Upload Kmake

src/tracing/agent.cc

@@ -0,0 +1,251 @@
+#include "tracing/agent.h"
+
+#include <string>
+#include "trace_event.h"
+#include "tracing/node_trace_buffer.h"
+#include "debug_utils-inl.h"
+#include "env-inl.h"
+
+namespace node {
+namespace tracing {
+
+class Agent::ScopedSuspendTracing {
+ public:
+  ScopedSuspendTracing(TracingController* controller, Agent* agent,
+                       bool do_suspend = true)
+    : controller_(controller), agent_(do_suspend ? agent : nullptr) {
+    if (do_suspend) {
+      CHECK(agent_->started_);
+      controller->StopTracing();
+    }
+  }
+
+  ~ScopedSuspendTracing() {
+    if (agent_ == nullptr) return;
+    TraceConfig* config = agent_->CreateTraceConfig();
+    if (config != nullptr) {
+      controller_->StartTracing(config);
+    }
+  }
+
+ private:
+  TracingController* controller_;
+  Agent* agent_;
+};
+
+namespace {
+
+std::set<std::string> flatten(
+    const std::unordered_map<int, std::multiset<std::string>>& map) {
+  std::set<std::string> result;
+  for (const auto& id_value : map)
+    result.insert(id_value.second.begin(), id_value.second.end());
+  return result;
+}
+
+}  // namespace
+
+using v8::platform::tracing::TraceConfig;
+using v8::platform::tracing::TraceWriter;
+using std::string;
+
+Agent::Agent() : tracing_controller_(new TracingController()) {
+  tracing_controller_->Initialize(nullptr);
+
+  CHECK_EQ(uv_loop_init(&tracing_loop_), 0);
+  CHECK_EQ(uv_async_init(&tracing_loop_,
+                         &initialize_writer_async_,
+                         [](uv_async_t* async) {
+    Agent* agent = ContainerOf(&Agent::initialize_writer_async_, async);
+    agent->InitializeWritersOnThread();
+  }), 0);
+  uv_unref(reinterpret_cast<uv_handle_t*>(&initialize_writer_async_));
+}
+
+void Agent::InitializeWritersOnThread() {
+  Mutex::ScopedLock lock(initialize_writer_mutex_);
+  while (!to_be_initialized_.empty()) {
+    AsyncTraceWriter* head = *to_be_initialized_.begin();
+    head->InitializeOnThread(&tracing_loop_);
+    to_be_initialized_.erase(head);
+  }
+  initialize_writer_condvar_.Broadcast(lock);
+}
+
+Agent::~Agent() {
+  categories_.clear();
+  writers_.clear();
+
+  StopTracing();
+
+  uv_close(reinterpret_cast<uv_handle_t*>(&initialize_writer_async_), nullptr);
+  uv_run(&tracing_loop_, UV_RUN_ONCE);
+  CheckedUvLoopClose(&tracing_loop_);
+}
+
+void Agent::Start() {
+  if (started_)
+    return;
+
+  NodeTraceBuffer* trace_buffer_ = new NodeTraceBuffer(
+      NodeTraceBuffer::kBufferChunks, this, &tracing_loop_);
+  tracing_controller_->Initialize(trace_buffer_);
+
+  // This thread should be created *after* async handles are created
+  // (within NodeTraceWriter and NodeTraceBuffer constructors).
+  // Otherwise the thread could shut down prematurely.
+  CHECK_EQ(0, uv_thread_create(&thread_, [](void* arg) {
+    Agent* agent = static_cast<Agent*>(arg);
+    uv_run(&agent->tracing_loop_, UV_RUN_DEFAULT);
+  }, this));
+  started_ = true;
+}
+
+AgentWriterHandle Agent::AddClient(
+    const std::set<std::string>& categories,
+    std::unique_ptr<AsyncTraceWriter> writer,
+    enum UseDefaultCategoryMode mode) {
+  Start();
+
+  const std::set<std::string>* use_categories = &categories;
+
+  std::set<std::string> categories_with_default;
+  if (mode == kUseDefaultCategories) {
+    categories_with_default.insert(categories.begin(), categories.end());
+    categories_with_default.insert(categories_[kDefaultHandleId].begin(),
+                                   categories_[kDefaultHandleId].end());
+    use_categories = &categories_with_default;
+  }
+
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this);
+  int id = next_writer_id_++;
+  AsyncTraceWriter* raw = writer.get();
+  writers_[id] = std::move(writer);
+  categories_[id] = { use_categories->begin(), use_categories->end() };
+
+  {
+    Mutex::ScopedLock lock(initialize_writer_mutex_);
+    to_be_initialized_.insert(raw);
+    uv_async_send(&initialize_writer_async_);
+    while (to_be_initialized_.count(raw) > 0)
+      initialize_writer_condvar_.Wait(lock);
+  }
+
+  return AgentWriterHandle(this, id);
+}
+
+AgentWriterHandle Agent::DefaultHandle() {
+  return AgentWriterHandle(this, kDefaultHandleId);
+}
+
+void Agent::StopTracing() {
+  if (!started_)
+    return;
+  // Perform final Flush on TraceBuffer. We don't want the tracing controller
+  // to flush the buffer again on destruction of the V8::Platform.
+  tracing_controller_->StopTracing();
+  tracing_controller_->Initialize(nullptr);
+  started_ = false;
+
+  // Thread should finish when the tracing loop is stopped.
+  uv_thread_join(&thread_);
+}
+
+void Agent::Disconnect(int client) {
+  if (client == kDefaultHandleId) return;
+  {
+    Mutex::ScopedLock lock(initialize_writer_mutex_);
+    to_be_initialized_.erase(writers_[client].get());
+  }
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this);
+  writers_.erase(client);
+  categories_.erase(client);
+}
+
+void Agent::Enable(int id, const std::set<std::string>& categories) {
+  if (categories.empty())
+    return;
+
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this,
+                               id != kDefaultHandleId);
+  categories_[id].insert(categories.begin(), categories.end());
+}
+
+void Agent::Disable(int id, const std::set<std::string>& categories) {
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this,
+                               id != kDefaultHandleId);
+  std::multiset<std::string>& writer_categories = categories_[id];
+  for (const std::string& category : categories) {
+    auto it = writer_categories.find(category);
+    if (it != writer_categories.end())
+      writer_categories.erase(it);
+  }
+}
+
+TraceConfig* Agent::CreateTraceConfig() const {
+  if (categories_.empty())
+    return nullptr;
+  TraceConfig* trace_config = new TraceConfig();
+  for (const auto& category : flatten(categories_)) {
+    trace_config->AddIncludedCategory(category.c_str());
+  }
+  return trace_config;
+}
+
+std::string Agent::GetEnabledCategories() const {
+  std::string categories;
+  for (const std::string& category : flatten(categories_)) {
+    if (!categories.empty())
+      categories += ',';
+    categories += category;
+  }
+  return categories;
+}
+
+void Agent::AppendTraceEvent(TraceObject* trace_event) {
+  for (const auto& id_writer : writers_)
+    id_writer.second->AppendTraceEvent(trace_event);
+}
+
+void Agent::AddMetadataEvent(std::unique_ptr<TraceObject> event) {
+  Mutex::ScopedLock lock(metadata_events_mutex_);
+  metadata_events_.push_back(std::move(event));
+}
+
+void Agent::Flush(bool blocking) {
+  {
+    Mutex::ScopedLock lock(metadata_events_mutex_);
+    for (const auto& event : metadata_events_)
+      AppendTraceEvent(event.get());
+  }
+
+  for (const auto& id_writer : writers_)
+    id_writer.second->Flush(blocking);
+}
+
+void TracingController::AddMetadataEvent(
+    const unsigned char* category_group_enabled,
+    const char* name,
+    int num_args,
+    const char** arg_names,
+    const unsigned char* arg_types,
+    const uint64_t* arg_values,
+    std::unique_ptr<v8::ConvertableToTraceFormat>* convertable_values,
+    unsigned int flags) {
+  std::unique_ptr<TraceObject> trace_event(new TraceObject);
+  trace_event->Initialize(
+      TRACE_EVENT_PHASE_METADATA, category_group_enabled, name,
+      node::tracing::kGlobalScope,  // scope
+      node::tracing::kNoId,         // id
+      node::tracing::kNoId,         // bind_id
+      num_args, arg_names, arg_types, arg_values, convertable_values,
+      TRACE_EVENT_FLAG_NONE,
+      CurrentTimestampMicroseconds(),
+      CurrentCpuTimestampMicroseconds());
+  Agent* node_agent = node::tracing::TraceEventHelper::GetAgent();
+  if (node_agent != nullptr)
+    node_agent->AddMetadataEvent(std::move(trace_event));
+}
+
+}  // namespace tracing
+}  // namespace node

