3 files changed, 121 insertions, 4 deletions
diff --git a/syncapi/storage/postgres/memberships_table.go b/syncapi/storage/postgres/memberships_table.go
new file mode 100644
index 00000000..6566544d
--- /dev/null
+++ b/syncapi/storage/postgres/memberships_table.go
@@ -0,0 +1,111 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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.
+
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/syncapi/storage/tables"
+	"github.com/matrix-org/dendrite/syncapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+// The memberships table is designed to track the last time that
+// the user was a given state. This allows us to find out the
+// most recent time that a user was invited to, joined or left
+// a room, either by choice or otherwise. This is important for
+// building history visibility.
+
+const membershipsSchema = `
+CREATE TABLE IF NOT EXISTS syncapi_memberships (
+    -- The 'room_id' key for the state event.
+    room_id TEXT NOT NULL,
+    -- The state event ID
+	user_id TEXT NOT NULL,
+	-- The status of the membership
+	membership TEXT NOT NULL,
+	-- The event ID that last changed the membership
+	event_id TEXT NOT NULL,
+	-- The stream position of the change
+	stream_pos BIGINT NOT NULL,
+	-- The topological position of the change in the room
+	topological_pos BIGINT NOT NULL,
+	-- Unique index
+	CONSTRAINT syncapi_memberships_unique UNIQUE (room_id, user_id, membership)
+);
+`
+
+const upsertMembershipSQL = "" +
+	"INSERT INTO syncapi_memberships (room_id, user_id, membership, event_id, stream_pos, topological_pos)" +
+	" VALUES ($1, $2, $3, $4, $5, $6)" +
+	" ON CONFLICT ON CONSTRAINT syncapi_memberships_unique" +
+	" DO UPDATE SET event_id = $4, stream_pos = $5, topological_pos = $6"
+
+const selectMembershipSQL = "" +
+	"SELECT event_id, stream_pos, topological_pos FROM syncapi_memberships" +
+	" WHERE room_id = $1 AND user_id = $2 AND membership = ANY($3)" +
+	" ORDER BY stream_pos DESC" +
+	" LIMIT 1"
+
+type membershipsStatements struct {
+	upsertMembershipStmt *sql.Stmt
+	selectMembershipStmt *sql.Stmt
+}
+
+func NewPostgresMembershipsTable(db *sql.DB) (tables.Memberships, error) {
+	s := &membershipsStatements{}
+	_, err := db.Exec(membershipsSchema)
+	if err != nil {
+		return nil, err
+	}
+	if s.upsertMembershipStmt, err = db.Prepare(upsertMembershipSQL); err != nil {
+		return nil, err
+	}
+	if s.selectMembershipStmt, err = db.Prepare(selectMembershipSQL); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+func (s *membershipsStatements) UpsertMembership(
+	ctx context.Context, txn *sql.Tx, event *gomatrixserverlib.HeaderedEvent,
+	streamPos, topologicalPos types.StreamPosition,
+) error {
+	membership, err := event.Membership()
+	if err != nil {
+		return fmt.Errorf("event.Membership: %w", err)
+	}
+	_, err = sqlutil.TxStmt(txn, s.upsertMembershipStmt).ExecContext(
+		ctx,
+		event.RoomID(),
+		*event.StateKey(),
+		membership,
+		event.EventID(),
+		streamPos,
+		topologicalPos,
+	)
+	return err
+}
+
+func (s *membershipsStatements) SelectMembership(
+	ctx context.Context, txn *sql.Tx, roomID, userID, memberships []string,
+) (eventID string, streamPos, topologyPos types.StreamPosition, err error) {
+	stmt := sqlutil.TxStmt(txn, s.selectMembershipStmt)
+	err = stmt.QueryRowContext(ctx, roomID, userID, memberships).Scan(&eventID, &streamPos, &topologyPos)
+	return
+}
diff --git a/syncapi/storage/postgres/output_room_events_topology_table.go b/syncapi/storage/postgres/output_room_events_topology_table.go
index cbd20a07..57774453 100644
--- a/syncapi/storage/postgres/output_room_events_topology_table.go
+++ b/syncapi/storage/postgres/output_room_events_topology_table.go
@@ -44,7 +44,8 @@ CREATE UNIQUE INDEX IF NOT EXISTS syncapi_event_topological_position_idx ON sync
 const insertEventInTopologySQL = "" +
 	"INSERT INTO syncapi_output_room_events_topology (event_id, topological_position, room_id, stream_position)" +
 	" VALUES ($1, $2, $3, $4)" +
-	" ON CONFLICT (topological_position, stream_position, room_id) DO UPDATE SET event_id = $1"
+	" ON CONFLICT (topological_position, stream_position, room_id) DO UPDATE SET event_id = $1" +
+	" RETURNING topological_position"
 
 const selectEventIDsInRangeASCSQL = "" +
 	"SELECT event_id FROM syncapi_output_room_events_topology" +
@@ -115,10 +116,10 @@ func NewPostgresTopologyTable(db *sql.DB) (tables.Topology, error) {
 // on the event's depth.
 func (s *outputRoomEventsTopologyStatements) InsertEventInTopology(
 	ctx context.Context, txn *sql.Tx, event *gomatrixserverlib.HeaderedEvent, pos types.StreamPosition,
-) (err error) {
-	_, err = s.insertEventInTopologyStmt.ExecContext(
+) (topoPos types.StreamPosition, err error) {
+	err = sqlutil.TxStmt(txn, s.insertEventInTopologyStmt).QueryRowContext(
 		ctx, event.EventID(), event.Depth(), event.RoomID(), pos,
-	)
+	).Scan(&topoPos)
 	return
 }
 
diff --git a/syncapi/storage/postgres/syncserver.go b/syncapi/storage/postgres/syncserver.go
index 0fbf3c23..a69fda4f 100644
--- a/syncapi/storage/postgres/syncserver.go
+++ b/syncapi/storage/postgres/syncserver.go
@@ -87,6 +87,10 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*SyncServerDatasource, e
 	if err != nil {
 		return nil, err
 	}
+	memberships, err := NewPostgresMembershipsTable(d.db)
+	if err != nil {
+		return nil, err
+	}
 	m := sqlutil.NewMigrations()
 	deltas.LoadFixSequences(m)
 	deltas.LoadRemoveSendToDeviceSentColumn(m)
@@ -106,6 +110,7 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*SyncServerDatasource, e
 		Filter:              filter,
 		SendToDevice:        sendToDevice,
 		Receipts:            receipts,
+		Memberships:         memberships,
 	}
 	return &d, nil
 }