Convert a synapse.events to async/await. (#7949)

4 files changed, 67 insertions, 68 deletions

diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 0bb216419a..69b53ca2bc 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -17,8 +17,6 @@ from typing import Optional
 import attr
 from nacl.signing import SigningKey
 
-from twisted.internet import defer
-
 from synapse.api.constants import MAX_DEPTH
 from synapse.api.errors import UnsupportedRoomVersionError
 from synapse.api.room_versions import (
@@ -95,31 +93,30 @@ class EventBuilder(object):
     def is_state(self):
         return self._state_key is not None
 
-    @defer.inlineCallbacks
-    def build(self, prev_event_ids):
+    async def build(self, prev_event_ids):
         """Transform into a fully signed and hashed event
 
         Args:
             prev_event_ids (list[str]): The event IDs to use as the prev events
 
         Returns:
-            Deferred[FrozenEvent]
+            FrozenEvent
         """
 
-        state_ids = yield defer.ensureDeferred(
-            self._state.get_current_state_ids(self.room_id, prev_event_ids)
+        state_ids = await self._state.get_current_state_ids(
+            self.room_id, prev_event_ids
         )
-        auth_ids = yield self._auth.compute_auth_events(self, state_ids)
+        auth_ids = await self._auth.compute_auth_events(self, state_ids)
 
         format_version = self.room_version.event_format
         if format_version == EventFormatVersions.V1:
-            auth_events = yield self._store.add_event_hashes(auth_ids)
-            prev_events = yield self._store.add_event_hashes(prev_event_ids)
+            auth_events = await self._store.add_event_hashes(auth_ids)
+            prev_events = await self._store.add_event_hashes(prev_event_ids)
         else:
             auth_events = auth_ids
             prev_events = prev_event_ids
 
-        old_depth = yield self._store.get_max_depth_of(prev_event_ids)
+        old_depth = await self._store.get_max_depth_of(prev_event_ids)
         depth = old_depth + 1
 
         # we cap depth of generated events, to ensure that they are not
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index f94cdcbaba..cca93e3a46 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -12,17 +12,19 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Optional, Union
+from typing import TYPE_CHECKING, Optional, Union
 
 import attr
 from frozendict import frozendict
 
-from twisted.internet import defer
-
 from synapse.appservice import ApplicationService
+from synapse.events import EventBase
 from synapse.logging.context import make_deferred_yieldable, run_in_background
 from synapse.types import StateMap
 
+if TYPE_CHECKING:
+    from synapse.storage.data_stores.main import DataStore
+
 
 @attr.s(slots=True)
 class EventContext:
@@ -129,8 +131,7 @@ class EventContext:
             delta_ids=delta_ids,
         )
 
-    @defer.inlineCallbacks
-    def serialize(self, event, store):
+    async def serialize(self, event: EventBase, store: "DataStore") -> dict:
         """Converts self to a type that can be serialized as JSON, and then
         deserialized by `deserialize`
 
@@ -146,7 +147,7 @@ class EventContext:
         # the prev_state_ids, so if we're a state event we include the event
         # id that we replaced in the state.
         if event.is_state():
-            prev_state_ids = yield self.get_prev_state_ids()
+            prev_state_ids = await self.get_prev_state_ids()
             prev_state_id = prev_state_ids.get((event.type, event.state_key))
         else:
             prev_state_id = None
@@ -214,8 +215,7 @@ class EventContext:
 
         return self._state_group
 
-    @defer.inlineCallbacks
-    def get_current_state_ids(self):
+    async def get_current_state_ids(self) -> Optional[StateMap[str]]:
         """
         Gets the room state map, including this event - ie, the state in ``state_group``
 
@@ -224,32 +224,31 @@ class EventContext:
         ``rejected`` is set.
 
         Returns:
-            Deferred[dict[(str, str), str]|None]: Returns None if state_group
-                is None, which happens when the associated event is an outlier.
+            Returns None if state_group is None, which happens when the associated
+            event is an outlier.
 
