1 //
2 // reference_counted.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 <boost/asio.hpp>
12 #include <iostream>
13 #include <memory>
14 #include <utility>
15 #include <vector>
16 #include <ctime>
17
18 using boost::asio::ip::tcp;
19
20 // A reference-counted non-modifiable buffer class.
21 class shared_const_buffer
22 {
23 public:
24 // Construct from a std::string.
shared_const_buffer(const std::string & data)25 explicit shared_const_buffer(const std::string& data)
26 : data_(new std::vector<char>(data.begin(), data.end())),
27 buffer_(boost::asio::buffer(*data_))
28 {
29 }
30
31 // Implement the ConstBufferSequence requirements.
32 typedef boost::asio::const_buffer value_type;
33 typedef const boost::asio::const_buffer* const_iterator;
begin() const34 const boost::asio::const_buffer* begin() const { return &buffer_; }
end() const35 const boost::asio::const_buffer* end() const { return &buffer_ + 1; }
36
37 private:
38 std::shared_ptr<std::vector<char> > data_;
39 boost::asio::const_buffer buffer_;
40 };
41
42 class session
43 : public std::enable_shared_from_this<session>
44 {
45 public:
session(tcp::socket socket)46 session(tcp::socket socket)
47 : socket_(std::move(socket))
48 {
49 }
50
start()51 void start()
52 {
53 do_write();
54 }
55
56 private:
do_write()57 void do_write()
58 {
59 std::time_t now = std::time(0);
60 shared_const_buffer buffer(std::ctime(&now));
61
62 auto self(shared_from_this());
63 boost::asio::async_write(socket_, buffer,
64 [self](boost::system::error_code /*ec*/, std::size_t /*length*/)
65 {
66 });
67 }
68
69 // The socket used to communicate with the client.
70 tcp::socket socket_;
71 };
72
73 class server
74 {
75 public:
server(boost::asio::io_context & io_context,short port)76 server(boost::asio::io_context& io_context, short port)
77 : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
78 {
79 do_accept();
80 }
81
82 private:
do_accept()83 void do_accept()
84 {
85 acceptor_.async_accept(
86 [this](boost::system::error_code ec, tcp::socket socket)
87 {
88 if (!ec)
89 {
90 std::make_shared<session>(std::move(socket))->start();
91 }
92
93 do_accept();
94 });
95 }
96
97 tcp::acceptor acceptor_;
98 };
99
main(int argc,char * argv[])100 int main(int argc, char* argv[])
101 {
102 try
103 {
104 if (argc != 2)
105 {
106 std::cerr << "Usage: reference_counted <port>\n";
107 return 1;
108 }
109
110 boost::asio::io_context io_context;
111
112 server s(io_context, std::atoi(argv[1]));
113
114 io_context.run();
115 }
116 catch (std::exception& e)
117 {
118 std::cerr << "Exception: " << e.what() << "\n";
119 }
120
121 return 0;
122 }
123