Handle request errors (#160)

example/grpc-web/lib/app.dart

@@ -11,8 +11,13 @@ class EchoApp {
   Future<void> echo(String message) async {
     _addLeftMessage(message);
 
-    final response = await _service.echo(new EchoRequest()..message = message);
-    _addRightMessage(response.message);
+    try {
+      final response =
+          await _service.echo(new EchoRequest()..message = message);
+      _addRightMessage(response.message);
+    } catch (error) {
+      _addRightMessage(error.toString());
+    }
   }
 
   void repeatEcho(String message, int count) {
@@ -23,6 +28,8 @@ class EchoApp {
       ..messageInterval = 500;
     _service.serverStreamingEcho(request).listen((response) {
       _addRightMessage(response.message);
+    }, onError: (error) {
+      _addRightMessage(error.toString());
     }, onDone: () => print('Closed connection to server.'));
   }
 

lib/src/client/call.dart

@@ -112,7 +112,8 @@ class ClientCall<Q, R> implements Response {
 
   void _sendRequest(ClientConnection connection, Map<String, String> metadata) {
     try {
-      _stream = connection.makeRequest(path, options.timeout, metadata);
+      _stream = connection.makeRequest(
+          path, options.timeout, metadata, _onRequestError);
     } catch (e) {
       _terminateWithError(new GrpcError.unavailable('Error making call: $e'));
       return;
@@ -249,7 +250,7 @@ class ClientCall<Q, R> implements Response {
   /// Error handler for the requests stream. Something went wrong while trying
   /// to send the request to the server. Abort the request, and forward the
   /// error to the user code on the [_responses] stream.
-  void _onRequestError(error) {
+  void _onRequestError(error, [StackTrace stackTrace]) {
     if (error is! GrpcError) {
       error = new GrpcError.unknown(error.toString());
     }

lib/src/client/channel.dart

@@ -69,7 +69,8 @@ abstract class ClientChannel {
   /// The connection may be shared between multiple RPCs.
   Future<ClientConnection> getConnection() async {
     if (_isShutdown) throw new GrpcError.unavailable('Channel shutting down.');
-    return _connection ??= new ClientConnection(host, port, options, connectTransport);
+    return _connection ??=
+        new ClientConnection(host, port, options, connectTransport);
   }
 
   /// Initiates a new RPC on this connection.

lib/src/client/connection.dart

@@ -16,9 +16,7 @@
 import 'dart:async';
 
 import 'package:grpc/src/client/channel.dart';
-import 'package:meta/meta.dart';
 
-import '../shared/status.dart';
 import 'call.dart';
 import 'options.dart';
 
@@ -99,9 +97,9 @@ class ClientConnection {
     }
   }
 
-  GrpcTransportStream makeRequest(
-      String path, Duration timeout, Map<String, String> metadata) {
-    return _transport.makeRequest(path, timeout, metadata);
+  GrpcTransportStream makeRequest(String path, Duration timeout,
+      Map<String, String> metadata, ErrorHandler onRequestFailure) {
+    return _transport.makeRequest(path, timeout, metadata, onRequestFailure);
   }
 
   void _startCall(ClientCall call) {

lib/src/client/transport/http2_transport.dart

@@ -30,17 +30,15 @@ import 'http2_credentials.dart';
 import 'transport.dart';
 
 class Http2TransportStream extends GrpcTransportStream {
-  TransportStream _transportStream;
-  StreamController<GrpcMessage> _incomingMessages;
-  StreamController<List<int>> _outgoingMessages;
+  final TransportStream _transportStream;
+  final StreamController<GrpcMessage> _incomingMessages = StreamController();
+  final StreamController<List<int>> _outgoingMessages = StreamController();
+  final ErrorHandler _onError;
 
   Stream<GrpcMessage> get incomingMessages => _incomingMessages.stream;
   StreamSink<List<int>> get outgoingMessages => _outgoingMessages.sink;
 
-  Http2TransportStream(this._transportStream) {
-    _incomingMessages = new StreamController();
-    _outgoingMessages = new StreamController();
-
+  Http2TransportStream(this._transportStream, this._onError) {
     _transportStream.incomingMessages
         .transform(new GrpcHttpDecoder())
         .transform(grpcDecompressor())
@@ -56,8 +54,8 @@ class Http2TransportStream extends GrpcTransportStream {
             cancelOnError: true);
   }
 
-  void _onRequestError() {
-    // TODO: Implement errors on requests
+  void _onRequestError(error) {
+    _onError(error);
   }
 