-                Maps a (type, state_key) to the event ID of the state event matching
-                this tuple.
+            Maps a (type, state_key) to the event ID of the state event matching
+            this tuple.
         """
         if self.rejected:
             raise RuntimeError("Attempt to access state_ids of rejected event")
 
-        yield self._ensure_fetched()
+        await self._ensure_fetched()
         return self._current_state_ids
 
-    @defer.inlineCallbacks
-    def get_prev_state_ids(self):
+    async def get_prev_state_ids(self):
         """
         Gets the room state map, excluding this event.
 
         For a non-state event, this will be the same as get_current_state_ids().
 
         Returns:
-            Deferred[dict[(str, str), str]|None]: Returns None if state_group
+            dict[(str, str), str]|None: Returns None if state_group
                 is None, which happens when the associated event is an outlier.
                 Maps a (type, state_key) to the event ID of the state event matching
                 this tuple.
         """
-        yield self._ensure_fetched()
+        await self._ensure_fetched()
         return self._prev_state_ids
 
     def get_cached_current_state_ids(self):
@@ -269,8 +268,8 @@ class EventContext:
 
         return self._current_state_ids
 
-    def _ensure_fetched(self):
-        return defer.succeed(None)
+    async def _ensure_fetched(self):
+        return None
 
 
 @attr.s(slots=True)
@@ -303,21 +302,20 @@ class _AsyncEventContextImpl(EventContext):
     _event_state_key = attr.ib(default=None)
     _fetching_state_deferred = attr.ib(default=None)
 
-    def _ensure_fetched(self):
+    async def _ensure_fetched(self):
         if not self._fetching_state_deferred:
             self._fetching_state_deferred = run_in_background(self._fill_out_state)
 
-        return make_deferred_yieldable(self._fetching_state_deferred)
+        return await make_deferred_yieldable(self._fetching_state_deferred)
 
-    @defer.inlineCallbacks
-    def _fill_out_state(self):
+    async def _fill_out_state(self):
         """Called to populate the _current_state_ids and _prev_state_ids
         attributes by loading from the database.
         """
         if self.state_group is None:
             return
 
-        self._current_state_ids = yield self._storage.state.get_state_ids_for_group(
+        self._current_state_ids = await self._storage.state.get_state_ids_for_group(
             self.state_group
         )
         if self._event_state_key is not None:
diff --git a/synapse/events/third_party_rules.py b/synapse/events/third_party_rules.py
index 459132d388..2956a64234 100644
--- a/synapse/events/third_party_rules.py
+++ b/synapse/events/third_party_rules.py
@@ -13,7 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+from synapse.events import EventBase
+from synapse.events.snapshot import EventContext
+from synapse.types import Requester
 
 
 class ThirdPartyEventRules(object):
@@ -39,76 +41,79 @@ class ThirdPartyEventRules(object):
                 config=config, http_client=hs.get_simple_http_client()
             )
 
-    @defer.inlineCallbacks
-    def check_event_allowed(self, event, context):
+    async def check_event_allowed(
+        self, event: EventBase, context: EventContext
+    ) -> bool:
         """Check if a provided event should be allowed in the given context.
 
         Args:
-            event (synapse.events.EventBase): The event to be checked.
-            context (synapse.events.snapshot.EventContext): The context of the event.
+            event: The event to be checked.
+            context: The context of the event.
 
         Returns:
-            defer.Deferred[bool]: True if the event should be allowed, False if not.
+            True if the event should be allowed, False if not.
         """
         if self.third_party_rules is None:
             return True
 
-        prev_state_ids = yield context.get_prev_state_ids()
+        prev_state_ids = await context.get_prev_state_ids()
 
         # Retrieve the state events from the database.
         state_events = {}
         for key, event_id in prev_state_ids.items():
-            state_events[key] = yield self.store.get_event(event_id, allow_none=True)
+            state_events[key] = await self.store.get_event(event_id, allow_none=True)
 
-        ret = yield self.third_party_rules.check_event_allowed(event, state_events)
+        ret = await self.third_party_rules.check_event_allowed(event, state_events)
         return ret
 
-    @defer.inlineCallbacks
-    def on_create_room(self, requester, config, is_requester_admin):
+    async def on_create_room(
+        self, requester: Requester, config: dict, is_requester_admin: bool
+    ) -> bool:
         """Intercept requests to create room to allow, deny or update the
         request config.
 
