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// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <deque>
#include <unordered_map>
#include <vector>
#include "include/v8-profiler.h"
#include "src/base/platform/time.h"
#include "src/objects.h"
#include "src/objects/fixed-array.h"
#include "src/objects/hash-table.h"
#include "src/objects/literal-objects.h"
#include "src/profiler/strings-storage.h"
#include "src/string-hasher.h"
#include "src/visitors.h"
namespace v8 {
namespace internal {
class AllocationTracker;
class AllocationTraceNode;
class HeapEntry;
class HeapIterator;
class HeapProfiler;
class HeapSnapshot;
class JSArrayBuffer;
class JSCollection;
class JSWeakCollection;
class SnapshotFiller;
struct SourceLocation {
SourceLocation(int entry_index, int scriptId, int line, int col)
: entry_index(entry_index), scriptId(scriptId), line(line), col(col) {}
const int entry_index;
const int scriptId;
const int line;
const int col;
class HeapGraphEdge BASE_EMBEDDED {
enum Type {
kContextVariable = v8::HeapGraphEdge::kContextVariable,
kElement = v8::HeapGraphEdge::kElement,
kProperty = v8::HeapGraphEdge::kProperty,
kInternal = v8::HeapGraphEdge::kInternal,
kHidden = v8::HeapGraphEdge::kHidden,
kShortcut = v8::HeapGraphEdge::kShortcut,
kWeak = v8::HeapGraphEdge::kWeak
HeapGraphEdge(Type type, const char* name, int from, int to);
HeapGraphEdge(Type type, int index, int from, int to);
void ReplaceToIndexWithEntry(HeapSnapshot* snapshot);
Type type() const { return TypeField::decode(bit_field_); }
int index() const {
DCHECK(type() == kElement || type() == kHidden);
return index_;
const char* name() const {
DCHECK(type() == kContextVariable || type() == kProperty ||
type() == kInternal || type() == kShortcut || type() == kWeak);
return name_;
V8_INLINE HeapEntry* from() const;
HeapEntry* to() const { return to_entry_; }
V8_INLINE Isolate* isolate() const;
V8_INLINE HeapSnapshot* snapshot() const;
int from_index() const { return FromIndexField::decode(bit_field_); }
class TypeField : public BitField<Type, 0, 3> {};
class FromIndexField : public BitField<int, 3, 29> {};
uint32_t bit_field_;
union {
// During entries population |to_index_| is used for storing the index,
// afterwards it is replaced with a pointer to the entry.
int to_index_;
HeapEntry* to_entry_;
union {
int index_;
const char* name_;
// HeapEntry instances represent an entity from the heap (or a special
// virtual node, e.g. root).
class HeapEntry BASE_EMBEDDED {
enum Type {
kHidden = v8::HeapGraphNode::kHidden,
kArray = v8::HeapGraphNode::kArray,
kString = v8::HeapGraphNode::kString,
kObject = v8::HeapGraphNode::kObject,
kCode = v8::HeapGraphNode::kCode,
kClosure = v8::HeapGraphNode::kClosure,
kRegExp = v8::HeapGraphNode::kRegExp,
kHeapNumber = v8::HeapGraphNode::kHeapNumber,
kNative = v8::HeapGraphNode::kNative,
kSynthetic = v8::HeapGraphNode::kSynthetic,
kConsString = v8::HeapGraphNode::kConsString,
kSlicedString = v8::HeapGraphNode::kSlicedString,
kSymbol = v8::HeapGraphNode::kSymbol,
kBigInt = v8::HeapGraphNode::kBigInt
static const int kNoEntry;
HeapEntry() { }
HeapEntry(HeapSnapshot* snapshot,
Type type,
const char* name,
SnapshotObjectId id,
size_t self_size,
unsigned trace_node_id);
HeapSnapshot* snapshot() { return snapshot_; }
Type type() const { return static_cast<Type>(type_); }
void set_type(Type type) { type_ = type; }
const char* name() const { return name_; }
void set_name(const char* name) { name_ = name; }
SnapshotObjectId id() const { return id_; }
size_t self_size() const { return self_size_; }
unsigned trace_node_id() const { return trace_node_id_; }
V8_INLINE int index() const;
int children_count() const { return children_count_; }
V8_INLINE int set_children_index(int index);
V8_INLINE void add_child(HeapGraphEdge* edge);
V8_INLINE HeapGraphEdge* child(int i);
V8_INLINE Isolate* isolate() const;
void SetIndexedReference(
HeapGraphEdge::Type type, int index, HeapEntry* entry);
void SetNamedReference(
HeapGraphEdge::Type type, const char* name, HeapEntry* entry);
void Print(
const char* prefix, const char* edge_name, int max_depth, int indent);
V8_INLINE std::deque<HeapGraphEdge*>::iterator children_begin();
V8_INLINE std::deque<HeapGraphEdge*>::iterator children_end();
const char* TypeAsString();
unsigned type_: 4;
int children_count_: 28;
int children_index_;
size_t self_size_;
HeapSnapshot* snapshot_;
const char* name_;
SnapshotObjectId id_;
// id of allocation stack trace top node
unsigned trace_node_id_;
// HeapSnapshot represents a single heap snapshot. It is stored in
// HeapProfiler, which is also a factory for
// HeapSnapshots. All HeapSnapshots share strings copied from JS heap
// to be able to return them even if they were collected.
