ceph/src/boost/libs/asio/example/cpp17/coroutines_ts/range_based_for.cpp

   1 //
   2 // range_based_for.cpp
   3 // ~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #include <boost/asio/experimental/co_spawn.hpp>
  12 #include <boost/asio/experimental/detached.hpp>
  13 #include <boost/asio/io_context.hpp>
  14 #include <boost/asio/ip/tcp.hpp>
  15 #include <boost/asio/signal_set.hpp>
  16 #include <boost/asio/write.hpp>
  17 #include <cstdio>
  18
  19 using boost::asio::ip::tcp;
  20 using boost::asio::experimental::awaitable;
  21 using boost::asio::experimental::co_spawn;
  22 using boost::asio::experimental::detached;
  23 namespace this_coro = boost::asio::experimental::this_coro;
  24
  25 class connection_iter
  26 {
  27   friend class connections;
  28   tcp::acceptor* acceptor_ = nullptr;
  29   tcp::socket socket_;
  30
  31   connection_iter(tcp::acceptor& a, tcp::socket s)
  32     : acceptor_(&a), socket_(std::move(s)) {}
  33
  34 public:
  35   tcp::socket operator*()
  36   {
  37     return std::move(socket_);
  38   }
  39
  40   awaitable<void> operator++()
  41   {
  42     auto token = co_await this_coro::token();
  43     socket_ = co_await acceptor_->async_accept(token);
  44   }
  45
  46   bool operator==(const connection_iter&) const noexcept
  47   {
  48     return false;
  49   }
  50
  51   bool operator!=(const connection_iter&) const noexcept
  52   {
  53     return true;
  54   }
  55 };
  56
  57 class connections
  58 {
  59   tcp::acceptor& acceptor_;
  60
  61 public:
  62   explicit connections(tcp::acceptor& a) : acceptor_(a) {}
  63
  64   awaitable<connection_iter> begin()
  65   {
  66     auto token = co_await this_coro::token();
  67     tcp::socket s = co_await acceptor_.async_accept(token);
  68     co_return connection_iter(acceptor_, std::move(s));
  69   }
  70
  71   connection_iter end()
  72   {
  73     return connection_iter(acceptor_,
  74         tcp::socket(acceptor_.get_executor().context()));
  75   }
  76 };
  77
  78 awaitable<void> listener(tcp::acceptor acceptor)
  79 {
  80   auto token = co_await this_coro::token();
  81
  82   for co_await (tcp::socket s : connections(acceptor))
  83   {
  84     co_await boost::asio::async_write(s, boost::asio::buffer("hello\r\n", 7), token);
  85   }
  86 }
  87
  88 int main()
  89 {
  90   try
  91   {
  92     boost::asio::io_context io_context(1);
  93
  94     boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
  95     signals.async_wait([&](auto, auto){ io_context.stop(); });
  96
  97     tcp::acceptor acceptor(io_context, {tcp::v4(), 55555});
  98     co_spawn(io_context,
  99         [acceptor = std::move(acceptor)]() mutable
 100         {
 101           return listener(std::move(acceptor));
 102         },
 103         detached);
 104
 105     io_context.run();
 106   }
 107   catch (std::exception& e)
 108   {
 109     std::printf("Exception: %s\n", e.what());
 110   }
 111 }