Resolve state after event against current room state when determining latest state changes (#1479)

* Resolve state after event against current room state when determining latest state changes

* Update sytest-whitelist

* Update sytest-whitelist, blacklist

roomserver/internal/input/input_latest_events.go

@@ -215,10 +215,27 @@ func (u *latestEventsUpdater) latestState() error {
 	var err error
 	roomState := state.NewStateResolution(u.api.DB, *u.roomInfo)
 
-	// Get a list of the current latest events.
+	// Get a list of the current room state events if available.
-	latestStateAtEvents := make([]types.StateAtEvent, len(u.latest))
+	var currentState []types.StateEntry
+	if u.roomInfo.StateSnapshotNID != 0 {
+		currentState, _ = roomState.LoadStateAtSnapshot(u.ctx, u.roomInfo.StateSnapshotNID)
+	}
+
+	// Get a list of the current latest events. This will include both
+	// the current room state and the latest events after the input event.
+	// The idea is that we will perform state resolution on this set and
+	// any conflicting events will be resolved properly.
+	latestStateAtEvents := make([]types.StateAtEvent, len(u.latest)+len(currentState))
+	offset := 0
+	for i := range currentState {
+		latestStateAtEvents[i] = types.StateAtEvent{
+			BeforeStateSnapshotNID: u.roomInfo.StateSnapshotNID,
+			StateEntry:             currentState[i],
+		}
+		offset++
+	}
 	for i := range u.latest {
-		latestStateAtEvents[i] = u.latest[i].StateAtEvent
+		latestStateAtEvents[offset+i] = u.latest[i].StateAtEvent
 	}
 
 	// Takes the NIDs of the latest events and creates a state snapshot

roomserver/state/state.go

@@ -118,7 +118,7 @@ func (v StateResolution) LoadCombinedStateAfterEvents(
 	// the snapshot of the room state before them was the same.
 	stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, uniqueStateSnapshotNIDs(stateNIDs))
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("v.db.StateBlockNIDs: %w", err)
 	}
 
 	var stateBlockNIDs []types.StateBlockNID
@@ -131,7 +131,7 @@ func (v StateResolution) LoadCombinedStateAfterEvents(
 	// multiple snapshots.
 	stateEntryLists, err := v.db.StateEntries(ctx, uniqueStateBlockNIDs(stateBlockNIDs))
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("v.db.StateEntries: %w", err)
 	}
 	stateBlockNIDsMap := stateBlockNIDListMap(stateBlockNIDLists)
 	stateEntriesMap := stateEntryListMap(stateEntryLists)
@@ -623,7 +623,7 @@ func (v StateResolution) calculateAndStoreStateAfterManyEvents(
 		v.calculateStateAfterManyEvents(ctx, v.roomInfo.RoomVersion, prevStates)
 	metrics.algorithm = algorithm
 	if err != nil {
-		return metrics.stop(0, err)
+		return metrics.stop(0, fmt.Errorf("v.calculateStateAfterManyEvents: %w", err))
 	}
 
 	// TODO: Check if we can encode the new state as a delta against the
@@ -642,6 +642,7 @@ func (v StateResolution) calculateStateAfterManyEvents(
 	// First stage: load the state after each of the prev events.
 	combined, err = v.LoadCombinedStateAfterEvents(ctx, prevStates)
 	if err != nil {
+		err = fmt.Errorf("v.LoadCombinedStateAfterEvents: %w", err)
 		algorithm = "_load_combined_state"
 		return
 	}
@@ -672,6 +673,7 @@ func (v StateResolution) calculateStateAfterManyEvents(
 		var resolved []types.StateEntry
 		resolved, err = v.resolveConflicts(ctx, roomVersion, notConflicted, conflicts)
 		if err != nil {
+			err = fmt.Errorf("v.resolveConflits: %w", err)
 			algorithm = "_resolve_conflicts"
 			return
 		}

sytest-blacklist

@@ -52,4 +52,9 @@ Inbound federation accepts a second soft-failed event
 Outbound federation requests missing prev_events and then asks for /state_ids and resolves the state
 
 # We don't implement lazy membership loading yet.
-The only membership state included in a gapped incremental sync is for senders in the timeline
+The only membership state included in a gapped incremental sync is for senders in the timeline
+
+# Blacklisted out of flakiness after #1479
+Invited user can reject local invite after originator leaves
+Invited user can reject invite for empty room
+If user leaves room, remote user changes device and rejoins we see update in /sync and /keys/changes

sytest-whitelist

@@ -400,8 +400,6 @@ Uninvited users cannot join the room
 Users cannot invite themselves to a room
 Users cannot invite a user that is already in the room
 Invited user can reject invite
-Invited user can reject invite for empty room
-Invited user can reject local invite after originator leaves
 PUT /rooms/:room_id/typing/:user_id sets typing notification
 Typing notification sent to local room members
 Typing notifications also sent to remote room members
@@ -431,7 +429,6 @@ A prev_batch token can be used in the v1 messages API
 We don't send redundant membership state across incremental syncs by default
 Typing notifications don't leak
 Users cannot kick users from a room they are not in
-Users cannot kick users who have already left a room
 User appears in user directory
 User directory correctly update on display name change
 User in shared private room does appear in user directory
@@ -451,7 +448,6 @@ Banned servers cannot backfill
 Inbound /v1/send_leave rejects leaves from other servers
 Guest users can accept invites to private rooms over federation
 AS user (not ghost) can join room without registering
-If user leaves room, remote user changes device and rejoins we see update in /sync and /keys/changes
 Can search public room list
 Can get remote public room list
 Asking for a remote rooms list, but supplying the local server's name, returns the local rooms list