         Args:
-            requester (Requester)
-            config (dict): The creation config from the client.
-            is_requester_admin (bool): If the requester is an admin
+            requester
+            config: The creation config from the client.
+            is_requester_admin: If the requester is an admin
 
         Returns:
-            defer.Deferred[bool]: Whether room creation is allowed or denied.
+            Whether room creation is allowed or denied.
         """
 
         if self.third_party_rules is None:
             return True
 
-        ret = yield self.third_party_rules.on_create_room(
+        ret = await self.third_party_rules.on_create_room(
             requester, config, is_requester_admin
         )
         return ret
 
-    @defer.inlineCallbacks
-    def check_threepid_can_be_invited(self, medium, address, room_id):
+    async def check_threepid_can_be_invited(
+        self, medium: str, address: str, room_id: str
+    ) -> bool:
         """Check if a provided 3PID can be invited in the given room.
 
         Args:
-            medium (str): The 3PID's medium.
-            address (str): The 3PID's address.
-            room_id (str): The room we want to invite the threepid to.
+            medium: The 3PID's medium.
+            address: The 3PID's address.
+            room_id: The room we want to invite the threepid to.
 
         Returns:
-            defer.Deferred[bool], True if the 3PID can be invited, False if not.
+            True if the 3PID can be invited, False if not.
         """
 
         if self.third_party_rules is None:
             return True
 
-        state_ids = yield self.store.get_filtered_current_state_ids(room_id)
-        room_state_events = yield self.store.get_events(state_ids.values())
+        state_ids = await self.store.get_filtered_current_state_ids(room_id)
+        room_state_events = await self.store.get_events(state_ids.values())
 
         state_events = {}
         for key, event_id in state_ids.items():
             state_events[key] = room_state_events[event_id]
 
-        ret = yield self.third_party_rules.check_threepid_can_be_invited(
+        ret = await self.third_party_rules.check_threepid_can_be_invited(
             medium, address, state_events
         )
         return ret
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 11f0d34ec8..2d42e268c6 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -18,8 +18,6 @@ from typing import Any, Mapping, Union
 
 from frozendict import frozendict
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, RelationTypes
 from synapse.api.errors import Codes, SynapseError
 from synapse.api.room_versions import RoomVersion
@@ -337,8 +335,9 @@ class EventClientSerializer(object):
             hs.config.experimental_msc1849_support_enabled
         )
 
-    @defer.inlineCallbacks
-    def serialize_event(self, event, time_now, bundle_aggregations=True, **kwargs):
+    async def serialize_event(
+        self, event, time_now, bundle_aggregations=True, **kwargs
+    ):
         """Serializes a single event.
 
         Args:
@@ -348,7 +347,7 @@ class EventClientSerializer(object):
             **kwargs: Arguments to pass to `serialize_event`
 
         Returns:
-            Deferred[dict]: The serialized event
+            dict: The serialized event
         """
         # To handle the case of presence events and the like
         if not isinstance(event, EventBase):
@@ -363,8 +362,8 @@ class EventClientSerializer(object):
         if not event.internal_metadata.is_redacted() and (
             self.experimental_msc1849_support_enabled and bundle_aggregations
         ):
-            annotations = yield self.store.get_aggregation_groups_for_event(event_id)
-            references = yield self.store.get_relations_for_event(
+            annotations = await self.store.get_aggregation_groups_for_event(event_id)
+            references = await self.store.get_relations_for_event(
                 event_id, RelationTypes.REFERENCE, direction="f"
             )
 
@@ -378,7 +377,7 @@ class EventClientSerializer(object):
 
             edit = None
             if event.type == EventTypes.Message:
-                edit = yield self.store.get_applicable_edit(event_id)
+                edit = await self.store.get_applicable_edit(event_id)
 
             if edit:
                 # If there is an edit replace the content, preserving existing