h2load: Refactor statistics hanlding to scale more upcoming new metrics

src/h2load.h

@@ -94,21 +94,21 @@ struct RequestStat {
   bool completed;
 };
 
+template<typename Duration>
+struct TimeStat {
+  // min, max, mean and sd (standard deviation)
+  Duration min, max, mean, sd;
+  // percentage of samples inside mean -/+ sd
+  double within_sd;
+};
+
 struct TimeStats {
-  // time for request: max, min, mean and sd (standard deviation)
-  std::chrono::microseconds request_time_max, request_time_min,
-      request_time_mean, request_time_sd;
-  // percentage of number of requests inside mean -/+ sd
-  double request_within_sd;
-  // time for connect: max, min, mean and sd (standard deviation)
-  std::chrono::microseconds connect_time_max, connect_time_min,
-      connect_time_mean, connect_time_sd;
-  // percentage of number of connects inside mean -/+ sd
-  double connect_within_sd;
-  // time to first byte: max, min, mean and sd (standard deviation)
-  std::chrono::microseconds ttfb_max, ttfb_min, ttfb_mean, ttfb_sd;
-  // percentage of number of connects inside mean -/+ sd
-  double ttfb_within_sd;
+  // time for request
+  TimeStat<std::chrono::microseconds> request;
+  // time for connect
+  TimeStat<std::chrono::microseconds> connect;
+  // time to first byte (TTFB)
+  TimeStat<std::chrono::microseconds> ttfb;
 };
 
 enum TimeStatType { STAT_REQUEST, STAT_CONNECT, STAT_FIRST_BYTE };
@@ -148,8 +148,8 @@ struct Stats {
   std::vector<std::chrono::steady_clock::time_point> start_times;
   // time to connect
   std::vector<std::chrono::steady_clock::time_point> connect_times;
-  // time to first byte
-  std::vector<std::chrono::steady_clock::time_point> time_to_first_bytes;
+  // time to first byte (TTFB)
+  std::vector<std::chrono::steady_clock::time_point> ttfbs;
 };
 
 enum ClientState { CLIENT_IDLE, CLIENT_CONNECTED };
@@ -236,7 +236,7 @@ struct Client {
   void record_request_time(RequestStat *req_stat);
   void record_start_time(Stats *stat);
   void record_connect_time(Stats *stat);
-  void record_time_to_first_byte(Stats *stat);
+  void record_ttfb(Stats *stat);
 
   void signal_write();
 };