Move service extension handler execution to a timer

sdk/lib/developer/extension.dart

 // Copyright (c) 2015, 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.
 
 part of dart.developer;
 
 class ServiceExtensionResponse {
   final String _result;
   final int _errorCode;
   final String _errorDetail;
@@ skipping 84 matching lines @@
     throw new ArgumentError('Extension already registered: $method');
   }
   if (handler is! ServiceExtensionHandler) {
     throw new ArgumentError.value(handler,
                                   'handler',
                                   'Must be a ServiceExtensionHandler');
   }
   _extensions[method] = handler;
 }
 
-bool _extensionExists(String method) {
-  return _extensions[method] != null;
-}
-
-bool _invokeExtension(String method,
-                      List<String> parameterKeys,
-                      List<String> parameterValues,
-                      SendPort replyPort,
-                      Object id) {
+bool _scheduleExtension(String method,
+                        List<String> parameterKeys,
+                        List<String> parameterValues,
+                        SendPort replyPort,
+                        Object id) {
   ServiceExtensionHandler handler = _extensions[method];
-  assert(handler != null);
-  var parameters = {};
-  for (var i = 0; i < parameterKeys.length; i++) {
-    parameters[parameterKeys[i]] = parameterValues[i];
+  if (handler == null) {
+    return false;
   }
-  var response;
-  try {
-    response = handler(method, parameters);
-  } catch (e, st) {
-    var errorDetails = (st == null) ? '$e' : '$e\n$st';
-    response = new ServiceExtensionResponse.error(
-        ServiceExtensionResponse.kExtensionError,
-        errorDetails);
-    _postResponse(replyPort, id, response);
-    return true;
-  }
-  if (response is! Future) {
-    response = new ServiceExtensionResponse.error(
-          ServiceExtensionResponse.kExtensionError,
-          "Extension handler must return a Future");
-    _postResponse(replyPort, id, response);
-    return true;
-  }
-  response.catchError((e, st) {
-    var errorDetails = (st == null) ? '$e' : '$e\n$st';
-    return new ServiceExtensionResponse.error(
-        ServiceExtensionResponse.kExtensionError,
-        errorDetails);
-  }).then((response) {
-    if (response == null) {
+  // Defer execution of handler until next event loop.
+  Timer.run(() {
+    var parameters = {};
+    for (var i = 0; i < parameterKeys.length; i++) {
+      parameters[parameterKeys[i]] = parameterValues[i];
+    }
+    var response;
+    try {
+      response = handler(method, parameters);
+    } catch (e, st) {
+      var errorDetails = (st == null) ? '$e' : '$e\n$st';
       response = new ServiceExtensionResponse.error(
           ServiceExtensionResponse.kExtensionError,
-          "Extension handler returned null");
+          errorDetails);
+      _postResponse(replyPort, id, response);
+      return;
     }
-    _postResponse(replyPort, id, response);
+    if (response is! Future) {
+      response = new ServiceExtensionResponse.error(
+            ServiceExtensionResponse.kExtensionError,
+            "Extension handler must return a Future");
+      _postResponse(replyPort, id, response);
+      return;
+    }
+    response.catchError((e, st) {
+      var errorDetails = (st == null) ? '$e' : '$e\n$st';
+      return new ServiceExtensionResponse.error(
+          ServiceExtensionResponse.kExtensionError,
+          errorDetails);
+    }).then((response) {
+      if (response == null) {
+        response = new ServiceExtensionResponse.error(
+            ServiceExtensionResponse.kExtensionError,
+            "Extension handler returned null");
+      }
+      _postResponse(replyPort, id, response);
+    });
   });
-  // Push an event on the event loop so that we invoke the scheduled microtasks.
-  Timer.run(() {});
   return true;
 }
 
 _postResponse(SendPort replyPort,
               Object id,
               ServiceExtensionResponse response) {
   assert(replyPort != null);
   if (id == null) {
     // No id -> no response.
     // TODO(johnmccutchan): This code and the code in service.cc leave the
@@ skipping 10 matching lines @@
     sb.write('"result":');
   }
   sb.write('${response._toString()},');
   if (id is String) {
     sb.write('"id":"$id"}');
   } else {
     sb.write('"id":$id}');
   }
   replyPort.send(sb.toString());
 }