fist working code of a tailable cursor

asyncio_mongo/protocol.py

@@ -32,10 +32,11 @@ _QUERY_OPTIONS = {
 
 
 class _MongoQuery(object):
-    def __init__(self, id, collection, limit):
+    def __init__(self, id, collection, limit, tailable=False):
         self.id = id
         self.limit = limit
         self.collection = collection
+        self.tailable = tailable
         self.documents = []
         self.future = asyncio.Future()
 
@@ -180,7 +181,7 @@ class MongoProtocol(asyncio.Protocol):
             query_opts |= _QUERY_OPTIONS["await_data"]
         query_opts = struct.pack("<i", query_opts)
 
-        query = _MongoQuery(self.__id, collection, limit)
+        query = _MongoQuery(self.__id, collection, limit, tailable)
         self.__queries[self.__id] = query
         self.send_message(2004, collection, message, query_opts)
         return query.future
@@ -196,6 +197,8 @@ class MongoProtocol(asyncio.Protocol):
             query = self.__queries.pop(request_id)
         except KeyError:
             return
+        if query.tailable:
+            query.documents = []
         if isinstance(documents, list):
             query.documents += documents
         else:
@@ -216,5 +219,10 @@ class MongoProtocol(asyncio.Protocol):
                     return
             self.__queries[self.__id] = query
             self.OP_GET_MORE(query.collection, next_batch, cursor_id)
+            if query.tailable and query.documents:
+                f = asyncio.Future()
+                _f = query.future
+                query.future = f
+                _f.set_result((f, documents))
         else:
             query.future.set_result(query.documents)