// HeapSnapshotGenerator fills in a HeapSnapshot.
class HeapSnapshot {
explicit HeapSnapshot(HeapProfiler* profiler);
void Delete();
HeapProfiler* profiler() { return profiler_; }
HeapEntry* root() { return &entries_[root_index_]; }
HeapEntry* gc_roots() { return &entries_[gc_roots_index_]; }
HeapEntry* gc_subroot(Root root) {
return &entries_[gc_subroot_indexes_[static_cast<int>(root)]];
std::vector<HeapEntry>& entries() { return entries_; }
std::deque<HeapGraphEdge>& edges() { return edges_; }
std::deque<HeapGraphEdge*>& children() { return children_; }
const std::vector<SourceLocation>& locations() const { return locations_; }
void RememberLastJSObjectId();
SnapshotObjectId max_snapshot_js_object_id() const {
return max_snapshot_js_object_id_;
void AddLocation(int entry, int scriptId, int line, int col);
HeapEntry* AddEntry(HeapEntry::Type type,
const char* name,
SnapshotObjectId id,
size_t size,
unsigned trace_node_id);
void AddSyntheticRootEntries();
HeapEntry* GetEntryById(SnapshotObjectId id);
std::vector<HeapEntry*>* GetSortedEntriesList();
void FillChildren();
void Print(int max_depth);
HeapEntry* AddRootEntry();
HeapEntry* AddGcRootsEntry();
HeapEntry* AddGcSubrootEntry(Root root, SnapshotObjectId id);
HeapProfiler* profiler_;
int root_index_;
int gc_roots_index_;
int gc_subroot_indexes_[static_cast<int>(Root::kNumberOfRoots)];
std::vector<HeapEntry> entries_;
std::deque<HeapGraphEdge> edges_;
std::deque<HeapGraphEdge*> children_;
std::vector<HeapEntry*> sorted_entries_;
std::vector<SourceLocation> locations_;
SnapshotObjectId max_snapshot_js_object_id_;
friend class HeapSnapshotTester;
class HeapObjectsMap {
struct TimeInterval {
explicit TimeInterval(SnapshotObjectId id)
: id(id), size(0), count(0), timestamp(base::TimeTicks::Now()) {}
SnapshotObjectId last_assigned_id() const { return id - kObjectIdStep; }
SnapshotObjectId id;
uint32_t size;
uint32_t count;
base::TimeTicks timestamp;
explicit HeapObjectsMap(Heap* heap);
Heap* heap() const { return heap_; }
SnapshotObjectId FindEntry(Address addr);
SnapshotObjectId FindOrAddEntry(Address addr,
unsigned int size,
bool accessed = true);
bool MoveObject(Address from, Address to, int size);
void UpdateObjectSize(Address addr, int size);
SnapshotObjectId last_assigned_id() const {
return next_id_ - kObjectIdStep;
void StopHeapObjectsTracking();
SnapshotObjectId PushHeapObjectsStats(OutputStream* stream,
int64_t* timestamp_us);
const std::vector<TimeInterval>& samples() const { return time_intervals_; }
SnapshotObjectId GenerateId(v8::RetainedObjectInfo* info);
static const int kObjectIdStep = 2;
static const SnapshotObjectId kInternalRootObjectId;
static const SnapshotObjectId kGcRootsObjectId;
static const SnapshotObjectId kGcRootsFirstSubrootId;
static const SnapshotObjectId kFirstAvailableObjectId;
void UpdateHeapObjectsMap();
void RemoveDeadEntries();
struct EntryInfo {
EntryInfo(SnapshotObjectId id, Address addr, unsigned int size,
bool accessed)
: id(id), addr(addr), size(size), accessed(accessed) {}
SnapshotObjectId id;
Address addr;
unsigned int size;
bool accessed;
SnapshotObjectId next_id_;
// TODO(jkummerow): Use a map that uses {Address} as the key type.
