1 //
2 // connect_pair.cpp
3 // ~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2021 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 <iostream>
12 #include <string>
13 #include <cctype>
14 #include <boost/asio.hpp>
15 #include <boost/thread/thread.hpp>
16 #include <boost/array.hpp>
17 #include <boost/bind/bind.hpp>
18
19 #if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
20
21 using boost::asio::local::stream_protocol;
22
23 class uppercase_filter
24 {
25 public:
uppercase_filter(boost::asio::io_context & io_context)26 uppercase_filter(boost::asio::io_context& io_context)
27 : socket_(io_context)
28 {
29 }
30
socket()31 stream_protocol::socket& socket()
32 {
33 return socket_;
34 }
35
start()36 void start()
37 {
38 // Wait for request.
39 socket_.async_read_some(boost::asio::buffer(data_),
40 boost::bind(&uppercase_filter::handle_read,
41 this, boost::asio::placeholders::error,
42 boost::asio::placeholders::bytes_transferred));
43 }
44
45 private:
handle_read(const boost::system::error_code & ec,std::size_t size)46 void handle_read(const boost::system::error_code& ec, std::size_t size)
47 {
48 if (!ec)
49 {
50 // Compute result.
51 for (std::size_t i = 0; i < size; ++i)
52 data_[i] = std::toupper(data_[i]);
53
54 // Send result.
55 boost::asio::async_write(socket_, boost::asio::buffer(data_, size),
56 boost::bind(&uppercase_filter::handle_write,
57 this, boost::asio::placeholders::error));
58 }
59 else
60 {
61 throw boost::system::system_error(ec);
62 }
63 }
64
handle_write(const boost::system::error_code & ec)65 void handle_write(const boost::system::error_code& ec)
66 {
67 if (!ec)
68 {
69 // Wait for request.
70 socket_.async_read_some(boost::asio::buffer(data_),
71 boost::bind(&uppercase_filter::handle_read,
72 this, boost::asio::placeholders::error,
73 boost::asio::placeholders::bytes_transferred));
74 }
75 else
76 {
77 throw boost::system::system_error(ec);
78 }
79 }
80
81 stream_protocol::socket socket_;
82 boost::array<char, 512> data_;
83 };
84
run(boost::asio::io_context * io_context)85 void run(boost::asio::io_context* io_context)
86 {
87 try
88 {
89 io_context->run();
90 }
91 catch (std::exception& e)
92 {
93 std::cerr << "Exception in thread: " << e.what() << "\n";
94 std::exit(1);
95 }
96 }
97
main()98 int main()
99 {
100 try
101 {
102 boost::asio::io_context io_context;
103
104 // Create filter and establish a connection to it.
105 uppercase_filter filter(io_context);
106 stream_protocol::socket socket(io_context);
107 boost::asio::local::connect_pair(socket, filter.socket());
108 filter.start();
109
110 // The io_context runs in a background thread to perform filtering.
111 boost::thread thread(boost::bind(run, &io_context));
112
113 for (;;)
114 {
115 // Collect request from user.
116 std::cout << "Enter a string: ";
117 std::string request;
118 std::getline(std::cin, request);
119
120 // Send request to filter.
121 boost::asio::write(socket, boost::asio::buffer(request));
122
123 // Wait for reply from filter.
124 std::vector<char> reply(request.size());
125 boost::asio::read(socket, boost::asio::buffer(reply));
126
127 // Show reply to user.
128 std::cout << "Result: ";
129 std::cout.write(&reply[0], request.size());
130 std::cout << std::endl;
131 }
132 }
133 catch (std::exception& e)
134 {
135 std::cerr << "Exception: " << e.what() << "\n";
136 std::exit(1);
137 }
138 }
139
140 #else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
141 # error Local sockets not available on this platform.
142 #endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
143