src/tracing/agent.h

@@ -0,0 +1,195 @@
+#ifndef SRC_TRACING_AGENT_H_
+#define SRC_TRACING_AGENT_H_
+
+#include "libplatform/v8-tracing.h"
+#include "uv.h"
+#include "util.h"
+#include "node_mutex.h"
+
+#include <list>
+#include <set>
+#include <string>
+#include <unordered_map>
+
+namespace v8 {
+class ConvertableToTraceFormat;
+class TracingController;
+}  // namespace v8
+
+namespace node {
+namespace tracing {
+
+using v8::platform::tracing::TraceConfig;
+using v8::platform::tracing::TraceObject;
+
+class Agent;
+
+class AsyncTraceWriter {
+ public:
+  virtual ~AsyncTraceWriter() = default;
+  virtual void AppendTraceEvent(TraceObject* trace_event) = 0;
+  virtual void Flush(bool blocking) = 0;
+  virtual void InitializeOnThread(uv_loop_t* loop) {}
+};
+
+class TracingController : public v8::platform::tracing::TracingController {
+ public:
+  TracingController() : v8::platform::tracing::TracingController() {}
+
+  int64_t CurrentTimestampMicroseconds() override {
+    return uv_hrtime() / 1000;
+  }
+  void AddMetadataEvent(
+      const unsigned char* category_group_enabled,
+      const char* name,
+      int num_args,
+      const char** arg_names,
+      const unsigned char* arg_types,
+      const uint64_t* arg_values,
+      std::unique_ptr<v8::ConvertableToTraceFormat>* convertable_values,
+      unsigned int flags);
+};
+
+class AgentWriterHandle {
+ public:
+  inline AgentWriterHandle() = default;
+  inline ~AgentWriterHandle() { reset(); }
+
+  inline AgentWriterHandle(AgentWriterHandle&& other);
+  inline AgentWriterHandle& operator=(AgentWriterHandle&& other);
+  inline bool empty() const { return agent_ == nullptr; }
+  inline void reset();
+
+  inline void Enable(const std::set<std::string>& categories);
+  inline void Disable(const std::set<std::string>& categories);
+
+  inline bool IsDefaultHandle();
+
+  inline Agent* agent() { return agent_; }
+
+  inline v8::TracingController* GetTracingController();
+
+  AgentWriterHandle(const AgentWriterHandle& other) = delete;
+  AgentWriterHandle& operator=(const AgentWriterHandle& other) = delete;
+
+ private:
+  inline AgentWriterHandle(Agent* agent, int id) : agent_(agent), id_(id) {}
+
+  Agent* agent_ = nullptr;
+  int id_ = 0;
+
+  friend class Agent;
+};
+
+class Agent {
+ public:
+  Agent();
+  ~Agent();
+
+  TracingController* GetTracingController() {
+    TracingController* controller = tracing_controller_.get();
+    CHECK_NOT_NULL(controller);
+    return controller;
+  }
+
+  enum UseDefaultCategoryMode {
+    kUseDefaultCategories,
+    kIgnoreDefaultCategories
+  };
+
+  // Destroying the handle disconnects the client
+  AgentWriterHandle AddClient(const std::set<std::string>& categories,
+                              std::unique_ptr<AsyncTraceWriter> writer,
+                              enum UseDefaultCategoryMode mode);
+  // A handle that is only used for managing the default categories
+  // (which can then implicitly be used through using `USE_DEFAULT_CATEGORIES`
+  // when adding a client later).
+  AgentWriterHandle DefaultHandle();
+
+  // Returns a comma-separated list of enabled categories.
+  std::string GetEnabledCategories() const;
+
+  // Writes to all writers registered through AddClient().
+  void AppendTraceEvent(TraceObject* trace_event);
+
+  void AddMetadataEvent(std::unique_ptr<TraceObject> event);
+  // Flushes all writers registered through AddClient().
+  void Flush(bool blocking);
+
+  TraceConfig* CreateTraceConfig() const;
+
+ private:
+  friend class AgentWriterHandle;
+
+  void InitializeWritersOnThread();
+
+  void Start();
+  void StopTracing();
+  void Disconnect(int client);
+
+  void Enable(int id, const std::set<std::string>& categories);
+  void Disable(int id, const std::set<std::string>& categories);
+
+  uv_thread_t thread_;
+  uv_loop_t tracing_loop_;
+
+  bool started_ = false;
+  class ScopedSuspendTracing;
+
+  // Each individual Writer has one id.
+  int next_writer_id_ = 1;
+  enum { kDefaultHandleId = -1 };
+  // These maps store the original arguments to AddClient(), by id.
+  std::unordered_map<int, std::multiset<std::string>> categories_;
+  std::unordered_map<int, std::unique_ptr<AsyncTraceWriter>> writers_;
+  std::unique_ptr<TracingController> tracing_controller_;
+
+  // Variables related to initializing per-event-loop properties of individual
+  // writers, such as libuv handles.
+  Mutex initialize_writer_mutex_;
+  ConditionVariable initialize_writer_condvar_;
+  uv_async_t initialize_writer_async_;
+  std::set<AsyncTraceWriter*> to_be_initialized_;
+
+  Mutex metadata_events_mutex_;
+  std::list<std::unique_ptr<TraceObject>> metadata_events_;
+};
+
+void AgentWriterHandle::reset() {
+  if (agent_ != nullptr)
+    agent_->Disconnect(id_);
+  agent_ = nullptr;
+}
+
+AgentWriterHandle& AgentWriterHandle::operator=(AgentWriterHandle&& other) {
+  reset();
+  agent_ = other.agent_;
+  id_ = other.id_;
+  other.agent_ = nullptr;
+  return *this;
+}
+
+AgentWriterHandle::AgentWriterHandle(AgentWriterHandle&& other) {
+  *this = std::move(other);
+}
+
+void AgentWriterHandle::Enable(const std::set<std::string>& categories) {
+  if (agent_ != nullptr) agent_->Enable(id_, categories);
+}
+
+void AgentWriterHandle::Disable(const std::set<std::string>& categories) {
+  if (agent_ != nullptr) agent_->Disable(id_, categories);
+}
+
+bool AgentWriterHandle::IsDefaultHandle() {
+  return agent_ != nullptr && id_ == Agent::kDefaultHandleId;
+}
+
+inline v8::TracingController* AgentWriterHandle::GetTracingController() {
+  return agent_ != nullptr ? agent_->GetTracingController() : nullptr;
+}
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_AGENT_H_

src/tracing/node_trace_buffer.cc

@@ -0,0 +1,199 @@
+#include "tracing/node_trace_buffer.h"
+
+#include <memory>
+#include "util-inl.h"
+
+namespace node {
+namespace tracing {
+
+InternalTraceBuffer::InternalTraceBuffer(size_t max_chunks, uint32_t id,
+                                         Agent* agent)
+    : flushing_(false), max_chunks_(max_chunks),
+      agent_(agent), id_(id) {
+  chunks_.resize(max_chunks);
+}
+
+TraceObject* InternalTraceBuffer::AddTraceEvent(uint64_t* handle) {
+  Mutex::ScopedLock scoped_lock(mutex_);
+  // Create new chunk if last chunk is full or there is no chunk.
+  if (total_chunks_ == 0 || chunks_[total_chunks_ - 1]->IsFull()) {
+    auto& chunk = chunks_[total_chunks_++];
+    if (chunk) {
+      chunk->Reset(current_chunk_seq_++);
+    } else {
+      chunk = std::make_unique<TraceBufferChunk>(current_chunk_seq_++);
+    }
+  }
+  auto& chunk = chunks_[total_chunks_ - 1];
+  size_t event_index;
+  TraceObject* trace_object = chunk->AddTraceEvent(&event_index);
+  *handle = MakeHandle(total_chunks_ - 1, chunk->seq(), event_index);
+  return trace_object;
+}
+
+TraceObject* InternalTraceBuffer::GetEventByHandle(uint64_t handle) {
+  Mutex::ScopedLock scoped_lock(mutex_);
+  if (handle == 0) {
+    // A handle value of zero never has a trace event associated with it.
+    return nullptr;
+  }
+  size_t chunk_index, event_index;
+  uint32_t buffer_id, chunk_seq;
+  ExtractHandle(handle, &buffer_id, &chunk_index, &chunk_seq, &event_index);
+  if (buffer_id != id_ || chunk_index >= total_chunks_) {
+    // Either the chunk belongs to the other buffer, or is outside the current
+    // range of chunks loaded in memory (the latter being true suggests that
+    // the chunk has already been flushed and is no longer in memory.)
+    return nullptr;
+  }
+  auto& chunk = chunks_[chunk_index];
+  if (chunk->seq() != chunk_seq) {
+    // Chunk is no longer in memory.
+    return nullptr;
+  }
+  return chunk->GetEventAt(event_index);
+}
+
+void InternalTraceBuffer::Flush(bool blocking) {
+  {
+    Mutex::ScopedLock scoped_lock(mutex_);
+    if (total_chunks_ > 0) {
+      flushing_ = true;
+      for (size_t i = 0; i < total_chunks_; ++i) {
+        auto& chunk = chunks_[i];
+        for (size_t j = 0; j < chunk->size(); ++j) {
+          TraceObject* trace_event = chunk->GetEventAt(j);
+          // Another thread may have added a trace that is yet to be
+          // initialized. Skip such traces.
+          // https://github.com/nodejs/node/issues/21038.
+          if (trace_event->name()) {
+            agent_->AppendTraceEvent(trace_event);
+          }
+        }
+      }
+      total_chunks_ = 0;
+      flushing_ = false;
+    }
+  }
+  agent_->Flush(blocking);
+}
+
+uint64_t InternalTraceBuffer::MakeHandle(
+    size_t chunk_index, uint32_t chunk_seq, size_t event_index) const {
+  return ((static_cast<uint64_t>(chunk_seq) * Capacity() +
+          chunk_index * TraceBufferChunk::kChunkSize + event_index) << 1) + id_;
+}
+
+void InternalTraceBuffer::ExtractHandle(
+    uint64_t handle, uint32_t* buffer_id, size_t* chunk_index,
+    uint32_t* chunk_seq, size_t* event_index) const {
+  *buffer_id = static_cast<uint32_t>(handle & 0x1);
+  handle >>= 1;
+  *chunk_seq = static_cast<uint32_t>(handle / Capacity());
+  size_t indices = handle % Capacity();
+  *chunk_index = indices / TraceBufferChunk::kChunkSize;
+  *event_index = indices % TraceBufferChunk::kChunkSize;
+}
+
+NodeTraceBuffer::NodeTraceBuffer(size_t max_chunks,
+    Agent* agent, uv_loop_t* tracing_loop)
+    : tracing_loop_(tracing_loop),
+      buffer1_(max_chunks, 0, agent),
+      buffer2_(max_chunks, 1, agent) {
+  current_buf_.store(&buffer1_);
+
+  flush_signal_.data = this;
+  int err = uv_async_init(tracing_loop_, &flush_signal_,
+                          NonBlockingFlushSignalCb);
+  CHECK_EQ(err, 0);
+
+  exit_signal_.data = this;
+  err = uv_async_init(tracing_loop_, &exit_signal_, ExitSignalCb);
+  CHECK_EQ(err, 0);
+}
+
+NodeTraceBuffer::~NodeTraceBuffer() {
+  uv_async_send(&exit_signal_);
+  Mutex::ScopedLock scoped_lock(exit_mutex_);
+  while (!exited_) {
+    exit_cond_.Wait(scoped_lock);
+  }
+}
+
+TraceObject* NodeTraceBuffer::AddTraceEvent(uint64_t* handle) {
+  // If the buffer is full, attempt to perform a flush.
+  if (!TryLoadAvailableBuffer()) {
+    // Assign a value of zero as the trace event handle.
+    // This is equivalent to calling InternalTraceBuffer::MakeHandle(0, 0, 0),
+    // and will cause GetEventByHandle to return NULL if passed as an argument.
+    *handle = 0;
+    return nullptr;
+  }
+  return current_buf_.load()->AddTraceEvent(handle);
+}
+
+TraceObject* NodeTraceBuffer::GetEventByHandle(uint64_t handle) {
+  return current_buf_.load()->GetEventByHandle(handle);
+}
+
+bool NodeTraceBuffer::Flush() {
+  buffer1_.Flush(true);
+  buffer2_.Flush(true);
+  return true;
+}
+
+// Attempts to set current_buf_ such that it references a buffer that can
+// write at least one trace event. If both buffers are unavailable this
+// method returns false; otherwise it returns true.
+bool NodeTraceBuffer::TryLoadAvailableBuffer() {
+  InternalTraceBuffer* prev_buf = current_buf_.load();
+  if (prev_buf->IsFull()) {
+    uv_async_send(&flush_signal_);  // trigger flush on a separate thread
+    InternalTraceBuffer* other_buf = prev_buf == &buffer1_ ?
+      &buffer2_ : &buffer1_;
+    if (!other_buf->IsFull()) {
+      current_buf_.store(other_buf);
+    } else {
+      return false;
+    }
+  }
+  return true;
+}
+
+// static
+void NodeTraceBuffer::NonBlockingFlushSignalCb(uv_async_t* signal) {
+  NodeTraceBuffer* buffer = static_cast<NodeTraceBuffer*>(signal->data);
+  if (buffer->buffer1_.IsFull() && !buffer->buffer1_.IsFlushing()) {
+    buffer->buffer1_.Flush(false);
+  }
+  if (buffer->buffer2_.IsFull() && !buffer->buffer2_.IsFlushing()) {
+    buffer->buffer2_.Flush(false);
+  }
+}
+
+// static
+void NodeTraceBuffer::ExitSignalCb(uv_async_t* signal) {
+  NodeTraceBuffer* buffer =
+      ContainerOf(&NodeTraceBuffer::exit_signal_, signal);
+
+  // Close both flush_signal_ and exit_signal_.
+  uv_close(reinterpret_cast<uv_handle_t*>(&buffer->flush_signal_),
+           [](uv_handle_t* signal) {
+    NodeTraceBuffer* buffer =
+        ContainerOf(&NodeTraceBuffer::flush_signal_,
+                    reinterpret_cast<uv_async_t*>(signal));
+
+    uv_close(reinterpret_cast<uv_handle_t*>(&buffer->exit_signal_),
+             [](uv_handle_t* signal) {
+      NodeTraceBuffer* buffer =
+          ContainerOf(&NodeTraceBuffer::exit_signal_,
+                      reinterpret_cast<uv_async_t*>(signal));
+        Mutex::ScopedLock scoped_lock(buffer->exit_mutex_);
+        buffer->exited_ = true;
+        buffer->exit_cond_.Signal(scoped_lock);
+    });
+  });
+}
+
+}  // namespace tracing
+}  // namespace node

