Working getrusage and wall clock metrics

usage.h

@@ -1,15 +1,29 @@
 #pragma once
 
+#include <chrono>
 #include <string>
+#include <sys/resource.h>
 
 namespace fireusage {
 
 class UsageTracker {
   public:
-	UsageTracker(const std::string_view& plural_resource_name);
+	void AddEvents(uint64_t num);
+	void AddEvent();
+
+	void Start();
+	void Stop();
+	void Log();
 
   private:
-	const std::string plural_resource_name_;
+	bool running_ = false;
+	uint64_t events_ = 0;
+	std::chrono::nanoseconds wall_time_;
+	std::chrono::nanoseconds user_time_;
+	std::chrono::nanoseconds sys_time_;
+
+	std::chrono::steady_clock::time_point start_time_;
+	rusage start_usage_;
 };
 
 } // namespace fireusage