From 914076d5943df467e750b85dda9ce843325943f4 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Tue, 5 Apr 2022 12:02:55 -0400
Subject: [PATCH 1/4] Remove references to unstable thread relation.

---
 synapse/api/constants.py                    |  2 -
 synapse/events/utils.py                     |  2 -
 synapse/handlers/message.py                 |  5 +-
 synapse/storage/databases/main/events.py    |  5 +-
 synapse/storage/databases/main/relations.py | 57 ++++++---------------
 5 files changed, 17 insertions(+), 54 deletions(-)

diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 92907415e651..0172eb60b8dc 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -179,8 +179,6 @@ class RelationTypes:
     REPLACE: Final = "m.replace"
     REFERENCE: Final = "m.reference"
     THREAD: Final = "m.thread"
-    # TODO Remove this in Synapse >= v1.57.0.
-    UNSTABLE_THREAD: Final = "io.element.thread"
 
 
 class LimitBlockingTypes:
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 918e87ed9cf1..3203e11b087a 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -525,8 +525,6 @@ def _inject_bundled_aggregations(
                 "current_user_participated": thread.current_user_participated,
             }
             serialized_aggregations[RelationTypes.THREAD] = thread_summary
-            if self._msc3440_enabled:
-                serialized_aggregations[RelationTypes.UNSTABLE_THREAD] = thread_summary
 
         # Include the bundled aggregations in the event.
         if serialized_aggregations:
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 7db6905c6165..47a63005a984 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -1102,10 +1102,7 @@ async def _validate_event_relation(self, event: EventBase) -> None:
                 raise SynapseError(400, "Can't send same reaction twice")
 
         # Don't attempt to start a thread if the parent event is a relation.
-        elif (
-            relation_type == RelationTypes.THREAD
-            or relation_type == RelationTypes.UNSTABLE_THREAD
-        ):
+        elif relation_type == RelationTypes.THREAD:
             if await self.store.event_includes_relation(relates_to):
                 raise SynapseError(
                     400, "Cannot start threads from an event with a relation"
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 3fcd5f5b99de..e3be537cee35 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -1819,10 +1819,7 @@ def _handle_event_relations(
         if rel_type == RelationTypes.REPLACE:
             txn.call_after(self.store.get_applicable_edit.invalidate, (parent_id,))
 
-        if (
-            rel_type == RelationTypes.THREAD
-            or rel_type == RelationTypes.UNSTABLE_THREAD
-        ):
+        if rel_type == RelationTypes.THREAD:
             txn.call_after(self.store.get_thread_summary.invalidate, (parent_id,))
             # It should be safe to only invalidate the cache if the user has not
             # previously participated in the thread, but that's difficult (and
diff --git a/synapse/storage/databases/main/relations.py b/synapse/storage/databases/main/relations.py
index db929ef523ee..43ca17232081 100644
--- a/synapse/storage/databases/main/relations.py
+++ b/synapse/storage/databases/main/relations.py
@@ -497,7 +497,7 @@ def _get_thread_summaries_txn(
                         AND parent.room_id = child.room_id
                     WHERE
                         %s
-                        AND %s
+                        AND relation_type = ?
                     ORDER BY parent.event_id, child.topological_ordering DESC, child.stream_ordering DESC
                 """
             else:
@@ -512,22 +512,16 @@ def _get_thread_summaries_txn(
                         AND parent.room_id = child.room_id
                     WHERE
                         %s
-                        AND %s
+                        AND relation_type = ?
                     ORDER BY child.topological_ordering DESC, child.stream_ordering DESC
                 """
 
             clause, args = make_in_list_sql_clause(
                 txn.database_engine, "relates_to_id", event_ids
             )
+            args.append(RelationTypes.THREAD)
 
-            if self._msc3440_enabled:
-                relations_clause = "(relation_type = ? OR relation_type = ?)"
-                args.extend((RelationTypes.THREAD, RelationTypes.UNSTABLE_THREAD))
-            else:
-                relations_clause = "relation_type = ?"
-                args.append(RelationTypes.THREAD)
-
-            txn.execute(sql % (clause, relations_clause), args)
+            txn.execute(sql % (clause,), args)
             latest_event_ids = {}
             for parent_event_id, child_event_id in txn:
                 # Only consider the latest threaded reply (by topological ordering).
@@ -547,7 +541,7 @@ def _get_thread_summaries_txn(
                     AND parent.room_id = child.room_id
                 WHERE
                     %s
-                    AND %s
+                    AND relation_type = ?
                 GROUP BY parent.event_id
             """
 
@@ -556,15 +550,9 @@ def _get_thread_summaries_txn(
             clause, args = make_in_list_sql_clause(
                 txn.database_engine, "relates_to_id", latest_event_ids.keys()
             )
+            args.append(RelationTypes.THREAD)
 
