int value;

std::mutex mut;

std::condition_variable cond;

Counter(int value) : value(value) { }

cout << "[ Auth ] Start" << endl;

// Send request to authenticator, check permissions, encrypt, decrypt...

sleepsec(20);

cout << "[ Auth ] Done" << endl;

for (auto&& fileName : lstFileName) {

// Read file

cout << "[ ReadFile ] Start " << fileName << endl;

sleepsec(10);

cout << "[ ReadFile ] Done " << fileName << endl;

{

std::unique_lock<std::mutex>(counter.mut);

--counter.value;

counter.cond.notify_one();

}

// Write log into disk

sleepsec(5);

cout << "[ WriteLog ]" << endl;

}

const vector<string> lstFileName = { "foo.html", "bar.json" };

Counter counter(lstFileName.size());

// The server checks auth user while reading files, concurrently

std::thread th(&processFiles, std::cref(lstFileName), std::ref(counter));

checkAuthUser();

// The server waits for completion of loading files

{

std::unique_lock<std::mutex> lk(counter.mut);

while (counter.value > 0) {

counter.cond.wait_for(lk, std::chrono::seconds(10)); // timeout = 10 seconds

}

}

cout << "\nNow user is authorized and files are loaded" << endl;

cout << "Do other tasks...\n" << endl;

th.join();