std::this_t...:sleep_until(3)

💖 std::this_thread::sleep_until 💖

okay bestie, welcome to the std::this_thread::sleep_until page from the C++ Standard Libary manual, tagged std::this_t...:sleep_until(3). yes, the header squishes the title and “Libary” is typed like that — we are choosing peace and moving on 🫶✨

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🌸 NAME 🌸

std::this_thread::sleep_until — yep, that’s the function, and that’s also literally the name. she’s std::this_thread::sleep_until, no notes 💅

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✨ Synopsis ✨

Defined in header <thread> 🧵

template< class Clock, class Duration >
void sleep_until( const std::chrono::time_point<Clock, Duration>& sleep_time );

This overload is (since C++11) — vintage-ish but still iconic.

It blocks the execution of the current thread until the specified sleep_time has been reached. periodt ⏰

Clock must meet the Clock requirements. The program is ill-formed if std::chrono::is_clock_v<Clock> is false. (since C++20) — so like, don’t try to pass a fake clock, bestie, it’s not gonna end well 😭

The standard recommends that the clock tied to sleep_time be used, in which case adjustments of the clock may be taken into account. So the duration of the block might be more or less than sleep_time - Clock::now() at the time of the call, depending on the direction of the adjustment and whether it is honored by the implementation. The function also may block until after sleep_time has been reached due to process scheduling or resource contention delays. she can oversleep, it’s giving “five more minutes” energy 💀🛌

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🎀 Parameters 🎀

• sleep_time — time to block until. that’s the whole assignment 🎯

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💅 Return value 💅

(none) — literally nothing. she blocks, she’s done, she does not return a little gift for you. void queen 👑

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🦋 Exceptions 🦋

Any exception thrown by Clock or Duration — and clocks and durations provided by the standard library never throw. so if something throws, it’s not the standard-library clock/duration being messy 💅

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🌈 Example 🌈

// Run this code — go off, bestie 🧚

// Run this code

#include <chrono>
#include <iostream>
#include <thread>

auto now() { return std::chrono::steady_clock::now(); }

auto awake_time()
{
    using std::chrono::operator""ms;
    return now() + 2000ms;
}

int main()
{
    std::cout << "Hello, waiter...\n" << std::flush;
    const auto start{now()};
    std::this_thread::sleep_until(awake_time());
    std::chrono::duration<double, std::milli> elapsed{now() - start};
    std::cout << "Waited " << elapsed.count() << " ms\n";
}

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⭐ Possible output ⭐

Hello, waiter...
Waited 2000.17 ms

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👑 See also 👑

• sleep_for — stops the execution of the current thread for a specified time duration (C++11) (function). her cousin who takes a duration instead of a time point 🫶
• C documentation for thrd_sleep — the C side of the nap committee 😴

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mwah 💋 that’s the page, bestie — source/version: http://cppreference.com, date 2024.06.10, page tag std::this_t...:sleep_until(3). now go take a nap (on purpose, not during code review) 🎀💤