Detailed heap snapshot usability improvement.

src/profile-generator.cc

Index: src/profile-generator.cc
diff --git a/src/profile-generator.cc b/src/profile-generator.cc
index 97de08e5bf96b3703699731c70ee817d4aa3e944..194a40395a251faa92e0aaf138e2ff1c2983052f 100644
--- a/src/profile-generator.cc
+++ b/src/profile-generator.cc
@@ -1308,19 +1308,6 @@ HeapEntry* HeapSnapshot::AddGcSubrootEntry(int tag,
 }
 
 
-HeapEntry* HeapSnapshot::AddNativesRootEntry(int children_count,
-                                                 int retainers_count) {
-  ASSERT(natives_root_entry_ == NULL);
-  return (natives_root_entry_ = AddEntry(
-      HeapEntry::kObject,
-      "(Native objects)",
-      HeapObjectsMap::kNativesRootObjectId,
-      0,
-      children_count,
-      retainers_count));
-}
-
-
 HeapEntry* HeapSnapshot::AddEntry(HeapEntry::Type type,
                                   const char* name,
                                   uint64_t id,
@@ -1402,10 +1389,8 @@ void HeapSnapshot::Print(int max_depth) {
 const uint64_t HeapObjectsMap::kInternalRootObjectId = 1;
 const uint64_t HeapObjectsMap::kGcRootsObjectId =
     HeapObjectsMap::kInternalRootObjectId + HeapObjectsMap::kObjectIdStep;
-const uint64_t HeapObjectsMap::kNativesRootObjectId =
-    HeapObjectsMap::kGcRootsObjectId + HeapObjectsMap::kObjectIdStep;
 const uint64_t HeapObjectsMap::kGcRootsFirstSubrootId =
-    HeapObjectsMap::kNativesRootObjectId + HeapObjectsMap::kObjectIdStep;
+    HeapObjectsMap::kGcRootsObjectId + HeapObjectsMap::kObjectIdStep;
 const uint64_t HeapObjectsMap::kFirstAvailableObjectId =
     HeapObjectsMap::kGcRootsFirstSubrootId +
     VisitorSynchronization::kNumberOfSyncTags * HeapObjectsMap::kObjectIdStep;
@@ -2712,11 +2697,6 @@ class GlobalHandlesExtractor : public ObjectVisitor {
   NativeObjectsExplorer* explorer_;
 };
 
-HeapThing const NativeObjectsExplorer::kNativesRootObject =
-    reinterpret_cast<HeapThing>(
-        static_cast<intptr_t>(HeapObjectsMap::kNativesRootObjectId));
-
-
 NativeObjectsExplorer::NativeObjectsExplorer(
     HeapSnapshot* snapshot, SnapshottingProgressReportingInterface* progress)
     : snapshot_(snapshot),
@@ -2724,6 +2704,7 @@ NativeObjectsExplorer::NativeObjectsExplorer(
       progress_(progress),
       embedder_queried_(false),
       objects_by_info_(RetainedInfosMatch),
+      native_groups_(StringsMatch),
       filler_(NULL) {
 }
 
@@ -2744,32 +2725,22 @@ NativeObjectsExplorer::~NativeObjectsExplorer() {
 
 HeapEntry* NativeObjectsExplorer::AllocateEntry(
     HeapThing ptr, int children_count, int retainers_count) {
-  if (ptr == kNativesRootObject) {
-    return snapshot_->AddNativesRootEntry(children_count, retainers_count);
-  } else {
-    v8::RetainedObjectInfo* info =
-        reinterpret_cast<v8::RetainedObjectInfo*>(ptr);
-    intptr_t elements = info->GetElementCount();
-    intptr_t size = info->GetSizeInBytes();
-    return snapshot_->AddEntry(
-        HeapEntry::kNative,
-        elements != -1 ?
-            collection_->names()->GetFormatted(
-                "%s / %" V8_PTR_PREFIX "d entries",
-                info->GetLabel(),
-                info->GetElementCount()) :
-                collection_->names()->GetCopy(info->GetLabel()),
-        HeapObjectsMap::GenerateId(info),
-        size != -1 ? static_cast<int>(size) : 0,
-        children_count,
-        retainers_count);
-  }
-}
-
-
-void NativeObjectsExplorer::AddRootEntries(SnapshotFillerInterface* filler) {
-  if (EstimateObjectsCount() <= 0) return;
-  filler->AddEntry(kNativesRootObject, this);
+  v8::RetainedObjectInfo* info =
+      reinterpret_cast<v8::RetainedObjectInfo*>(ptr);
+  intptr_t elements = info->GetElementCount();
+  intptr_t size = info->GetSizeInBytes();
+  return snapshot_->AddEntry(
+      HeapEntry::kNative,
+      elements != -1 ?
+          collection_->names()->GetFormatted(
+              "%s / %" V8_PTR_PREFIX "d entries",
+              info->GetLabel(),
+              info->GetElementCount()) :
+          collection_->names()->GetCopy(info->GetLabel()),
+      HeapObjectsMap::GenerateId(info),
+      size != -1 ? static_cast<int>(size) : 0,
+      children_count,
+      retainers_count);
 }
 
