MSC4140: put delay_id in unsigned data for sender

changelog.d/19479.feature

@@ -0,0 +1 @@
+[MSC4140: Cancellable delayed events](https://github.com/matrix-org/matrix-spec-proposals/pull/4140): When persisting a delayed event to the timeline, include its `delay_id` in the event's `unsigned` section in `/sync` responses to the event sender.

rust/src/events/internal_metadata.rs

@@ -57,6 +57,7 @@ enum EventInternalMetadataData {
     PolicyServerSpammy(bool),
     Redacted(bool),
     TxnId(Box<str>),
+    DelayId(Box<str>),
     TokenId(i64),
     DeviceId(Box<str>),
 }
@@ -115,6 +116,10 @@ impl EventInternalMetadataData {
                 pyo3::intern!(py, "txn_id"),
                 o.into_pyobject(py).unwrap_infallible().into_any(),
             ),
+            EventInternalMetadataData::DelayId(o) => (
+                pyo3::intern!(py, "delay_id"),
+                o.into_pyobject(py).unwrap_infallible().into_any(),
+            ),
             EventInternalMetadataData::TokenId(o) => (
                 pyo3::intern!(py, "token_id"),
                 o.into_pyobject(py).unwrap_infallible().into_any(),
@@ -179,6 +184,12 @@ impl EventInternalMetadataData {
                     .map(String::into_boxed_str)
                     .with_context(|| format!("'{key_str}' has invalid type"))?,
             ),
+            "delay_id" => EventInternalMetadataData::DelayId(
+                value
+                    .extract()
+                    .map(String::into_boxed_str)
+                    .with_context(|| format!("'{key_str}' has invalid type"))?,
+            ),
             "token_id" => EventInternalMetadataData::TokenId(
                 value
                     .extract()
@@ -472,6 +483,17 @@ impl EventInternalMetadata {
         set_property!(self, TxnId, obj.into_boxed_str());
     }
 
+    /// The delay ID, set only if the event was a delayed event.
+    #[getter]
+    fn get_delay_id(&self) -> PyResult<&str> {
+        let s = get_property!(self, DelayId)?;
+        Ok(s)
+    }
+    #[setter]
+    fn set_delay_id(&mut self, obj: String) {
+        set_property!(self, DelayId, obj.into_boxed_str());
+    }
+
     /// The access token ID of the user who sent this event, if any.
     #[getter]
     fn get_token_id(&self) -> PyResult<i64> {

synapse/events/utils.py

@@ -412,7 +412,7 @@ class SerializeEventConfig:
     # Function to convert from federation format to client format
     event_format: Callable[[JsonDict], JsonDict] = format_event_for_client_v1
     # The entity that requested the event. This is used to determine whether to include
-    # the transaction_id in the unsigned section of the event.
+    # the transaction_id and delay_id in the unsigned section of the event.
     requester: Requester | None = None
     # List of event fields to include. If empty, all fields will be returned.
     only_event_fields: list[str] | None = None
@@ -475,44 +475,49 @@ def serialize_event(
             config=config,
         )
 
