#include <iostream>
#include<thread>
#include<vector>
#include<math.h>
#include<string>
#include<functional>
#include<mutex>

std::mutex m;
template<typename TFunc>
void calcIntegral(TFunc& func, double a, double b, long long steps, double& result) {
	double localResult = 0;
	double step = (b - a) / steps;
	while (a <= b) {
		localResult += func(a) * step;
		a += step;
	}
	std::lock_guard<std::mutex> guard(m);
	result += localResult;
}

/*mutex m;
void Foo() {
	for (int i = 0; i < 100; i++) {
		m.lock();
		cout << "Thread: " << this_thread::get_id() << '\n';
		m.unlock();
	}
}*/

int main()
{
	/*vector<thread> threads;

	for (int i = 0; i < 10; i++) {
		threads.emplace_back(Foo);
	}

	for (auto& tr : threads) {
		if (tr.joinable())
			tr.join();
	}
	thread thread(Foo);
	Foo();
	thread.join();*/


	auto start = std::chrono::system_clock::now();
	std::function<double(double)> f{ [](double x) {return x; } };
	unsigned long long steps = 100000000ULL;
	unsigned threadCount = 8;

	double result = 0;

	std::vector<std::thread> threads;

	for (int i = 0; i < threadCount; i++)
	{
		threads.emplace_back(calcIntegral<std::function<double(double)>>,
			std::ref(f),
			1.0 / threadCount * i,
			1.0 / threadCount * (i + 1),
			steps / threadCount,
			std::ref(result)
		);
	}

	for (auto& tr : threads)
	{
		if (tr.joinable())
			tr.join();
	}

	auto end = std::chrono::system_clock::now();
	std::chrono::duration<double, std::milli> diff = end - start;


	std::cout << "Time milisec = " << diff.count() << '\n'
		      << "Result = " << result << '\n';
	return 0;
}