Christopher Kohlhoff
09716d71f3
Enabled deferred awaiting for coros, regularized use_coro, and fixed allocator handling.
...
This means that use_coro does not return a coro object, just like
use_awaitable does, i.e. it's an overhead that buys us type erasure.
Allocators can now be set for coro by including allocator_arg in the
coro signature.
2022-11-03 17:29:53 +11:00
klemens-morgenstern
ecca8406c0
Added experimental::coro class template.
...
The coro type is a C++20 coroutine primitive for resumable functions,
with the ability to combine both asynchronous waiting (co_await) and
yielding (co_yield) into a single, stateful control flow. For example:
#include <boostasio.hpp>
#include <boostasio/experimental/coro.hpp>
using boost::asio::ip::tcp;
boost::asio::experimental::coro<std::string> reader(tcp::socket& sock)
{
std::string buf;
while (sock.is_open())
{
std::size_t n = co_await boost::asio::async_read_until(
sock, boost::asio::dynamic_buffer(buf), '\n',
boost::asio::experimental::use_coro);
co_yield buf.substr(0, n);
buf.erase(0, n);
}
}
boost::asio::awaitable<void> consumer(tcp::socket sock)
{
auto r = reader(sock);
auto msg1 = co_await r.async_resume(boost::asio::use_awaitable);
std::cout << "Message 1: " << msg1.value_or("\n");
auto msg2 = co_await r.async_resume(boost::asio::use_awaitable);
std::cout << "Message 2: " << msg2.value_or("\n");
}
boost::asio::awaitable<void> listen(tcp::acceptor& acceptor)
{
for (;;)
{
co_spawn(
acceptor.get_executor(),
consumer(co_await acceptor.async_accept(boost::asio::use_awaitable)),
boost::asio::detached);
}
}
int main()
{
boost::asio::io_context ctx;
tcp::acceptor acceptor(ctx, {tcp::v4(), 54321});
co_spawn(ctx, listen(acceptor), boost::asio::detached);
ctx.run();
}
2021-07-01 21:34:51 +10:00