-    # If we have a txn_id saved in the internal_metadata, we should include it in the
-    # unsigned section of the event if it was sent by the same session as the one
-    # requesting the event.
-    txn_id: str | None = getattr(e.internal_metadata, "txn_id", None)
-    if (
-        txn_id is not None
-        and config.requester is not None
-        and config.requester.user.to_string() == e.sender
-    ):
-        # Some events do not have the device ID stored in the internal metadata,
-        # this includes old events as well as those created by appservice, guests,
-        # or with tokens minted with the admin API. For those events, fallback
-        # to using the access token instead.
-        event_device_id: str | None = getattr(e.internal_metadata, "device_id", None)
-        if event_device_id is not None:
-            if event_device_id == config.requester.device_id:
-                d["unsigned"]["transaction_id"] = txn_id
-
-        else:
-            # Fallback behaviour: only include the transaction ID if the event
-            # was sent from the same access token.
-            #
-            # For regular users, the access token ID can be used to determine this.
-            # This includes access tokens minted with the admin API.
-            #
-            # For guests and appservice users, we can't check the access token ID
-            # so assume it is the same session.
-            event_token_id: int | None = getattr(e.internal_metadata, "token_id", None)
-            if (
-                (
-                    event_token_id is not None
-                    and config.requester.access_token_id is not None
-                    and event_token_id == config.requester.access_token_id
+    # If we have applicable fields saved in the internal_metadata, include them in the
+    # unsigned section of the event if the event was sent by the same session (or when
+    # appropriate, just the same sender) as the one requesting the event.
+    if config.requester is not None and config.requester.user.to_string() == e.sender:
+        txn_id: str | None = getattr(e.internal_metadata, "txn_id", None)
+        if txn_id is not None:
+            # Some events do not have the device ID stored in the internal metadata,
+            # this includes old events as well as those created by appservice, guests,
+            # or with tokens minted with the admin API. For those events, fallback
+            # to using the access token instead.
+            event_device_id: str | None = getattr(
+                e.internal_metadata, "device_id", None
+            )
+            if event_device_id is not None:
+                if event_device_id == config.requester.device_id:
+                    d["unsigned"]["transaction_id"] = txn_id
+
+            else:
+                # Fallback behaviour: only include the transaction ID if the event
+                # was sent from the same access token.
+                #
+                # For regular users, the access token ID can be used to determine this.
+                # This includes access tokens minted with the admin API.
+                #
+                # For guests and appservice users, we can't check the access token ID
+                # so assume it is the same session.
+                event_token_id: int | None = getattr(
+                    e.internal_metadata, "token_id", None
                 )
-                or config.requester.is_guest
-                or config.requester.app_service
-            ):
-                d["unsigned"]["transaction_id"] = txn_id
+                if (
+                    (
+                        event_token_id is not None
+                        and config.requester.access_token_id is not None
+                        and event_token_id == config.requester.access_token_id
+                    )
+                    or config.requester.is_guest
+                    or config.requester.app_service
+                ):
+                    d["unsigned"]["transaction_id"] = txn_id
+
+        delay_id: str | None = getattr(e.internal_metadata, "delay_id", None)
+        if delay_id is not None:
+            d["unsigned"]["org.matrix.msc4140.delay_id"] = delay_id
 
     # invite_room_state and knock_room_state are a list of stripped room state events
     # that are meant to provide metadata about a room to an invitee/knocker. They are

synapse/handlers/delayed_events.py

@@ -560,6 +560,7 @@ async def _send_event(
                     action=membership,
                     content=event.content,
                     origin_server_ts=event.origin_server_ts,
+                    delay_id=event.delay_id,
                 )
             else:
                 event_dict: JsonDict = {
@@ -585,6 +586,7 @@ async def _send_event(
                     requester,
                     event_dict,
                     txn_id=txn_id,
+                    delay_id=event.delay_id,
                 )
                 event_id = sent_event.event_id
         except ShadowBanError:

synapse/handlers/message.py

@@ -585,6 +585,7 @@ async def create_event(
         state_map: StateMap[str] | None = None,
         for_batch: bool = False,
         current_state_group: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[EventBase, UnpersistedEventContextBase]:
         """
         Given a dict from a client, create a new event. If bool for_batch is true, will
@@ -600,7 +601,7 @@ async def create_event(
         Args:
             requester
             event_dict: An entire event
-            txn_id
+            txn_id: The transaction ID.
             prev_event_ids:
                 the forward extremities to use as the prev_events for the
                 new event.
@@ -639,6 +640,8 @@ async def create_event(
             current_state_group: the current state group, used only for creating events for
                 batch persisting
 
+            delay_id: The delay ID of this event, if it was a delayed event.
+
         Raises:
             ResourceLimitError if server is blocked to some resource being
             exceeded
@@ -726,6 +729,9 @@ async def create_event(
         if txn_id is not None:
             builder.internal_metadata.txn_id = txn_id
 
+        if delay_id is not None:
+            builder.internal_metadata.delay_id = delay_id
+
         builder.internal_metadata.outlier = outlier
 
         event, unpersisted_context = await self.create_new_client_event(
@@ -966,6 +972,7 @@ async def create_and_send_nonmember_event(
         ignore_shadow_ban: bool = False,
         outlier: bool = False,
         depth: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[EventBase, int]:
         """
         Creates an event, then sends it.
@@ -994,6 +1001,7 @@ async def create_and_send_nonmember_event(
             depth: Override the depth used to order the event in the DAG.
                 Should normally be set to None, which will cause the depth to be calculated
                 based on the prev_events.
+            delay_id: The delay ID of this event, if it was a delayed event.
 
