v8-profiler.h

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// Copyright 2010 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.
 
#ifndef V8_V8_PROFILER_H_
#define V8_V8_PROFILER_H_
 
#include <limits.h>
 
#include <memory>
#include <unordered_set>
#include <vector>
 
#include "cppgc/common.h"          // NOLINT(build/include_directory)
#include "v8-local-handle.h"       // NOLINT(build/include_directory)
#include "v8-message.h"            // NOLINT(build/include_directory)
#include "v8-persistent-handle.h"  // NOLINT(build/include_directory)

namespace v8 {
 
enum class EmbedderStateTag : uint8_t;
class HeapGraphNode;
struct HeapStatsUpdate;
class Object;
enum StateTag : uint16_t;
 
using NativeObject = void*;
using SnapshotObjectId = uint32_t;
using ProfilerId = uint32_t;
 
struct CpuProfileDeoptFrame {
  int script_id;
  size_t position;
};
 
namespace internal {
class CpuProfile;
}  // namespace internal
 
}  // namespace v8
 
#ifdef V8_OS_WIN
template class V8_EXPORT std::vector<v8::CpuProfileDeoptFrame>;
#endif
 
namespace v8 {
 
struct V8_EXPORT CpuProfileDeoptInfo {
  const char* deopt_reason;
  std::vector<CpuProfileDeoptFrame> stack;
};
 
}  // namespace v8
 
#ifdef V8_OS_WIN
template class V8_EXPORT std::vector<v8::CpuProfileDeoptInfo>;
#endif
 
namespace v8 {

class V8_EXPORT CpuProfileNode {
 public:
  struct LineTick {
    int line;

    unsigned int hit_count;
  };
 
  // An annotation hinting at the source of a CpuProfileNode.
  enum SourceType {
    // User-supplied script with associated resource information.
    kScript = 0,
    // Native scripts and provided builtins.
    kBuiltin = 1,
    // Callbacks into native code.
    kCallback = 2,
    // VM-internal functions or state.
    kInternal = 3,
    // A node that failed to symbolize.
    kUnresolved = 4,
  };

  Local<String> GetFunctionName() const;

  const char* GetFunctionNameStr() const;

  int GetScriptId() const;

  Local<String> GetScriptResourceName() const;

  const char* GetScriptResourceNameStr() const;

  bool IsScriptSharedCrossOrigin() const;

  int GetLineNumber() const;

  int GetColumnNumber() const;

  unsigned int GetHitLineCount() const;

  bool GetLineTicks(LineTick* entries, unsigned int length) const;

  const char* GetBailoutReason() const;

  unsigned GetHitCount() const;

  unsigned GetNodeId() const;

  SourceType GetSourceType() const;

  int GetChildrenCount() const;

  const CpuProfileNode* GetChild(int index) const;

  const CpuProfileNode* GetParent() const;

  const std::vector<CpuProfileDeoptInfo>& GetDeoptInfos() const;
 
  static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
  static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
};

class V8_EXPORT OutputStream {
 public:
  enum WriteResult { kContinue = 0, kAbort = 1 };
  virtual ~OutputStream() = default;
  virtual void EndOfStream() = 0;
  virtual int GetChunkSize() { return 1024; }
  virtual WriteResult WriteAsciiChunk(char* data, int size) = 0;
  virtual WriteResult WriteHeapStatsChunk(HeapStatsUpdate* data, int count) {
    return kAbort;
  }
};

class V8_EXPORT CpuProfile {
 public:
  enum SerializationFormat {
    kJSON = 0  // See format description near 'Serialize' method.
  };

  Local<String> GetTitle() const;

  const CpuProfileNode* GetTopDownRoot() const;

  int GetSamplesCount() const;

  const CpuProfileNode* GetSample(int index) const;

  int64_t GetSampleTimestamp(int index) const;

  int64_t GetStartTime() const;

  StateTag GetSampleState(int index) const;

