Refactor the way we set `outlier` (#11634)

* `_auth_and_persist_outliers`: mark persisted events as outliers

Mark any events that get persisted via `_auth_and_persist_outliers` as, well,
outliers.

Currently this will be a no-op as everything will already be flagged as an
outlier, but I'm going to change that.

* `process_remote_join`: stop flagging as outlier

The events are now flagged as outliers later on, by `_auth_and_persist_outliers`.

* `send_join`: remove `outlier=True`

The events created here are returned in the result of `send_join` to
`FederationHandler.do_invite_join`. From there they are passed into
`FederationEventHandler.process_remote_join`, which passes them to
`_auth_and_persist_outliers`... which sets the `outlier` flag.

* `get_event_auth`: remove `outlier=True`

stop flagging the events returned by `get_event_auth` as outliers. This method
is only called by `_get_remote_auth_chain_for_event`, which passes the results
into `_auth_and_persist_outliers`, which will flag them as outliers.

* `_get_remote_auth_chain_for_event`: remove `outlier=True`

we pass all the events into `_auth_and_persist_outliers`, which will now flag
the events as outliers.

* `_check_sigs_and_hash_and_fetch`: remove unused `outlier` parameter

This param is now never set to True, so we can remove it.

* `_check_sigs_and_hash_and_fetch_one`: remove unused `outlier` param

This is no longer set anywhere, so we can remove it.

* `get_pdu`: remove unused `outlier` parameter

... and chase it down into `get_pdu_from_destination_raw`.

* `event_from_pdu_json`: remove redundant `outlier` param

This is never set to `True`, so can be removed.

* changelog

* update docstring

1 files changed, 1 insertions, 6 deletions

diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py

index 4df90e02d7..addc0bf000 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -215,15 +215,12 @@ def _is_invite_via_3pid(event: EventBase) -> bool:
     )
 
 
-def event_from_pdu_json(
-    pdu_json: JsonDict, room_version: RoomVersion, outlier: bool = False
-) -> EventBase:
+def event_from_pdu_json(pdu_json: JsonDict, room_version: RoomVersion) -> EventBase:
     """Construct an EventBase from an event json received over federation
 
     Args:
         pdu_json: pdu as received over federation
         room_version: The version of the room this event belongs to
-        outlier: True to mark this event as an outlier
 
     Raises:
         SynapseError: if the pdu is missing required fields or is otherwise
@@ -247,6 +244,4 @@ def event_from_pdu_json(
         validate_canonicaljson(pdu_json)
 
     event = make_event_from_dict(pdu_json, room_version)
-    event.internal_metadata.outlier = outlier
-
     return event