Exchange dialect information for remote database

drift/lib/isolate.dart

@@ -98,12 +98,11 @@ class DriftIsolate {
   ///
   /// Setting the [isolateDebugLog] is only helpful when debugging drift itself.
   /// It will print messages exchanged between the two isolates.
-  // todo: breaking: Make synchronous in drift 2
   Future<DatabaseConnection> connect({
     bool isolateDebugLog = false,
     bool singleClientMode = false,
   }) async {
-    return remote(
+    return connectToRemoteAndInitialize(
       _open(),
       debugLog: isolateDebugLog,
       serialize: serialize,

drift/lib/remote.dart

@@ -97,7 +97,7 @@ abstract class DriftServer {
   /// the message may be any Dart object.
   ///
   /// After calling [serve], you can obtain a [DatabaseConnection] on the other
-  /// end of the [channel] by calling [remote].
+  /// end of the [channel] by calling [connectToRemoteAndInitialize].
   ///
   /// __Warning__: As long as this library is marked experimental, the protocol
   /// might change with every drift version. For this reason, make sure that
@@ -134,6 +134,17 @@ abstract class DriftServer {
 ///
 /// The optional [debugLog] can be enabled to print incoming and outgoing
 /// messages.
+///
+/// __NOTE__: This synchronous method has a flaw, as its [QueryExecutor.dialect]
+/// is always going to be [SqlDialect.sqlite]. While this not a problem in most
+/// scenarios where that is the actual database, it makes it harder to use with
+/// other database clients. The [connectToRemoteAndInitialize] method does not
+/// have this issue.
+///
+/// Due to this problem, it is recommended to avoid [remote] altogether. If you
+/// know the dialect beforehand, you can wrap [connectToRemoteAndInitialize] in
+/// a [DatabaseConnection.delayed] to get a connection sychronously.
+@Deprecated('Use the asynchronous `connectToRemoteAndInitialize` instead')
 DatabaseConnection remote(
   StreamChannel<Object?> channel, {
   bool debugLog = false,
@@ -144,6 +155,37 @@ DatabaseConnection remote(
   return client.connection;
 }
 
+/// Connects to a remote server over a two-way communication channel.
+///
+/// The other end of the [channel] must be attached to a drift server with
+/// [DriftServer.serve] for this setup to work.
+///
+/// If it is known that only a single client will connect to this database
+/// server, [singleClientMode] can be enabled.
+/// When enabled, [shutdown] is implicitly called when the database connection
+/// is closed. This may make it easier to dispose the remote isolate or server.
+/// Also, update notifications for table updates don't have to be sent which
+/// reduces load on the connection.
+///
+/// If [serialize] is true, drift will only send [bool], [int], [double],
+/// [Uint8List], [String] or [List]'s thereof over the channel. Otherwise,
+/// the message may be any Dart object.
+/// The value of [serialize] for [connectToRemoteAndInitialize] must be the same
+/// value passed to [DriftServer.serve].
+///
+/// The optional [debugLog] can be enabled to print incoming and outgoing
+/// messages.
+Future<DatabaseConnection> connectToRemoteAndInitialize(
+  StreamChannel<Object?> channel, {
+  bool debugLog = false,
+  bool serialize = true,
+  bool singleClientMode = false,
+}) async {
+  final client = DriftClient(channel, debugLog, serialize, singleClientMode);
+  await client.serverInfo;
+  return client.connection;
+}
+
 /// Sends a shutdown request over a channel.
 ///
 /// On the remote side, the corresponding channel must have been passed to

drift/lib/src/remote/client_impl.dart

@@ -14,6 +14,12 @@ import 'protocol.dart';
 class DriftClient {
   final DriftCommunication _channel;
 