  EmbedderStateTag GetSampleEmbedderState(int index) const;

  int64_t GetEndTime() const;

  void Delete();

  void Serialize(OutputStream* stream,
                 SerializationFormat format = kJSON) const;
};
 
enum CpuProfilingMode {
  // In the resulting CpuProfile tree, intermediate nodes in a stack trace
  // (from the root to a leaf) will have line numbers that point to the start
  // line of the function, rather than the line of the callsite of the child.
  kLeafNodeLineNumbers,
  // In the resulting CpuProfile tree, nodes are separated based on the line
  // number of their callsite in their parent.
  kCallerLineNumbers,
};
 
// Determines how names are derived for functions sampled.
enum CpuProfilingNamingMode {
  // Use the immediate name of functions at compilation time.
  kStandardNaming,
  // Use more verbose naming for functions without names, inferred from scope
  // where possible.
  kDebugNaming,
};
 
enum CpuProfilingLoggingMode {
  // Enables logging when a profile is active, and disables logging when all
  // profiles are detached.
  kLazyLogging,
  // Enables logging for the lifetime of the CpuProfiler. Calls to
  // StartRecording are faster, at the expense of runtime overhead.
  kEagerLogging,
};
 
// Enum for returning profiling status. Once StartProfiling is called,
// we want to return to clients whether the profiling was able to start
// correctly, or return a descriptive error.
enum class CpuProfilingStatus {
  kStarted,
  kAlreadyStarted,
  kErrorTooManyProfilers
};

struct CpuProfilingResult {
  const ProfilerId id;
  const CpuProfilingStatus status;
};

class V8_EXPORT DiscardedSamplesDelegate {
 public:
  DiscardedSamplesDelegate() = default;
 
  virtual ~DiscardedSamplesDelegate() = default;
  virtual void Notify() = 0;
 
  ProfilerId GetId() const { return profiler_id_; }
 
 private:
  friend internal::CpuProfile;
 
  void SetId(ProfilerId id) { profiler_id_ = id; }
 
  ProfilerId profiler_id_;
};

class V8_EXPORT CpuProfilingOptions {
 public:
  // Indicates that the sample buffer size should not be explicitly limited.
  static const unsigned kNoSampleLimit = UINT_MAX;

  CpuProfilingOptions(
      CpuProfilingMode mode = kLeafNodeLineNumbers,
      unsigned max_samples = kNoSampleLimit, int sampling_interval_us = 0,
      MaybeLocal<Context> filter_context = MaybeLocal<Context>());
 
  CpuProfilingOptions(CpuProfilingOptions&&) = default;
  CpuProfilingOptions& operator=(CpuProfilingOptions&&) = default;
 
  CpuProfilingMode mode() const { return mode_; }
  unsigned max_samples() const { return max_samples_; }
  int sampling_interval_us() const { return sampling_interval_us_; }
 
 private:
  friend class internal::CpuProfile;
 
  bool has_filter_context() const { return !filter_context_.IsEmpty(); }
  void* raw_filter_context() const;
 
  CpuProfilingMode mode_;
  unsigned max_samples_;
  int sampling_interval_us_;
  Global<Context> filter_context_;
};

class V8_EXPORT CpuProfiler {
 public:
  static CpuProfiler* New(Isolate* isolate,
                          CpuProfilingNamingMode = kDebugNaming,
                          CpuProfilingLoggingMode = kLazyLogging);

  static void CollectSample(
      Isolate* isolate, const std::optional<uint64_t> trace_id = std::nullopt);

  void Dispose();

  void SetSamplingInterval(int us);

  void SetUsePreciseSampling(bool);

  CpuProfilingResult Start(
      CpuProfilingOptions options,
      std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);

  CpuProfilingResult Start(
      Local<String> title, CpuProfilingOptions options,
      std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);

  CpuProfilingResult Start(
      Local<String> title, CpuProfilingMode mode, bool record_samples = false,
      unsigned max_samples = CpuProfilingOptions::kNoSampleLimit);

  CpuProfilingResult Start(Local<String> title, bool record_samples = false);

