Windows: sleep_for is dependent on system clock

[joaomoreno]

Hey there! 👋

We've hit this issue in VS Code: microsoft/vscode#41136

Ultimately here's the problem: std::this_thread::sleep_for is poorly implemented in Windows and depends on the system clock. When the thread is sleeping and the system clock is changed to a previous time, the sleep takes longer than expected, apparently by as much as the system clock was changed.

The bug easily reproduces with this snippet:

#include "stdafx.h"
#include <iostream>
#include <chrono>
#include <thread>

int main()
{
	while (true) {
		std::cout << "sleeping for 500ms" << std::endl;
		std::this_thread::sleep_for(std::chrono::milliseconds(500));
	}

    return 0;
}

Simply go back in time and one of the 500ms sleep_for calls will take much longer.

---

I found a comment in here which indicates that sleep_until doesn't have the same issue, though I don't really verify that. I tried using both system_clock and steady_clock to compute the sleep_until argument; the bug still happens.

Of course, using the WinAPI call Sleep works like a charm.

Would you accept a PR in which I replace sleep_for calls for Sleep calls in Windows?

[gabime]

Sure. I prefer it the be implemented in the details/os.h file for obvoius reasons