   @override
@@ -132,12 +130,12 @@ class Http2Transport extends Transport {
   }
 
   @override
-  GrpcTransportStream makeRequest(
-      String path, Duration timeout, Map<String, String> metadata) {
+  GrpcTransportStream makeRequest(String path, Duration timeout,
+      Map<String, String> metadata, ErrorHandler onError) {
     final headers = createCallHeaders(
         options.credentials.isSecure, authority, path, timeout, metadata);
     final stream = transportConnection.makeRequest(headers);
-    return new Http2TransportStream(stream);
+    return new Http2TransportStream(stream, onError);
   }
 
   @override

lib/src/client/transport/transport.dart

@@ -19,6 +19,7 @@ import '../../shared/message.dart';
 
 typedef void SocketClosedHandler();
 typedef void ActiveStateHandler(bool isActive);
+typedef void ErrorHandler(error);
 
 abstract class GrpcTransportStream {
   Stream<GrpcMessage> get incomingMessages;
@@ -32,8 +33,8 @@ abstract class Transport {
   SocketClosedHandler onSocketClosed;
 
   Future<void> connect();
-  GrpcTransportStream makeRequest(
-      String path, Duration timeout, Map<String, String> metadata);
+  GrpcTransportStream makeRequest(String path, Duration timeout,
+      Map<String, String> metadata, ErrorHandler onRequestFailure);
   Future<void> finish();
   Future<void> terminate();
 }

lib/src/client/transport/web_streams.dart

@@ -13,7 +13,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-
 import 'dart:convert';
 import 'dart:math';
 import 'dart:typed_data';
@@ -157,4 +156,3 @@ class _GrpcWebConversionSink extends ChunkedConversionSink<ByteBuffer> {
     _out.close();
   }
 }
-

lib/src/client/transport/xhr_transport.dart

@@ -17,6 +17,7 @@ import 'dart:async';
 import 'dart:html';
 import 'dart:typed_data';
 
+import 'package:grpc/src/shared/status.dart';
 import 'package:meta/meta.dart';
 
 import '../../shared/message.dart';
@@ -24,11 +25,12 @@ import 'transport.dart';
 import 'web_streams.dart';
 
 class XhrTransportStream implements GrpcTransportStream {
-  HttpRequest _request;
+  final HttpRequest _request;
+  final ErrorHandler _onError;
   int _requestBytesRead = 0;
-  StreamController<ByteBuffer> _incomingProcessor;
-  StreamController<GrpcMessage> _incomingMessages;
-  StreamController<List<int>> _outgoingMessages;
+  final StreamController<ByteBuffer> _incomingProcessor = StreamController();
+  final StreamController<GrpcMessage> _incomingMessages = StreamController();
+  final StreamController<List<int>> _outgoingMessages = StreamController();
 
   @override
   Stream<GrpcMessage> get incomingMessages => _incomingMessages.stream;
@@ -36,48 +38,43 @@ class XhrTransportStream implements GrpcTransportStream {
   @override
   StreamSink<List<int>> get outgoingMessages => _outgoingMessages.sink;
 
-  XhrTransportStream(this._request) {
-    _incomingProcessor = StreamController();
-    _incomingMessages = StreamController();
-    _outgoingMessages = StreamController();
-
-    _incomingProcessor.stream
-        .transform(GrpcWebDecoder())
-        .transform(grpcDecompressor())
-        .listen(_incomingMessages.add,
-            onError: _incomingMessages.addError,
-            onDone: _incomingMessages.close);
-
+  XhrTransportStream(this._request, this._onError) {
     _outgoingMessages.stream
         .map(frame)
-        .listen((data) => _request.send(data));
+        .listen((data) => _request.send(data), cancelOnError: true);
 
     _request.onReadyStateChange.listen((data) {
-      final contentType = _request.getResponseHeader('Content-Type');
-      if (contentType == null) {
+      if (_incomingMessages.isClosed) {
         return;
       }
-
-      if (_request.readyState == HttpRequest.HEADERS_RECEIVED) {
-        if (contentType.startsWith('application/grpc')) {
-          if (_request.response == null) {
-            return;
+      switch (_request.readyState) {
+        case HttpRequest.HEADERS_RECEIVED:
+          _onHeadersReceived();
+          break;
+        case HttpRequest.DONE:
+          if (_request.status != 200) {
+            _onError(GrpcError.unavailable(
+                'XhrConnection status ${_request.status}'));
+          } else {
+            _close();
           }
-
-          // Force a metadata message with headers
-          final headers = GrpcMetadata(_request.responseHeaders);
-          _incomingMessages.add(headers);
-        }
-      }
-
-      if (_request.readyState == HttpRequest.DONE) {
-        _incomingProcessor.close();
-        _outgoingMessages.close();
+          break;
       }
     });
 