 
@@ -2835,19 +2806,61 @@ bool NativeObjectsExplorer::IterateAndExtractReferences(
       SetWrapperNativeReferences(objects->at(i), info);
     }
   }
-  SetRootNativesRootReference();
+  SetRootNativeRootsReference();
   filler_ = NULL;
   return true;
 }
 
 
+class NativeGroupRetainedObjectInfo : public v8::RetainedObjectInfo {
+ public:
+  explicit NativeGroupRetainedObjectInfo(const char* label)
+      : disposed_(false),
+        hash_(reinterpret_cast<intptr_t>(label)),
+        label_(label) {
+  }
+
+  virtual ~NativeGroupRetainedObjectInfo() {}
+  virtual void Dispose() {
+    CHECK(!disposed_);
+    disposed_ = true;
+  }
+  virtual bool IsEquivalent(RetainedObjectInfo* other) {
+    return hash_ == other->GetHash() && !strcmp(label_, other->GetLabel());
+  }
+  virtual intptr_t GetHash() { return hash_; }
+  virtual const char* GetLabel() { return label_; }
+
+ private:
+  bool disposed_;
+  int hash_;
+  const char* label_;
+};
+
+
+NativeGroupRetainedObjectInfo* NativeObjectsExplorer::FindOrAddGroupInfo(
+    const char* label) {
+  const char* label_copy = collection_->names()->GetCopy(label);
+  intptr_t hash = HashSequentialString(label_copy, strlen(label_copy),
+                                       HEAP->HashSeed());
+  HashMap::Entry* entry = native_groups_.Lookup(const_cast<char*>(label_copy),
+                                                hash, true);
+  if (entry->value == NULL)
+    entry->value = new NativeGroupRetainedObjectInfo(label);
+  return static_cast<NativeGroupRetainedObjectInfo*>(entry->value);
+}
+
+
 void NativeObjectsExplorer::SetNativeRootReference(
     v8::RetainedObjectInfo* info) {
   HeapEntry* child_entry = filler_->FindOrAddEntry(info, this);
   ASSERT(child_entry != NULL);
-  filler_->SetIndexedAutoIndexReference(
-      HeapGraphEdge::kElement,
-      kNativesRootObject, snapshot_->natives_root(),
+  NativeGroupRetainedObjectInfo* group_info =
+      FindOrAddGroupInfo(info->GetGroupLabel());
+  HeapEntry* group_entry = filler_->FindOrAddEntry(group_info, this);
+  filler_->SetNamedAutoIndexReference(
+      HeapGraphEdge::kInternal,
+      group_info, group_entry,
       info, child_entry);
 }
 
@@ -2868,11 +2881,19 @@ void NativeObjectsExplorer::SetWrapperNativeReferences(
 }
 
 
-void NativeObjectsExplorer::SetRootNativesRootReference() {
-  filler_->SetIndexedAutoIndexReference(
-      HeapGraphEdge::kElement,
-      V8HeapExplorer::kInternalRootObject, snapshot_->root(),
-      kNativesRootObject, snapshot_->natives_root());
+void NativeObjectsExplorer::SetRootNativeRootsReference() {
+  for (HashMap::Entry* entry = native_groups_.Start();
+       entry;
+       entry = native_groups_.Next(entry)) {
+    NativeGroupRetainedObjectInfo* group_info =
+        static_cast<NativeGroupRetainedObjectInfo*>(entry->value);
+    HeapEntry* group_entry = filler_->FindOrAddEntry(group_info, this);
+    ASSERT(group_entry != NULL);
+    filler_->SetIndexedAutoIndexReference(
+        HeapGraphEdge::kElement,
+        V8HeapExplorer::kInternalRootObject, snapshot_->root(),
+        group_info, group_entry);
+  }
 }
 
 
@@ -3107,7 +3128,6 @@ void HeapSnapshotGenerator::SetProgressTotal(int iterations_count) {
 bool HeapSnapshotGenerator::CountEntriesAndReferences() {
   SnapshotCounter counter(&entries_);
   v8_heap_explorer_.AddRootEntries(&counter);
-  dom_explorer_.AddRootEntries(&counter);
   return
       v8_heap_explorer_.IterateAndExtractReferences(&counter) &&
       dom_explorer_.IterateAndExtractReferences(&counter);