From 0536d0c9beb15fce5f2ca24b4565f79f3140943f Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Mon, 3 Feb 2020 20:35:40 +0000
Subject: [PATCH] make FederationClient.backfill async

---
 synapse/federation/federation_client.py | 26 +++++++++++--------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index f99d17a7d..297292f38 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -17,7 +17,7 @@
 import copy
 import itertools
 import logging
-from typing import Dict, Iterable
+from typing import Dict, Iterable, List, Tuple
 
 from prometheus_client import Counter
 
@@ -37,7 +37,7 @@ from synapse.api.room_versions import (
     EventFormatVersions,
     RoomVersions,
 )
-from synapse.events import builder, room_version_to_event_format
+from synapse.events import EventBase, builder, room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.logging.context import make_deferred_yieldable
 from synapse.logging.utils import log_function
@@ -170,21 +170,17 @@ class FederationClient(FederationBase):
         sent_queries_counter.labels("client_one_time_keys").inc()
         return self.transport_layer.claim_client_keys(destination, content, timeout)
 
-    @defer.inlineCallbacks
-    @log_function
-    def backfill(self, dest, room_id, limit, extremities):
-        """Requests some more historic PDUs for the given context from the
+    async def backfill(
+        self, dest: str, room_id: str, limit: int, extremities: Iterable[str]
+    ) -> List[EventBase]:
+        """Requests some more historic PDUs for the given room from the
         given destination server.
 
         Args:
             dest (str): The remote homeserver to ask.
             room_id (str): The room_id to backfill.
-            limit (int): The maximum number of PDUs to return.
-            extremities (list): List of PDU id and origins of the first pdus
-                we have seen from the context
-
-        Returns:
-            Deferred: Results in the received PDUs.
+            limit (int): The maximum number of events to return.
+            extremities (list): our current backwards extremities, to backfill from
         """
         logger.debug("backfill extrem=%s", extremities)
 
@@ -192,13 +188,13 @@ class FederationClient(FederationBase):
         if not extremities:
             return
 
-        transaction_data = yield self.transport_layer.backfill(
+        transaction_data = await self.transport_layer.backfill(
             dest, room_id, extremities, limit
         )
 
         logger.debug("backfill transaction_data=%r", transaction_data)
 
-        room_version = yield self.store.get_room_version_id(room_id)
+        room_version = await self.store.get_room_version_id(room_id)
         format_ver = room_version_to_event_format(room_version)
 
         pdus = [
@@ -207,7 +203,7 @@ class FederationClient(FederationBase):
         ]
 
         # FIXME: We should handle signature failures more gracefully.
-        pdus[:] = yield make_deferred_yieldable(
+        pdus[:] = await make_deferred_yieldable(
             defer.gatherResults(
                 self._check_sigs_and_hashes(room_version, pdus), consumeErrors=True
             ).addErrback(unwrapFirstError)