_QUEUE_GC_FREQ_MSECS, io_loop)
     pc.start()