when_all.cpp

// The MIT License (MIT)
//
// Copyright (c) 2021 Mateusz Pusz
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
 
#include <mp-coro/async.h>
#include <mp-coro/sync_await.h>
#include <mp-coro/task.h>
#include <mp-coro/when_all.h>
#include <iostream>
#include <syncstream>
#include <thread>
 
struct tid_t {
    friend std::ostream &operator<<(std::ostream &os, tid_t) {
        return os << "(tid=" << std::this_thread::get_id() << ')';
    }
};
inline constexpr tid_t tid;
 
template <typename Rep, typename Period>
void sleep_for(std::chrono::duration<Rep, Period> d) {
    std::osyncstream(std::cout) << tid << ": about to sleep\n";
    std::this_thread::sleep_for(d);
    std::osyncstream(std::cout) << tid << ": about to return\n";
}
 
struct lifetime {
    const char *txt = "active (default-constructed)";
 
    lifetime() = default;
    lifetime(const lifetime &) { txt = "active (copy-constructed)"; }
    lifetime &operator=(const lifetime &) {
        txt = "active (copy-assigned)";
        return *this;
    }
 
    lifetime(lifetime &&other) noexcept {
        txt = "active (move-constructed)", other.txt = "unspecified (move-constructed-from)";
    }
    lifetime &operator=(lifetime &&other) noexcept {
        txt = "active (move-assigned)";
        other.txt = "unspecified (move-assigned-from)";
        return *this;
    }
 
    ~lifetime() { txt = "destructed"; }
 
    void operator()() const { std::cout << "[lifetime] " << txt << '\n'; }
};
 
int main() {
    using namespace mp_coro;
    using namespace std::chrono_literals;
 
    try {
        {
            auto func = [obj = lifetime {}] { obj(); };
            auto work = when_all(async(func), async(func), async(func));
            sync_await(work);
        }
 
        {
            auto func = [obj = lifetime {}] { obj(); };
            sync_await(when_all(async(func), async(func), async(func)));
        }
 
        {
            auto a1 = async([obj = lifetime {}] { obj(); });
            auto a2 = async([obj = lifetime {}] { obj(); });
            auto a3 = async([obj = lifetime {}] { obj(); });
            sync_await(when_all(std::move(a1), std::move(a2), std::move(a3)));
        }
 
        {
            auto work = when_all(async([] { return 1; }), async([] { return 2; }),
                                 async([] { return 3; }), async([] { return 4; }));
            auto [v1, v2, v3, v4] = sync_await(work);
            std::cout << "v1: " << v1 << ", v2: " << v2 << ", v3: " << v3 << ", v4: " << v4 << '\n';
        }
 
        {
            auto [v1, v2, v3, v4] =
                sync_await(when_all(async([] { return 5; }), async([] { return 6; }),
                                    async([] { return 7; }), async([] { return 8; })));
            std::cout << "v1: " << v1 << ", v2: " << v2 << ", v3: " << v3 << ", v4: " << v4 << '\n';
        }
 
        {
            std::vector<task<void>> v;
            for (int i = 0; i < 3; ++i)
                v.push_back(make_task(async([] { sleep_for(1s); })));
            sync_await(when_all(std::move(v)));
        }
 
        {
            std::vector<task<void>> v;
            for (int i = 0; i < 3; ++i)
                v.push_back(make_task(async([] { sleep_for(1s); })));
            auto a = when_all(v);
            sync_await(a);
        }
    } catch (const std::exception &ex) {
        std::cout << "Unhandled exception: " << ex.what() << '\n';
    }
}