#include <atomic>
#include <chrono>
#include <iostream>
#include <random>
#include <thread>
#include <utility>
#include <vector>
#include <mutex>

constexpr long long size= 100000; //size elemente pt suma

constexpr long long firBound=  2500;
constexpr long long secBound=  5000;
constexpr long long thiBound=  7500;
constexpr long long fouBound= 10000;

constexpr long long firBound1=  5000;//in caz ca se vor doar 2 th
constexpr long long secBound1=  10000;//in caz ca se vor doar 2 th
//var1
std::mutex myMutex;//protejeaza resursele shared sa fie accesate simultan de mai multe th
void sumUp(unsigned long long& sum, const std::vector<int>& val, unsigned long long beg, unsigned long long end){
    for (auto it= beg; it < end; ++it){
        std::lock_guard<std::mutex> myLock(myMutex);
        sum+= val[it];
    }//aici se face suma propriu zisa
}
//end varianta1

//varianta2 mai rapida ca si unu dar se poate folosi oricare
//la atomic nu mai este necesara protectia resurselor partajate fiindca deja avem int care e element atomic si care nu poate fi shared
/*void sumUp(std::atomic<unsigned long long>& sum, const std::vector<int>& val, unsigned long long beg, unsigned long long end){
    for (auto it= beg; it < end; ++it){
        sum+= val[it];
    }
}*/
//end varianta2
int main(){

  std::cout << std::endl;

  std::vector<int> randValues;
  randValues.reserve(size);

  std::mt19937 engine;  //generator pseudo random
  std::uniform_int_distribution<> uniformDist(1,10);//distributia de la 1 la 10
  for ( long long i=0 ; i< size ; ++i) randValues.push_back(uniformDist(engine));//efectiv generarea vectorului
//var1
  unsigned long long sum= 0; //asta merge cu mutex ->se declara variabila sum long long egal cu 0
//end var1

//varianta2
  //std::atomic<unsigned long long> sum(0); //avem sum declarata ca long long atomic egala cu 0 //asta merge cu varianta cu atomic
//end varianta2
  auto start = std::chrono::system_clock::now();//masurare timp

  std::thread t1(sumUp,std::ref(sum),std::ref(randValues),0,firBound);//initializare th1...
  std::thread t2(sumUp,std::ref(sum),std::ref(randValues),firBound,secBound);
  std::thread t3(sumUp,std::ref(sum),std::ref(randValues),secBound,thiBound);
  std::thread t4(sumUp,std::ref(sum),std::ref(randValues),thiBound,fouBound);


  t1.join();//run th1..
  t2.join();
  t3.join();
  t4.join();
  std::chrono::duration<double> dur= std::chrono::system_clock::now() - start;//masurare timp end
  std::cout << "Time for addition " << dur.count() << " seconds" << std::endl;
  std::cout << "Result: " << sum << std::endl;
  for(int k=1;k<=size;k++)
  {
      std::cout<< randValues[k]<< ",";
  }

  std::cout << std::endl;
  system("pause");
}