New GC related APIs: Implicit references.

src/heap-snapshot-generator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1970 matching lines @@
   isolate->global_handles()->RemoveObjectGroups();
   isolate->heap()->CallGCEpilogueCallbacks(major_gc_type);
   // Record objects that are not in ObjectGroups, but have class ID.
   GlobalHandlesExtractor extractor(this);
   isolate->global_handles()->IterateAllRootsWithClassIds(&extractor);
   embedder_queried_ = true;
 }
 
 void NativeObjectsExplorer::FillImplicitReferences() {
   Isolate* isolate = Isolate::Current();
-  List<ImplicitRefGroup*>* groups =
+  List<ObjectGroupConnection>* ref_groups =
       isolate->global_handles()->implicit_ref_groups();
-  for (int i = 0; i < groups->length(); ++i) {
-    ImplicitRefGroup* group = groups->at(i);
-    HeapObject* parent = *group->parent_;
-    int parent_entry =
-        filler_->FindOrAddEntry(parent, native_entries_allocator_)->index();
-    ASSERT(parent_entry != HeapEntry::kNoEntry);
-    Object*** children = group->children_;
-    for (size_t j = 0; j < group->length_; ++j) {
-      Object* child = *children[j];
-      HeapEntry* child_entry =
-          filler_->FindOrAddEntry(child, native_entries_allocator_);
-      filler_->SetNamedReference(
-          HeapGraphEdge::kInternal,
-          parent_entry,
-          "native",
-          child_entry);
+  List<ObjectGroupRepresentativeObject>* representative_objects =
+      isolate->global_handles()->representative_objects();
+
+  if (ref_groups->length() == 0)
+    return;
+
+  ref_groups->Sort();
+  representative_objects->Sort();
+
+  int representative_objects_index = 0;
+  UniqueId current_group_id(0);
+  size_t current_group_start = 0;
+  for (int i = 0; i <= ref_groups->length(); ++i) {
+    if (i == 0)
+      current_group_id = ref_groups->at(i).id;
+    if (i == ref_groups->length() || current_group_id != ref_groups->at(i).id) {
+      // Group detected: objects in indices [current_group_start, i[.
+
+      // Find the representative object for this group.
+      while (representative_objects_index < representative_objects->length() &&
+             representative_objects->at(representative_objects_index).id <
+             current_group_id)
+        ++representative_objects_index;
+
+      if (representative_objects_index < representative_objects->length() &&
+          representative_objects->at(representative_objects_index).id ==
+              current_group_id) {
+        HeapObject* parent =
+            *(representative_objects->at(representative_objects_index).object);
+
+        int parent_entry =
+            filler_->FindOrAddEntry(parent, native_entries_allocator_)->index();
+        ASSERT(parent_entry != HeapEntry::kNoEntry);
+
+        for (int j = current_group_start; j < i; ++j) {
+          Object* child = *(ref_groups->at(j).object);
+          HeapEntry* child_entry =
+              filler_->FindOrAddEntry(child, native_entries_allocator_);
+          filler_->SetNamedReference(
+              HeapGraphEdge::kInternal,
+              parent_entry,
+              "native",
+              child_entry);
+        }
+      } else {
+        // This should not happen: representative object for a group was not

[Michael Starzinger, 2013/04/16 10:42:16]

Add an "UNREACHABLE();" here.

[marja, 2013/04/16 12:28:37]

Done.

+        // set!
+      }
+      if (i < ref_groups->length()) {
+        current_group_id = ref_groups->at(i).id;
+        current_group_start = i;
+      }
     }
   }
   isolate->global_handles()->RemoveImplicitRefGroups();
 }
 
 List<HeapObject*>* NativeObjectsExplorer::GetListMaybeDisposeInfo(
     v8::RetainedObjectInfo* info) {
   HashMap::Entry* entry =
       objects_by_info_.Lookup(info, InfoHash(info), true);
   if (entry->value != NULL) {
@@ skipping 701 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SortHashMap(
     HashMap* map, List<HashMap::Entry*>* sorted_entries) {
   for (HashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p))
     sorted_entries->Add(p);
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 } }  // namespace v8::internal