src/tracing/node_trace_buffer.h

@@ -0,0 +1,83 @@
+#ifndef SRC_TRACING_NODE_TRACE_BUFFER_H_
+#define SRC_TRACING_NODE_TRACE_BUFFER_H_
+
+#include "tracing/agent.h"
+#include "node_mutex.h"
+#include "libplatform/v8-tracing.h"
+
+#include <atomic>
+
+namespace node {
+namespace tracing {
+
+using v8::platform::tracing::TraceBuffer;
+using v8::platform::tracing::TraceBufferChunk;
+using v8::platform::tracing::TraceObject;
+
+// forward declaration
+class NodeTraceBuffer;
+
+class InternalTraceBuffer {
+ public:
+  InternalTraceBuffer(size_t max_chunks, uint32_t id, Agent* agent);
+
+  TraceObject* AddTraceEvent(uint64_t* handle);
+  TraceObject* GetEventByHandle(uint64_t handle);
+  void Flush(bool blocking);
+  bool IsFull() const {
+    return total_chunks_ == max_chunks_ && chunks_[total_chunks_ - 1]->IsFull();
+  }
+  bool IsFlushing() const {
+    return flushing_;
+  }
+
+ private:
+  uint64_t MakeHandle(size_t chunk_index, uint32_t chunk_seq,
+                      size_t event_index) const;
+  void ExtractHandle(uint64_t handle, uint32_t* buffer_id, size_t* chunk_index,
+                     uint32_t* chunk_seq, size_t* event_index) const;
+  size_t Capacity() const { return max_chunks_ * TraceBufferChunk::kChunkSize; }
+
+  Mutex mutex_;
+  bool flushing_;
+  size_t max_chunks_;
+  Agent* agent_;
+  std::vector<std::unique_ptr<TraceBufferChunk>> chunks_;
+  size_t total_chunks_ = 0;
+  uint32_t current_chunk_seq_ = 1;
+  uint32_t id_;
+};
+
+class NodeTraceBuffer : public TraceBuffer {
+ public:
+  NodeTraceBuffer(size_t max_chunks, Agent* agent, uv_loop_t* tracing_loop);
+  ~NodeTraceBuffer() override;
+
+  TraceObject* AddTraceEvent(uint64_t* handle) override;
+  TraceObject* GetEventByHandle(uint64_t handle) override;
+  bool Flush() override;
+
+  static const size_t kBufferChunks = 1024;
+
+ private:
+  bool TryLoadAvailableBuffer();
+  static void NonBlockingFlushSignalCb(uv_async_t* signal);
+  static void ExitSignalCb(uv_async_t* signal);
+
+  uv_loop_t* tracing_loop_;
+  uv_async_t flush_signal_;
+  uv_async_t exit_signal_;
+  bool exited_ = false;
+  // Used exclusively for exit logic.
+  Mutex exit_mutex_;
+  // Used to wait until async handles have been closed.
+  ConditionVariable exit_cond_;
+  std::atomic<InternalTraceBuffer*> current_buf_;
+  InternalTraceBuffer buffer1_;
+  InternalTraceBuffer buffer2_;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_NODE_TRACE_BUFFER_H_

