Delay connecting to RabbitMQ until it's necessary

Previously we were connecting at import-time.

(imported from commit 9a638f0d238f3b6b00feb4aa524098a64953cb92)

zerver/lib/queue.py

@@ -230,10 +230,16 @@ class TornadoQueueClient(SimpleQueueClient):
             lambda: self.channel.basic_consume(wrapped_consumer, queue=queue_name,
                 consumer_tag=self._generate_ctag(queue_name)))
 
-if settings.RUNNING_INSIDE_TORNADO and settings.USING_RABBITMQ:
-    queue_client = TornadoQueueClient()
-elif settings.USING_RABBITMQ:
-    queue_client = SimpleQueueClient()
+queue_client = None
+def get_queue_client():
+    global queue_client
+    if queue_client is None:
+        if settings.RUNNING_INSIDE_TORNADO and settings.USING_RABBITMQ:
+            queue_client = TornadoQueueClient()
+        elif settings.USING_RABBITMQ:
+            queue_client = SimpleQueueClient()
+
+    return queue_client
 
 def setup_tornado_rabbitmq():
     # When tornado is shut down, disconnect cleanly from rabbitmq
@@ -250,7 +256,7 @@ queue_lock = threading.RLock()
 def queue_json_publish(queue_name, event, processor):
     with queue_lock:
         if settings.USING_RABBITMQ:
-            queue_client.json_publish(queue_name, event)
+            get_queue_client().json_publish(queue_name, event)
         else:
             processor(event)
 

zerver/management/commands/runtornado.py

@@ -26,7 +26,7 @@ from zerver.lib.socket import get_sockjs_router, respond_send_message
 from zerver.middleware import async_request_stop
 
 if settings.USING_RABBITMQ:
-    from zerver.lib.queue import queue_client
+    from zerver.lib.queue import get_queue_client
 
 class Command(BaseCommand):
     option_list = BaseCommand.option_list + (
@@ -80,6 +80,7 @@ class Command(BaseCommand):
             print "Quit the server with %s." % (quit_command,)
 
             if settings.USING_RABBITMQ:
+                queue_client = get_queue_client()
                 # Process notifications received via RabbitMQ
                 def process_notification(chan, method, props, data):
                     tornado_callbacks.process_notification(data)