+  SqlDialect _serverDialect = SqlDialect.sqlite;
+  final Completer<ServerInfo> _serverInfo = Completer();
+
+  /// Waits for the first [ServerInfo] message to this client.
+  Future<ServerInfo> get serverInfo => _serverInfo.future;
+
   /// Whether we know that only a single client will use the database server.
   ///
   /// In this case, we shutdown the server after the client disconnects and
@@ -51,6 +57,9 @@ class DriftClient {
       return _connectedDb.beforeOpen(executor, payload.details);
     } else if (payload is NotifyTablesUpdated) {
       _streamStore.handleTableUpdates(payload.updates.toSet(), true);
+    } else if (payload is ServerInfo) {
+      _serverDialect = payload.dialect;
+      _serverInfo.complete(payload);
     }
   }
 }
@@ -62,6 +71,9 @@ abstract class _BaseExecutor extends QueryExecutor {
   // ignore: unused_element, https://github.com/dart-lang/sdk/issues/49007
   _BaseExecutor(this.client, [this._executorId]);
 
+  @override
+  SqlDialect get dialect => client._serverDialect;
+
   @override
   Future<void> runBatched(BatchedStatements statements) {
     return client._channel
@@ -129,9 +141,6 @@ class _RemoteQueryExecutor extends _BaseExecutor {
   Completer<void>? _setSchemaVersion;
   Future<bool>? _serverIsOpen;
 
-  @override
-  SqlDialect get dialect => SqlDialect.sqlite;
-
   @override
   TransactionExecutor beginTransaction() {
     return _RemoteTransactionExecutor(client, _executorId);

drift/lib/src/remote/protocol.dart

@@ -22,6 +22,8 @@ class DriftProtocol {
   static const _tag_DirectValue = 10;
   static const _tag_SelectResult = 11;
   static const _tag_RequestCancellation = 12;
+  static const _tag_ServerInfo = 13;
+
   static const _tag_BigInt = 'bigint';
 
   Object? serialize(Message message) {
@@ -103,6 +105,11 @@ class DriftProtocol {
       ];
     } else if (payload is EnsureOpen) {
       return [_tag_EnsureOpen, payload.schemaVersion, payload.executorId];
+    } else if (payload is ServerInfo) {
+      return [
+        _tag_ServerInfo,
+        payload.dialect.name,
+      ];
     } else if (payload is RunBeforeOpen) {
       return [
         _tag_RunBeforeOpen,
@@ -189,6 +196,8 @@ class DriftProtocol {
         return RunTransactionAction(control, readNullableInt(2));
       case _tag_EnsureOpen:
         return EnsureOpen(readInt(1), readNullableInt(2));
+      case _tag_ServerInfo:
+        return ServerInfo(SqlDialect.values.byName(fullMessage![1] as String));
       case _tag_RunBeforeOpen:
         return RunBeforeOpen(
           OpeningDetails(readNullableInt(1), readInt(2)),
@@ -408,6 +417,17 @@ class EnsureOpen {
   }
 }
 
+class ServerInfo {
+  final SqlDialect dialect;
+
+  ServerInfo(this.dialect);
+
+  @override
+  String toString() {
+    return 'ServerInfo($dialect)';
+  }
+}
+
 /// Sent from the server to the client when it should run the before open
 /// callback.
 class RunBeforeOpen {

drift/lib/src/remote/server_impl.dart

@@ -54,6 +54,7 @@ class ServerImplementation implements DriftServer {
 
     final comm = DriftCommunication(channel, serialize: serialize);
     comm.setRequestHandler((request) => _handleRequest(comm, request));
+    comm.request(ServerInfo(connection.executor.dialect));
 
     _activeChannels.add(comm);
     comm.closed.then((_) => _activeChannels.remove(comm));

drift/lib/src/runtime/api/connection.dart

@@ -44,15 +44,17 @@ class DatabaseConnection {
   ///   }
   /// }
   /// ```
-  factory DatabaseConnection.delayed(FutureOr<DatabaseConnection> connection) {
+  factory DatabaseConnection.delayed(FutureOr<DatabaseConnection> connection,
+      {SqlDialect dialect = SqlDialect.sqlite}) {
     if (connection is DatabaseConnection) {
       return connection;
     }
 
     return DatabaseConnection(
-      LazyDatabase(() async => (await connection).executor),
+      LazyDatabase(() async => (await connection).executor, dialect: dialect),
       streamQueries: DelayedStreamQueryStore(
-          connection.then((conn) => conn.streamQueries)),
+        connection.then((conn) => conn.streamQueries),
+      ),
     );
   }
 

drift/test/remote_test.dart

@@ -29,8 +29,9 @@ void main() {
         DriftServer(testInMemoryDatabase(), allowRemoteShutdown: true);
     server.serve(controller.foreign);
 
