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

   1 //
   2 // range_based_for.cpp
   3 // ~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2019 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/co_spawn.hpp>
  12 #include <boost/asio/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::awaitable;
  21 using boost::asio::co_spawn;
  22 using boost::asio::detached;
  23 using boost::asio::use_awaitable;
  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     socket_ = co_await acceptor_->async_accept(use_awaitable);
  43   }
  44
  45   bool operator==(const connection_iter&) const noexcept
  46   {
  47     return false;
  48   }
  49
  50   bool operator!=(const connection_iter&) const noexcept
  51   {
  52     return true;
  53   }
  54 };
  55
  56 class connections
  57 {
  58   tcp::acceptor& acceptor_;
  59
  60 public:
  61   explicit connections(tcp::acceptor& a) : acceptor_(a) {}
  62
  63   awaitable<connection_iter> begin()
  64   {
  65     tcp::socket s = co_await acceptor_.async_accept(use_awaitable);
  66     co_return connection_iter(acceptor_, std::move(s));
  67   }
  68
  69   connection_iter end()
  70   {
  71     return connection_iter(acceptor_,
  72         tcp::socket(acceptor_.get_executor()));
  73   }
  74 };
  75
  76 awaitable<void> listener(tcp::acceptor acceptor)
  77 {
  78   for co_await (tcp::socket s : connections(acceptor))
  79   {
  80     co_await boost::asio::async_write(s, boost::asio::buffer("hello\r\n", 7), use_awaitable);
  81   }
  82 }
  83
  84 int main()
  85 {
  86   try
  87   {
  88     boost::asio::io_context io_context(1);
  89
  90     boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
  91     signals.async_wait([&](auto, auto){ io_context.stop(); });
  92
  93     tcp::acceptor acceptor(io_context, {tcp::v4(), 55555});
  94     co_spawn(io_context,
  95         [acceptor = std::move(acceptor)]() mutable
  96         {
  97           return listener(std::move(acceptor));
  98         },
  99         detached);
 100
 101     io_context.run();
 102   }
 103   catch (std::exception& e)
 104   {
 105     std::printf("Exception: %s\n", e.what());
 106   }
 107 }