}

  ~VariableInfo();

 private:
  int index_;
  std::string name_;
  Var* var_;
  std::optional<ManagedStackTrace> definition_stack_trace_;

  // We can't use a optional<mutex_lock> here because it confuses the compiler's
  // thread safety analysis. Instead we use a boolean flag and release the lock
  // in the VariableInfo destructor.
  bool lock_held_ = false;
  bool shared_lock_held_ = false;

                          std::vector<Tensor>* outputs) const {
  return Run(RunOptions(), inputs, fetch_outputs, run_outputs, outputs,
             nullptr);
}

Status ClientSession::Impl::MaybeExtendGraph() const {
  mutex_lock l(mu_);
  int num_nodes = graph_->num_node_ids();
  if (num_nodes > last_num_graph_nodes_) {
    GraphDef graph_def;
    graph_->ToGraphDefSubRange(&graph_def, last_num_graph_nodes_);
    last_num_graph_nodes_ = num_nodes;

// 20 bits - total number of references (read+write+misc).
// 20 bits - number of outstanding read waiters.
// 20 bits - number of outstanding write waiters.
const (
	mutexClosed  = 1 << 0
	mutexRLock   = 1 << 1
	mutexWLock   = 1 << 2
	mutexRef     = 1 << 3
	mutexRefMask = (1<<20 - 1) << 3
	mutexRWait   = 1 << 23
	mutexRMask   = (1<<20 - 1) << 23
	mutexWWait   = 1 << 43
	mutexWMask   = (1<<20 - 1) << 43
)

    if (max_age_ == 0) {
      return;
    }
    absl::MutexLock lock(&mu_);
    InsertLocked(key, value);
  }

  // Delete the entry with key `key`. Return true if the entry was found for
  // `key`, false if the entry was not found. In both cases, there is no entry
  // with key `key` existed after the call.
  bool Delete(const std::string& key) {
    absl::MutexLock lock(&mu_);
    return DeleteLocked(key);
  }

// while allowing other goroutines to run.

const (
	mutex_unlocked = 0
	mutex_locked   = 1

	active_spin     = 4
	active_spin_cnt = 30
)

func mutexContended(l *mutex) bool {
	return false
}

func lock(l *mutex) {
	lockWithRank(l, getLockRank(l))
}

func lock2(l *mutex) {
	if l.key == mutex_locked {
		// wasm is single-threaded so we should never
		// observe this.
		throw("self deadlock")

//	futexwakeup(addr *uint32, cnt uint32)
//		If any procs are sleeping on addr, wake up at most cnt.

const (
	mutex_unlocked = 0
	mutex_locked   = 1
	mutex_sleeping = 2

	active_spin     = 4
	active_spin_cnt = 30
	passive_spin    = 1
)

// Possible lock states are mutex_unlocked, mutex_locked and mutex_sleeping.
// mutex_sleeping means that there is presumably at least one sleeping thread.

const (
	mutex_unlocked = 0
	mutex_locked   = 1

	note_cleared = 0
	note_woken   = 1
	note_timeout = 2

	active_spin     = 4
	active_spin_cnt = 30
	passive_spin    = 1
)

func mutexContended(l *mutex) bool {
	return false
}

func lock(l *mutex) {
	lockWithRank(l, getLockRank(l))
}

func lock2(l *mutex) {
	if l.key == mutex_locked {
		// js/wasm is single-threaded so we should never

  // contention in production code, but is acceptable in a testing
  // framework.

  // Join an existing circle.
  void join(linked_ptr_internal const* ptr)
      GTEST_LOCK_EXCLUDED_(g_linked_ptr_mutex) {
    MutexLock lock(&g_linked_ptr_mutex);

    linked_ptr_internal const* p = ptr;
    while (p->next_ != ptr) p = p->next_;
    p->next_ = this;
    next_ = ptr;
  }

  // contention in production code, but is acceptable in a testing
  // framework.

  // Join an existing circle.
  void join(linked_ptr_internal const* ptr)
      GTEST_LOCK_EXCLUDED_(g_linked_ptr_mutex) {
    MutexLock lock(&g_linked_ptr_mutex);

    linked_ptr_internal const* p = ptr;
    while (p->next_ != ptr) p = p->next_;
    p->next_ = this;
    next_ = ptr;
  }