add profiling code

include/Profiling.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <boost/circular_buffer.hpp>
+#include <boost/thread/synchronized_value.hpp>
+#include <chrono>
+#include <cstddef>
+
+namespace prof {
+
+using Duration = std::chrono::duration<double, std::milli>;
+using TimePoint = std::chrono::high_resolution_clock::time_point;
+
+/// Returns the current time.
+TimePoint now();
+
+/// Returns a sub-millisecond resolution duration between start and end.
+Duration duration(const TimePoint& start, const TimePoint& end);
+
+/// Calculates and stores the moving average over K samples of execution time data
+/// for some single unit of code. Threadsafe.
+struct UnitExecutionTime {
+    UnitExecutionTime();
+
+    /// Adds a sample to the collection, overriding the oldest sample if needed.
+    void add_sample(const Duration& dur);
+
+    /// Calculates the average duration over the `measurement_count()` measurements.
+    Duration average_duration() const;
+
+    /// Returns the number of elements the moving average is calculated over.
+    size_t measurement_count();
+
+private:
+    boost::synchronized_value<boost::circular_buffer<Duration>> m_measurements;
+};
+
+/// Holds profiles for multiple units by name. Threadsafe.
+struct UnitProfileCollection {
+    /// Adds a sample to the collection, overriding the oldest sample if needed.
+    void add_sample(const std::string& unit, const Duration& duration);
+
+    /// Calculates the average duration over the `measurement_count()` measurements.
+    Duration average_duration(const std::string& unit);
+
+    /// Returns the number of elements the moving average is calculated over.
+    size_t measurement_count(const std::string& unit);
+
+private:
+    boost::synchronized_value<std::unordered_map<std::string, UnitExecutionTime>> m_map;
+};
+
+}