max_timeout_for_std_cv_wait_for.cpp

#include <chrono>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <thread>

using namespace std::chrono;

struct lock_context
{
	std::mutex m_lock;
	std::condition_variable m_cv;
	bool m_triggered{false};
};

void trigger_thread(lock_context & ctx)
{
	std::this_thread::sleep_for(seconds{1});

	std::lock_guard<std::mutex> lock{ctx.m_lock};
	ctx.m_triggered = true;
	ctx.m_cv.notify_one();
}

int main()
{
	lock_context ctx;
	std::thread trigger{trigger_thread, std::ref(ctx)};

	{
		std::unique_lock<std::mutex> lock{ctx.m_lock};
		int multiplier = 1;
		while(!ctx.m_triggered)
		{
			const auto started_at = steady_clock::now();

			const auto wait_time = (steady_clock::time_point::max() - started_at)
					- hours{24*multiplier};

			std::cout << "wait_time: " << duration_cast<milliseconds>(
					wait_time).count() << "ms, days: "
					<< multiplier << std::endl;

			ctx.m_cv.wait_for(lock, wait_time,
					[&ctx]{ return ctx.m_triggered; });

			const auto finished_at = steady_clock::now();

			std::cout << "wait for: " << duration_cast<milliseconds>(
					finished_at - started_at).count() << "ms" << std::endl;

			if(!ctx.m_triggered)
				multiplier += 1000;
		}
	}

	trigger.join();

	return 0;
}