nano::elapse () helper

nano/lib/stats.cpp

@@ -281,29 +281,25 @@ void nano::stats::run_one (std::unique_lock<std::shared_mutex> & lock)
 	debug_assert (!mutex.try_lock ());
 	debug_assert (lock.owns_lock ());
 
-	auto now = std::chrono::steady_clock::now (); // Only sample clock if necessary as this impacts node performance due to frequent usage
-
 	// TODO: Replace with a proper std::chrono time
 	std::time_t time = std::chrono::system_clock::to_time_t (std::chrono::system_clock::now ());
 	tm local_tm = *localtime (&time);
 
 	// Counters
 	if (config.log_counters_interval.count () > 0)
 	{
-		if (nano::elapsed (log_last_count_writeout, config.log_counters_interval))
+		if (nano::elapse (log_last_count_writeout, config.log_counters_interval))
 		{
 			log_counters_impl (log_count, local_tm);
-			log_last_count_writeout = now;
 		}
 	}
 
 	// Samples
 	if (config.log_samples_interval.count () > 0)
 	{
-		if (nano::elapsed (log_last_sample_writeout, config.log_samples_interval))
+		if (nano::elapse (log_last_sample_writeout, config.log_samples_interval))
 		{
 			log_samples_impl (log_sample, local_tm);
-			log_last_sample_writeout = now;
 		}
 	}
 }

nano/lib/utility.hpp

@@ -192,7 +192,16 @@ constexpr TARGET_TYPE narrow_cast (SOURCE_TYPE const & val)
 
 // Issue #3748
 void sort_options_description (const boost::program_options::options_description & source, boost::program_options::options_description & target);
+}
 
+/*
+ * Clock utilities
+ */
+namespace nano
+{
+/**
+ * Steady clock should always be used for measuring time intervals
+ */
 using clock = std::chrono::steady_clock;
 
 /**
@@ -214,6 +223,22 @@ bool elapsed (nano::clock::time_point const & last, Duration const & duration)
 {
 	return elapsed (last, duration, nano::clock::now ());
 }
+
+/**
+ * Check whether time elapsed since `last` is greater than `duration` and update `last` if true
+ * Force usage of steady clock
+ */
+template <typename Duration>
+bool elapse (nano::clock::time_point & last, Duration const & duration)
+{
+	auto now = nano::clock::now ();
+	if (last + duration < now)
+	{
+		last = now;
+		return true;
+	}
+	return false;
+}
 }
 
 namespace nano::util