Added tracking of memory usage within ApiNativeScopes. Usage to be displayed within Observatory.

runtime/vm/dart_api_state.h

 // Copyright (c) 2012, 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.
 
 #ifndef RUNTIME_VM_DART_API_STATE_H_
 #define RUNTIME_VM_DART_API_STATE_H_
 
 #include "include/dart_api.h"
 
 #include "platform/utils.h"
@@ skipping 656 matching lines @@
 };
 
 
 class ApiNativeScope {
  public:
   ApiNativeScope() {
     // Currently no support for nesting native scopes.
     ASSERT(Current() == NULL);
     OSThread::SetThreadLocal(Api::api_native_key_,
                              reinterpret_cast<uword>(this));
+    // We manually increment the memory usage counter since there is memory
+    // initially allocated within the zone on creation.
+    IncrementNativeScopeMemoryUsage(zone_.GetZone()->CapacityInBytes());
   }
 
   ~ApiNativeScope() {
     ASSERT(Current() == this);
     OSThread::SetThreadLocal(Api::api_native_key_, 0);
+    // We must also manually decrement the memory usage counter since the native
+    // is still holding it's initial memory and ~Zone() won't be able to
+    // determine which memory usage counter to decrement.
+    DecrementNativeScopeMemoryUsage(zone_.GetZone()->CapacityInBytes());
   }
 
   static inline ApiNativeScope* Current() {
     return reinterpret_cast<ApiNativeScope*>(
         OSThread::GetThreadLocal(Api::api_native_key_));
   }
 
+  static intptr_t current_memory_usage() { return current_memory_usage_; }
+
+  static void IncrementNativeScopeMemoryUsage(intptr_t size) {
+    AtomicOperations::IncrementBy(&current_memory_usage_, size);
+  }
+
+  static void DecrementNativeScopeMemoryUsage(intptr_t size) {
+    AtomicOperations::DecrementBy(&current_memory_usage_, size);
+  }
+
   Zone* zone() {
     Zone* result = zone_.GetZone();
     ASSERT(result->handles()->CountScopedHandles() == 0);
     ASSERT(result->handles()->CountZoneHandles() == 0);
     return result;
   }
 
  private:
+  // The current total memory usage within ApiNativeScopes.
+  static intptr_t current_memory_usage_;
+
   ApiZone zone_;
 };
 
 
 // Api growable arrays use a zone for allocation. The constructor
 // picks the zone from the current isolate if in an isolate
 // environment. When outside an isolate environment it picks the zone
 // from the current native scope.
 template <typename T>
 class ApiGrowableArray : public BaseGrowableArray<T, ValueObject> {
@@ skipping 134 matching lines @@
   ref->set_callback(callback);
   ref->set_is_queued_for_finalization(false);
   // This may trigger GC, so it must be called last.
   ref->SetExternalSize(external_size, isolate);
   return ref;
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_DART_API_STATE_H_