-            if self._msc3440_enabled:
-                relations_clause = "(relation_type = ? OR relation_type = ?)"
-                args.extend((RelationTypes.THREAD, RelationTypes.UNSTABLE_THREAD))
-            else:
-                relations_clause = "relation_type = ?"
-                args.append(RelationTypes.THREAD)
-
-            txn.execute(sql % (clause, relations_clause), args)
+            txn.execute(sql % (clause,), args)
             counts = dict(cast(List[Tuple[str, int]], txn.fetchall()))
 
             return counts, latest_event_ids
@@ -622,7 +610,7 @@ async def get_threaded_messages_per_user(
                 parent.event_id = relates_to_id
                 AND parent.room_id = child.room_id
             WHERE
-                %s
+                relation_type = ?
                 AND %s
                 AND %s
             GROUP BY parent.event_id, child.sender
@@ -638,16 +626,9 @@ def _get_threaded_messages_per_user_txn(
                 txn.database_engine, "relates_to_id", event_ids
             )
 
-            if self._msc3440_enabled:
-                relations_clause = "(relation_type = ? OR relation_type = ?)"
-                relations_args = [RelationTypes.THREAD, RelationTypes.UNSTABLE_THREAD]
-            else:
-                relations_clause = "relation_type = ?"
-                relations_args = [RelationTypes.THREAD]
-
             txn.execute(
-                sql % (users_sql, events_clause, relations_clause),
-                users_args + events_args + relations_args,
+                sql % (users_sql, events_clause),
+                [RelationTypes.THREAD] + users_args + events_args,
             )
             return {(row[0], row[1]): row[2] for row in txn}
 
@@ -677,7 +658,7 @@ async def get_threads_participated(
             user participated in that event's thread, otherwise false.
         """
 
-        def _get_thread_summary_txn(txn: LoggingTransaction) -> Set[str]:
+        def _get_threads_participated_txn(txn: LoggingTransaction) -> Set[str]:
             # Fetch whether the requester has participated or not.
             sql = """
                 SELECT DISTINCT relates_to_id
@@ -688,28 +669,20 @@ def _get_thread_summary_txn(txn: LoggingTransaction) -> Set[str]:
                     AND parent.room_id = child.room_id
                 WHERE
                     %s
-                    AND %s
+                    AND relation_type = ?
                     AND child.sender = ?
             """
 
             clause, args = make_in_list_sql_clause(
                 txn.database_engine, "relates_to_id", event_ids
             )
+            args.extend([RelationTypes.THREAD, user_id])
 
-            if self._msc3440_enabled:
-                relations_clause = "(relation_type = ? OR relation_type = ?)"
-                args.extend((RelationTypes.THREAD, RelationTypes.UNSTABLE_THREAD))
-            else:
-                relations_clause = "relation_type = ?"
-                args.append(RelationTypes.THREAD)
-
-            args.append(user_id)
-
-            txn.execute(sql % (clause, relations_clause), args)
+            txn.execute(sql % (clause,), args)
             return {row[0] for row in txn.fetchall()}
 
         participated_threads = await self.db_pool.runInteraction(
-            "get_thread_summary", _get_thread_summary_txn
+            "get_threads_participated", _get_threads_participated_txn
         )
 
         return {event_id: event_id in participated_threads for event_id in event_ids}

From c4c2e2fa8390a3ee0cb4a1474cbf5997daa75a06 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Tue, 5 Apr 2022 12:04:33 -0400
Subject: [PATCH 2/4] Remove unstable identifiers for filtering parameters.

---
 synapse/api/filtering.py    | 12 ------------
 tests/api/test_filtering.py |  4 +---
 2 files changed, 1 insertion(+), 15 deletions(-)

diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index 27e97d6f372d..4a808e33fee1 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -89,9 +89,7 @@
         "org.matrix.not_labels": {"type": "array", "items": {"type": "string"}},
         # MSC3440, filtering by event relations.
         "related_by_senders": {"type": "array", "items": {"type": "string"}},
-        "io.element.relation_senders": {"type": "array", "items": {"type": "string"}},
         "related_by_rel_types": {"type": "array", "items": {"type": "string"}},
-        "io.element.relation_types": {"type": "array", "items": {"type": "string"}},
     },
 }
 
@@ -323,16 +321,6 @@ def __init__(self, hs: "HomeServer", filter_json: JsonDict):
         self.related_by_senders = self.filter_json.get("related_by_senders", None)
         self.related_by_rel_types = self.filter_json.get("related_by_rel_types", None)
 
-        # Fallback to the unstable prefix if the stable version is not given.
-        if hs.config.experimental.msc3440_enabled:
-            self.related_by_senders = self.related_by_senders or self.filter_json.get(
-                "io.element.relation_senders", None
-            )
-            self.related_by_rel_types = (
-                self.related_by_rel_types
-                or self.filter_json.get("io.element.relation_types", None)
-            )
-
     def filters_all_types(self) -> bool:
         return "*" in self.not_types
 
diff --git a/tests/api/test_filtering.py b/tests/api/test_filtering.py
index 8c3354ce3c79..985d6e397d36 100644
--- a/tests/api/test_filtering.py
+++ b/tests/api/test_filtering.py
@@ -481,9 +481,7 @@ def test_filter_relations(self):
         # events). This is a bit cheeky, but tests the logic of _check_event_relations.
 