  CpuProfilingStatus StartProfiling(
      Local<String> title, CpuProfilingOptions options,
      std::unique_ptr<DiscardedSamplesDelegate> delegate = nullptr);

  CpuProfilingStatus StartProfiling(
      Local<String> title, CpuProfilingMode mode, bool record_samples = false,
      unsigned max_samples = CpuProfilingOptions::kNoSampleLimit);

  CpuProfilingStatus StartProfiling(Local<String> title,
                                    bool record_samples = false);

  CpuProfile* Stop(ProfilerId id);

  CpuProfile* StopProfiling(Local<String> title);

  static void UseDetailedSourcePositionsForProfiling(Isolate* isolate);
 
 private:
  CpuProfiler();
  ~CpuProfiler();
  CpuProfiler(const CpuProfiler&);
  CpuProfiler& operator=(const CpuProfiler&);
};

class V8_EXPORT HeapGraphEdge {
 public:
  enum Type {
    kContextVariable = 0,  // A variable from a function context.
    kElement = 1,          // An element of an array.
    kProperty = 2,         // A named object property.
    kInternal = 3,         // A link that can't be accessed from JS,
                           // thus, its name isn't a real property name
                           // (e.g. parts of a ConsString).
    kHidden = 4,           // A link that is needed for proper sizes
                           // calculation, but may be hidden from user.
    kShortcut = 5,         // A link that must not be followed during
                           // sizes calculation.
    kWeak = 6              // A weak reference (ignored by the GC).
  };

  Type GetType() const;

  Local<Value> GetName() const;

  const HeapGraphNode* GetFromNode() const;

  const HeapGraphNode* GetToNode() const;
};
 

class V8_EXPORT HeapGraphNode {
 public:
  enum Type {
    kHidden = 0,         // Hidden node, may be filtered when shown to user.
    kArray = 1,          // An array of elements.
    kString = 2,         // A string.
    kObject = 3,         // A JS object (except for arrays and strings).
    kCode = 4,           // Compiled code.
    kClosure = 5,        // Function closure.
    kRegExp = 6,         // RegExp.
    kHeapNumber = 7,     // Number stored in the heap.
    kNative = 8,         // Native object (not from V8 heap).
    kSynthetic = 9,      // Synthetic object, usually used for grouping
                         // snapshot items together.
    kConsString = 10,    // Concatenated string. A pair of pointers to strings.
    kSlicedString = 11,  // Sliced string. A fragment of another string.
    kSymbol = 12,        // A Symbol (ES6).
    kBigInt = 13,        // BigInt.
    kObjectShape = 14,   // Internal data used for tracking the shapes (or
                         // "hidden classes") of JS objects.
  };

  Type GetType() const;

  Local<String> GetName() const;

  SnapshotObjectId GetId() const;

  size_t GetShallowSize() const;

  int GetChildrenCount() const;

  const HeapGraphEdge* GetChild(int index) const;
};

class V8_EXPORT HeapSnapshot {
 public:
  enum SerializationFormat {
    kJSON = 0  // See format description near 'Serialize' method.
  };

  const HeapGraphNode* GetRoot() const;

  const HeapGraphNode* GetNodeById(SnapshotObjectId id) const;

  int GetNodesCount() const;

  const HeapGraphNode* GetNode(int index) const;

  SnapshotObjectId GetMaxSnapshotJSObjectId() const;

  void Delete();

  void Serialize(OutputStream* stream,
                 SerializationFormat format = kJSON) const;
};
 

class V8_EXPORT ActivityControl {
 public:
  enum ControlOption {
    kContinue = 0,
    kAbort = 1
  };
  virtual ~ActivityControl() = default;
  virtual ControlOption ReportProgressValue(uint32_t done, uint32_t total) = 0;
};

class V8_EXPORT AllocationProfile {
 public:
  struct Allocation {
    size_t size;

    unsigned int count;
  };

  struct Node {
    Local<String> name;