-    final client =
-        remote(controller.local.expectedToClose, singleClientMode: true);
+    final client = await connectToRemoteAndInitialize(
+        controller.local.expectedToClose,
+        singleClientMode: true);
     final db = TodoDb.connect(client);
 
     await db.todosTable.select().get();
@@ -47,7 +48,7 @@ void main() {
       final controller = StreamChannelController();
       server.serve(controller.foreign, serialize: false);
 
-      final client = remote(
+      final client = await connectToRemoteAndInitialize(
         controller.local.transformSink(StreamSinkTransformer.fromHandlers(
           handleData: (data, out) {
             expect(data, isNot(isA<NotifyTablesUpdated>()));
@@ -117,7 +118,7 @@ void main() {
     server.serve(channelController.foreign.changeStream(_checkStreamOfSimple),
         serialize: true);
 
-    final connection = remote(
+    final connection = await connectToRemoteAndInitialize(
         channelController.local
             .changeStream(_checkStreamOfSimple)
             .expectedToClose,
@@ -162,7 +163,8 @@ void main() {
     server.serve(controller.foreign);
     addTearDown(server.shutdown);
 
-    final db = TodoDb.connect(remote(controller.local));
+    final db =
+        TodoDb.connect(await connectToRemoteAndInitialize(controller.local));
     addTearDown(db.close);
 
     await db.transaction(() async {
@@ -190,6 +192,19 @@ void main() {
     verify(innerTransactions[1].send());
     verify(outerTransaction.send());
   });
+
+  test('reports correct dialect of remote', () async {
+    final executor = MockExecutor();
+    when(executor.dialect).thenReturn(SqlDialect.postgres);
+
+    final controller = StreamChannelController();
+    final server = DriftServer(DatabaseConnection(executor))
+      ..serve(controller.foreign);
+
+    final client = await connectToRemoteAndInitialize(controller.local);
+    await server.shutdown();
+    expect(client.executor.dialect, SqlDialect.postgres);
+  });
 }
 
 Stream<Object?> _checkStreamOfSimple(Stream<Object?> source) {

examples/app/lib/database/connection/web.dart

@@ -15,7 +15,8 @@ const _useWorker = true;
 DatabaseConnection connect({bool isInWebWorker = false}) {
   if (_useWorker && !isInWebWorker) {
     final worker = SharedWorker('shared_worker.dart.js');
-    return remote(worker.port!.channel());
+    return DatabaseConnection.delayed(
+        connectToRemoteAndInitialize(worker.port!.channel()));
   } else {
     return DatabaseConnection.delayed(Future.sync(() async {
       // We're using the experimental wasm support in Drift because this gives

examples/flutter_web_worker_example/lib/src/platform/platform_web.dart

@@ -16,6 +16,7 @@ class PlatformInterface {
   static DatabaseConnection _connectToWorker(String databaseName) {
     final worker = SharedWorker(
         kReleaseMode ? 'worker.dart.min.js' : 'worker.dart.js', databaseName);
-    return remote(worker.port!.channel());
+    return DatabaseConnection.delayed(
+        connectToRemoteAndInitialize(worker.port!.channel()));
   }
 }

examples/web_worker_example/web/main.dart

@@ -4,9 +4,9 @@ import 'package:drift/remote.dart';
 import 'package:drift/web.dart';
 import 'package:web_worker_example/database.dart';
 
-void main() {
+void main() async {
   final worker = SharedWorker('worker.dart.js');
-  final connection = remote(worker.port!.channel());
+  final connection = await connectToRemoteAndInitialize(worker.port!.channel());
   final db = MyDatabase(connection);
 
   final output = document.getElementById('output')!;