Track CPU usage during compression operations

Summary: In order to compare compression performance, wall time for processing aren't enough, we also need to know how much CPU time was spent.

Reviewed By: kiminoue7

Differential Revision: D52235516

fbshipit-source-id: 42d80dbce28915b3578ec3bfc6ef7529574fda37

vrs/os/Time.cpp

@@ -20,6 +20,12 @@
 
 #include <vrs/os/Platform.h>
 
+#if IS_MAC_PLATFORM() || IS_LINUX_PLATFORM()
+#include <sys/resource.h>
+#elif IS_WINDOWS_PLATFORM()
+#include <Windows.h>
+#endif
+
 namespace vrs {
 namespace os {
 
@@ -40,5 +46,52 @@ int64_t getTimestampMs() {
   return duration_cast<std::chrono::milliseconds>(steady_clock::now().time_since_epoch()).count();
 }
 
+bool getProcessCpuTimes(double& outUserCpuTime, double& outSystemCpuTime) {
+#if IS_MAC_PLATFORM() || IS_LINUX_PLATFORM()
+  struct rusage r_usage;
+  getrusage(RUSAGE_SELF, &r_usage);
+  const double cMicroseconds = 1e-6;
+  outUserCpuTime = r_usage.ru_utime.tv_sec + r_usage.ru_utime.tv_usec * cMicroseconds;
+  outSystemCpuTime = r_usage.ru_stime.tv_sec + r_usage.ru_stime.tv_usec * cMicroseconds;
+  return true;
+
+#elif IS_WINDOWS_PLATFORM()
+  FILETIME start;
+  FILETIME exit;
+  ULARGE_INTEGER kernelTime;
+  ULARGE_INTEGER userTime;
+
+  if (GetProcessTimes(
+          GetCurrentProcess(),
+          &start,
+          &exit,
+          reinterpret_cast<PFILETIME>(&kernelTime),
+          reinterpret_cast<PFILETIME>(&userTime)) == 0) {
+    outUserCpuTime = 0;
+    outSystemCpuTime = 0;
+    return false;
+  }
+
+  const double cSecFactor = 1e-7; // source is a count of 0.1us
+  outUserCpuTime = userTime.QuadPart * cSecFactor;
+  outSystemCpuTime = kernelTime.QuadPart * cSecFactor;
+  return true;
+
+#else
+  outUserCpuTime = 0;
+  outSystemCpuTime = 0;
+  return false;
+#endif
+}
+
+double getTotalProcessCpuTime() {
+  double user = 0;
+  double kernel = 0;
+  if (!getProcessCpuTimes(user, kernel)) {
+    return 0;
+  }
+  return user + kernel;
+}
+
 } // namespace os
 } // namespace vrs

vrs/os/Time.h

@@ -41,5 +41,13 @@ int64_t getTimestampMs();
 /// Therefore, using double is misleading & dangerous.
 int64_t getCurrentTimeSecSinceEpoch();
 
+/// Get process usage time, splitting User CPU time and System CPU time
+/// Returns false if not implemented on that platform.
+bool getProcessCpuTimes(double& outUserCpuTime, double& outSystemCpuTime);
+
+/// Get User and System CPU time as one
+/// Returns 0 if not supported.
+double getTotalProcessCpuTime();
+
 } // namespace os
 } // namespace vrs

vrs/os/Utils.h

@@ -43,6 +43,10 @@ int64_t fileTell(std::FILE* file);
 int fileSeek(std::FILE* file, int64_t offset, int origin);
 int fileSetSize(std::FILE* file, int64_t size);
 
+inline bool fileWriteString(FILE* f, const std::string& str) {
+  return os::fileWrite(str.c_str(), 1, str.size(), f) == str.size();
+}
+
 /// Misc helpers
 int remove(const std::string& path); // file or folder
 int rename(const std::string& originalName, const std::string& newName); // file or folder