nghttpx: Update log time stamp in millisecond interval

src/shrpx_log.cc

@@ -141,7 +141,7 @@ Log::~Log() {
   char buf[4_k];
   auto tty = lgconf->errorlog_tty;
 
-  lgconf->update_tstamp(std::chrono::system_clock::now());
+  lgconf->update_tstamp_millis(std::chrono::system_clock::now());
 
   // Error log format: <datetime> <master-pid> <current-pid>
   // <thread-id> <level> (<filename>:<line>) <msg>

src/shrpx_log_config.cc

@@ -96,6 +96,20 @@ LogConfig *log_config() { return config.get(); }
 void delete_log_config() {}
 #endif // NOTHREADS
 
+void LogConfig::update_tstamp_millis(
+    const std::chrono::system_clock::time_point &now) {
+  if (std::chrono::duration_cast<std::chrono::milliseconds>(
+          now.time_since_epoch()) ==
+      std::chrono::duration_cast<std::chrono::milliseconds>(
+          time_str_updated.time_since_epoch())) {
+    return;
+  }
+
+  time_str_updated = now;
+
+  tstamp = std::make_shared<Timestamp>(now);
+}
+
 void LogConfig::update_tstamp(
     const std::chrono::system_clock::time_point &now) {
   auto t0 = std::chrono::system_clock::to_time_t(time_str_updated);

src/shrpx_log_config.h

@@ -59,6 +59,11 @@ struct LogConfig {
   bool errorlog_tty;
 
   LogConfig();
+  // Updates time stamp if difference between time_str_updated and now
+  // is 1 or more milliseconds.
+  void update_tstamp_millis(const std::chrono::system_clock::time_point &now);
+  // Updates time stamp if difference between time_str_updated and
+  // now, converted to time_t, is 1 or more seconds.
   void update_tstamp(const std::chrono::system_clock::time_point &now);
 };