5 // Copyright (c) 2003-2014 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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)
15 #include <type_traits>
17 #include <boost/asio.hpp>
19 using boost::asio::ip::tcp;
21 // Class to manage the memory to be used for handler-based custom allocation.
22 // It contains a single block of memory which may be returned for allocation
23 // requests. If the memory is in use when an allocation request is made, the
24 // allocator delegates allocation to the global heap.
25 class handler_allocator
33 handler_allocator(const handler_allocator&) = delete;
34 handler_allocator& operator=(const handler_allocator&) = delete;
36 void* allocate(std::size_t size)
38 if (!in_use_ && size < sizeof(storage_))
45 return ::operator new(size);
49 void deallocate(void* pointer)
51 if (pointer == &storage_)
57 ::operator delete(pointer);
62 // Storage space used for handler-based custom memory allocation.
63 typename std::aligned_storage<1024>::type storage_;
65 // Whether the handler-based custom allocation storage has been used.
69 // Wrapper class template for handler objects to allow handler memory
70 // allocation to be customised. Calls to operator() are forwarded to the
71 // encapsulated handler.
72 template <typename Handler>
73 class custom_alloc_handler
76 custom_alloc_handler(handler_allocator& a, Handler h)
82 template <typename ...Args>
83 void operator()(Args&&... args)
85 handler_(std::forward<Args>(args)...);
88 friend void* asio_handler_allocate(std::size_t size,
89 custom_alloc_handler<Handler>* this_handler)
91 return this_handler->allocator_.allocate(size);
94 friend void asio_handler_deallocate(void* pointer, std::size_t /*size*/,
95 custom_alloc_handler<Handler>* this_handler)
97 this_handler->allocator_.deallocate(pointer);
101 handler_allocator& allocator_;
105 // Helper function to wrap a handler object to add custom allocation.
106 template <typename Handler>
107 inline custom_alloc_handler<Handler> make_custom_alloc_handler(
108 handler_allocator& a, Handler h)
110 return custom_alloc_handler<Handler>(a, h);
114 : public std::enable_shared_from_this<session>
117 session(tcp::socket socket)
118 : socket_(std::move(socket))
130 auto self(shared_from_this());
131 socket_.async_read_some(boost::asio::buffer(data_),
132 make_custom_alloc_handler(allocator_,
133 [this, self](boost::system::error_code ec, std::size_t length)
142 void do_write(std::size_t length)
144 auto self(shared_from_this());
145 boost::asio::async_write(socket_, boost::asio::buffer(data_, length),
146 make_custom_alloc_handler(allocator_,
147 [this, self](boost::system::error_code ec, std::size_t /*length*/)
156 // The socket used to communicate with the client.
159 // Buffer used to store data received from the client.
160 std::array<char, 1024> data_;
162 // The allocator to use for handler-based custom memory allocation.
163 handler_allocator allocator_;
169 server(boost::asio::io_service& io_service, short port)
170 : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
179 acceptor_.async_accept(socket_,
180 [this](boost::system::error_code ec)
184 std::make_shared<session>(std::move(socket_))->start();
191 tcp::acceptor acceptor_;
195 int main(int argc, char* argv[])
201 std::cerr << "Usage: server <port>\n";
205 boost::asio::io_service io_service;
206 server s(io_service, std::atoi(argv[1]));
209 catch (std::exception& e)
211 std::cerr << "Exception: " << e.what() << "\n";