Make IsolateChannel's controllers synchronous.

lib/src/isolate_channel.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:isolate';
 
 import 'package:async/async.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import '../stream_channel.dart';
 
+import 'dart:io';
+
 /// A [StreamChannel] that communicates over a [ReceivePort]/[SendPort] pair,
 /// presumably with another isolate.
 ///
 /// The remote endpoint doesn't necessarily need to be running an
 /// [IsolateChannel]. This can be used with any two ports, although the
 /// [StreamChannel] semantics mean that this class will treat them as being
 /// paired (for example, closing the [sink] will cause the [stream] to stop
 /// emitting events).
 ///
 /// The underlying isolate ports have no notion of closing connections. This
@@ skipping 23 matching lines @@
     var sinkCompleter = new StreamSinkCompleter<T>();
     var channel = new IsolateChannel._(
         streamCompleter.stream, sinkCompleter.sink);
 
     // The first message across the ReceivePort should be a SendPort pointing to
     // the remote end. If it's not, we'll make the stream emit an error
     // complaining.
     var subscription;
     subscription = receivePort.listen((message) {
       if (message is SendPort) {
-        var controller = new StreamChannelController(allowForeignErrors: false);
+        var controller = new StreamChannelController(
+            allowForeignErrors: false, sync: true);
         new SubscriptionStream<T>(subscription).pipe(controller.local.sink);
         controller.local.stream.listen(message.send,
             onDone: receivePort.close);
 
         streamCompleter.setSourceStream(controller.foreign.stream);
         sinkCompleter.setDestinationSink(controller.foreign.sink);
         return;
       }
 
       streamCompleter.setError(
@@ skipping 17 matching lines @@
   /// at least until the next major version release.
   factory IsolateChannel.connectSend(SendPort sendPort) {
     var receivePort = new ReceivePort();
     sendPort.send(receivePort.sendPort);
     return new IsolateChannel(receivePort, sendPort);
   }
 
   /// Creates a stream channel that receives messages from [receivePort] and
   /// sends them over [sendPort].
   factory IsolateChannel(ReceivePort receivePort, SendPort sendPort) {
-    var controller = new StreamChannelController(allowForeignErrors: false);
+    var controller = new StreamChannelController(
+        allowForeignErrors: false, sync: true);
     receivePort.pipe(controller.local.sink);
     controller.local.stream.listen(sendPort.send, onDone: receivePort.close);
     return new IsolateChannel._(
         controller.foreign.stream, controller.foreign.sink);
   }
 
   IsolateChannel._(this.stream, this.sink);
 }