1 files changed, 19 insertions, 11 deletions
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index e850e45e46..a9abdf42e0 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -13,17 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import List, Tuple
+from typing import TYPE_CHECKING, List, Optional, Tuple
 
 from synapse.appservice import ApplicationService
 from synapse.handlers._base import BaseHandler
 from synapse.types import JsonDict, ReadReceipt, get_domain_from_id
 
+if TYPE_CHECKING:
+    from synapse.app.homeserver import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class ReceiptsHandler(BaseHandler):
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
 
         self.server_name = hs.config.server_name
@@ -36,7 +39,7 @@ class ReceiptsHandler(BaseHandler):
         self.clock = self.hs.get_clock()
         self.state = hs.get_state_handler()
 
-    async def _received_remote_receipt(self, origin, content):
+    async def _received_remote_receipt(self, origin: str, content: JsonDict) -> None:
         """Called when we receive an EDU of type m.receipt from a remote HS.
         """
         receipts = []
@@ -63,11 +66,11 @@ class ReceiptsHandler(BaseHandler):
 
         await self._handle_new_receipts(receipts)
 
-    async def _handle_new_receipts(self, receipts):
+    async def _handle_new_receipts(self, receipts: List[ReadReceipt]) -> bool:
         """Takes a list of receipts, stores them and informs the notifier.
         """
-        min_batch_id = None
-        max_batch_id = None
+        min_batch_id = None  # type: Optional[int]
+        max_batch_id = None  # type: Optional[int]
 
         for receipt in receipts:
             res = await self.store.insert_receipt(
@@ -89,7 +92,8 @@ class ReceiptsHandler(BaseHandler):
             if max_batch_id is None or max_persisted_id > max_batch_id:
                 max_batch_id = max_persisted_id
 
-        if min_batch_id is None:
+        # Either both of these should be None or neither.
+        if min_batch_id is None or max_batch_id is None:
             # no new receipts
             return False
 
@@ -103,7 +107,9 @@ class ReceiptsHandler(BaseHandler):
 
         return True
 
-    async def received_client_receipt(self, room_id, receipt_type, user_id, event_id):
+    async def received_client_receipt(
+        self, room_id: str, receipt_type: str, user_id: str, event_id: str
+    ) -> None:
         """Called when a client tells us a local user has read up to the given
         event_id in the room.
         """
@@ -123,10 +129,12 @@ class ReceiptsHandler(BaseHandler):
 
 
 class ReceiptEventSource:
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         self.store = hs.get_datastore()
 
-    async def get_new_events(self, from_key, room_ids, **kwargs):
+    async def get_new_events(
+        self, from_key: int, room_ids: List[str], **kwargs
+    ) -> Tuple[List[JsonDict], int]:
         from_key = int(from_key)
         to_key = self.get_current_key()
 
@@ -171,5 +179,5 @@ class ReceiptEventSource:
 
         return (events, to_key)
 
-    def get_current_key(self, direction="f"):
+    def get_current_key(self, direction: str = "f") -> int:
         return self.store.get_max_receipt_stream_id()