connect_pair.cpp 3.0 KB

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  1. //
  2. // connect_pair.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. #include <array>
  11. #include <iostream>
  12. #include <string>
  13. #include <cctype>
  14. #include <boost/asio.hpp>
  15. #include <boost/thread/thread.hpp>
  16. #if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
  17. using boost::asio::local::stream_protocol;
  18. class uppercase_filter
  19. {
  20. public:
  21. uppercase_filter(stream_protocol::socket sock)
  22. : socket_(std::move(sock))
  23. {
  24. read();
  25. }
  26. private:
  27. void read()
  28. {
  29. socket_.async_read_some(boost::asio::buffer(data_),
  30. [this](boost::system::error_code ec, std::size_t size)
  31. {
  32. if (!ec)
  33. {
  34. // Compute result.
  35. for (std::size_t i = 0; i < size; ++i)
  36. data_[i] = std::toupper(data_[i]);
  37. // Send result.
  38. write(size);
  39. }
  40. else
  41. {
  42. throw boost::system::system_error(ec);
  43. }
  44. });
  45. }
  46. void write(std::size_t size)
  47. {
  48. boost::asio::async_write(socket_, boost::asio::buffer(data_, size),
  49. [this](boost::system::error_code ec, std::size_t /*size*/)
  50. {
  51. if (!ec)
  52. {
  53. // Wait for request.
  54. read();
  55. }
  56. else
  57. {
  58. throw boost::system::system_error(ec);
  59. }
  60. });
  61. }
  62. stream_protocol::socket socket_;
  63. std::array<char, 512> data_;
  64. };
  65. int main()
  66. {
  67. try
  68. {
  69. boost::asio::io_context io_context;
  70. // Create a connected pair and pass one end to a filter.
  71. stream_protocol::socket socket(io_context);
  72. stream_protocol::socket filter_socket(io_context);
  73. boost::asio::local::connect_pair(socket, filter_socket);
  74. uppercase_filter filter(std::move(filter_socket));
  75. // The io_context runs in a background thread to perform filtering.
  76. boost::thread thread(
  77. [&io_context]()
  78. {
  79. try
  80. {
  81. io_context.run();
  82. }
  83. catch (std::exception& e)
  84. {
  85. std::cerr << "Exception in thread: " << e.what() << "\n";
  86. std::exit(1);
  87. }
  88. });
  89. for (;;)
  90. {
  91. // Collect request from user.
  92. std::cout << "Enter a string: ";
  93. std::string request;
  94. std::getline(std::cin, request);
  95. // Send request to filter.
  96. boost::asio::write(socket, boost::asio::buffer(request));
  97. // Wait for reply from filter.
  98. std::vector<char> reply(request.size());
  99. boost::asio::read(socket, boost::asio::buffer(reply));
  100. // Show reply to user.
  101. std::cout << "Result: ";
  102. std::cout.write(&reply[0], request.size());
  103. std::cout << std::endl;
  104. }
  105. }
  106. catch (std::exception& e)
  107. {
  108. std::cerr << "Exception: " << e.what() << "\n";
  109. std::exit(1);
  110. }
  111. }
  112. #else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
  113. # error Local sockets not available on this platform.
  114. #endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)