src/tracing/node_trace_writer.cc

@@ -0,0 +1,240 @@
+#include "tracing/node_trace_writer.h"
+
+#include "util-inl.h"
+
+#include <fcntl.h>
+#include <cstring>
+
+namespace node {
+namespace tracing {
+
+NodeTraceWriter::NodeTraceWriter(const std::string& log_file_pattern)
+    : log_file_pattern_(log_file_pattern) {}
+
+void NodeTraceWriter::InitializeOnThread(uv_loop_t* loop) {
+  CHECK_NULL(tracing_loop_);
+  tracing_loop_ = loop;
+
+  flush_signal_.data = this;
+  int err = uv_async_init(tracing_loop_, &flush_signal_,
+                          [](uv_async_t* signal) {
+    NodeTraceWriter* trace_writer =
+        ContainerOf(&NodeTraceWriter::flush_signal_, signal);
+    trace_writer->FlushPrivate();
+  });
+  CHECK_EQ(err, 0);
+
+  exit_signal_.data = this;
+  err = uv_async_init(tracing_loop_, &exit_signal_, ExitSignalCb);
+  CHECK_EQ(err, 0);
+}
+
+void NodeTraceWriter::WriteSuffix() {
+  // If our final log file has traces, then end the file appropriately.
+  // This means that if no trace events are recorded, then no trace file is
+  // produced.
+  bool should_flush = false;
+  {
+    Mutex::ScopedLock scoped_lock(stream_mutex_);
+    if (total_traces_ > 0) {
+      total_traces_ = kTracesPerFile;  // Act as if we reached the file limit.
+      should_flush = true;
+    }
+  }
+  if (should_flush) {
+    Flush(true);
+  }
+}
+
+NodeTraceWriter::~NodeTraceWriter() {
+  WriteSuffix();
+  uv_fs_t req;
+  if (fd_ != -1) {
+    CHECK_EQ(0, uv_fs_close(nullptr, &req, fd_, nullptr));
+    uv_fs_req_cleanup(&req);
+  }
+  uv_async_send(&exit_signal_);
+  Mutex::ScopedLock scoped_lock(request_mutex_);
+  while (!exited_) {
+    exit_cond_.Wait(scoped_lock);
+  }
+}
+
+void replace_substring(std::string* target,
+                       const std::string& search,
+                       const std::string& insert) {
+  size_t pos = target->find(search);
+  for (; pos != std::string::npos; pos = target->find(search, pos)) {
+    target->replace(pos, search.size(), insert);
+    pos += insert.size();
+  }
+}
+
+void NodeTraceWriter::OpenNewFileForStreaming() {
+  ++file_num_;
+  uv_fs_t req;
+
+  // Evaluate a JS-style template string, it accepts the values ${pid} and
+  // ${rotation}
+  std::string filepath(log_file_pattern_);
+  replace_substring(&filepath, "${pid}", std::to_string(uv_os_getpid()));
+  replace_substring(&filepath, "${rotation}", std::to_string(file_num_));
+
+  if (fd_ != -1) {
+    CHECK_EQ(uv_fs_close(nullptr, &req, fd_, nullptr), 0);
+    uv_fs_req_cleanup(&req);
+  }
+
+  fd_ = uv_fs_open(nullptr, &req, filepath.c_str(),
+      O_CREAT | O_WRONLY | O_TRUNC, 0644, nullptr);
+  uv_fs_req_cleanup(&req);
+  if (fd_ < 0) {
+    fprintf(stderr, "Could not open trace file %s: %s\n",
+                    filepath.c_str(),
+                    uv_strerror(fd_));
+    fd_ = -1;
+  }
+}
+
+void NodeTraceWriter::AppendTraceEvent(TraceObject* trace_event) {
+  Mutex::ScopedLock scoped_lock(stream_mutex_);
+  // If this is the first trace event, open a new file for streaming.
+  if (total_traces_ == 0) {
+    OpenNewFileForStreaming();
+    // Constructing a new JSONTraceWriter object appends "{\"traceEvents\":["
+    // to stream_.
+    // In other words, the constructor initializes the serialization stream
+    // to a state where we can start writing trace events to it.
+    // Repeatedly constructing and destroying json_trace_writer_ allows
+    // us to use V8's JSON writer instead of implementing our own.
+    json_trace_writer_.reset(TraceWriter::CreateJSONTraceWriter(stream_));
+  }
+  ++total_traces_;
+  json_trace_writer_->AppendTraceEvent(trace_event);
+}
+
+void NodeTraceWriter::FlushPrivate() {
+  std::string str;
+  int highest_request_id;
+  {
+    Mutex::ScopedLock stream_scoped_lock(stream_mutex_);
+    if (total_traces_ >= kTracesPerFile) {
+      total_traces_ = 0;
+      // Destroying the member JSONTraceWriter object appends "]}" to
+      // stream_ - in other words, ending a JSON file.
+      json_trace_writer_.reset();
+    }
+    // str() makes a copy of the contents of the stream.
+    str = stream_.str();
+    stream_.str("");
+    stream_.clear();
+  }
+  {
+    Mutex::ScopedLock request_scoped_lock(request_mutex_);
+    highest_request_id = num_write_requests_;
+  }
+  WriteToFile(std::move(str), highest_request_id);
+}
+
+void NodeTraceWriter::Flush(bool blocking) {
+  Mutex::ScopedLock scoped_lock(request_mutex_);
+  {
+    // We need to lock the mutexes here in a nested fashion; stream_mutex_
+    // protects json_trace_writer_, and without request_mutex_ there might be
+    // a time window in which the stream state changes?
+    Mutex::ScopedLock stream_mutex_lock(stream_mutex_);
+    if (!json_trace_writer_)
+      return;
+  }
+  int request_id = ++num_write_requests_;
+  int err = uv_async_send(&flush_signal_);
+  CHECK_EQ(err, 0);
+  if (blocking) {
+    // Wait until data associated with this request id has been written to disk.
+    // This guarantees that data from all earlier requests have also been
+    // written.
+    while (request_id > highest_request_id_completed_) {
+      request_cond_.Wait(scoped_lock);
+    }
+  }
+}
+
+void NodeTraceWriter::WriteToFile(std::string&& str, int highest_request_id) {
+  if (fd_ == -1) return;
+
+  uv_buf_t buf = uv_buf_init(nullptr, 0);
+  {
+    Mutex::ScopedLock lock(request_mutex_);
+    write_req_queue_.emplace(WriteRequest {
+      std::move(str), highest_request_id
+    });
+    if (write_req_queue_.size() == 1) {
+      buf = uv_buf_init(
+          const_cast<char*>(write_req_queue_.front().str.c_str()),
+          write_req_queue_.front().str.length());
+    }
+  }
+  // Only one write request for the same file descriptor should be active at
+  // a time.
+  if (buf.base != nullptr && fd_ != -1) {
+    StartWrite(buf);
+  }
+}
+
+void NodeTraceWriter::StartWrite(uv_buf_t buf) {
+  int err = uv_fs_write(
+      tracing_loop_, &write_req_, fd_, &buf, 1, -1,
+      [](uv_fs_t* req) {
+        NodeTraceWriter* writer =
+            ContainerOf(&NodeTraceWriter::write_req_, req);
+        writer->AfterWrite();
+      });
+  CHECK_EQ(err, 0);
+}
+
+void NodeTraceWriter::AfterWrite() {
+  CHECK_GE(write_req_.result, 0);
+  uv_fs_req_cleanup(&write_req_);
+
+  uv_buf_t buf = uv_buf_init(nullptr, 0);
+  {
+    Mutex::ScopedLock scoped_lock(request_mutex_);
+    int highest_request_id = write_req_queue_.front().highest_request_id;
+    write_req_queue_.pop();
+    highest_request_id_completed_ = highest_request_id;
+    request_cond_.Broadcast(scoped_lock);
+    if (!write_req_queue_.empty()) {
+      buf = uv_buf_init(
+          const_cast<char*>(write_req_queue_.front().str.c_str()),
+          write_req_queue_.front().str.length());
+    }
+  }
+  if (buf.base != nullptr && fd_ != -1) {
+    StartWrite(buf);
+  }
+}
+
+// static
+void NodeTraceWriter::ExitSignalCb(uv_async_t* signal) {
+  NodeTraceWriter* trace_writer =
+      ContainerOf(&NodeTraceWriter::exit_signal_, signal);
+  // Close both flush_signal_ and exit_signal_.
+  uv_close(reinterpret_cast<uv_handle_t*>(&trace_writer->flush_signal_),
+           [](uv_handle_t* signal) {
+             NodeTraceWriter* trace_writer =
+                 ContainerOf(&NodeTraceWriter::flush_signal_,
+                             reinterpret_cast<uv_async_t*>(signal));
+             uv_close(
+                 reinterpret_cast<uv_handle_t*>(&trace_writer->exit_signal_),
+                 [](uv_handle_t* signal) {
+                   NodeTraceWriter* trace_writer =
+                       ContainerOf(&NodeTraceWriter::exit_signal_,
+                                   reinterpret_cast<uv_async_t*>(signal));
+                   Mutex::ScopedLock scoped_lock(trace_writer->request_mutex_);
+                   trace_writer->exited_ = true;
+                   trace_writer->exit_cond_.Signal(scoped_lock);
+                 });
+           });
+}
+}  // namespace tracing
+}  // namespace node

src/tracing/node_trace_writer.h

@@ -0,0 +1,75 @@
+#ifndef SRC_TRACING_NODE_TRACE_WRITER_H_
+#define SRC_TRACING_NODE_TRACE_WRITER_H_
+
+#include <sstream>
+#include <queue>
+
+#include "libplatform/v8-tracing.h"
+#include "tracing/agent.h"
+#include "uv.h"
+
+namespace node {
+namespace tracing {
+
+using v8::platform::tracing::TraceObject;
+using v8::platform::tracing::TraceWriter;
+
+class NodeTraceWriter : public AsyncTraceWriter {
+ public:
+  explicit NodeTraceWriter(const std::string& log_file_pattern);
+  ~NodeTraceWriter() override;
+
+  void InitializeOnThread(uv_loop_t* loop) override;
+  void AppendTraceEvent(TraceObject* trace_event) override;
+  void Flush(bool blocking) override;
+
+  static const int kTracesPerFile = 1 << 19;
+
+ private:
+  struct WriteRequest {
+    std::string str;
+    int highest_request_id;
+  };
+
+  void AfterWrite();
+  void StartWrite(uv_buf_t buf);
+  void OpenNewFileForStreaming();
+  void WriteToFile(std::string&& str, int highest_request_id);
+  void WriteSuffix();
+  void FlushPrivate();
+  static void ExitSignalCb(uv_async_t* signal);
+
+  uv_loop_t* tracing_loop_ = nullptr;
+  // Triggers callback to initiate writing the contents of stream_ to disk.
+  uv_async_t flush_signal_;
+  // Triggers callback to close async objects, ending the tracing thread.
+  uv_async_t exit_signal_;
+  // Prevents concurrent R/W on state related to serialized trace data
+  // before it's written to disk, namely stream_ and total_traces_
+  // as well as json_trace_writer_.
+  Mutex stream_mutex_;
+  // Prevents concurrent R/W on state related to write requests.
+  // If both mutexes are locked, request_mutex_ has to be locked first.
+  Mutex request_mutex_;
+  // Allows blocking calls to Flush() to wait on a condition for
+  // trace events to be written to disk.
+  ConditionVariable request_cond_;
+  // Used to wait until async handles have been closed.
+  ConditionVariable exit_cond_;
+  int fd_ = -1;
+  uv_fs_t write_req_;
+  std::queue<WriteRequest> write_req_queue_;
+  int num_write_requests_ = 0;
+  int highest_request_id_completed_ = 0;
+  int total_traces_ = 0;
+  int file_num_ = 0;
+  std::string log_file_pattern_;
+  std::ostringstream stream_;
+  std::unique_ptr<TraceWriter> json_trace_writer_;
+  bool exited_ = false;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_NODE_TRACE_WRITER_H_

src/tracing/trace_event.cc

@@ -0,0 +1,42 @@
+#include "tracing/trace_event.h"
+#include "node.h"
+
+namespace node {
+namespace tracing {
+
+Agent* g_agent = nullptr;
+v8::TracingController* g_controller = nullptr;
+
+void TraceEventHelper::SetAgent(Agent* agent) {
+  if (agent) {
+    g_agent = agent;
+    g_controller = agent->GetTracingController();
+  } else {
+    g_agent = nullptr;
+    g_controller = nullptr;
+  }
+}
+
+Agent* TraceEventHelper::GetAgent() {
+  return g_agent;
+}
+
+v8::TracingController* TraceEventHelper::GetTracingController() {
+  return g_controller;
+}
+
+void TraceEventHelper::SetTracingController(v8::TracingController* controller) {
+  g_controller = controller;
+}
+
+}  // namespace tracing
+
+v8::TracingController* GetTracingController() {
+  return tracing::TraceEventHelper::GetTracingController();
+}
+
+void SetTracingController(v8::TracingController* controller) {
+  tracing::TraceEventHelper::SetTracingController(controller);
+}
+
+}  // namespace node

