report: add average CPU consumption

node-report currently produces absolute CPU consumption
from the time since the process started. By making use of
the load time and the current time, convert this into an
average consumption rate which is easily consumable.

src/node_report.cc

@@ -106,6 +106,8 @@ static char report_directory[NR_MAXPATH + 1] = ""; // defaults to current workin
 std::string version_string = UNKNOWN_NODEVERSION_STRING;
 std::string commandline_string = "";
 static TIME_TYPE loadtime_tm_struct; // module load time
+static time_t load_time; // module load time absolute
+static time_t current_time; // current time absolute
 
 /*******************************************************************************
  * Functions to process node-report configuration options:
@@ -294,6 +296,7 @@ void SetVersionString(Isolate* isolate) {
  * Function to save the node-report module load time value
  *******************************************************************************/
 void SetLoadTime() {
+  time(&load_time);
 #ifdef _WIN32
   GetLocalTime(&loadtime_tm_struct);
 #else  // UNIX, OSX
@@ -383,6 +386,7 @@ void TriggerNodeReport(Isolate* isolate, DumpEvent event, const char* message, c
   report_active = true;
 
   // Obtain the current time and the pid (platform dependent)
+  time(&current_time);
   TIME_TYPE tm_struct;
 #ifdef _WIN32
   GetLocalTime(&tm_struct);
@@ -1020,6 +1024,11 @@ static void PrintGCStatistics(std::ostream& out, Isolate* isolate) {
  ******************************************************************************/
 static void PrintResourceUsage(std::ostream& out) {
   char buf[64];
+  double cpu_abs;
+  double cpu_percentage;
+  long int diff_time = current_time - load_time;
+  if(diff_time == 0)
+    diff_time = 1; // avoid devision by zero.
   out << "\n================================================================================";
   out << "\n==== Resource Usage ============================================================\n";
 
@@ -1030,14 +1039,20 @@ static void PrintResourceUsage(std::ostream& out) {
 #if defined(__APPLE__) || defined(_AIX)
     snprintf( buf, sizeof(buf), "%ld.%06d", stats.ru_utime.tv_sec, stats.ru_utime.tv_usec);
     out << "\n  User mode CPU: " << buf << " secs";
+    cpu_abs = std::stod(buf);
     snprintf( buf, sizeof(buf), "%ld.%06d", stats.ru_stime.tv_sec, stats.ru_stime.tv_usec);
     out << "\n  Kernel mode CPU: " << buf << " secs";
+    cpu_abs += std::stod(buf);
 #else
     snprintf( buf, sizeof(buf), "%ld.%06ld", stats.ru_utime.tv_sec, stats.ru_utime.tv_usec);
     out << "\n  User mode CPU: " << buf << " secs";
+    cpu_abs = std::stod(buf);
     snprintf( buf, sizeof(buf), "%ld.%06ld", stats.ru_stime.tv_sec, stats.ru_stime.tv_usec);
     out << "\n  Kernel mode CPU: " << buf << " secs";
+    cpu_abs += std::stod(buf);
 #endif
+    cpu_percentage = (cpu_abs / diff_time) * 100;
+    out << "\n  Average Consumption : "<< cpu_percentage << "%";
     out << "\n  Maximum resident set size: ";
     WriteInteger(out, stats.ru_maxrss * 1024);
     out << " bytes\n  Page faults: " << stats.ru_majflt << " (I/O required) "
@@ -1051,14 +1066,20 @@ static void PrintResourceUsage(std::ostream& out) {
 #if defined(__APPLE__) || defined(_AIX)
     snprintf( buf, sizeof(buf), "%ld.%06d", stats.ru_utime.tv_sec, stats.ru_utime.tv_usec);
     out << "\n  User mode CPU: " << buf << " secs";
+    cpu_abs = std::stod(buf);
     snprintf( buf, sizeof(buf), "%ld.%06d", stats.ru_stime.tv_sec, stats.ru_stime.tv_usec);
     out << "\n  Kernel mode CPU: " << buf << " secs";
+    cpu_abs += std::stod(buf);
 #else
     snprintf( buf, sizeof(buf), "%ld.%06ld", stats.ru_utime.tv_sec, stats.ru_utime.tv_usec);
     out << "\n  User mode CPU: " << buf << " secs";
+    cpu_abs = std::stod(buf);
     snprintf( buf, sizeof(buf), "%ld.%06ld", stats.ru_stime.tv_sec, stats.ru_stime.tv_usec);
     out << "\n  Kernel mode CPU: " << buf << " secs";
+    cpu_abs += std::stod(buf);
 #endif
+    cpu_percentage = (cpu_abs / diff_time) * 100;
+    out << "\n  Average Consumption : " << cpu_percentage << "%";
     out << "\n  Filesystem activity: " << stats.ru_inblock << " reads "
         << stats.ru_oublock << " writes";
   }