base::HashMap entries_map_;
std::vector<EntryInfo> entries_;
std::vector<TimeInterval> time_intervals_;
Heap* heap_;
// A typedef for referencing anything that can be snapshotted living
// in any kind of heap memory.
typedef void* HeapThing;
// An interface that creates HeapEntries by HeapThings.
class HeapEntriesAllocator {
virtual ~HeapEntriesAllocator() { }
virtual HeapEntry* AllocateEntry(HeapThing ptr) = 0;
// The HeapEntriesMap instance is used to track a mapping between
// real heap objects and their representations in heap snapshots.
class HeapEntriesMap {
int Map(HeapThing thing);
void Pair(HeapThing thing, int entry);
static uint32_t Hash(HeapThing thing) {
return ComputeIntegerHash(
base::HashMap entries_;
friend class HeapObjectsSet;
class HeapObjectsSet {
void Clear();
bool Contains(Object* object);
void Insert(Object* obj);
const char* GetTag(Object* obj);
void SetTag(Object* obj, const char* tag);
bool is_empty() const { return entries_.occupancy() == 0; }
base::HashMap entries_;
class SnapshottingProgressReportingInterface {
virtual ~SnapshottingProgressReportingInterface() { }
virtual void ProgressStep() = 0;
virtual bool ProgressReport(bool force) = 0;
// An implementation of V8 heap graph extractor.
class V8HeapExplorer : public HeapEntriesAllocator {
V8HeapExplorer(HeapSnapshot* snapshot,
SnapshottingProgressReportingInterface* progress,
v8::HeapProfiler::ObjectNameResolver* resolver);
virtual ~V8HeapExplorer();
virtual HeapEntry* AllocateEntry(HeapThing ptr);
int EstimateObjectsCount();
bool IterateAndExtractReferences(SnapshotFiller* filler);
void TagGlobalObjects();
void TagCodeObject(Code* code);
void TagBuiltinCodeObject(Code* code, const char* name);
HeapEntry* AddEntry(Address address,
HeapEntry::Type type,
const char* name,
size_t size);
static JSFunction* GetConstructor(JSReceiver* receiver);
static String* GetConstructorName(JSObject* object);
void MarkVisitedField(int offset);
HeapEntry* AddEntry(HeapObject* object);
HeapEntry* AddEntry(HeapObject* object,
HeapEntry::Type type,
const char* name);
const char* GetSystemEntryName(HeapObject* object);
void ExtractLocation(int entry, HeapObject* object);
void ExtractLocationForJSFunction(int entry, JSFunction* func);
void ExtractReferences(int entry, HeapObject* obj);
void ExtractJSGlobalProxyReferences(int entry, JSGlobalProxy* proxy);
void ExtractJSObjectReferences(int entry, JSObject* js_obj);
void ExtractStringReferences(int entry, String* obj);
void ExtractSymbolReferences(int entry, Symbol* symbol);
void ExtractJSCollectionReferences(int entry, JSCollection* collection);
void ExtractJSWeakCollectionReferences(int entry,
JSWeakCollection* collection);
void ExtractEphemeronHashTableReferences(int entry,
EphemeronHashTable* table);
void ExtractContextReferences(int entry, Context* context);
void ExtractMapReferences(int entry, Map* map);
void ExtractSharedFunctionInfoReferences(int entry,
SharedFunctionInfo* shared);
void ExtractScriptReferences(int entry, Script* script);
void ExtractAccessorInfoReferences(int entry, AccessorInfo* accessor_info);
void ExtractAccessorPairReferences(int entry, AccessorPair* accessors);
void ExtractCodeReferences(int entry, Code* code);
void ExtractCellReferences(int entry, Cell* cell);
