return absl::OkStatus();
}

// Tracks monotonic sequence numbers for graphs.
class ClusterSequenceNumberGenerator {
 public:
  void Reset() {
    mutex_lock lock(mu_);
    sequence_numbers_.clear();
  }

  int64 GetNext(uint64 key) {
    mutex_lock lock(mu_);
    return sequence_numbers_[key]++;
  }

  static ClusterSequenceNumberGenerator& Global() {
    static ClusterSequenceNumberGenerator* gen =

  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadWithParam);
};

// MutexBase and Mutex implement mutex on pthreads-based platforms. They
// are used in conjunction with class MutexLock:
//
//   Mutex mutex;
//   ...
//   MutexLock lock(&mutex);  // Acquires the mutex and releases it at the end
//                            // of the current scope.
//
// MutexBase implements behavior for both statically and dynamically