Add queue support for draining a queue completely

(imported from commit 50cc52f8b5b74b274024222596c6f2bd27832c89)

zephyr/lib/queue.py

@@ -106,6 +106,24 @@ class SimpleQueueClient(object):
             return callback(ch, method, properties, simplejson.loads(body))
         return self.register_consumer(queue_name, wrapped_callback)
 
+    def drain_queue(self, queue_name, json=False):
+        "Returns all messages in the desired queue"
+        messages =[]
+        def opened():
+            while True:
+                (meta, _, message) = self.channel.basic_get(queue_name)
+
+                if not message:
+                    break;
+
+                self.channel.basic_ack(meta.delivery_tag)
+                if json:
+                    message = simplejson.loads(message)
+                messages.append(message)
+
+        self.ensure_queue(queue_name, opened)
+        return messages
+
     def start_consuming(self):
         self.channel.start_consuming()