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

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 9d4356c5140777598b0c67ebc3d293fc3bcacc37..afaec338a420631d801673c98b8d424047f73bb2 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -5462,6 +5462,13 @@ HeapStatistics::HeapStatistics(): total_heap_size_(0),
                                   heap_size_limit_(0) { }
 
 
+HeapSpaceStatistics::HeapSpaceStatistics(): space_name_(0),
+                                            space_size_(0),
+                                            space_used_size_(0),
+                                            space_avalable_size_(0),
+                                            physical_space_size_(0) { }
+
+
 bool v8::V8::InitializeICU(const char* icu_data_file) {
   return i::InitializeICU(icu_data_file);
 }
@@ -6999,6 +7006,40 @@ void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
 }
 
 
+int Isolate::NumberOfHeapSpaces() { return i::LAST_SPACE - i::FIRST_SPACE + 1; }

[rmcilroy, 2015/04/15 10:21:42]

nit - newline for body

[ssid, 2015/04/15 10:43:58]

Done.

+
+
+void Isolate::GetHeapSpaceStatistics(HeapSpaceStatistics* space_statistics,
+                                     int index) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  i::Heap* heap = isolate->heap();

[rmcilroy, 2015/04/15 10:21:42]

check for space_statistics being null.

[rmcilroy, 2015/04/15 10:21:42]

check for index out-of-bounds

[ssid, 2015/04/15 10:43:57]

Done.

+  if (index == i::NEW_SPACE) {
+    space_statistics->space_name_ = heap->GetSpaceName(i::NEW_SPACE);
+    space_statistics->space_size_ = heap->new_space()->CommittedMemory();
+    space_statistics->space_used_size_ = heap->new_space()->Size();

[rmcilroy, 2015/04/15 10:21:42]

SizeOfObjects

[ssid, 2015/04/15 10:29:20]

PrintShortHeapStatistics() uses Size() and not SizeOfObjects()
https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/heap/heap.c...

[rmcilroy, 2015/04/15 12:17:40]

SizeOfObjects() calls Size() for the newspace, so let's keep them consistent.

+    space_statistics->space_avalable_size_ = heap->new_space()->Available();
+    space_statistics->physical_space_size_ =
+        heap->new_space()->CommittedPhysicalMemory();
+  } else if (index >= i::FIRST_PAGED_SPACE && index <= i::LAST_PAGED_SPACE) {
+    space_statistics->space_name_ = heap->GetSpaceName(index);
+    space_statistics->space_size_ = heap->paged_space(index)->CommittedMemory();
+    space_statistics->space_used_size_ =
+        heap->paged_space(index)->SizeOfObjects();
+    space_statistics->space_avalable_size_ =
+        heap->paged_space(index)->Available();
+    space_statistics->physical_space_size_ =
+        heap->paged_space(index)->CommittedPhysicalMemory();
+  } else if (index == i::LO_SPACE) {
+    space_statistics->space_name_ = heap->GetSpaceName(i::LO_SPACE);
+    space_statistics->space_size_ = heap->lo_space()->CommittedMemory();
+    space_statistics->space_used_size_ = heap->lo_space()->SizeOfObjects();
+    space_statistics->space_avalable_size_ = heap->lo_space()->Available();

[rmcilroy, 2015/04/15 10:21:42]

Does the Spaces superclass have these methods defined? If so you could pull out
the appropriate "Space" object and just do the code to fill in the
space_statistics object once. If the methods aren't there on the superclass it
might be worth doing this if all subclasses of the Space define the methods
anyway. 

[ssid, 2015/04/15 10:29:20]

The only line i can pull out of these three cases is GetSpaceName(x)
Other all functions are different for the three. These are defined in the
classes : PagedSpace, LargeObjectSpace and NewSpace.

[rmcilroy, 2015/04/15 12:17:40]

+hpayer

As mentioned, you could you make these functions virtual abstract in Space and
have the implementations in each of the spaces be overrides.

Hannes: Are you aware of any reason that these methods are defined in the
subclasses and aren't virtual abstract functions in Space which are overridden
by the specific subclass? Would it cause any issue to make this change for code
clarity?

[Hannes Payer (out of office), 2015/04/15 21:09:23]

Hmm, should be possible. I cannot think of any reason why that wouldn't work.
Would definitely cleaner in that case.  

+    space_statistics->physical_space_size_ =
+        heap->lo_space()->CommittedPhysicalMemory();
+  }
+}
+
+
 void Isolate::GetStackSample(const RegisterState& state, void** frames,
                              size_t frames_limit, SampleInfo* sample_info) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);