Testing Parallel sorting using MSVC 17 and C++17 parallel algorithms

msvc17parallel.cpp

// Be sure to set your project to use the ISO C++17 Standard (/std:c++17) under 
// C++ Language Standard in Properties... C/C++... Language...
#include <string>
#include <iostream>
#include <algorithm>
#include <execution>
#include <random>
#include <chrono>
#include <iomanip>

// All this should be in a header, but I'm doing this for ease of use in a Gist
// Readability
using TimePointRef = std::chrono::time_point<std::chrono::steady_clock> &;
using TimePoint = std::chrono::high_resolution_clock::time_point;
using DurationDblRef = std::chrono::duration<double> &;
using DurationDbl = std::chrono::duration<double>;
void GetTotalTime(DurationDblRef totalTime, TimePointRef startTime);
void PrintResults(char *funcName, DurationDblRef totalTime);
static TimePoint GetTime(void);

// Return time in seconds as a double.
static TimePoint GetTime(void)
{
	return std::chrono::high_resolution_clock::now();
}

void TestIt()
{
	std::vector<int> vec;
	std::vector<int> cpyVec;
	std::random_device rd;				// Will be used to obtain a seed for the random number engine
	std::mt19937 gen(rd());				// Standard mersenne_twister_engine seeded with rd()
	std::uniform_int_distribution<> dis(1, 1000);
	DurationDbl totalTime;

	for (int j = 0; j < 4000000; j++)
	{
		vec.push_back(dis(gen));
	}

	auto startTime = GetTime();
	for (int i = 0; i < 20; i++)
	{
		cpyVec = vec;
		std::sort(std::execution::par, cpyVec.begin(), cpyVec.end());       // parallel
	}
	GetTotalTime(totalTime, startTime);
	PrintResults((char*)"parallel", totalTime);

	startTime = GetTime();
	for (int i = 0; i < 20; i++)
	{
		cpyVec = vec;
		std::sort(std::execution::par_unseq, cpyVec.begin(), cpyVec.end()); // parallel and vectorized
	}
	GetTotalTime(totalTime, startTime);
	PrintResults((char*)"par & vect", totalTime);

	startTime = GetTime();
	for (int i = 0; i < 20; i++)
	{
		cpyVec = vec;
		std::sort(cpyVec.begin(), cpyVec.end()); // standard sort
	}
	
	GetTotalTime(totalTime, startTime);
	PrintResults((char*)"Plane Old Sort", totalTime);

	cpyVec = vec;
	startTime = GetTime();
	for (int i = 0; i < 20; i++)
	{
		cpyVec = vec;
		std::sort(std::execution::seq, cpyVec.begin(), cpyVec.end()); // sequential
	}
	GetTotalTime(totalTime, startTime);
	PrintResults((char*)"Sequential", totalTime);

}

void PrintResults(char *funcName, DurationDblRef totalTime)
{
	std::string fname(funcName);
	fname += ":";
	std::cout << std::left << std::setw(15) << funcName << std::right << std::setw(12) << totalTime.count() << " Seconds\n";
}


void GetTotalTime(DurationDblRef totalTime, TimePointRef startTime)
{
	totalTime = std::chrono::duration_cast<DurationDbl>(GetTime() - startTime);
}

int main()
{
	TestIt();
	return 0;
}