Adding V8 api to get memory statistics of spaces in V8::Heap.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 8019a4522b4bafb811263bc39bb53e516fbeb2b6..0884f9b8ca79d78f838e2bcded5f1aef1c17c936 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -4853,12 +4853,34 @@ typedef void (*InterruptCallback)(Isolate* isolate, void* data);
 class V8_EXPORT HeapStatistics {
  public:
   HeapStatistics();
+
+  class SpaceStatistics {
+   public:
+    size_t size() { return size_of_objects_; }
+    size_t committed_memory() { return committed_memory_; }
+    size_t avalable() { return available_memory_; }
+
+   private:
+    size_t size_of_objects_;
+    size_t committed_memory_;
+    size_t available_memory_;
+
+    friend class HeapStatisticsHelper;
+  };
+
   size_t total_heap_size() { return total_heap_size_; }
   size_t total_heap_size_executable() { return total_heap_size_executable_; }
   size_t total_physical_size() { return total_physical_size_; }
   size_t used_heap_size() { return used_heap_size_; }
   size_t heap_size_limit() { return heap_size_limit_; }
 
+  SpaceStatistics* new_space_statistics() { return &new_space_stats_; }
+  SpaceStatistics* old_space_statistics() { return &old_space_stats_; }
+  SpaceStatistics* code_space_statistics() { return &code_space_stats_; }
+  SpaceStatistics* map_space_statistics() { return &map_space_stats_; }
+  SpaceStatistics* cell_space_statistics() { return &cell_space_stats_; }
+  SpaceStatistics* lo_space_statistics() { return &lo_space_stats_; }
+
  private:
   size_t total_heap_size_;
   size_t total_heap_size_executable_;
@@ -4866,7 +4888,14 @@ class V8_EXPORT HeapStatistics {
   size_t used_heap_size_;
   size_t heap_size_limit_;
 
-  friend class V8;
+  SpaceStatistics new_space_stats_;
+  SpaceStatistics old_space_stats_;
+  SpaceStatistics code_space_stats_;
+  SpaceStatistics map_space_stats_;
+  SpaceStatistics cell_space_stats_;
+  SpaceStatistics lo_space_stats_;

[rmcilroy, 2015/04/13 12:48:23]

Maybe we want to make this a bit more opaque to avoid hard-coding the name /
number of spaces.  How about an array of SpaceStatistics which are named and the
heap just fills in those that it knows about?

+
+  friend class HeapStatisticsHelper;
   friend class Isolate;
 };