    Local<String> script_name;

    int script_id;

    int start_position;

    int line_number;

    int column_number;

    uint32_t node_id;

    std::vector<Node*> children;

    std::vector<Allocation> allocations;
  };

  struct Sample {
    uint32_t node_id;

    size_t size;

    unsigned int count;

    uint64_t sample_id;
  };

  virtual Node* GetRootNode() = 0;
  virtual const std::vector<Sample>& GetSamples() = 0;
 
  virtual ~AllocationProfile() = default;
 
  static const int kNoLineNumberInfo = Message::kNoLineNumberInfo;
  static const int kNoColumnNumberInfo = Message::kNoColumnInfo;
};

class V8_EXPORT EmbedderGraph {
 public:
  class Node {
   public:
    enum class Detachedness : uint8_t {
      kUnknown = 0,
      kAttached = 1,
      kDetached = 2,
    };
 
    Node() = default;
    virtual ~Node() = default;
    virtual const char* Name() = 0;
    virtual size_t SizeInBytes() = 0;
    virtual Node* WrapperNode() { return nullptr; }
    virtual bool IsRootNode() { return false; }
    virtual bool IsEmbedderNode() { return true; }
    virtual const char* NamePrefix() { return nullptr; }

    virtual NativeObject GetNativeObject() { return nullptr; }

    virtual Detachedness GetDetachedness() { return Detachedness::kUnknown; }

    virtual const void* GetAddress() { return nullptr; }
 
    Node(const Node&) = delete;
    Node& operator=(const Node&) = delete;
  };

  virtual Node* V8Node(const v8::Local<v8::Value>& value) = 0;

  virtual Node* V8Node(const v8::Local<v8::Data>& value);

  virtual Node* AddNode(std::unique_ptr<Node> node) = 0;

  virtual void AddEdge(Node* from, Node* to, const char* name = nullptr) = 0;

  virtual void AddNativeSize(size_t size) {}
 
  virtual ~EmbedderGraph() = default;
};
 
class QueryObjectPredicate {
 public:
  virtual ~QueryObjectPredicate() = default;
  virtual bool Filter(v8::Local<v8::Object> object) = 0;
};

class V8_EXPORT HeapProfiler {
 public:
  void QueryObjects(v8::Local<v8::Context> context,
                    QueryObjectPredicate* predicate,
                    std::vector<v8::Global<v8::Object>>* objects);
 
  enum SamplingFlags {
    kSamplingNoFlags = 0,
    kSamplingForceGC = 1 << 0,
    kSamplingIncludeObjectsCollectedByMajorGC = 1 << 1,
    kSamplingIncludeObjectsCollectedByMinorGC = 1 << 2,
  };

  typedef void (*BuildEmbedderGraphCallback)(v8::Isolate* isolate,
                                             v8::EmbedderGraph* graph,
                                             void* data);

  using GetDetachednessCallback = EmbedderGraph::Node::Detachedness (*)(
      v8::Isolate* isolate, const v8::Local<v8::Value>& v8_value,
      uint16_t class_id, void* data);

  int GetSnapshotCount();

  const HeapSnapshot* GetHeapSnapshot(int index);

  SnapshotObjectId GetObjectId(Local<Value> value);

  SnapshotObjectId GetObjectId(NativeObject value);

  Local<Value> FindObjectById(SnapshotObjectId id);

  void ClearObjectIds();

  static const SnapshotObjectId kUnknownObjectId = 0;

  class ObjectNameResolver {
   public:
    virtual const char* GetName(Local<Object> object) = 0;
 
   protected:
    virtual ~ObjectNameResolver() = default;
  };
 
  enum class HeapSnapshotMode {
    kRegular,
    kExposeInternals,
  };
 
  enum class NumericsMode {
    kHideNumericValues,
    kExposeNumericValues
  };
 
  struct HeapSnapshotOptions final {
    // Manually define default constructor here to be able to use it in
    // `TakeSnapshot()` below.
    // NOLINTNEXTLINE
    HeapSnapshotOptions() {}