src/tracing/trace_event.h

@@ -0,0 +1,722 @@
+// Copyright 2015 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 SRC_TRACING_TRACE_EVENT_H_
+#define SRC_TRACING_TRACE_EVENT_H_
+
+#include "v8-platform.h"
+#include "tracing/agent.h"
+#include "trace_event_common.h"
+#include <atomic>
+
+// This header file defines implementation details of how the trace macros in
+// trace_event_common.h collect and store trace events. Anything not
+// implementation-specific should go in trace_macros_common.h instead of here.
+
+
+// The pointer returned from GetCategoryGroupEnabled() points to a
+// value with zero or more of the following bits. Used in this class only.
+// The TRACE_EVENT macros should only use the value as a bool.
+// These values must be in sync with macro values in trace_log.h in
+// chromium.
+enum CategoryGroupEnabledFlags {
+  // Category group enabled for the recording mode.
+  kEnabledForRecording_CategoryGroupEnabledFlags = 1 << 0,
+  // Category group enabled by SetEventCallbackEnabled().
+  kEnabledForEventCallback_CategoryGroupEnabledFlags = 1 << 2,
+  // Category group enabled to export events to ETW.
+  kEnabledForETWExport_CategoryGroupEnabledFlags = 1 << 3,
+};
+
+// By default, const char* argument values are assumed to have long-lived scope
+// and will not be copied. Use this macro to force a const char* to be copied.
+#define TRACE_STR_COPY(str) node::tracing::TraceStringWithCopy(str)
+
+// By default, uint64 ID argument values are not mangled with the Process ID in
+// TRACE_EVENT_ASYNC macros. Use this macro to force Process ID mangling.
+#define TRACE_ID_MANGLE(id) node::tracing::TraceID::ForceMangle(id)
+
+// By default, pointers are mangled with the Process ID in TRACE_EVENT_ASYNC
+// macros. Use this macro to prevent Process ID mangling.
+#define TRACE_ID_DONT_MANGLE(id) node::tracing::TraceID::DontMangle(id)
+
+// By default, trace IDs are eventually converted to a single 64-bit number. Use
+// this macro to add a scope string.
+#define TRACE_ID_WITH_SCOPE(scope, id) \
+  trace_event_internal::TraceID::WithScope(scope, id)
+
+#define INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE() \
+  *INTERNAL_TRACE_EVENT_UID(category_group_enabled) &                    \
+      (kEnabledForRecording_CategoryGroupEnabledFlags |                  \
+       kEnabledForEventCallback_CategoryGroupEnabledFlags)
+
+// The following macro has no implementation, but it needs to exist since
+// it gets called from scoped trace events. It cannot call UNIMPLEMENTED()
+// since an empty implementation is a valid one.
+#define INTERNAL_TRACE_MEMORY(category, name)
+
+////////////////////////////////////////////////////////////////////////////////
+// Implementation specific tracing API definitions.
+
+// Get a pointer to the enabled state of the given trace category. Only
+// long-lived literal strings should be given as the category group. The
+// returned pointer can be held permanently in a local static for example. If
+// the unsigned char is non-zero, tracing is enabled. If tracing is enabled,
+// TRACE_EVENT_API_ADD_TRACE_EVENT can be called. It's OK if tracing is disabled
+// between the load of the tracing state and the call to
+// TRACE_EVENT_API_ADD_TRACE_EVENT, because this flag only provides an early out
+// for best performance when tracing is disabled.
+// const uint8_t*
+//     TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(const char* category_group)
+#define TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED              \
+  node::tracing::TraceEventHelper::GetCategoryGroupEnabled
+
+// Get the number of times traces have been recorded. This is used to implement
+// the TRACE_EVENT_IS_NEW_TRACE facility.
+// unsigned int TRACE_EVENT_API_GET_NUM_TRACES_RECORDED()
+#define TRACE_EVENT_API_GET_NUM_TRACES_RECORDED UNIMPLEMENTED()
+
+// Add a trace event to the platform tracing system.
+// uint64_t TRACE_EVENT_API_ADD_TRACE_EVENT(
+//                    char phase,
+//                    const uint8_t* category_group_enabled,
+//                    const char* name,
+//                    const char* scope,
+//                    uint64_t id,
+//                    uint64_t bind_id,
+//                    int num_args,
+//                    const char** arg_names,
+//                    const uint8_t* arg_types,
+//                    const uint64_t* arg_values,
+//                    unsigned int flags)
+#define TRACE_EVENT_API_ADD_TRACE_EVENT node::tracing::AddTraceEventImpl
+
+// Add a trace event to the platform tracing system.
+// uint64_t TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
+//                    char phase,
+//                    const uint8_t* category_group_enabled,
+//                    const char* name,
+//                    const char* scope,
+//                    uint64_t id,
+//                    uint64_t bind_id,
+//                    int num_args,
+//                    const char** arg_names,
+//                    const uint8_t* arg_types,
+//                    const uint64_t* arg_values,
+//                    unsigned int flags,
+//                    int64_t timestamp)
+#define TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP \
+  node::tracing::AddTraceEventWithTimestampImpl
+
+// Set the duration field of a COMPLETE trace event.
+// void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
+//     const uint8_t* category_group_enabled,
+//     const char* name,
+//     uint64_t id)
+#define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION                           \
+  if (auto controller =                                                       \
+         node::tracing::TraceEventHelper::GetTracingController())             \
+      controller->UpdateTraceEventDuration
+
+// Adds a metadata event to the trace log. The |AppendValueAsTraceFormat| method
+// on the convertable value will be called at flush time.
+// TRACE_EVENT_API_ADD_METADATA_EVENT(
+//     const unsigned char* category_group_enabled,
+//     const char* event_name,
+//     const char* arg_name,
+//     std::unique_ptr<ConvertableToTraceFormat> arg_value)
+#define TRACE_EVENT_API_ADD_METADATA_EVENT node::tracing::AddMetadataEvent
+
+// Defines atomic operations used internally by the tracing system.
+#define TRACE_EVENT_API_ATOMIC_WORD std::atomic<intptr_t>
+#define TRACE_EVENT_API_ATOMIC_WORD_VALUE intptr_t
+#define TRACE_EVENT_API_ATOMIC_LOAD(var) (var).load()
+#define TRACE_EVENT_API_ATOMIC_STORE(var, value) (var).store(value)
+
+////////////////////////////////////////////////////////////////////////////////
+
+// Implementation detail: trace event macros create temporary variables
+// to keep instrumentation overhead low. These macros give each temporary
+// variable a unique name based on the line number to prevent name collisions.
+#define INTERNAL_TRACE_EVENT_UID3(a, b) trace_event_unique_##a##b
+#define INTERNAL_TRACE_EVENT_UID2(a, b) INTERNAL_TRACE_EVENT_UID3(a, b)
+#define INTERNAL_TRACE_EVENT_UID(name_prefix) \
+  INTERNAL_TRACE_EVENT_UID2(name_prefix, __LINE__)
+
+// Implementation detail: internal macro to create static category.
+// No barriers are needed, because this code is designed to operate safely
+// even when the unsigned char* points to garbage data (which may be the case
+// on processors without cache coherency).
+// TODO(fmeawad): This implementation contradicts that we can have a different
+// configuration for each isolate,
+// https://code.google.com/p/v8/issues/detail?id=4563
+#define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO_CUSTOM_VARIABLES(             \
+    category_group, atomic, category_group_enabled)                          \
+  category_group_enabled =                                                   \
+      reinterpret_cast<const uint8_t*>(TRACE_EVENT_API_ATOMIC_LOAD(atomic)); \
+  if (!category_group_enabled) {                                             \
+    category_group_enabled =                                                 \
+        TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(category_group);          \
+    TRACE_EVENT_API_ATOMIC_STORE(                                            \
+        atomic, reinterpret_cast<TRACE_EVENT_API_ATOMIC_WORD_VALUE>(         \
+                    category_group_enabled));                                \
+  }
+
+#define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group)             \
+  static TRACE_EVENT_API_ATOMIC_WORD INTERNAL_TRACE_EVENT_UID(atomic) {0}; \
+  const uint8_t* INTERNAL_TRACE_EVENT_UID(category_group_enabled);         \
+  INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO_CUSTOM_VARIABLES(                 \
+      category_group, INTERNAL_TRACE_EVENT_UID(atomic),                    \
+      INTERNAL_TRACE_EVENT_UID(category_group_enabled));
+
+// Implementation detail: internal macro to create static category and add
+// event if the category is enabled.
+#define INTERNAL_TRACE_EVENT_ADD(phase, category_group, name, flags, ...)    \
+  do {                                                                       \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                  \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {  \
+      node::tracing::AddTraceEvent(                                          \
+          phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,     \
+          node::tracing::kGlobalScope, node::tracing::kNoId,                 \
+          node::tracing::kNoId, flags, ##__VA_ARGS__);                       \
+    }                                                                        \
+  } while (0)
+
+// Implementation detail: internal macro to create static category and add begin
+// event if the category is enabled. Also adds the end event when the scope
+// ends.
+#define INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, ...)           \
+  INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                    \
+  node::tracing::ScopedTracer INTERNAL_TRACE_EVENT_UID(tracer);              \
+  if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {    \
+    uint64_t h = node::tracing::AddTraceEvent(                               \
+        TRACE_EVENT_PHASE_COMPLETE,                                          \
+        INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,              \
+        node::tracing::kGlobalScope, node::tracing::kNoId,                   \
+        node::tracing::kNoId, TRACE_EVENT_FLAG_NONE, ##__VA_ARGS__);         \
+    INTERNAL_TRACE_EVENT_UID(tracer)                                         \
+        .Initialize(INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,  \
+                    h);                                                      \
+  }
+
+#define INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_FLOW(category_group, name,     \
+                                                  bind_id, flow_flags, ...) \
+  INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                   \
+  node::tracing::ScopedTracer INTERNAL_TRACE_EVENT_UID(tracer);             \
+  if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {   \
+    unsigned int trace_event_flags = flow_flags;                            \
+    node::tracing::TraceID trace_event_bind_id(bind_id,                     \
+                                               &trace_event_flags);         \