         # Filter for a particular sender.
-        definition = {
-            "io.element.relation_senders": ["@foo:bar"],
-        }
+        definition = {"related_by_senders": ["@foo:bar"]}
 
         async def events_have_relations(*args, **kwargs):
             return ["$with_relation"]

From fcb7c2ea5771de247e292fc5c2262cf32308216f Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Tue, 5 Apr 2022 12:07:00 -0400
Subject: [PATCH 3/4] Remove the experimental config flag.

---
 synapse/config/experimental.py              |  2 --
 synapse/events/utils.py                     |  4 ----
 synapse/rest/client/versions.py             |  1 -
 synapse/server.py                           |  2 +-
 synapse/storage/databases/main/relations.py | 21 +--------------------
 5 files changed, 2 insertions(+), 28 deletions(-)

diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 0dd4c5958111..f93028d91b53 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -26,8 +26,6 @@ class ExperimentalConfig(Config):
     def read_config(self, config: JsonDict, **kwargs: Any) -> None:
         experimental = config.get("experimental_features") or {}
 
-        # MSC3440 (thread relation)
-        self.msc3440_enabled: bool = experimental.get("msc3440_enabled", False)
         # MSC3666: including bundled relations in /search.
         self.msc3666_enabled: bool = experimental.get("msc3666_enabled", False)
 
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 3203e11b087a..43c3241fb0d1 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -39,7 +39,6 @@
 
 if TYPE_CHECKING:
     from synapse.handlers.relations import BundledAggregations
-    from synapse.server import HomeServer
 
 
 # Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
@@ -396,9 +395,6 @@ class EventClientSerializer:
     clients.
     """
 
-    def __init__(self, hs: "HomeServer"):
-        self._msc3440_enabled = hs.config.experimental.msc3440_enabled
-
     def serialize_event(
         self,
         event: Union[JsonDict, EventBase],
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 9a65aa484360..7ee6b5505b20 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -100,7 +100,6 @@ def on_GET(self, request: Request) -> Tuple[int, JsonDict]:
                     # Adds support for jump to date endpoints (/timestamp_to_event) as per MSC3030
                     "org.matrix.msc3030": self.config.experimental.msc3030_enabled,
                     # Adds support for thread relations, per MSC3440.
-                    "org.matrix.msc3440": self.config.experimental.msc3440_enabled,
                     "org.matrix.msc3440.stable": True,  # TODO: remove when "v1.3" is added above
                 },
             },
diff --git a/synapse/server.py b/synapse/server.py
index 380369db923e..37c72bd83a9f 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -758,7 +758,7 @@ def get_oidc_handler(self) -> "OidcHandler":
 
     @cache_in_self
     def get_event_client_serializer(self) -> EventClientSerializer:
-        return EventClientSerializer(self)
+        return EventClientSerializer()
 
     @cache_in_self
     def get_password_policy_handler(self) -> PasswordPolicyHandler:
diff --git a/synapse/storage/databases/main/relations.py b/synapse/storage/databases/main/relations.py
index 43ca17232081..70c89309ed26 100644
--- a/synapse/storage/databases/main/relations.py
+++ b/synapse/storage/databases/main/relations.py
@@ -14,7 +14,6 @@
 
 import logging
 from typing import (
-    TYPE_CHECKING,
     Collection,
     Dict,
     FrozenSet,
@@ -32,20 +31,12 @@
 from synapse.api.constants import RelationTypes
 from synapse.events import EventBase
 from synapse.storage._base import SQLBaseStore
-from synapse.storage.database import (
-    DatabasePool,
-    LoggingDatabaseConnection,
-    LoggingTransaction,
-    make_in_list_sql_clause,
-)
+from synapse.storage.database import LoggingTransaction, make_in_list_sql_clause
 from synapse.storage.databases.main.stream import generate_pagination_where_clause
 from synapse.storage.engines import PostgresEngine
 from synapse.types import JsonDict, RoomStreamToken, StreamToken
 from synapse.util.caches.descriptors import cached, cachedList
 
-if TYPE_CHECKING:
-    from synapse.server import HomeServer
-
 logger = logging.getLogger(__name__)
 
 
@@ -63,16 +54,6 @@ class _RelatedEvent:
 
 
 class RelationsWorkerStore(SQLBaseStore):
-    def __init__(
-        self,
-        database: DatabasePool,
-        db_conn: LoggingDatabaseConnection,
-        hs: "HomeServer",
-    ):
-        super().__init__(database, db_conn, hs)
-
-        self._msc3440_enabled = hs.config.experimental.msc3440_enabled
-
     @cached(uncached_args=("event",), tree=True)
     async def get_relations_for_event(
         self,

From c2b9868020186cc2064d82e5095f0e7246b3bab2 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Tue, 5 Apr 2022 12:12:30 -0400
Subject: [PATCH 4/4] Newsfragment

---
 changelog.d/12382.removal | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/12382.removal

diff --git a/changelog.d/12382.removal b/changelog.d/12382.removal
new file mode 100644
index 000000000000..eb91186340f7
--- /dev/null
+++ b/changelog.d/12382.removal
@@ -0,0 +1 @@
+Remove unstable identifiers from [MSC3440](https://github.com/matrix-org/matrix-doc/pull/3440).