A minimalist C++11 performance measurement helper

perf.hpp

#include <chrono>
#include <iostream>

/// @brief Scoped performance measurement class.
///
/// To use this class, instantiate a @c perf_t object inside a scope. Once the
/// object goes out of scope, the elapsed time (in nanoseconds) will be printed
/// to stdout.
///
/// @code{.cpp}
/// void my_function() {
///   perf_t perf("my_function");
///   ...
///   // The elapsed time will be printed here.
/// }
/// @endcode
class perf_t {
public:
  /// @brief Constructor (start time measurement).
  /// @param name The name of the perf point.
  explicit perf_t(const std::string& name)
      : m_name(name), m_start(std::chrono::high_resolution_clock::now()) {}

  /// @brief Destructor (print elapsed time).
  ~perf_t() {
    const auto end = std::chrono::high_resolution_clock::now();
    const auto dt_ns =
        std::chrono::duration_cast<std::chrono::nanoseconds>(end - m_start)
            .count();
    std::cout << m_name << ": " << dt_ns << " ns\n";
  }

private:
  const std::string m_name;
  const std::chrono::high_resolution_clock::time_point m_start;
};