Function echo

example/cpp20/coroutines/timeout.cpp:19–28

using ip::tcp;

awaitable<void> echo(tcp::socket& sock, time_point& deadline)
{
  char data[4196];
  for (;;)
  {
    deadline = std::chrono::steady_clock::now() + std::chrono::seconds(10);
    auto n = co_await sock.async_read_some(buffer(data), use_awaitable);
    co_await async_write(sock, buffer(data, n), use_awaitable);
  }
}

awaitable<void> watchdog(time_point& deadline)
{