Track async causal stack traces

runtime/observatory/lib/src/service/object.dart

 // Copyright (c) 2014, 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 service;
 
 // Some value smaller than the object ring, so requesting a large array
 // doesn't result in an expired ref because the elements lapped it in the
 // object ring.
 const int kDefaultFieldLimit = 100;
@@ skipping 4372 matching lines @@
     vmName = map['name'];
     value = map['value'];
     min = map['min'];
     max = map['max'];
   }
 
   String toString() => "ServiceMetric($_id)";
 }
 
 class Frame extends ServiceObject implements M.Frame {
+  M.FrameKind kind = M.FrameKind.regular;
   int index;
   ServiceFunction function;
   SourceLocation location;
   Code code;
   List<ServiceMap> variables = <ServiceMap>[];
+  String marker;
 
   Frame._empty(ServiceObject owner) : super._empty(owner);
 
   void _update(Map map, bool mapIsRef) {
     assert(!mapIsRef);
     _loaded = true;
     _upgradeCollection(map, owner);
+    this.kind = _fromString(map['kind']);
+    this.marker = map['marker'];
     this.index = map['index'];
     this.function = map['function'];
     this.location = map['location'];
     this.code = map['code'];
-    this.variables = map['vars'];
+    this.variables = map['vars'] ?? [];
   }
 
-  String toString() => "Frame(${function.qualifiedName} $location)";
+  M.FrameKind _fromString(String frameKind) {
+    if (frameKind == null) {
+      return M.FrameKind.regular;
+    }
+    switch (frameKind) {
+      case 'kRegular': return M.FrameKind.regular;
+      case 'kAsyncCausal': return M.FrameKind.asyncCausal;
+      case 'kAsyncSuspensionMarker': return M.FrameKind.asyncSuspensionMarker;
+      default:
+        throw new UnsupportedError('Unknown FrameKind: $frameKind');
+    }
+  }
+
+  String toString() => "Frame([$kind] ${function.qualifiedName} $location)";
 }
 
 class ServiceMessage extends ServiceObject {
   int index;
   String messageObjectId;
   int size;
   ServiceFunction handler;
   SourceLocation location;
 
   ServiceMessage._empty(ServiceObject owner) : super._empty(owner);
@@ skipping 91 matching lines @@
     var v = list[i];
     if ((v is Map) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is List) {
       _upgradeList(v, owner);
     } else if (v is Map) {
       _upgradeMap(v, owner);
     }
   }
 }