[dds] Switch DAP server mode to directly using stdin/stdout

Change-Id: Id2a8d8c9274b96cf32788e11d4452954a4f9c091
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/205500
Reviewed-by: Ben Konyi <[email protected]>

Author: DanTup

pkg/dds/lib/src/dap/adapters/dart_cli.dart

@@ -53,7 +53,9 @@ class DartCliDebugAdapter extends DartDebugAdapter<DartLaunchRequestArguments> {
           enableDds: enableDds,
           enableAuthCodes: enableAuthCodes,
           logger: logger,
-        );
+        ) {
+    channel.closed.then((_) => shutdown());
+  }
 
   Future<void> debuggerConnected(vm.VM vmInfo) async {
     if (!isAttach) {

pkg/dds/lib/src/dap/protocol_stream_transformers.dart

@@ -4,7 +4,6 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:typed_data';
 
 class InvalidEncodingError {
   final String headers;
@@ -107,28 +106,3 @@ class ProtocolHeaders {
   final String? encoding;
   ProtocolHeaders(this.rawHeaders, this.contentLength, this.encoding);
 }
-
-/// Transforms a stream of [Uint8List]s to [List<int>]s. Used because
-/// [ServerSocket] and [Socket] use [Uint8List] but stdin and stdout use
-/// [List<int>] and the LSP server needs to operate against both.
-class Uint8ListTransformer extends StreamTransformerBase<Uint8List, List<int>> {
-  // TODO(dantup): Is there a built-in (or better) way to do this?
-  @override
-  Stream<List<int>> bind(Stream<Uint8List> stream) {
-    late StreamSubscription<Uint8List> input;
-    late StreamController<List<int>> _output;
-    _output = StreamController<List<int>>(
-      onListen: () {
-        input = stream.listen(
-          (uints) => _output.add(uints),
-          onError: _output.addError,
-          onDone: _output.close,
-        );
-      },
-      onPause: () => input.pause(),
-      onResume: () => input.resume(),
-      onCancel: () => input.cancel(),
-    );
-    return _output.stream;
-  }
-}

pkg/dds/lib/src/dap/server.dart

@@ -3,92 +3,45 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:dds/src/dap/adapters/dart.dart';
-import 'package:pedantic/pedantic.dart';
 
 import 'adapters/dart_cli.dart';
 import 'logging.dart';
 import 'protocol_stream.dart';
-import 'protocol_stream_transformers.dart';
 
-/// A DAP server that binds to a port and runs in multi-session mode.
+/// A DAP server that communicates over a [ByteStreamServerChannel], usually
+/// constructed from the processes stdin/stdout streams.
+///
+/// The server runs in single-user mode and services only a single client. For
+/// multiple debug sessions, there would be multiple servers (and the editor
+/// would have a client for each of them).
 class DapServer {
-  final ServerSocket _socket;
+  final ByteStreamServerChannel channel;
+  late final DartDebugAdapter adapter;
   final bool ipv6;
   final bool enableDds;
   final bool enableAuthCodes;
   final Logger? logger;
-  final _channels = <ByteStreamServerChannel>{};
-  final _adapters = <DartDebugAdapter>{};
 
-  DapServer._(
-    this._socket, {
+  DapServer(
+    Stream<List<int>> _input,
+    StreamSink<List<int>> _output, {
     this.ipv6 = false,
     this.enableDds = true,
     this.enableAuthCodes = true,
     this.logger,
-  }) {
-    _socket.listen(_acceptConnection);
-  }
-
-  String get host => _socket.address.host;
-  int get port => _socket.port;
-
-  Future<void> stop() async {
-    _channels.forEach((client) => client.close());
-    await _socket.close();
-  }
-
-  void _acceptConnection(Socket client) {
-    final address = client.remoteAddress;
-    logger?.call('Accepted connection from $address');
-    client.done.then((_) {
-      logger?.call('Connection from $address closed');
-    });
-    _createAdapter(client.transform(Uint8ListTransformer()), client);
-  }
-
-  void _createAdapter(Stream<List<int>> _input, StreamSink<List<int>> _output) {
-    // TODO(dantup): This is hard-coded to DartCliDebugAdapter but will
-    //   ultimately need to support having a factory passed in to support
-    //   tests and/or being used in flutter_tools.
-    final channel = ByteStreamServerChannel(_input, _output, logger);
-    final adapter = DartCliDebugAdapter(
+  }) : channel = ByteStreamServerChannel(_input, _output, logger) {
+    adapter = DartCliDebugAdapter(
       channel,
       ipv6: ipv6,
       enableDds: enableDds,
       enableAuthCodes: enableAuthCodes,
       logger: logger,
     );
-    _channels.add(channel);
-    _adapters.add(adapter);
-    unawaited(channel.closed.then((_) {
-      _channels.remove(channel);
-      _adapters.remove(adapter);
-      adapter.shutdown();
-    }));
   }
 
-  /// Starts a DAP Server listening on [host]:[port].
-  static Future<DapServer> create({
-    String? host,
-    int port = 0,
-    bool ipv6 = false,
-    bool enableDdds = true,
-    bool enableAuthCodes = true,
-    Logger? logger,
-  }) async {
-    final hostFallback =
-        ipv6 ? InternetAddress.loopbackIPv6 : InternetAddress.loopbackIPv4;
-    final _socket = await ServerSocket.bind(host ?? hostFallback, port);
-    return DapServer._(
-      _socket,
-      ipv6: ipv6,
-      enableDds: enableDdds,
-      enableAuthCodes: enableAuthCodes,
-      logger: logger,
-    );
+  void stop() {
+    channel.close();
   }
 }