void ExtractFeedbackCellReferences(int entry, FeedbackCell* feedback_cell);
void ExtractPropertyCellReferences(int entry, PropertyCell* cell);
void ExtractAllocationSiteReferences(int entry, AllocationSite* site);
void ExtractArrayBoilerplateDescriptionReferences(
int entry, ArrayBoilerplateDescription* value);
void ExtractJSArrayBufferReferences(int entry, JSArrayBuffer* buffer);
void ExtractJSPromiseReferences(int entry, JSPromise* promise);
void ExtractJSGeneratorObjectReferences(int entry,
JSGeneratorObject* generator);
void ExtractFixedArrayReferences(int entry, FixedArray* array);
void ExtractFeedbackVectorReferences(int entry,
FeedbackVector* feedback_vector);
template <typename T>
void ExtractWeakArrayReferences(int header_size, int entry, T* array);
void ExtractPropertyReferences(JSObject* js_obj, int entry);
void ExtractAccessorPairProperty(JSObject* js_obj, int entry, Name* key,
Object* callback_obj, int field_offset = -1);
void ExtractElementReferences(JSObject* js_obj, int entry);
void ExtractInternalReferences(JSObject* js_obj, int entry);
bool IsEssentialObject(Object* object);
bool IsEssentialHiddenReference(Object* parent, int field_offset);
void SetContextReference(HeapObject* parent_obj,
int parent,
String* reference_name,
Object* child,
int field_offset);
void SetNativeBindReference(HeapObject* parent_obj,
int parent,
const char* reference_name,
Object* child);
void SetElementReference(HeapObject* parent_obj,
int parent,
int index,
Object* child);
void SetInternalReference(HeapObject* parent_obj,
int parent,
const char* reference_name,
Object* child,
int field_offset = -1);
void SetInternalReference(HeapObject* parent_obj,
int parent,
int index,
Object* child,
int field_offset = -1);
void SetHiddenReference(HeapObject* parent_obj, int parent, int index,
Object* child, int field_offset);
void SetWeakReference(HeapObject* parent_obj,
int parent,
const char* reference_name,
Object* child_obj,
int field_offset);
void SetWeakReference(HeapObject* parent_obj,
int parent,
int index,
Object* child_obj,
int field_offset);
void SetPropertyReference(HeapObject* parent_obj, int parent,
Name* reference_name, Object* child,
const char* name_format_string = nullptr,
int field_offset = -1);
void SetDataOrAccessorPropertyReference(
PropertyKind kind, JSObject* parent_obj, int parent, Name* reference_name,
Object* child, const char* name_format_string = nullptr,
int field_offset = -1);
void SetUserGlobalReference(Object* user_global);
void SetRootGcRootsReference();
void SetGcRootsReference(Root root);
void SetGcSubrootReference(Root root, const char* description, bool is_weak,
Object* child);
const char* GetStrongGcSubrootName(Object* object);
void TagObject(Object* obj, const char* tag);
HeapEntry* GetEntry(Object* obj);
Heap* heap_;
HeapSnapshot* snapshot_;
StringsStorage* names_;
HeapObjectsMap* heap_object_map_;
SnapshottingProgressReportingInterface* progress_;
SnapshotFiller* filler_;
HeapObjectsSet objects_tags_;
HeapObjectsSet strong_gc_subroot_names_;
HeapObjectsSet user_roots_;
v8::HeapProfiler::ObjectNameResolver* global_object_name_resolver_;
std::vector<bool> visited_fields_;
friend class IndexedReferencesExtractor;
friend class RootsReferencesExtractor;
class NativeGroupRetainedObjectInfo;
// An implementation of retained native objects extractor.
