Remove experimental MSC2716 implementation to incrementally import history into existing rooms (#15748)

Context for why we're removing the implementation:

 - https://github.com/matrix-org/matrix-spec-proposals/pull/2716#issuecomment-1487441010
 - https://github.com/matrix-org/matrix-spec-proposals/pull/2716#issuecomment-1504262734

Anyone wanting to continue MSC2716, should also address these leftover tasks: https://github.com/matrix-org/synapse/issues/10737

Closes https://github.com/matrix-org/synapse/issues/10737 in the fact that it is not longer necessary to track those things.

1 files changed, 0 insertions, 211 deletions

diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py
index 4b8d8328d7..0f3b0744f1 100644
--- a/tests/storage/test_event_federation.py
+++ b/tests/storage/test_event_federation.py
@@ -20,7 +20,6 @@ from parameterized import parameterized
 
 from twisted.test.proto_helpers import MemoryReactor
 
-from synapse.api.constants import EventTypes
 from synapse.api.room_versions import (
     KNOWN_ROOM_VERSIONS,
     EventFormatVersions,
@@ -924,216 +923,6 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase):
         backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
         self.assertEqual(backfill_event_ids, ["b3", "b2", "b1"])
 
-    def _setup_room_for_insertion_backfill_tests(self) -> _BackfillSetupInfo:
-        """
-        Sets up a room with various insertion event backward extremities to test
-        backfill functions against.
-
-        Returns:
-            _BackfillSetupInfo including the `room_id` to test against and
-            `depth_map` of events in the room
-        """
-        room_id = "!backfill-room-test:some-host"
-
-        depth_map: Dict[str, int] = {
-            "1": 1,
-            "2": 2,
-            "insertion_eventA": 3,
-            "3": 4,
-            "insertion_eventB": 5,
-            "4": 6,
-            "5": 7,
-        }
-
-        def populate_db(txn: LoggingTransaction) -> None:
-            # Insert the room to satisfy the foreign key constraint of
-            # `event_failed_pull_attempts`
-            self.store.db_pool.simple_insert_txn(
-                txn,
-                "rooms",
-                {
-                    "room_id": room_id,
-                    "creator": "room_creator_user_id",
-                    "is_public": True,
-                    "room_version": "6",
-                },
-            )
-
-            # Insert our server events
-            stream_ordering = 0
-            for event_id, depth in depth_map.items():
-                self.store.db_pool.simple_insert_txn(
-                    txn,
-                    table="events",
-                    values={
-                        "event_id": event_id,
-                        "type": EventTypes.MSC2716_INSERTION
-                        if event_id.startswith("insertion_event")
-                        else "test_regular_type",
-                        "room_id": room_id,
-                        "depth": depth,
-                        "topological_ordering": depth,
-                        "stream_ordering": stream_ordering,
-                        "processed": True,
-                        "outlier": False,
-                    },
-                )
-
-                if event_id.startswith("insertion_event"):
-                    self.store.db_pool.simple_insert_txn(
-                        txn,
-                        table="insertion_event_extremities",
-                        values={
-                            "event_id": event_id,
-                            "room_id": room_id,
-                        },
-                    )
-
-                stream_ordering += 1
-
-        self.get_success(
-            self.store.db_pool.runInteraction(
-                "_setup_room_for_insertion_backfill_tests_populate_db",
-                populate_db,
-            )
-        )
-
-        return _BackfillSetupInfo(room_id=room_id, depth_map=depth_map)
-
-    def test_get_insertion_event_backward_extremities_in_room(self) -> None:
-        """
-        Test to make sure only insertion event backward extremities that are
-        older and come before the `current_depth` are returned.
-        """
-        setup_info = self._setup_room_for_insertion_backfill_tests()
-        room_id = setup_info.room_id
-        depth_map = setup_info.depth_map
-
-        # Try at "insertion_eventB"
-        backfill_points = self.get_success(
-            self.store.get_insertion_event_backward_extremities_in_room(
-                room_id, depth_map["insertion_eventB"], limit=100
-            )
-        )
-        backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
-        self.assertEqual(backfill_event_ids, ["insertion_eventB", "insertion_eventA"])
-
-        # Try at "insertion_eventA"