+    uint64_t h = node::tracing::AddTraceEvent(                              \
+        TRACE_EVENT_PHASE_COMPLETE,                                         \
+        INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,             \
+        node::tracing::kGlobalScope, node::tracing::kNoId,                  \
+        trace_event_bind_id.raw_id(), trace_event_flags, ##__VA_ARGS__);    \
+    INTERNAL_TRACE_EVENT_UID(tracer)                                        \
+        .Initialize(INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, \
+                    h);                                                     \
+  }
+
+// Implementation detail: internal macro to create static category and add
+// event if the category is enabled.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_ID(phase, category_group, name, id,      \
+                                         flags, ...)                           \
+  do {                                                                         \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                    \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {    \
+      unsigned int trace_event_flags = flags | TRACE_EVENT_FLAG_HAS_ID;        \
+      node::tracing::TraceID trace_event_trace_id(id,                          \
+                                                  &trace_event_flags);         \
+      node::tracing::AddTraceEvent(                                            \
+          phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,       \
+          trace_event_trace_id.scope(), trace_event_trace_id.raw_id(),         \
+          node::tracing::kNoId, trace_event_flags, ##__VA_ARGS__);             \
+    }                                                                          \
+  } while (0)
+
+// Adds a trace event with a given timestamp.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(phase, category_group, name, \
+                                                timestamp, flags, ...)       \
+  do {                                                                       \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                  \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {  \
+      node::tracing::AddTraceEventWithTimestamp(                     \
+          phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,     \
+          node::tracing::kGlobalScope, node::tracing::kNoId, \
+          node::tracing::kNoId, flags, timestamp, ##__VA_ARGS__);    \
+    }                                                                        \
+  } while (0)
+
+// Adds a trace event with a given id and timestamp. Not Implemented.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_ID_AND_TIMESTAMP(     \
+    phase, category_group, name, id, timestamp, flags, ...) \
+  UNIMPLEMENTED()
+
+// Adds a trace event with a given id, thread_id, and timestamp. Not
+// Implemented.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                  \
+    phase, category_group, name, id, thread_id, timestamp, flags, ...)       \
+  do {                                                                       \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                  \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {  \
+      unsigned int trace_event_flags = flags | TRACE_EVENT_FLAG_HAS_ID;      \
+      node::tracing::TraceID trace_event_trace_id(id,                        \
+                                                  &trace_event_flags);       \
+      node::tracing::AddTraceEventWithTimestamp(                             \
+          phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,     \
+          trace_event_trace_id.scope(), trace_event_trace_id.raw_id(),       \
+          node::tracing::kNoId, trace_event_flags, timestamp, ##__VA_ARGS__);\
+    }                                                                        \
+  } while (0)
+
+#define INTERNAL_TRACE_EVENT_METADATA_ADD(category_group, name, ...)  \
+  do { \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group); \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
+      TRACE_EVENT_API_ADD_METADATA_EVENT( \
+          INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, \
+          ##__VA_ARGS__); \
+    } \
+  } while(0)
+
+// Enter and leave a context based on the current scope.
+#define INTERNAL_TRACE_EVENT_SCOPED_CONTEXT(category_group, name, context) \
+  struct INTERNAL_TRACE_EVENT_UID(ScopedContext) {                         \
+   public:                                                                 \
+    INTERNAL_TRACE_EVENT_UID(ScopedContext)(uint64_t cid) : cid_(cid) {    \
+      TRACE_EVENT_ENTER_CONTEXT(category_group, name, cid_);               \
+    }                                                                      \
+    ~INTERNAL_TRACE_EVENT_UID(ScopedContext)() {                           \
+      TRACE_EVENT_LEAVE_CONTEXT(category_group, name, cid_);               \
+    }                                                                      \
+                                                                           \
+   private:                                                                \
+    /* Local class friendly DISALLOW_COPY_AND_ASSIGN */                    \
+    INTERNAL_TRACE_EVENT_UID(ScopedContext)                                \
+    (const INTERNAL_TRACE_EVENT_UID(ScopedContext)&) {}                    \
+    void operator=(const INTERNAL_TRACE_EVENT_UID(ScopedContext)&) {}      \
+    uint64_t cid_;                                                         \
+  };                                                                       \
+  INTERNAL_TRACE_EVENT_UID(ScopedContext)                                  \
+  INTERNAL_TRACE_EVENT_UID(scoped_context)(context);
+
+namespace node {
+namespace tracing {
+
+// Specify these values when the corresponding argument of AddTraceEvent is not
+// used.
+const int kZeroNumArgs = 0;
+const decltype(nullptr) kGlobalScope = nullptr;
+const uint64_t kNoId = 0;
+
+class TraceEventHelper {
+ public:
+  static v8::TracingController* GetTracingController();
+  static void SetTracingController(v8::TracingController* controller);
+
+  static Agent* GetAgent();
+  static void SetAgent(Agent* agent);
+
+  static inline const uint8_t* GetCategoryGroupEnabled(const char* group) {
+    v8::TracingController* controller = GetTracingController();
+    static const uint8_t disabled = 0;
+    if (controller == nullptr) [[unlikely]] {
+      return &disabled;
+    }
+    return controller->GetCategoryGroupEnabled(group);
+  }
+};
+
+// TraceID encapsulates an ID that can either be an integer or pointer. Pointers
+// are by default mangled with the Process ID so that they are unlikely to
+// collide when the same pointer is used on different processes.
+class TraceID {
+ public:
+  class WithScope {
+   public:
+    WithScope(const char* scope, uint64_t raw_id)
+        : scope_(scope), raw_id_(raw_id) {}
+    uint64_t raw_id() const { return raw_id_; }
+    const char* scope() const { return scope_; }
+
+   private:
+    const char* scope_ = nullptr;
+    uint64_t raw_id_;
+  };
+
+  class DontMangle {
+   public:
+    explicit DontMangle(const void* raw_id)
+        : raw_id_(static_cast<uint64_t>(reinterpret_cast<uintptr_t>(raw_id))) {}
+    explicit DontMangle(uint64_t raw_id) : raw_id_(raw_id) {}
+    explicit DontMangle(unsigned int raw_id) : raw_id_(raw_id) {}
+    explicit DontMangle(uint16_t raw_id) : raw_id_(raw_id) {}
+    explicit DontMangle(unsigned char raw_id) : raw_id_(raw_id) {}
+    explicit DontMangle(int64_t raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit DontMangle(int raw_id) : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit DontMangle(int16_t raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit DontMangle(signed char raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit DontMangle(WithScope scoped_id)
+        : scope_(scoped_id.scope()), raw_id_(scoped_id.raw_id()) {}
+    const char* scope() const { return scope_; }
+    uint64_t raw_id() const { return raw_id_; }
+
+   private:
+    const char* scope_ = nullptr;
+    uint64_t raw_id_;
+  };
+
+  class ForceMangle {
+   public:
+    explicit ForceMangle(uint64_t raw_id) : raw_id_(raw_id) {}
+    explicit ForceMangle(unsigned int raw_id) : raw_id_(raw_id) {}
+    explicit ForceMangle(uint16_t raw_id) : raw_id_(raw_id) {}
+    explicit ForceMangle(unsigned char raw_id) : raw_id_(raw_id) {}
+    explicit ForceMangle(int64_t raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit ForceMangle(int raw_id) : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit ForceMangle(int16_t raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    explicit ForceMangle(signed char raw_id)
+        : raw_id_(static_cast<uint64_t>(raw_id)) {}
+    uint64_t raw_id() const { return raw_id_; }
+
+   private:
+    uint64_t raw_id_;
+  };
+
+  TraceID(const void* raw_id, unsigned int* flags)
+      : raw_id_(static_cast<uint64_t>(reinterpret_cast<uintptr_t>(raw_id))) {
+    *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
+  }
+  TraceID(ForceMangle raw_id, unsigned int* flags) : raw_id_(raw_id.raw_id()) {
+    *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
+  }
+  TraceID(DontMangle maybe_scoped_id, unsigned int* flags)
+      : scope_(maybe_scoped_id.scope()), raw_id_(maybe_scoped_id.raw_id()) {}
+  TraceID(uint64_t raw_id, unsigned int* flags) : raw_id_(raw_id) {
+    (void)flags;
+  }
+  TraceID(unsigned int raw_id, unsigned int* flags) : raw_id_(raw_id) {
+    (void)flags;
+  }
+  TraceID(uint16_t raw_id, unsigned int* flags) : raw_id_(raw_id) {
+    (void)flags;
+  }
+  TraceID(unsigned char raw_id, unsigned int* flags) : raw_id_(raw_id) {
+    (void)flags;
+  }
+  TraceID(int64_t raw_id, unsigned int* flags)
+      : raw_id_(static_cast<uint64_t>(raw_id)) {
+    (void)flags;
+  }
+  TraceID(int raw_id, unsigned int* flags)
+      : raw_id_(static_cast<uint64_t>(raw_id)) {
+    (void)flags;
+  }
+  TraceID(int16_t raw_id, unsigned int* flags)
+      : raw_id_(static_cast<uint64_t>(raw_id)) {
+    (void)flags;
+  }
+  TraceID(signed char raw_id, unsigned int* flags)
+      : raw_id_(static_cast<uint64_t>(raw_id)) {
+    (void)flags;
+  }
+  TraceID(WithScope scoped_id, unsigned int* flags)
+      : scope_(scoped_id.scope()), raw_id_(scoped_id.raw_id()) {}
+
+  uint64_t raw_id() const { return raw_id_; }
+  const char* scope() const { return scope_; }
+
+ private:
+  const char* scope_ = nullptr;
+  uint64_t raw_id_;
+};
+
+// Simple union to store various types as uint64_t.
+union TraceValueUnion {
+  bool as_bool;
+  uint64_t as_uint;
+  int64_t as_int;
+  double as_double;
+  const void* as_pointer;
+  const char* as_string;
+};
+
+// Simple container for const char* that should be copied instead of retained.
+class TraceStringWithCopy {
+ public:
+  explicit TraceStringWithCopy(const char* str) : str_(str) {}
+  operator const char*() const { return str_; }
+
+ private:
+  const char* str_;
+};
+
+static inline uint64_t AddTraceEventImpl(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
+    const char** arg_names, const uint8_t* arg_types,
+    const uint64_t* arg_values, unsigned int flags) {
+  std::unique_ptr<v8::ConvertableToTraceFormat> arg_convertibles[2];