class NativeObjectsExplorer {
NativeObjectsExplorer(HeapSnapshot* snapshot,
SnapshottingProgressReportingInterface* progress);
virtual ~NativeObjectsExplorer();
int EstimateObjectsCount();
bool IterateAndExtractReferences(SnapshotFiller* filler);
void FillRetainedObjects();
void FillEdges();
std::vector<HeapObject*>* GetVectorMaybeDisposeInfo(
v8::RetainedObjectInfo* info);
void SetNativeRootReference(v8::RetainedObjectInfo* info);
void SetRootNativeRootsReference();
void SetWrapperNativeReferences(HeapObject* wrapper,
v8::RetainedObjectInfo* info);
void VisitSubtreeWrapper(Object** p, uint16_t class_id);
struct RetainedInfoHasher {
std::size_t operator()(v8::RetainedObjectInfo* info) const {
return ComputeIntegerHash(static_cast<uint32_t>(info->GetHash()));
struct RetainedInfoEquals {
bool operator()(v8::RetainedObjectInfo* info1,
v8::RetainedObjectInfo* info2) const {
return info1 == info2 || info1->IsEquivalent(info2);
NativeGroupRetainedObjectInfo* FindOrAddGroupInfo(const char* label);
HeapEntry* EntryForEmbedderGraphNode(EmbedderGraph::Node* node);
Isolate* isolate_;
HeapSnapshot* snapshot_;
StringsStorage* names_;
bool embedder_queried_;
HeapObjectsSet in_groups_;
std::unordered_map<v8::RetainedObjectInfo*, std::vector<HeapObject*>*,
RetainedInfoHasher, RetainedInfoEquals>
std::unordered_map<const char*, NativeGroupRetainedObjectInfo*,
SeededStringHasher, StringEquals>
std::unique_ptr<HeapEntriesAllocator> synthetic_entries_allocator_;
std::unique_ptr<HeapEntriesAllocator> native_entries_allocator_;
std::unique_ptr<HeapEntriesAllocator> embedder_graph_entries_allocator_;
// Used during references extraction.
SnapshotFiller* filler_;
v8::HeapProfiler::RetainerEdges edges_;
static HeapThing const kNativesRootObject;
friend class GlobalHandlesExtractor;
class HeapSnapshotGenerator : public SnapshottingProgressReportingInterface {
HeapSnapshotGenerator(HeapSnapshot* snapshot,
v8::ActivityControl* control,
v8::HeapProfiler::ObjectNameResolver* resolver,
Heap* heap);
bool GenerateSnapshot();
bool FillReferences();
void ProgressStep();
bool ProgressReport(bool force = false);
void InitProgressCounter();
HeapSnapshot* snapshot_;
v8::ActivityControl* control_;
V8HeapExplorer v8_heap_explorer_;
NativeObjectsExplorer dom_explorer_;
// Mapping from HeapThing pointers to HeapEntry* pointers.
HeapEntriesMap entries_;
// Used during snapshot generation.
int progress_counter_;
int progress_total_;
Heap* heap_;
class OutputStreamWriter;
class HeapSnapshotJSONSerializer {
explicit HeapSnapshotJSONSerializer(HeapSnapshot* snapshot)
: snapshot_(snapshot),
writer_(nullptr) {}
void Serialize(v8::OutputStream* stream);
V8_INLINE static bool StringsMatch(void* key1, void* key2) {
return strcmp(reinterpret_cast<char*>(key1),
reinterpret_cast<char*>(key2)) == 0;
V8_INLINE static uint32_t StringHash(const void* string);
int GetStringId(const char* s);
V8_INLINE int to_node_index(const HeapEntry* e);
V8_INLINE int to_node_index(int entry_index);
void SerializeEdge(HeapGraphEdge* edge, bool first_edge);
void SerializeEdges();
void SerializeImpl();
void SerializeNode(const HeapEntry* entry);
void SerializeNodes();
void SerializeSnapshot();
void SerializeTraceTree();
void SerializeTraceNode(AllocationTraceNode* node);
void SerializeTraceNodeInfos();
void SerializeSamples();
void SerializeString(const unsigned char* s);
void SerializeStrings();
void SerializeLocation(const SourceLocation& location);
void SerializeLocations();
static const int kEdgeFieldsCount;
static const int kNodeFieldsCount;
HeapSnapshot* snapshot_;
base::CustomMatcherHashMap strings_;
int next_node_id_;
int next_string_id_;
OutputStreamWriter* writer_;
friend class HeapSnapshotJSONSerializerEnumerator;
friend class HeapSnapshotJSONSerializerIterator;
} // namespace internal
} // namespace v8