1 //
2 // connect_pair.cpp
3 // ~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2020 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 <array>
12 #include <iostream>
13 #include <string>
14 #include <cctype>
15 #include <boost/asio.hpp>
16 #include <boost/thread/thread.hpp>
17
18 #if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
19
20 using boost::asio::local::stream_protocol;
21
22 class uppercase_filter
23 {
24 public:
uppercase_filter(stream_protocol::socket sock)25 uppercase_filter(stream_protocol::socket sock)
26 : socket_(std::move(sock))
27 {
28 read();
29 }
30
31 private:
read()32 void read()
33 {
34 socket_.async_read_some(boost::asio::buffer(data_),
35 [this](boost::system::error_code ec, std::size_t size)
36 {
37 if (!ec)
38 {
39 // Compute result.
40 for (std::size_t i = 0; i < size; ++i)
41 data_[i] = std::toupper(data_[i]);
42
43 // Send result.
44 write(size);
45 }
46 else
47 {
48 throw boost::system::system_error(ec);
49 }
50 });
51 }
52
write(std::size_t size)53 void write(std::size_t size)
54 {
55 boost::asio::async_write(socket_, boost::asio::buffer(data_, size),
56 [this](boost::system::error_code ec, std::size_t /*size*/)
57 {
58 if (!ec)
59 {
60 // Wait for request.
61 read();
62 }
63 else
64 {
65 throw boost::system::system_error(ec);
66 }
67 });
68 }
69
70 stream_protocol::socket socket_;
71 std::array<char, 512> data_;
72 };
73
main()74 int main()
75 {
76 try
77 {
78 boost::asio::io_context io_context;
79
80 // Create a connected pair and pass one end to a filter.
81 stream_protocol::socket socket(io_context);
82 stream_protocol::socket filter_socket(io_context);
83 boost::asio::local::connect_pair(socket, filter_socket);
84 uppercase_filter filter(std::move(filter_socket));
85
86 // The io_context runs in a background thread to perform filtering.
87 boost::thread thread(
88 [&io_context]()
89 {
90 try
91 {
92 io_context.run();
93 }
94 catch (std::exception& e)
95 {
96 std::cerr << "Exception in thread: " << e.what() << "\n";
97 std::exit(1);
98 }
99 });
100
101 for (;;)
102 {
103 // Collect request from user.
104 std::cout << "Enter a string: ";
105 std::string request;
106 std::getline(std::cin, request);
107
108 // Send request to filter.
109 boost::asio::write(socket, boost::asio::buffer(request));
110
111 // Wait for reply from filter.
112 std::vector<char> reply(request.size());
113 boost::asio::read(socket, boost::asio::buffer(reply));
114
115 // Show reply to user.
116 std::cout << "Result: ";
117 std::cout.write(&reply[0], request.size());
118 std::cout << std::endl;
119 }
120 }
121 catch (std::exception& e)
122 {
123 std::cerr << "Exception: " << e.what() << "\n";
124 std::exit(1);
125 }
126 }
127
128 #else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
129 # error Local sockets not available on this platform.
130 #endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
131