Add a slaved events store class

Add a test to check that get_room_names_and_aliases does the same
thing on both the master and on the slave data store.

synapse/replication/slave/storage/events.py

@@ -0,0 +1,198 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
+
+from synapse.api.constants import EventTypes
+from synapse.events import FrozenEvent
+from synapse.storage import DataStore
+from synapse.storage.room import RoomStore
+from synapse.storage.roommember import RoomMemberStore
+from synapse.storage.event_federation import EventFederationStore
+from synapse.storage.state import StateStore
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+import ujson as json
+
+# So, um, we want to borrow a load of functions intended for reading from
+# a DataStore, but we don't want to take functions that either write to the
+# DataStore or are cached and don't have cache invalidation logic.
+#
+# Rather than write duplicate versions of those functions, or lift them to
+# a common base class, we going to grab the underlying __func__ object from
+# the method descriptor on the DataStore and chuck them into our class.
+
+
+class SlavedEventStore(BaseSlavedStore):
+
+    def __init__(self, db_conn, hs):
+        super(SlavedEventStore, self).__init__(db_conn, hs)
+        self._stream_id_gen = SlavedIdTracker(
+            db_conn, "events", "stream_ordering",
+        )
+        self._backfill_id_gen = SlavedIdTracker(
+            db_conn, "events", "stream_ordering", step=-1
+        )
+        events_max = self._stream_id_gen.get_current_token()
+        event_cache_prefill, min_event_val = self._get_cache_dict(
+            db_conn, "events",
+            entity_column="room_id",
+            stream_column="stream_ordering",
+            max_value=events_max,
+        )
+        self._events_stream_cache = StreamChangeCache(
+            "EventsRoomStreamChangeCache", min_event_val,
+            prefilled_cache=event_cache_prefill,
+        )
+
+    # Cached functions can't be accessed through a class instance so we need
+    # to reach inside the __dict__ to extract them.
+    get_room_name_and_aliases = RoomStore.__dict__["get_room_name_and_aliases"]
+    get_rooms_for_user = RoomMemberStore.__dict__["get_rooms_for_user"]
+    get_users_in_room = RoomMemberStore.__dict__["get_users_in_room"]
+    get_latest_event_ids_in_room = EventFederationStore.__dict__[
+        "get_latest_event_ids_in_room"
+    ]
+    _get_current_state_for_key = StateStore.__dict__[
+        "_get_current_state_for_key"
+    ]
+
+    get_current_state = DataStore.get_current_state.__func__
+    get_current_state_for_key = DataStore.get_current_state_for_key.__func__
+    _get_rooms_for_user_where_membership_is_txn = (
+        DataStore._get_rooms_for_user_where_membership_is_txn.__func__
+    )
+    get_rooms_for_user_where_membership_is = (
+        DataStore.get_rooms_for_user_where_membership_is.__func__
+    )
+    get_membership_changes_for_user = (
+        DataStore.get_membership_changes_for_user.__func__
+    )
+    get_room_events_max_id = DataStore.get_room_events_max_id.__func__
+    get_room_events_stream_for_room = (
+        DataStore.get_room_events_stream_for_room.__func__
+    )
+    _set_before_and_after = DataStore._set_before_and_after
+
+    _get_events = DataStore._get_events.__func__
+    _get_events_from_cache = DataStore._get_events_from_cache.__func__
+
+    _invalidate_get_event_cache = DataStore._invalidate_get_event_cache.__func__
+    _parse_events_txn = DataStore._parse_events_txn.__func__
+    _get_events_txn = DataStore._get_events_txn.__func__
+    _fetch_events_txn = DataStore._fetch_events_txn.__func__
+    _fetch_event_rows = DataStore._fetch_event_rows.__func__
+    _get_event_from_row_txn = DataStore._get_event_from_row_txn.__func__
+
+    def stream_positions(self):
+        result = super(SlavedEventStore, self).stream_positions()
+        result["events"] = self._stream_id_gen.get_current_token()
+        result["backfilled"] = self._backfill_id_gen.get_current_token()
+        return result
+
+    def process_replication(self, result):
+        state_resets = set(
+            r[0] for r in result.get("state_resets", {"rows": []})["rows"]
+        )
+
+        stream = result.get("events")
+        if stream:
+            self._stream_id_gen.advance(stream["position"])
+            for row in stream["rows"]:
+                self._process_replication_row(
+                    row, backfilled=False, state_resets=state_resets
+                )
+
+        stream = result.get("backfill")
+        if stream:
+            self._backfill_id_gen.advance(stream["position"])
+            for row in stream["rows"]:
+                self._process_replication_row(
+                    row, backfilled=True, state_resets=state_resets
+                )
+
+        stream = result.get("forward_ex_outliers")
+        if stream:
+            for row in stream["rows"]:
+                event_id = row[1]
+                self._invalidate_get_event_cache(event_id)
+
+        stream = result.get("backward_ex_outliers")
+        if stream:
+            for row in stream["rows"]:
+                event_id = row[1]
+                self._invalidate_get_event_cache(event_id)
+
+        return super(SlavedEventStore, self).process_replication(result)
+
+    def _process_replication_row(self, row, backfilled, state_resets):
+        position = row[0]
+        internal = json.loads(row[1])
+        event_json = json.loads(row[2])
+
+        event = FrozenEvent(event_json, internal_metadata_dict=internal)
+        self._invalidate_caches_for_event(
+            event, backfilled, reset_state=position in state_resets
+        )
+
+    def _invalidate_caches_for_event(self, event, backfilled, reset_state):
+        if reset_state:
+            self._get_current_state_for_key.invalidate_all()
+            self.get_rooms_for_user.invalidate_all()
+            self.get_users_in_room.invalidate((event.room_id,))
+            # self.get_joined_hosts_for_room.invalidate((event.room_id,))
+            self.get_room_name_and_aliases.invalidate((event.room_id,))
+
+        self._invalidate_get_event_cache(event.event_id)
+
+        if not backfilled:
+            self._events_stream_cache.entity_has_changed(
+                event.room_id, event.internal_metadata.stream_ordering
+            )
+
+        # self.get_unread_event_push_actions_by_room_for_user.invalidate_many(
+        #     (event.room_id,)
+        # )
+
+        if event.type == EventTypes.Redaction:
+            self._invalidate_get_event_cache(event.redacts)
+
+        if event.type == EventTypes.Member:
+            self.get_rooms_for_user.invalidate((event.state_key,))
+            # self.get_joined_hosts_for_room.invalidate((event.room_id,))
+            self.get_users_in_room.invalidate((event.room_id,))
+            # self._membership_stream_cache.entity_has_changed(
+            #    event.state_key, event.internal_metadata.stream_ordering
+            # )
+
+        if not event.is_state():
+            return
+
+        if backfilled:
+            return
+
+        if (not event.internal_metadata.is_invite_from_remote()
+                and event.internal_metadata.is_outlier()):
+            return
+
+        self._get_current_state_for_key.invalidate((
+            event.room_id, event.type, event.state_key
+        ))
+
+        if event.type in [EventTypes.Name, EventTypes.Aliases]:
+            self.get_room_name_and_aliases.invalidate(
+                (event.room_id,)
+            )
+            pass