-        backfill_points = self.get_success(
-            self.store.get_insertion_event_backward_extremities_in_room(
-                room_id, depth_map["insertion_eventA"], limit=100
-            )
-        )
-        backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
-        # Event "2" has a depth of 2 but is not included here because we only
-        # know the approximate depth of 5 from our event "3".
-        self.assertListEqual(backfill_event_ids, ["insertion_eventA"])
-
-    def test_get_insertion_event_backward_extremities_in_room_excludes_events_we_have_attempted(
-        self,
-    ) -> None:
-        """
-        Test to make sure that insertion events we have attempted to backfill
-        (and within backoff timeout duration) do not show up as an event to
-        backfill again.
-        """
-        setup_info = self._setup_room_for_insertion_backfill_tests()
-        room_id = setup_info.room_id
-        depth_map = setup_info.depth_map
-
-        # Record some attempts to backfill these events which will make
-        # `get_insertion_event_backward_extremities_in_room` exclude them
-        # because we haven't passed the backoff interval.
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventA", "fake cause"
-            )
-        )
-
-        # No time has passed since we attempted to backfill ^
-
-        # Try at "insertion_eventB"
-        backfill_points = self.get_success(
-            self.store.get_insertion_event_backward_extremities_in_room(
-                room_id, depth_map["insertion_eventB"], limit=100
-            )
-        )
-        backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
-        # Only the backfill points that we didn't record earlier exist here.
-        self.assertEqual(backfill_event_ids, ["insertion_eventB"])
-
-    def test_get_insertion_event_backward_extremities_in_room_attempted_event_retry_after_backoff_duration(
-        self,
-    ) -> None:
-        """
-        Test to make sure after we fake attempt to backfill event
-        "insertion_eventA" many times, we can see retry and see the
-        "insertion_eventA" again after the backoff timeout duration has
-        exceeded.
-        """
-        setup_info = self._setup_room_for_insertion_backfill_tests()
-        room_id = setup_info.room_id
-        depth_map = setup_info.depth_map
-
-        # Record some attempts to backfill these events which will make
-        # `get_backfill_points_in_room` exclude them because we
-        # haven't passed the backoff interval.
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventB", "fake cause"
-            )
-        )
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventA", "fake cause"
-            )
-        )
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventA", "fake cause"
-            )
-        )
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventA", "fake cause"
-            )
-        )
-        self.get_success(
-            self.store.record_event_failed_pull_attempt(
-                room_id, "insertion_eventA", "fake cause"
-            )
-        )
-
-        # Now advance time by 2 hours and we should only be able to see
-        # "insertion_eventB" because we have waited long enough for the single
-        # attempt (2^1 hours) but we still shouldn't see "insertion_eventA"
-        # because we haven't waited long enough for this many attempts.
-        self.reactor.advance(datetime.timedelta(hours=2).total_seconds())
-
-        # Try at "insertion_eventA" and make sure that "insertion_eventA" is not
-        # in the list because we've already attempted many times
-        backfill_points = self.get_success(
-            self.store.get_insertion_event_backward_extremities_in_room(
-                room_id, depth_map["insertion_eventA"], limit=100
-            )
-        )
-        backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
-        self.assertEqual(backfill_event_ids, [])
-
-        # Now advance time by 20 hours (above 2^4 because we made 4 attemps) and
-        # see if we can now backfill it
-        self.reactor.advance(datetime.timedelta(hours=20).total_seconds())
-
-        # Try at "insertion_eventA" again after we advanced enough time and we
-        # should see "insertion_eventA" again
-        backfill_points = self.get_success(
-            self.store.get_insertion_event_backward_extremities_in_room(
-                room_id, depth_map["insertion_eventA"], limit=100
-            )
-        )
-        backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
-        self.assertEqual(backfill_event_ids, ["insertion_eventA"])
-
     def test_get_event_ids_with_failed_pull_attempts(self) -> None:
         """
         Test to make sure we properly get event_ids based on whether they have any