Reimplemented zone memory tracking to avoid race conditions that were causing crashes in the previo…

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 1501 matching lines @@
   String fileAndLine;
 
   DartError error;
   StreamController _snapshotFetch;
 
   List<ByteData> _chunksInProgress;
 
   List<Thread> get threads => _threads;
   final List<Thread> _threads = new List<Thread>();
 
-  int get memoryHighWatermark => _memoryHighWatermark;
-  int _memoryHighWatermark = 0;
+  int get zoneHighWatermark => _zoneHighWatermark;
+  int _zoneHighWatermark = 0;
 
   int get numZoneHandles => _numZoneHandles;
   int _numZoneHandles;
 
   int get numScopedHandles => _numScopedHandles;
   int _numScopedHandles;
 
   void _loadHeapSnapshot(ServiceEvent event) {
     if (_snapshotFetch == null || _snapshotFetch.isClosed) {
       // No outstanding snapshot request. Presumably another client asked for a
@@ skipping 117 matching lines @@
     extensionRPCs.clear();
     if (map['extensionRPCs'] != null) {
       extensionRPCs.addAll(map['extensionRPCs']);
     }
 
     threads.clear();
     if (map['_threads'] != null) {
       threads.addAll(map['_threads']);
     }
 
-    int currentMemoryHighWatermark = 0;
+    int currentZoneHighWatermark = 0;
     for (var i = 0; i < threads.length; i++) {
-      currentMemoryHighWatermark += threads[i].memoryHighWatermark;
+      currentZoneHighWatermark += threads[i].zoneHighWatermark;
     }
 
-    if (currentMemoryHighWatermark > _memoryHighWatermark) {
-      _memoryHighWatermark = currentMemoryHighWatermark;
+    if (currentZoneHighWatermark > _zoneHighWatermark) {
+      _zoneHighWatermark = currentZoneHighWatermark;
     }
 
     _numZoneHandles = map['_numZoneHandles'];
     _numScopedHandles = map['_numScopedHandles'];
   }
 
   Future<TagProfile> updateTagProfile() {
     return isolate.invokeRpcNoUpgrade('_getTagProfile', {}).then((Map map) {
       var seconds = new DateTime.now().millisecondsSinceEpoch / 1000.0;
       tagProfile._processTagProfile(seconds, map);
@@ skipping 1421 matching lines @@
 
   String toString() => 'Sentinel($kind)';
   String get shortName => valueAsString;
 }
 
 class Thread extends ServiceObject implements M.Thread {
   M.ThreadKind get kind => _kind;
   M.ThreadKind _kind;
   String get kindString => _kindString;
   String _kindString;
-  int get memoryHighWatermark => _memoryHighWatermark;
-  int _memoryHighWatermark;
-
-  // TODO(bkonyi): zones will always be empty. See issue #28885.
-  List<Zone> get zones => _zones;
-  final List<Zone> _zones = new List<Zone>();
+  int get zoneHighWatermark => _zoneHighWatermark;
+  int _zoneHighWatermark;
+  int get zoneCapacity => _zoneCapacity;
+  int _zoneCapacity;
 
   Thread._empty(ServiceObjectOwner owner) : super._empty(owner);
 
   void _update(Map map, bool mapIsRef) {
     String rawKind = map['kind'];
 
     switch (rawKind) {
       case "kUnknownTask":
         _kind = M.ThreadKind.unknownTask;
         _kindString = 'unknown';
@@ skipping 15 matching lines @@
         _kindString = 'marker';
         break;
       case "kFinalizerTask":
         _kind = M.ThreadKind.finalizerTask;
         _kindString = 'finalizer';
         break;
       default:
         assert(false);
     }
 
-    _memoryHighWatermark = int.parse(map['_memoryHighWatermark']);
+    _zoneHighWatermark = int.parse(map['_zoneHighWatermark']);
+    _zoneCapacity = int.parse(map['_zoneCapacity']);
   }
 }
 
 class Zone implements M.Zone {
   int get capacity => _capacity;
   int _capacity;
   int get used => _used;
   int _used;
 
   Zone(this._capacity, this._used);
@@ skipping 1464 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);
     }
   }
 }