+    _request.onError.listen((ProgressEvent event) {
+      if (_incomingMessages.isClosed) {
+        return;
+      }
+      _onError(GrpcError.unavailable('XhrConnection connection-error'));
+      terminate();
+    });
+
     _request.onProgress.listen((_) {
-      // use response over responseText as most browsers don't support
+      if (_incomingMessages.isClosed) {
+        return;
+      }
+      // Use response over responseText as most browsers don't support
       // using responseText during an onProgress event.
       final responseString = _request.response as String;
       final bytes = Uint8List.fromList(
@@ -86,12 +83,48 @@ class XhrTransportStream implements GrpcTransportStream {
       _requestBytesRead = responseString.length;
       _incomingProcessor.add(bytes);
     });
+
+    _incomingProcessor.stream
+        .transform(GrpcWebDecoder())
+        .transform(grpcDecompressor())
+        .listen(_incomingMessages.add,
+            onError: _onError, onDone: _incomingMessages.close);
+  }
+
+  _onHeadersReceived() {
+    final contentType = _request.getResponseHeader('Content-Type');
+    if (_request.status != 200) {
+      _onError(
+          GrpcError.unavailable('XhrConnection status ${_request.status}'));
+      return;
+    }
+    if (contentType == null) {
+      _onError(GrpcError.unavailable('XhrConnection missing Content-Type'));
+      return;
+    }
+    if (!contentType.startsWith('application/grpc')) {
+      _onError(
+          GrpcError.unavailable('XhrConnection bad Content-Type $contentType'));
+      return;
+    }
+    if (_request.response == null) {
+      _onError(GrpcError.unavailable('XhrConnection request null response'));
+      return;
+    }
+
+    // Force a metadata message with headers.
+    final headers = GrpcMetadata(_request.responseHeaders);
+    _incomingMessages.add(headers);
+  }
+
+  _close() {
+    _incomingProcessor.close();
+    _outgoingMessages.close();
   }
 
   @override
   Future<void> terminate() async {
-    await _incomingProcessor.close();
-    await _outgoingMessages.close();
+    _close();
     _request.abort();
   }
 }
@@ -124,17 +157,16 @@ class XhrTransport extends Transport {
   }
 
   @override
-  GrpcTransportStream makeRequest(
-      String path, Duration timeout, Map<String, String> metadata) {
+  GrpcTransportStream makeRequest(String path, Duration timeout,
+      Map<String, String> metadata, ErrorHandler onError) {
     _request = HttpRequest();
     _request.open('POST', '${host}:${port}${path}');
 
     initializeRequest(_request, metadata);
 
-    return XhrTransportStream(_request);
+    return XhrTransportStream(_request, onError);
   }
 
   @override
   Future<void> terminate() async {}
 }
-

lib/src/client/web_channel.dart

@@ -27,6 +27,6 @@ Future<Transport> connectXhrTransport(
 }
 
 class GrpcWebClientChannel extends ClientChannel {
-  GrpcWebClientChannel.xhr(String host,
-      {int port = 443}) : super(host, connectXhrTransport, port: port);
-}
+  GrpcWebClientChannel.xhr(String host, {int port = 443})
+      : super(host, connectXhrTransport, port: port);
+}

lib/src/shared/message.dart

@@ -52,12 +52,12 @@ List<int> frame(List<int> payload) {
 StreamTransformer<GrpcMessage, GrpcMessage> grpcDecompressor() =>
     new StreamTransformer<GrpcMessage, GrpcMessage>.fromHandlers(
         handleData: (GrpcMessage value, EventSink<GrpcMessage> sink) {
-          if (value is GrpcData) {
-            if (value.isCompressed) {
-              // TODO(dart-lang/grpc-dart#6): Actually handle decompression.
-              sink.add(new GrpcData(value.data, isCompressed: false));
-              return;
-            }
-          }
-          sink.add(value);
-        });
+      if (value is GrpcData) {
+        if (value.isCompressed) {
+          // TODO(dart-lang/grpc-dart#6): Actually handle decompression.
+          sink.add(new GrpcData(value.data, isCompressed: false));
+          return;
+        }
+      }
+      sink.add(value);
+    });