+  if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[0].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[0])));
+  }
+  if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[1].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[1])));
+  }
+  // DCHECK(num_args, 2);
+  v8::TracingController* controller =
+      node::tracing::TraceEventHelper::GetTracingController();
+  if (controller == nullptr) return 0;
+  return controller->AddTraceEvent(phase, category_group_enabled, name, scope, id,
+                                   bind_id, num_args, arg_names, arg_types,
+                                   arg_values, arg_convertibles, flags);
+}
+
+static V8_INLINE uint64_t AddTraceEventWithTimestampImpl(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, int32_t num_args,
+    const char** arg_names, const uint8_t* arg_types,
+    const uint64_t* arg_values, unsigned int flags, int64_t timestamp) {
+  std::unique_ptr<v8::ConvertableToTraceFormat> arg_convertibles[2];
+  if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[0].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[0])));
+  }
+  if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[1].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[1])));
+  }
+  // DCHECK_LE(num_args, 2);
+  v8::TracingController* controller =
+      node::tracing::TraceEventHelper::GetTracingController();
+  if (controller == nullptr) return 0;
+  return controller->AddTraceEventWithTimestamp(
+      phase, category_group_enabled, name, scope, id, bind_id, num_args,
+      arg_names, arg_types, arg_values, arg_convertibles, flags, timestamp);
+}
+
+static V8_INLINE void AddMetadataEventImpl(
+    const uint8_t* category_group_enabled, const char* name, int32_t num_args,
+    const char** arg_names, const uint8_t* arg_types,
+    const uint64_t* arg_values, unsigned int flags) {
+  std::unique_ptr<v8::ConvertableToTraceFormat> arg_convertibles[2];
+  if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[0].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[0])));
+  }
+  if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
+    arg_convertibles[1].reset(reinterpret_cast<v8::ConvertableToTraceFormat*>(
+        static_cast<intptr_t>(arg_values[1])));
+  }
+  node::tracing::Agent* agent =
+      node::tracing::TraceEventHelper::GetAgent();
+  if (agent == nullptr) return;
+  return agent->GetTracingController()->AddMetadataEvent(
+      category_group_enabled, name, num_args, arg_names, arg_types, arg_values,
+      arg_convertibles, flags);
+}
+
+// Define SetTraceValue for each allowed type. It stores the type and
+// value in the return arguments. This allows this API to avoid declaring any
+// structures so that it is portable to third_party libraries.
+#define INTERNAL_DECLARE_SET_TRACE_VALUE(actual_type, union_member,         \
+                                         value_type_id)                     \
+  static inline void SetTraceValue(actual_type arg, unsigned char* type,    \
+                                   uint64_t* value) {                       \
+    TraceValueUnion type_value;                                             \
+    type_value.union_member = arg;                                          \
+    *type = value_type_id;                                                  \
+    *value = type_value.as_uint;                                            \
+  }
+// Simpler form for int types that can be safely casted.
+#define INTERNAL_DECLARE_SET_TRACE_VALUE_INT(actual_type, value_type_id)    \
+  static inline void SetTraceValue(actual_type arg, unsigned char* type,    \
+                                   uint64_t* value) {                       \
+    *type = value_type_id;                                                  \
+    *value = static_cast<uint64_t>(arg);                                    \
+  }
+
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(uint64_t, TRACE_VALUE_TYPE_UINT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned int, TRACE_VALUE_TYPE_UINT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(uint16_t, TRACE_VALUE_TYPE_UINT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned char, TRACE_VALUE_TYPE_UINT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int64_t, TRACE_VALUE_TYPE_INT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int, TRACE_VALUE_TYPE_INT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int16_t, TRACE_VALUE_TYPE_INT)
+INTERNAL_DECLARE_SET_TRACE_VALUE_INT(signed char, TRACE_VALUE_TYPE_INT)
+INTERNAL_DECLARE_SET_TRACE_VALUE(bool, as_bool, TRACE_VALUE_TYPE_BOOL)
+INTERNAL_DECLARE_SET_TRACE_VALUE(double, as_double, TRACE_VALUE_TYPE_DOUBLE)
+INTERNAL_DECLARE_SET_TRACE_VALUE(const void*, as_pointer,
+                                 TRACE_VALUE_TYPE_POINTER)
+INTERNAL_DECLARE_SET_TRACE_VALUE(const char*, as_string,
+                                 TRACE_VALUE_TYPE_STRING)
+INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, as_string,
+                                 TRACE_VALUE_TYPE_COPY_STRING)
+
+#undef INTERNAL_DECLARE_SET_TRACE_VALUE
+#undef INTERNAL_DECLARE_SET_TRACE_VALUE_INT
+
+static inline void SetTraceValue(v8::ConvertableToTraceFormat* convertable_value,
+                                    unsigned char* type, uint64_t* value) {
+  *type = TRACE_VALUE_TYPE_CONVERTABLE;
+  *value = static_cast<uint64_t>(reinterpret_cast<intptr_t>(convertable_value));
+}
+
+template <typename T>
+static inline typename std::enable_if<
+    std::is_convertible<T*, v8::ConvertableToTraceFormat*>::value>::type
+SetTraceValue(std::unique_ptr<T> ptr, unsigned char* type, uint64_t* value) {
+  SetTraceValue(ptr.release(), type, value);
+}
+
+// These AddTraceEvent template
+// function is defined here instead of in the macro, because the arg_values
+// could be temporary objects, such as std::string. In order to store
+// pointers to the internal c_str and pass through to the tracing API,
+// the arg_values must live throughout these procedures.
+
+static inline uint64_t AddTraceEvent(char phase,
+                                        const uint8_t* category_group_enabled,
+                                        const char* name, const char* scope,
+                                        uint64_t id, uint64_t bind_id,
+                                        unsigned int flags) {
+  return TRACE_EVENT_API_ADD_TRACE_EVENT(phase, category_group_enabled, name,
+                                         scope, id, bind_id, kZeroNumArgs,
+                                         nullptr, nullptr, nullptr, flags);
+}
+
+template <class ARG1_TYPE>
+static inline uint64_t AddTraceEvent(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
+    const char* arg1_name, ARG1_TYPE&& arg1_val) {
+  const int num_args = 1;
+  uint8_t arg_type;
+  uint64_t arg_value;
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_type, &arg_value);
+  return TRACE_EVENT_API_ADD_TRACE_EVENT(
+      phase, category_group_enabled, name, scope, id, bind_id, num_args,
+      &arg1_name, &arg_type, &arg_value, flags);
+}
+
+template <class ARG1_TYPE, class ARG2_TYPE>
+static inline uint64_t AddTraceEvent(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
+    const char* arg1_name, ARG1_TYPE&& arg1_val, const char* arg2_name,
+    ARG2_TYPE&& arg2_val) {
+  const int num_args = 2;
+  const char* arg_names[2] = {arg1_name, arg2_name};
+  unsigned char arg_types[2];
+  uint64_t arg_values[2];
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_types[0],
+                &arg_values[0]);
+  SetTraceValue(std::forward<ARG2_TYPE>(arg2_val), &arg_types[1],
+                &arg_values[1]);
+  return TRACE_EVENT_API_ADD_TRACE_EVENT(
+      phase, category_group_enabled, name, scope, id, bind_id, num_args,
+      arg_names, arg_types, arg_values, flags);
+}
+
+static V8_INLINE uint64_t AddTraceEventWithTimestamp(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
+    int64_t timestamp) {
+  return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
+      phase, category_group_enabled, name, scope, id, bind_id, kZeroNumArgs,
+      nullptr, nullptr, nullptr, flags, timestamp);
+}
+
+template <class ARG1_TYPE>
+static V8_INLINE uint64_t AddTraceEventWithTimestamp(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
+    int64_t timestamp, const char* arg1_name, ARG1_TYPE&& arg1_val) {
+  const int num_args = 1;
+  uint8_t arg_type;
+  uint64_t arg_value;
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_type, &arg_value);
+  return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
+      phase, category_group_enabled, name, scope, id, bind_id, num_args,
+      &arg1_name, &arg_type, &arg_value, flags, timestamp);
+}
+
+template <class ARG1_TYPE, class ARG2_TYPE>
+static V8_INLINE uint64_t AddTraceEventWithTimestamp(
+    char phase, const uint8_t* category_group_enabled, const char* name,
+    const char* scope, uint64_t id, uint64_t bind_id, unsigned int flags,
+    int64_t timestamp, const char* arg1_name, ARG1_TYPE&& arg1_val,
+    const char* arg2_name, ARG2_TYPE&& arg2_val) {
+  const int num_args = 2;
+  const char* arg_names[2] = {arg1_name, arg2_name};
+  unsigned char arg_types[2];
+  uint64_t arg_values[2];
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_types[0],
+                &arg_values[0]);
+  SetTraceValue(std::forward<ARG2_TYPE>(arg2_val), &arg_types[1],
+                &arg_values[1]);
+  return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
+      phase, category_group_enabled, name, scope, id, bind_id, num_args,
+      arg_names, arg_types, arg_values, flags, timestamp);
+}
+
+template <class ARG1_TYPE>
+static V8_INLINE void AddMetadataEvent(
+    const uint8_t* category_group_enabled, const char* name,
+    const char* arg1_name, ARG1_TYPE&& arg1_val) {
+  const int num_args = 1;
+  uint8_t arg_type;
+  uint64_t arg_value;
+  SetTraceValue(std::forward<ARG1_TYPE>(arg1_val), &arg_type, &arg_value);
+  AddMetadataEventImpl(
+      category_group_enabled, name, num_args, &arg1_name, &arg_type, &arg_value,
+      TRACE_EVENT_FLAG_NONE);
+}
+
+// Used by TRACE_EVENTx macros. Do not use directly.
+class ScopedTracer {
+ public:
+  // Note: members of data_ intentionally left uninitialized. See Initialize.
+  ScopedTracer() : p_data_(nullptr) {}
+
+  ~ScopedTracer() {
+    if (p_data_ && *data_.category_group_enabled)
+      TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
+          data_.category_group_enabled, data_.name, data_.event_handle);
+  }
+
+  void Initialize(const uint8_t* category_group_enabled, const char* name,
+                  uint64_t event_handle) {
+    data_.category_group_enabled = category_group_enabled;
+    data_.name = name;
+    data_.event_handle = event_handle;
+    p_data_ = &data_;
+  }
+
+ private:
+  // This Data struct workaround is to avoid initializing all the members
+  // in Data during construction of this object, since this object is always
+  // constructed, even when tracing is disabled. If the members of Data were
+  // members of this class instead, compiler warnings occur about potential
+  // uninitialized accesses.
+  struct Data {
+    const uint8_t* category_group_enabled;
+    const char* name;
+    uint64_t event_handle;
+  };
+  Data* p_data_;
+  Data data_;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_TRACE_EVENT_H_

