Use a FrozenEvent base class for types

2 files changed, 37 insertions, 16 deletions

diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index f813fa2fe7..2691ac5545 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -257,7 +257,26 @@ class EventBase(object):
         return [e for e, _ in self.auth_events]
 
 
-class FrozenEvent(EventBase):
+class FrozenEventBase(EventBase):
+    """Base class for fully initialised events.
+    """
+
+    @property
+    def event_id(self) -> str:
+        raise NotImplementedError()
+
+    @property
+    def type(self) -> str:
+        raise NotImplementedError()
+
+    @property
+    def state_key(self) -> str:
+        """Raises if there is no state key.
+        """
+        raise NotImplementedError()
+
+
+class FrozenEvent(FrozenEventBase):
     format_version = EventFormatVersions.V1  # All events of this type are V1
 
     def __init__(self, event_dict, internal_metadata_dict={}, rejected_reason=None):
@@ -305,7 +324,7 @@ class FrozenEvent(EventBase):
         )
 
 
-class FrozenEventV2(EventBase):
+class FrozenEventV2(FrozenEventBase):
     format_version = EventFormatVersions.V2  # All events of this type are V2
 
     def __init__(self, event_dict, internal_metadata_dict={}, rejected_reason=None):
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 6bd21ff761..3933f06c54 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -25,18 +25,18 @@ from prometheus_client import Counter
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.filtering import FilterCollection
-from synapse.events import EventBase
+from synapse.events import FrozenEventBase
 from synapse.logging.context import LoggingContext
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.storage.roommember import MemberSummary
 from synapse.storage.state import StateFilter
 from synapse.types import (
+    Collection,
     JsonDict,
     RoomStreamToken,
     StateMap,
     StreamToken,
     UserID,
-    Collection,
 )
 from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -84,7 +84,7 @@ class SyncConfig:
 @attr.s(slots=True, frozen=True)
 class TimelineBatch:
     prev_batch = attr.ib(type=StreamToken)
-    events = attr.ib(type=List[EventBase])
+    events = attr.ib(type=List[FrozenEventBase])
     limited = attr.ib(bool)
 
     def __nonzero__(self) -> bool:
@@ -100,7 +100,7 @@ class TimelineBatch:
 class JoinedSyncResult:
     room_id = attr.ib(type=str)
     timeline = attr.ib(type=TimelineBatch)
-    state = attr.ib(type=StateMap[EventBase])
+    state = attr.ib(type=StateMap[FrozenEventBase])
     ephemeral = attr.ib(type=List[JsonDict])
     account_data = attr.ib(type=List[JsonDict])
     unread_notifications = attr.ib(type=JsonDict)
@@ -126,7 +126,7 @@ class JoinedSyncResult:
 class ArchivedSyncResult:
     room_id = attr.ib(type=str)
     timeline = attr.ib(type=TimelineBatch)
-    state = attr.ib(type=StateMap[EventBase])
+    state = attr.ib(type=StateMap[FrozenEventBase])
     account_data = attr.ib(type=List[JsonDict])
 
     def __nonzero__(self) -> bool:
@@ -141,7 +141,7 @@ class ArchivedSyncResult:
 @attr.s(slots=True, frozen=True)
 class InvitedSyncResult:
     room_id = attr.ib(type=str)
-    invite = attr.ib(type=EventBase)
+    invite = attr.ib(type=FrozenEventBase)
 
     def __nonzero__(self) -> bool:
         """Invited rooms should always be reported to the client"""
@@ -419,7 +419,7 @@ class SyncHandler(object):
         sync_config: SyncConfig,
         now_token: StreamToken,
         since_token: Optional[StreamToken] = None,
-        potential_recents: Optional[List[EventBase]] = None,
+        potential_recents: Optional[List[FrozenEventBase]] = None,
         newly_joined_room: bool = False,
     ) -> TimelineBatch:
         """
@@ -539,7 +539,7 @@ class SyncHandler(object):
         )
 
     async def get_state_after_event(
-        self, event: EventBase, state_filter: StateFilter = StateFilter.all()
+        self, event: FrozenEventBase, state_filter: StateFilter = StateFilter.all()
     ) -> StateMap[str]:
         """
         Get the room state after the given event
@@ -593,7 +593,7 @@ class SyncHandler(object):
         room_id: str,
         sync_config: SyncConfig,
         batch: TimelineBatch,
-        state: StateMap[EventBase],
+        state: StateMap[FrozenEventBase],
         now_token: StreamToken,
     ) -> Optional[JsonDict]:
         """ Works out a room summary block for this room, summarising the number
@@ -743,7 +743,7 @@ class SyncHandler(object):
         since_token: Optional[StreamToken],
         now_token: StreamToken,
         full_state: bool,
-    ) -> StateMap[EventBase]:
+    ) -> StateMap[FrozenEventBase]:
         """ Works out the difference in state between the start of the timeline
         and the previous sync.
 
@@ -922,7 +922,7 @@ class SyncHandler(object):
                     if t[0] == EventTypes.Member:
                         cache.set(t[1], event_id)
 
-        state = {}  # type: Dict[str, EventBase]
+        state = {}  # type: Dict[str, FrozenEventBase]
         if state_ids:
             state = await self.store.get_events(list(state_ids.values()))
 
@@ -1488,7 +1488,7 @@ class SyncHandler(object):
             user_id, since_token.room_key, now_token.room_key
         )
 
-        mem_change_events_by_room_id = {}  # type: Dict[str, List[EventBase]]
+        mem_change_events_by_room_id = {}  # type: Dict[str, List[FrozenEventBase]]
         for event in rooms_changed:
             mem_change_events_by_room_id.setdefault(event.room_id, []).append(event)
 
@@ -1607,7 +1607,9 @@ class SyncHandler(object):
                 # This is all screaming out for a refactor, as the logic here is
                 # subtle and the moving parts numerous.
                 if leave_event.internal_metadata.is_out_of_band_membership():
-                    batch_events = [leave_event]  # type: Optional[List[EventBase]]
+                    batch_events = [
+                        leave_event
+                    ]  # type: Optional[List[FrozenEventBase]]
                 else:
                     batch_events = None
 
@@ -2070,7 +2072,7 @@ class RoomSyncResultBuilder(object):
 
     room_id = attr.ib(type=str)
     rtype = attr.ib(type=str)
-    events = attr.ib(type=Optional[List[EventBase]])
+    events = attr.ib(type=Optional[List[FrozenEventBase]])
     newly_joined = attr.ib(type=bool)
     full_state = attr.ib(type=bool)
     since_token = attr.ib(type=Optional[StreamToken])