Measure cpu time

[Dennis]

On Friday, 7 May 2021 at 08:25:43 UTC, Andre Pany wrote:
> Is there some equivalent function in Phobos to get the cpu time 
> on linux?

I don't think so, but you can use `core.sys.posix.sys.resource: 
rusage`.

If you want to use it on Windows as well, this is a code snippet 
I wrote for that:
```D
/// Describes how much cpu time a process has been getting
struct CpuUsage {
	/// Time that the process has executed in kernel mode in 
microseconds
	ulong kernelTimeUs;

	/// Time that the process has executed in user mode in 
microseconds
	ulong userTimeUs;
}

bool getCpuUsage(out CpuUsage r) {
	version(Windows) {
		void* currentProcess = GetCurrentProcess();
		FILETIME creationTime; // time that process was created
		FILETIME exitTime; // undefined if process has not exited
		FILETIME kernelTime; // ru_stime
		FILETIME userTime; // ru_utime
		if (GetProcessTimes(currentProcess, &creationTime, &exitTime, 
&kernelTime, &userTime) == 0) {
			return false; // GetLastError();
		}
		ulong toMicroseconds(FILETIME ft)  {
			return (ft.dwLowDateTime | cast(ulong) ft.dwHighDateTime << 
32) / 10;
		}
		r.kernelTimeUs = toMicroseconds(kernelTime);
		r.userTimeUs = toMicroseconds(userTime);
	} else version(Posix) {
		rusage rusageStruct;
		if (getrusage(RUSAGE_SELF, &rusageStruct) == -1) {
			return false; //errno
		}
		auto toMicroseconds(timeval t) {
			return cast(ulong) t.tv_sec * 1_000_000 + t.tv_usec;
		}
		r.kernelTimeUs = toMicroseconds(rusageStruct.ru_stime);
		r.userTimeUs = toMicroseconds(rusageStruct.ru_utime);
	}
	return true;
}
```
On Windows you need to link to "Psapi.lib", e.g. with 
`pragma(lib, "Psapi.lib")` or `libs "Psapi.lib"` in dub.sdl.