         Returns:
             The event, and its stream ordering (if deduplication happened,
@@ -1090,6 +1098,7 @@ async def create_and_send_nonmember_event(
                 ignore_shadow_ban=ignore_shadow_ban,
                 outlier=outlier,
                 depth=depth,
+                delay_id=delay_id,
             )
 
     async def _create_and_send_nonmember_event_locked(
@@ -1103,6 +1112,7 @@ async def _create_and_send_nonmember_event_locked(
         ignore_shadow_ban: bool = False,
         outlier: bool = False,
         depth: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[EventBase, int]:
         room_id = event_dict["room_id"]
 
@@ -1131,6 +1141,7 @@ async def _create_and_send_nonmember_event_locked(
                     state_event_ids=state_event_ids,
                     outlier=outlier,
                     depth=depth,
+                    delay_id=delay_id,
                 )
                 context = await unpersisted_context.persist(event)
 

synapse/handlers/room_member.py

@@ -408,6 +408,7 @@ async def _local_membership_update(
         require_consent: bool = True,
         outlier: bool = False,
         origin_server_ts: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[str, int]:
         """
         Internal membership update function to get an existing event or create
@@ -440,6 +441,7 @@ async def _local_membership_update(
                 opposed to being inline with the current DAG.
             origin_server_ts: The origin_server_ts to use if a new event is created. Uses
                 the current timestamp if set to None.
+            delay_id: The delay ID of this event, if it was a delayed event.
 
         Returns:
             Tuple of event ID and stream ordering position
@@ -492,6 +494,7 @@ async def _local_membership_update(
                     depth=depth,
                     require_consent=require_consent,
                     outlier=outlier,
+                    delay_id=delay_id,
                 )
                 context = await unpersisted_context.persist(event)
                 prev_state_ids = await context.get_prev_state_ids(
@@ -587,6 +590,7 @@ async def update_membership(
         state_event_ids: list[str] | None = None,
         depth: int | None = None,
         origin_server_ts: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[str, int]:
         """Update a user's membership in a room.
 
@@ -617,6 +621,7 @@ async def update_membership(
                 based on the prev_events.
             origin_server_ts: The origin_server_ts to use if a new event is created. Uses
                 the current timestamp if set to None.
+            delay_id: The delay ID of this event, if it was a delayed event.
 
         Returns:
             A tuple of the new event ID and stream ID.
@@ -679,6 +684,7 @@ async def update_membership(
                             state_event_ids=state_event_ids,
                             depth=depth,
                             origin_server_ts=origin_server_ts,
+                            delay_id=delay_id,
                         )
 
         return result
@@ -701,6 +707,7 @@ async def update_membership_locked(
         state_event_ids: list[str] | None = None,
         depth: int | None = None,
         origin_server_ts: int | None = None,
+        delay_id: str | None = None,
     ) -> tuple[str, int]:
         """Helper for update_membership.
 
@@ -733,6 +740,7 @@ async def update_membership_locked(
                 based on the prev_events.
             origin_server_ts: The origin_server_ts to use if a new event is created. Uses
                 the current timestamp if set to None.
+            delay_id: The delay ID of this event, if it was a delayed event.
 
         Returns:
             A tuple of the new event ID and stream ID.
@@ -943,6 +951,7 @@ async def update_membership_locked(
                 require_consent=require_consent,
                 outlier=outlier,
                 origin_server_ts=origin_server_ts,
+                delay_id=delay_id,
             )
 
         latest_event_ids = await self.store.get_prev_events_for_room(room_id)
@@ -1201,6 +1210,7 @@ async def update_membership_locked(
             require_consent=require_consent,
             outlier=outlier,
             origin_server_ts=origin_server_ts,
+            delay_id=delay_id,
         )
 
     async def check_for_any_membership_in_room(

synapse/synapse_rust/events.pyi

@@ -38,6 +38,8 @@ class EventInternalMetadata:
 
     txn_id: str
     """The transaction ID, if it was set when the event was created."""
+    delay_id: str
+    """The delay ID, set only if the event was a delayed event."""
     token_id: int
     """The access token ID of the user who sent this event, if any."""
     device_id: str