This is a single header file library for CPP coroutine

This repo is a part of: https://github.com/yunate/dd/

Tests and demos: https://github.com/yunate/ddcoroutine/blob/main/test/test_case_coroutine.cpp

corountine + iocp + windows socket components(TCP/UDP/HTTP (s) server/HTTP (s) client): https://github.com/yunate/dd/tree/main/projects/ddbase/network

corountine + iocp + windows http(s) server demo: https://github.com/yunate/dd/blob/main/projects/test/ddbase/network/test_case_http_server.cpp

corountine + iocp + windows http(s) client demo: https://github.com/yunate/dd/blob/main/projects/test/ddbase/network/test_case_http_client.cpp

corountine + iocp + windows http(s) request demo: https://github.com/yunate/dd/blob/main/projects/test/ddbase/network/test_case_http_requester.cpp

License

Do WTF you want to but report the issue you met to this repo.

Useage:

Import to your project:

Copy the ddcoroutine.h file to your project and include it.

#include "include/ddcoroutine.h"

Define a co-function

Just use ddcroutine<T> as a function return, the template T is the truly return type:

ddcoroutine<void> co_test_void() {
    co_return;
}

ddcoroutine<int> co_test_int() {
    co_return 1;
}

Wrap a async function to co-function

Assuming we have an asynchronous function:

void async_io(const std::function<void(void)>& callback) {
    std::thread([callback]() {
        callback();
    }).detach();
}

Change it to a co-function:

• auto ddawaitable(const ddco_task& task)

This function can wrap a async function to an awaitable object:

ddcoroutine<void> co_io() {
    co_await ddawaitable([](const ddresume_helper& resumer) {
        async_io([resumer]() {
            resumer.lazy_resume();
        });
    });
}

Note that the wrapped function must be async(whose callback function will be called in another thread or the next loop). If the wrapped function is uncertain whether it is asynchronous or not, use auto ddawaitable_ex(const ddco_task& task) or ddcoroutine<void> ddcoroutine_from(ddco_task task) instead.

• auto ddawaitable_ex(const ddco_task& task)

This is similar to ddawaitable, but the difference is that ddawaitable_ex does not require the wrapped function to be asynchronous. The cost is some additional judgment processing. Therefore, if you can ensure that the wrapped function is always asynchronous, use ddawaitable to get a better performance. Otherwise, use ddawaitable_ex function.

ddcoroutine<void> co_io() {
    co_await ddawaitable_ex([](const ddresume_helper& resumer) {
        async_io([resumer]() {
            resumer.lazy_resume();
        });
    });
}

• ddcoroutine<void> ddcoroutine_from(ddco_task task)

This function implements the same function as auto ddawaitable_ex(const ddco_task& task), but the difference is that its return value is ddcoroutine<void>, which will be very useful because most of the input parameters of the other utility functions below are ddcoroutine<void>.

ddcoroutine<void> co_io() {
    co_await ddcoroutine_from([](const ddresume_helper& resumer) {
        async_io([resumer]() {
            resumer.lazy_resume();
        });
    });
}

Call a co-function in a co-function

Use co_await to suspend current co-function until the called co-function run to end.

void test_normal() {}
ddcoroutine<void> test() {
    // call a normal function.
    test_normal();

    // `co_test_void` will end directly, and co_await will be immediately resumed.
    co_await co_test_void();

    // `co_test_int` will end directly, and co_await will be immediately resumed, and retrieve the return value.
    int x = co_await co_test_int();

    // `co_io` will not end directly, co_await will be suspended and will be resumed when `async_io`'s callback is called.
    co_await co_io();
    co_return;
}

Call a co-function in a normal function

Just call a co-function as a normal function, the caller function will not be suspended:

int main() {
    ddcoroutine<void> co_ctx = co_io();

    // loop
    while (true) {
        std::sleep(1000);
    }
}

Note that, before the coroutine funtion run to the end, the co-function's return object(co_ctx) cannot be release. if you do not want to manage its lifecycle, use void ddcoroutine_run(const ddcoroutine<void>& r):

int main() {
    // run co_io
    ddcoroutine_run(co_io());

    // loop
    while (true) {
        std::sleep(1000);
    }
}

Wait for multiple co-functions

ddcoroutine<void> test() {
    // the co_await will be suspend until `co_io`, `co_test_void`, `co_test_int` are all resumed.
    co_await ddcoroutine_all({
        co_io(),
        co_test_void(),
        ddcoroutine_from(co_test_int())
    });
    co_return;
}