Close isolate connection on exit

Fix for https://github.com/simolus3/drift/issues/3449#issuecomment-3045322812

# Conflicts:
#	drift/CHANGELOG.md
#	drift/lib/native.dart

drift/CHANGELOG.md

@@ -1,3 +1,18 @@
+## 2.28.0-dev
+
+- Query delegates: Support nested transactions in `SupportedTransactionDelegate`.
+- Fix drift server isolates leaking when their only client isolate exits without closing the database.
+
+## 2.27.0
+
+- Allow passing `sqlite3` callback to `NativeDatabase` to customize how SQLite
+  bindings are obtained.
+
+## 2.26.1
+
+- Add `isNotNull()` column filter for the manager APIs.
+- Add optional `orderBy` parameter to more aggregate function extension.
+
 ## 2.26.0
 
 - Add support for window functions with `WindowFunctionExpression`.

drift/lib/native.dart

@@ -431,15 +431,19 @@ class _NativeIsolateStartup {
 
   static Future<void> start(_NativeIsolateStartup startup) async {
     await startup.isolateSetup?.call();
-    final isolate = DriftIsolate.inCurrent(() {
-      return DatabaseConnection(NativeDatabase(
-        File(startup.path),
-        logStatements: startup.enableLogs,
-        cachePreparedStatements: startup.cachePreparedStatements,
-        enableMigrations: startup.enableMigrations,
-        setup: startup.setup,
-      ));
-    });
+    final isolate = DriftIsolate.inCurrent(
+      () {
+        return DatabaseConnection(NativeDatabase(
+          File(startup.path),
+          logStatements: startup.enableLogs,
+          cachePreparedStatements: startup.cachePreparedStatements,
+          enableMigrations: startup.enableMigrations,
+          setup: startup.setup,
+        ));
+      },
+      shutdownAfterLastDisconnect: true,
+      killIsolateWhenDone: true,
+    );
 
     startup.sendServer.send(isolate);
   }

drift/lib/src/isolate.dart

@@ -36,7 +36,13 @@ Future<(StreamChannel, bool)> connectToServer(
   // If the isolate accepts the connection, it sends us a send port back which
   // is then used for the rest of the communication.
   final receive = ReceivePort('drift client receive');
-  serverConnectPort.send([receive.sendPort, serialize]);
+  serverConnectPort.send([
+    receive.sendPort,
+    serialize,
+    // The server isolate will use addOnExitListener to mark the connection as
+    // closed when the isolate shuts down.
+    Isolate.current.controlPort
+  ]);
 
   final controller =
       StreamChannelController<Object?>(allowForeignErrors: false, sync: true);
@@ -105,16 +111,21 @@ class RunningDriftServer {
           closeConnectionAfterShutdown: closeConnectionAfterShutdown,
         ) {
     final subscription = connectPort.listen((message) {
-      if (message is List && message.length == 2) {
+      if (message
+          case [
+            final sendPort as SendPort,
+            final serialize as bool,
+            final closeOnExit as SendPort
+          ]) {
         if (onlyAcceptSingleConnection) {
           connectPort.close();
         }
 
-        final sendPort = message[0]! as SendPort;
-        final serialize = message[1]! as bool;
+        final clientIsolate = Isolate(closeOnExit);
         final receiveForConnection =
             ReceivePort('drift channel #${_counter++}');
-        sendPort.send(receiveForConnection.sendPort);
+        final sendPortForRemote = receiveForConnection.sendPort;
+        sendPort.send(sendPortForRemote);
 
         final controller = StreamChannelController<Object?>(
             allowForeignErrors: false, sync: true);
@@ -122,11 +133,6 @@ class RunningDriftServer {
           if (message == disconnectMessage) {
             // Client closed the connection
             controller.local.sink.close();
-
-            if (onlyAcceptSingleConnection) {
-              // The only connection was closed, so shut down the server.
-              server.shutdown();
-            }
           } else {
             controller.local.sink.add(message);
           }
@@ -137,9 +143,12 @@ class RunningDriftServer {
           sendPort.send(disconnectMessage);
         });
 
+        clientIsolate.addOnExitListener(sendPortForRemote,
+            response: disconnectMessage);
         _activeConnections++;
         server.serve(controller.foreign, serialize: serialize).whenComplete(() {
           _activeConnections--;
+          clientIsolate.removeErrorListener(sendPortForRemote);
 
           if (_activeConnections == 0 && shutDownAfterLastDisconnect) {
             server.shutdown();

drift/test/isolate_test.dart

@@ -174,6 +174,26 @@ void main() {
     await db.close();
   }, tags: 'background_isolate');
 
+  test('can close server when client isolate exits', () async {
+    final shutdownCalled = Completer<void>();
+    final isolate = DriftIsolate.inCurrent(
+      () => NativeDatabase.memory(),
+      shutdownAfterLastDisconnect: true,
+      beforeShutdown: shutdownCalled.complete,
+    );
+
+    await Isolate.run(() async {
+      final connection = await isolate.connect();
+      // Ensure the statement works
+      await TodoDb(connection).customStatement('SELECT 1');
+
+      // Close the isolate without closing the database
+    });
+
+    // This should still shut down the server.
+    await shutdownCalled.future;
+  });
+
   test('shutting down will close the underlying executor', () async {
     final mockExecutor = MockExecutor();
     final isolate =