How to determine if condition_variable::wait_for timed out - multithreading

Question

I have a class which allows to wait on a condition_variable taking care of the spurious wake ups. Following is the code:
Code:
// CondVarWrapper.hpp
#pragma once
#include <mutex>
#include <chrono>
#include <condition_variable>
class CondVarWrapper {
public:
void Signal() {
std::unique_lock<std::mutex> unique_lock(mutex);
cond_var_signalled = true;
unique_lock.unlock();
cond_var.notify_one();
}
// TODO: WaitFor needs to return false if timed out waiting
bool WaitFor(const std::chrono::seconds timeout) {
std::unique_lock<std::mutex> unique_lock(mutex);
bool timed_out = false;
// How to determine if wait_for timed out ?
cond_var.wait_for(unique_lock, timeout, [this] {
return cond_var_signalled;
});
cond_var_signalled = false;
return timed_out;
}
void Wait() {
std::unique_lock<std::mutex> unique_lock(mutex);
cond_var.wait(unique_lock, [this] {
return cond_var_signalled;
});
cond_var_signalled = false;
}
private:
bool cond_var_signalled = false;
std::mutex mutex;
std::condition_variable cond_var;
};
// main.cpp
#include "CondVarWrapper.hpp"
#include <iostream>
#include <string>
#include <thread>
int main() {
CondVarWrapper cond_var_wrapper;
std::thread my_thread = std::thread([&cond_var_wrapper]{
std::cout << "Thread started" << std::endl;
if (cond_var_wrapper.WaitFor(std::chrono::seconds(1))) {
std::cout << "Wait ended before timeout" << std::endl;
} else {
std::cout << "Timed out waiting" << std::endl;
}
});
std::this_thread::sleep_for(std::chrono::seconds(6));
// Uncomment following line to see the timeout working
cond_var_wrapper.Signal();
my_thread.join();
}
Question:
In the method WaitFor, I need to determine if cond_var timed out waiting? How do I do that? WaitFor should return false when it timed out waiting else it should return true. Is that possible?
I see cv_status explained on cppreference but struggling to find a good expample of how to use it.