Simplify send-to-device messaging (#1702)

* Simplify send-to-device messaging

* Don't return error if there's no work to do

* Remove SQLite migrations for now

* Tweak Postgres migrations

* Tweaks

* Fixes

* Cleanup separately

* Fix SQLite migration

syncapi/storage/postgres/deltas/20201211125500_sequences.go

@@ -24,6 +24,7 @@ import (
 
 func LoadFromGoose() {
 	goose.AddMigration(UpFixSequences, DownFixSequences)
+	goose.AddMigration(UpRemoveSendToDeviceSentColumn, DownRemoveSendToDeviceSentColumn)
 }
 
 func LoadFixSequences(m *sqlutil.Migrations) {

syncapi/storage/postgres/deltas/20210112130000_sendtodevice_sentcolumn.go

@@ -0,0 +1,48 @@
+// 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 deltas
+
+import (
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+)
+
+func LoadRemoveSendToDeviceSentColumn(m *sqlutil.Migrations) {
+	m.AddMigration(UpRemoveSendToDeviceSentColumn, DownRemoveSendToDeviceSentColumn)
+}
+
+func UpRemoveSendToDeviceSentColumn(tx *sql.Tx) error {
+	_, err := tx.Exec(`
+		ALTER TABLE syncapi_send_to_device
+		  DROP COLUMN IF EXISTS sent_by_token;
+	`)
+	if err != nil {
+		return fmt.Errorf("failed to execute upgrade: %w", err)
+	}
+	return nil
+}
+
+func DownRemoveSendToDeviceSentColumn(tx *sql.Tx) error {
+	_, err := tx.Exec(`
+		ALTER TABLE syncapi_send_to_device
+		  ADD COLUMN IF NOT EXISTS sent_by_token TEXT;
+	`)
+	if err != nil {
+		return fmt.Errorf("failed to execute downgrade: %w", err)
+	}
+	return nil
+}