Add a channel to communication with server

pkg/analyzer_plugin/lib/src/channel/isolate_channel.dart

Index: pkg/analyzer_plugin/lib/src/channel/isolate_channel.dart
diff --git a/pkg/analyzer_plugin/lib/src/channel/isolate_channel.dart b/pkg/analyzer_plugin/lib/src/channel/isolate_channel.dart
new file mode 100644
index 0000000000000000000000000000000000000000..7472483872f7acae0a48e0bbe58ac7944c5eb653
--- /dev/null
+++ b/pkg/analyzer_plugin/lib/src/channel/isolate_channel.dart
@@ -0,0 +1,74 @@
+// Copyright (c) 2017, 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:analyzer_plugin/channel/channel.dart';
+import 'package:analyzer_plugin/protocol/protocol.dart';
+
+/**
+ * The object that allows a [ServerPlugin] to receive [Request]s and to return
+ * both [Response]s and [Notification]s.
+ */
+class IsolateChannel implements PluginCommunicationChannel {

[scheglov, 2017/01/31 21:00:40]

Maybe a bit more specific documentation comment.

[Brian Wilkerson, 2017/01/31 21:11:31]

Oops! Too many things going on at one time. I'll catch this in the next CL.

+  /**
+   * The port used to send notifications and responses to the server.
+   */
+  SendPort _sendPort;
+
+  /**
+   * The port used to receive requests from the server.
+   */
+  ReceivePort _receivePort;
+
+  /**
+   * The subscription that needs to be cancelled when the channel is closed.
+   */
+  StreamSubscription _subscription;
+
+  /**
+   * Initialize a newly created channel to communicate with the server.
+   */
+  IsolateChannel(this._sendPort) {
+    _receivePort = new ReceivePort();
+    _sendPort.send(_receivePort.sendPort);
+  }
+
+  @override
+  void close() {
+    if (_subscription != null) {
+      _subscription.cancel();
+      _subscription = null;
+    }
+  }
+
+  @override
+  void listen(void onRequest(Request request),
+      {Function onError, void onDone()}) {
+    void onData(data) {
+      Map<String, Object> requestMap = data;
+      Request request = new Request.fromJson(requestMap);
+      if (request != null) {
+        onRequest(request);
+      }
+    }
+
+    if (_subscription != null) {
+      throw new StateError('Only one listener is allowed per channel');
+    }
+    _subscription = _receivePort.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: false);
+  }
+
+  @override
+  void sendNotification(Notification notification) {
+    _sendPort.send(notification.toJson());
+  }
+
+  @override
+  void sendResponse(Response response) {
+    _sendPort.send(response.toJson());
+  }
+}