src/tracing/traced_value.cc

@@ -0,0 +1,222 @@
+// Copyright 2016 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 "tracing/traced_value.h"
+
+#if defined(NODE_HAVE_I18N_SUPPORT)
+#include <unicode/utf8.h>
+#include <unicode/utypes.h>
+#endif
+
+#include <cmath>
+#include <cstdio>
+#include <sstream>
+#include <string>
+
+#if defined(_STLP_VENDOR_CSTD)
+// STLPort doesn't import fpclassify into the std namespace.
+#define FPCLASSIFY_NAMESPACE
+#else
+#define FPCLASSIFY_NAMESPACE std
+#endif
+
+namespace node {
+namespace tracing {
+
+namespace {
+
+std::string EscapeString(const char* value) {
+  std::string result;
+  result += '"';
+  char number_buffer[10];
+#if defined(NODE_HAVE_I18N_SUPPORT)
+  int32_t len = strlen(value);
+  int32_t p = 0;
+  int32_t i = 0;
+  for (; i < len; p = i) {
+    UChar32 c;
+    U8_NEXT_OR_FFFD(value, i, len, c);
+    switch (c) {
+      case '\b': result += "\\b"; break;
+      case '\f': result += "\\f"; break;
+      case '\n': result += "\\n"; break;
+      case '\r': result += "\\r"; break;
+      case '\t': result += "\\t"; break;
+      case '\\': result += "\\\\"; break;
+      case '"': result += "\\\""; break;
+      default:
+        if (c < 32 || c > 126) {
+          snprintf(
+              number_buffer, arraysize(number_buffer), "\\u%04X",
+              static_cast<uint16_t>(static_cast<uint16_t>(c)));
+          result += number_buffer;
+        } else {
+          result.append(value + p, i - p);
+        }
+    }
+  }
+#else
+  // If we do not have ICU, use a modified version of the non-UTF8 aware
+  // code from V8's own TracedValue implementation. Note, however, This
+  // will not produce correctly serialized results for UTF8 values.
+  while (*value) {
+    char c = *value++;
+    switch (c) {
+      case '\b': result += "\\b"; break;
+      case '\f': result += "\\f"; break;
+      case '\n': result += "\\n"; break;
+      case '\r': result += "\\r"; break;
+      case '\t': result += "\\t"; break;
+      case '\\': result += "\\\\"; break;
+      case '"': result += "\\\""; break;
+      default:
+        if (c < '\x20') {
+          snprintf(
+              number_buffer, arraysize(number_buffer), "\\u%04X",
+              static_cast<unsigned>(static_cast<unsigned char>(c)));
+          result += number_buffer;
+        } else {
+          result += c;
+        }
+    }
+  }
+#endif  // defined(NODE_HAVE_I18N_SUPPORT)
+  result += '"';
+  return result;
+}
+
+std::string DoubleToCString(double v) {
+  switch (FPCLASSIFY_NAMESPACE::fpclassify(v)) {
+    case FP_NAN: return "\"NaN\"";
+    case FP_INFINITE: return (v < 0.0 ? "\"-Infinity\"" : "\"Infinity\"");
+    case FP_ZERO: return "0";
+    default:
+      // This is a far less sophisticated version than the one used inside v8.
+      std::ostringstream stream;
+      stream.imbue(std::locale::classic());  // Ignore current locale
+      stream << v;
+      return stream.str();
+  }
+}
+
+}  // namespace
+
+std::unique_ptr<TracedValue> TracedValue::Create() {
+  return std::unique_ptr<TracedValue>(new TracedValue(false));
+}
+
+std::unique_ptr<TracedValue> TracedValue::CreateArray() {
+  return std::unique_ptr<TracedValue>(new TracedValue(true));
+}
+
+TracedValue::TracedValue(bool root_is_array) :
+    first_item_(true), root_is_array_(root_is_array) {}
+
+void TracedValue::SetInteger(const char* name, int value) {
+  WriteName(name);
+  data_ += std::to_string(value);
+}
+
+void TracedValue::SetDouble(const char* name, double value) {
+  WriteName(name);
+  data_ += DoubleToCString(value);
+}
+
+void TracedValue::SetBoolean(const char* name, bool value) {
+  WriteName(name);
+  data_ += value ? "true" : "false";
+}
+
+void TracedValue::SetNull(const char* name) {
+  WriteName(name);
+  data_ += "null";
+}
+
+void TracedValue::SetString(const char* name, const char* value) {
+  WriteName(name);
+  data_ += EscapeString(value);
+}
+
+void TracedValue::BeginDictionary(const char* name) {
+  WriteName(name);
+  data_ += '{';
+  first_item_ = true;
+}
+
+void TracedValue::BeginArray(const char* name) {
+  WriteName(name);
+  data_ += '[';
+  first_item_ = true;
+}
+
+void TracedValue::AppendInteger(int value) {
+  WriteComma();
+  data_ += std::to_string(value);
+}
+
+void TracedValue::AppendDouble(double value) {
+  WriteComma();
+  data_ += DoubleToCString(value);
+}
+
+void TracedValue::AppendBoolean(bool value) {
+  WriteComma();
+  data_ += value ? "true" : "false";
+}
+
+void TracedValue::AppendNull() {
+  WriteComma();
+  data_ += "null";
+}
+
+void TracedValue::AppendString(const char* value) {
+  WriteComma();
+  data_ += EscapeString(value);
+}
+
+void TracedValue::BeginDictionary() {
+  WriteComma();
+  data_ += '{';
+  first_item_ = true;
+}
+
+void TracedValue::BeginArray() {
+  WriteComma();
+  data_ += '[';
+  first_item_ = true;
+}
+
+void TracedValue::EndDictionary() {
+  data_ += '}';
+  first_item_ = false;
+}
+
+void TracedValue::EndArray() {
+  data_ += ']';
+  first_item_ = false;
+}
+
+void TracedValue::WriteComma() {
+  if (first_item_) {
+    first_item_ = false;
+  } else {
+    data_ += ',';
+  }
+}
+
+void TracedValue::WriteName(const char* name) {
+  WriteComma();
+  data_ += '"';
+  data_ += name;
+  data_ += "\":";
+}
+
+void TracedValue::AppendAsTraceFormat(std::string* out) const {
+  *out += root_is_array_ ? '[' : '{';
+  *out += data_;
+  *out += root_is_array_ ? ']' : '}';
+}
+
+}  // namespace tracing
+}  // namespace node

src/tracing/traced_value.h

@@ -0,0 +1,70 @@
+// Copyright 2016 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 SRC_TRACING_TRACED_VALUE_H_
+#define SRC_TRACING_TRACED_VALUE_H_
+
+#include "node.h"
+#include "util.h"
+#include "v8.h"
+
+#include <cstddef>
+#include <memory>
+#include <string>
+
+namespace node {
+namespace tracing {
+
+class TracedValue : public v8::ConvertableToTraceFormat {
+ public:
+  ~TracedValue() override = default;
+
+  static std::unique_ptr<TracedValue> Create();
+  static std::unique_ptr<TracedValue> CreateArray();
+
+  void EndDictionary();
+  void EndArray();
+
+  // These methods assume that |name| is a long lived "quoted" string.
+  void SetInteger(const char* name, int value);
+  void SetDouble(const char* name, double value);
+  void SetBoolean(const char* name, bool value);
+  void SetNull(const char* name);
+  void SetString(const char* name, const char* value);
+  void SetString(const char* name, const std::string& value) {
+    SetString(name, value.c_str());
+  }
+  void BeginDictionary(const char* name);
+  void BeginArray(const char* name);
+
+  void AppendInteger(int);
+  void AppendDouble(double);
+  void AppendBoolean(bool);
+  void AppendNull();
+  void AppendString(const char*);
+  void AppendString(const std::string& value) { AppendString(value.c_str()); }
+  void BeginArray();
+  void BeginDictionary();
+
+  // ConvertableToTraceFormat implementation.
+  void AppendAsTraceFormat(std::string* out) const override;
+
+  TracedValue(const TracedValue&) = delete;
+  TracedValue& operator=(const TracedValue&) = delete;
+
+ private:
+  explicit TracedValue(bool root_is_array = false);
+
+  void WriteComma();
+  void WriteName(const char* name);
+
+  std::string data_;
+  bool first_item_;
+  bool root_is_array_;
+};
+
+}  // namespace tracing
+}  // namespace node
+
+#endif  // SRC_TRACING_TRACED_VALUE_H_