Example of using concurrent asynchronous tasks in C++

async-sandwich.cpp

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

using namespace std::literals;

static std::mutex println_mutex;

constexpr auto println = [](auto... stuff) {
	std::lock_guard guard(println_mutex);
	(std::cout << ... << stuff) << std::endl;
};

constexpr auto sleep_for = [](auto x) {
	std::this_thread::sleep_for(x);
};

void get_bread() {
	println("[bread] Making dough...");
	sleep_for(2s);
	println("[bread] Shaping dough...");
	sleep_for(2s);
	println("[bread] Preheating oven...");
	sleep_for(2s);
	println("[bread] Baking dough...");
	sleep_for(4s);
	println("[bread] Taking bread out of the oven...");
	sleep_for(1s);
	println("[bread] Bread baked!");
}

void get_ham() {
	println("[ham] Going to the market...");
	sleep_for(10s);
	println("[ham] Looking for ham...");
	sleep_for(3s);
	println("[ham] At the cashier...");
	sleep_for(5s);
	println("[ham] Going back home...");
	sleep_for(10s);
	println("[ham] We have ham!");
}

int main() {
	{
		auto bread = std::async(get_bread);
		auto ham = std::async(get_ham);
	}

	println("We have a sandwich!");

	return 0;
}