[traff_assessment_tool] Show decoding time

Signed-off-by: mvglasow <michael -at- vonglasow.com>

tools/traff_assessment_tool/resumable_timer.hpp

@@ -0,0 +1,81 @@
+#pragma once
+
+#include <chrono>
+
+namespace base
+{
+/**
+ * @brief A timer which can be paused and resumed.
+ *
+ * On creation, the timer is in paused state.
+ *
+ * Elapsed time can be queried in any state (running or paused). In running state, it will return
+ * the currently elapsed time, and the result will increase with each subsequent call. In paused
+ * state, it will return the time elapsed when the timer was last paused, and the result is stable
+ * between calls as long as the timer remains paused.
+ */
+class ResumableTimer
+{
+public:
+  std::chrono::steady_clock::duration TimeElapsed() const;
+
+  template <typename Duration>
+  Duration TimeElapsedAs() const
+  {
+    return std::chrono::duration_cast<Duration>(TimeElapsed());
+  }
+
+  double ElapsedSeconds() const { return TimeElapsedAs<std::chrono::duration<double>>().count(); }
+  uint64_t ElapsedMilliseconds() const { return TimeElapsedAs<std::chrono::milliseconds>().count(); }
+  uint64_t ElapsedNanoseconds() const { return TimeElapsedAs<std::chrono::nanoseconds>().count(); }
+
+  /**
+   * @brief Pauses the timer, i.e. freezes its current value and stops it from advancing further.
+   *
+   * Pausing an already paused timer is a no-op.
+   */
+  void Pause();
+
+  /**
+   * @brief Resumes the timer, i.e. causes it to advance further from its previous value.
+   *
+   * Resuming a running timer is a no-op.
+   */
+  void Resume();
+
+  /**
+   * @brief Resets the timer to zero.
+   *
+   * Resetting the timer will not change its paused/running state. That is, resetting a running
+   * timer will cause it to count upward from zero immediately, whereas resetting a paused timer
+   * will set its value to zero and keep it there until resumed.
+   */
+  void Reset();
+private:
+  /**
+   * @brief The time at which the timer was last started.
+   *
+   * Valid only if the timer is running.
+   *
+   * When first starting a timer after it has been created or reset, this value is set to current
+   * time. When resuming a timer, this value us set to current time minus `m_prevTimeElapsed`, so
+   * that the timer value for a currently running timer is always the difference between this value
+   * and current time.
+   */
+  std::chrono::steady_clock::time_point m_startTime;
+
+  /**
+   * @brief Whether the timer is currently running.
+   */
+  bool m_isRunning = false;
+
+  /**
+   * @brief The time elapsed when the timer was last paused.
+   *
+   * Valid only if the timer is paused.
+   *
+   * Initially zero, reset to zero when the timer is reset or resumed.
+   */
+  std::chrono::steady_clock::duration m_prevTimeElapsed = std::chrono::steady_clock::duration::zero();
+};
+}  // namespace base