atomics_test.cc

atomics.cc

#include <atomic>
#include <iostream>
#include <thread>
#include <vector>
#include <string>

usign namespace std;

atomic<int> lock(0);

atomic<int>& increment() {
  atomic_fetch_add(&lock, 1);
  return lock;
}

void decrement() {
  atomic_fetch_sub(&lock, 1);
}

void aquire() {
  while(increment() != 1) {
    decrement();
  }
}

void release() {
  decrement();
}

void thr(void*) {
  auto tid = this_thread::get_id();
  while(true) {
    cout << tid << " : Running" << endl;
    aquire();
    cout << tid << " : Got lock" << endl;
    release();
    cout << tid << " : Release lock" << endl;
  }
}

int main(int argc, char** argv) {
  auto conc = thread::hardware_concurrency();
  if(argc > 1) {
    conc = stoi(argv[1]);
  }
  vector<thread> v(conc);
  
  for(size_t i = 0; i < v.size(); ++i) {
    v[i] = thread(thr, nullptr);
  }
  
  for(size_t i = 0; i < v.size(); ++i) {
    v[i].join()
  }
  
  return 0;
}