    ActivityControl* control = nullptr;
    ObjectNameResolver* global_object_name_resolver = nullptr;
    HeapSnapshotMode snapshot_mode = HeapSnapshotMode::kRegular;
    NumericsMode numerics_mode = NumericsMode::kHideNumericValues;
    cppgc::EmbedderStackState stack_state =
        cppgc::EmbedderStackState::kMayContainHeapPointers;
  };

  const HeapSnapshot* TakeHeapSnapshot(
      const HeapSnapshotOptions& options = HeapSnapshotOptions());

  const HeapSnapshot* TakeHeapSnapshot(
      ActivityControl* control,
      ObjectNameResolver* global_object_name_resolver = nullptr,
      bool hide_internals = true, bool capture_numeric_value = false);

  std::vector<v8::Local<v8::Value>> GetDetachedJSWrapperObjects();

  void StartTrackingHeapObjects(bool track_allocations = false);

  SnapshotObjectId GetHeapStats(OutputStream* stream,
                                int64_t* timestamp_us = nullptr);

  void StopTrackingHeapObjects();

  bool StartSamplingHeapProfiler(uint64_t sample_interval = 512 * 1024,
                                 int stack_depth = 16,
                                 SamplingFlags flags = kSamplingNoFlags);

  void StopSamplingHeapProfiler();

  AllocationProfile* GetAllocationProfile();

  void DeleteAllHeapSnapshots();
 
  void AddBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
                                     void* data);
  void RemoveBuildEmbedderGraphCallback(BuildEmbedderGraphCallback callback,
                                        void* data);
 
  void SetGetDetachednessCallback(GetDetachednessCallback callback, void* data);

  bool IsTakingSnapshot();

  const char* CopyNameForHeapSnapshot(const char* name);

  static const uint16_t kPersistentHandleNoClassId = 0;
 
 private:
  HeapProfiler();
  ~HeapProfiler();
  HeapProfiler(const HeapProfiler&);
  HeapProfiler& operator=(const HeapProfiler&);
};

struct HeapStatsUpdate {
  HeapStatsUpdate(uint32_t index, uint32_t count, uint32_t size)
    : index(index), count(count), size(size) { }
  uint32_t index;  // Index of the time interval that was changed.
  uint32_t count;  // New value of count field for the interval with this index.
  uint32_t size;  // New value of size field for the interval with this index.
};
 
#define CODE_EVENTS_LIST(V)                          \
  V(Builtin)                                         \
  V(Callback)                                        \
  V(Eval)                                            \
  V(Function)                                        \
  V(InterpretedFunction)                             \
  V(Handler)                                         \
  V(BytecodeHandler)                                 \
  V(LazyCompile) /* Unused, use kFunction instead */ \
  V(RegExp)                                          \
  V(Script)                                          \
  V(Stub)                                            \
  V(Relocation)

enum CodeEventType {
  kUnknownType = 0
#define V(Name) , k##Name##Type
  CODE_EVENTS_LIST(V)
#undef V
};

class V8_EXPORT CodeEvent {
 public:
  uintptr_t GetCodeStartAddress();
  size_t GetCodeSize();
  Local<String> GetFunctionName();
  Local<String> GetScriptName();
  int GetScriptLine();
  int GetScriptColumn();
  CodeEventType GetCodeType();
  const char* GetComment();
 
  static const char* GetCodeEventTypeName(CodeEventType code_event_type);
 
  uintptr_t GetPreviousCodeStartAddress();
};

class V8_EXPORT CodeEventHandler {
 public:
  explicit CodeEventHandler(Isolate* isolate);
  virtual ~CodeEventHandler();

  virtual void Handle(CodeEvent* code_event) = 0;

  void Enable();

  void Disable();
 
 private:
  CodeEventHandler();
  CodeEventHandler(const CodeEventHandler&);
  CodeEventHandler& operator=(const CodeEventHandler&);
  void* internal_listener_;
};
 
}  // namespace v8
 
 
#endif  // V8_V8_PROFILER_H_