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

   1 //
   2 // double_buffered_echo_server.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::co_spawn;
  21 using boost::asio::experimental::detached;
  22 namespace this_coro = boost::asio::experimental::this_coro;
  23
  24 template <typename T>
  25   using awaitable = boost::asio::experimental::awaitable<
  26     T, boost::asio::io_context::executor_type>;
  27
  28 awaitable<void> echo(tcp::socket s)
  29 {
  30  auto token = co_await this_coro::token();
  31
  32  try
  33  {
  34    char data1[1024];
  35    char data2[1024];
  36
  37    char* p1 = data1;
  38    char* p2 = data2;
  39
  40    // Perform initial read into first buffer.
  41    size_t n = co_await s.async_read_some(boost::asio::buffer(p1, 1024), token);
  42
  43    for (;;)
  44    {
  45      // Swap received data to other buffer and initiate write operation.
  46      std::swap(p1, p2);
  47      auto write_result = boost::asio::async_write(s, boost::asio::buffer(p2, n), token);
  48
  49      // Perform next read while write operation is in progress.
  50      n = co_await s.async_read_some(boost::asio::buffer(p1, 1024), token);
  51
  52      // Wait for write operation to complete before proceeding.
  53      co_await write_result;
  54    }
  55  }
  56  catch (std::exception& e)
  57  {
  58    std::printf("echo Exception: %s\n", e.what());
  59  }
  60 }
  61
  62 awaitable<void> listener()
  63 {
  64   auto executor = co_await this_coro::executor();
  65   auto token = co_await this_coro::token();
  66
  67   tcp::acceptor acceptor(executor.context(), {tcp::v4(), 55555});
  68   for (;;)
  69   {
  70     tcp::socket socket = co_await acceptor.async_accept(token);
  71     co_spawn(executor,
  72         [socket = std::move(socket)]() mutable
  73         {
  74           return echo(std::move(socket));
  75         },
  76         detached);
  77   }
  78 }
  79
  80 int main()
  81 {
  82   try
  83   {
  84     boost::asio::io_context io_context(1);
  85
  86     boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
  87     signals.async_wait([&](auto, auto){ io_context.stop(); });
  88
  89     co_spawn(io_context, listener, detached);
  90
  91     io_context.run();
  92   }
  93   catch (std::exception& e)
  94   {
  95     std::printf("Exception: %s\n", e.what());
  96   }
  97 }