Add v8::HeapGraphNode::GetHeapValue method.

src/profile-generator.cc

 // Copyright 2011 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 997 matching lines @@
 
 
 int HeapEntry::RetainedSize(bool exact) {
   if (exact && (retained_size_ & kExactRetainedSizeTag) == 0) {
     CalculateExactRetainedSize();
   }
   return retained_size_ & (~kExactRetainedSizeTag);
 }
 
 
+Handle<HeapObject> HeapEntry::GetHeapObject() {
+  return snapshot_->collection()->FindHeapObjectById(id());
+}
+
+
 template<class Visitor>
 void HeapEntry::ApplyAndPaintAllReachable(Visitor* visitor) {
   List<HeapEntry*> list(10);
   list.Add(this);
   this->paint_reachable();
   visitor->Apply(this);
   while (!list.is_empty()) {
     HeapEntry* entry = list.RemoveLast();
     Vector<HeapGraphEdge> children = entry->children();
     for (int i = 0; i < children.length(); ++i) {
@@ skipping 340 matching lines @@
       entries_map_(AddressesMatch),
       entries_(new List<EntryInfo>()) { }
 
 
 HeapObjectsMap::~HeapObjectsMap() {
   delete entries_;
 }
 
 
 void HeapObjectsMap::SnapshotGenerationFinished() {
-    initial_fill_mode_ = false;
-    RemoveDeadEntries();
+  initial_fill_mode_ = false;
+  RemoveDeadEntries();
 }
 
 
 uint64_t HeapObjectsMap::FindObject(Address addr) {
   if (!initial_fill_mode_) {
     uint64_t existing = FindEntry(addr);
     if (existing != 0) return existing;
   }
   uint64_t id = next_id_;
   next_id_ += 2;
@@ skipping 125 matching lines @@
 
 
 void HeapSnapshotsCollection::RemoveSnapshot(HeapSnapshot* snapshot) {
   snapshots_.RemoveElement(snapshot);
   unsigned uid = snapshot->uid();
   snapshots_uids_.Remove(reinterpret_cast<void*>(uid),
                          static_cast<uint32_t>(uid));
 }
 
 
+Handle<HeapObject> HeapSnapshotsCollection::FindHeapObjectById(uint64_t id) {
+  // First perform a full GC in order to avoid dead objects.
+  HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
+  AssertNoAllocation no_allocation;
+  HeapObject* object = NULL;
+  HeapIterator iterator(HeapIterator::kFilterUnreachable);
+  // Make sure that object with the given id is still reachable.
+  for (HeapObject* obj = iterator.next();
+       obj != NULL;
+       obj = iterator.next()) {
+    if (ids_.FindObject(obj->address()) == id) {

[Vyacheslav Egorov (Chromium), 2011/09/26 14:22:10]

this is not going to work if obj was in new space or was on the page that was
compacted.

we either will fail to find the object or will return the wrong one.

[mnaganov (inactive), 2011/09/26 14:28:19]

What do you mean? We start keeping IDs for heap objects after the first heap
snapshot has been done. We should have 'HeapProfiler::ObjectMoveEvent' in proper
places to track existing object moves, and new objects are added when we are
taking the next snapshot.

+      ASSERT(object == NULL);
+      object = obj;
+      // Can't break -- kFilterUnreachable requires full heap traversal.

[Vyacheslav Egorov (Chromium), 2011/09/26 14:22:10]

We can fix this by switching kFilterUnreachable from intrusive marking to
mark-bits based marking (just saying).

[mnaganov (inactive), 2011/09/26 14:28:19]

Yes, that's a good idea. I will create a bug to track this.

+    }
+  }
+  return object != NULL ? Handle<HeapObject>(object) : Handle<HeapObject>();
+}
+
+
 HeapEntry *const HeapEntriesMap::kHeapEntryPlaceholder =
     reinterpret_cast<HeapEntry*>(1);
 
 HeapEntriesMap::HeapEntriesMap()
     : entries_(HeapThingsMatch),
       entries_count_(0),
       total_children_count_(0),
       total_retainers_count_(0) {
 }
 
@@ skipping 1833 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