ceph/src/boost/libs/asio/example/cpp03/allocation/server.cpp

   1 //
   2 // server.cpp
   3 // ~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 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 <cstdlib>
  12 #include <iostream>
  13 #include <boost/aligned_storage.hpp>
  14 #include <boost/array.hpp>
  15 #include <boost/bind.hpp>
  16 #include <boost/enable_shared_from_this.hpp>
  17 #include <boost/noncopyable.hpp>
  18 #include <boost/shared_ptr.hpp>
  19 #include <boost/asio.hpp>
  20
  21 using boost::asio::ip::tcp;
  22
  23 // Class to manage the memory to be used for handler-based custom allocation.
  24 // It contains a single block of memory which may be returned for allocation
  25 // requests. If the memory is in use when an allocation request is made, the
  26 // allocator delegates allocation to the global heap.
  27 class handler_memory
  28   : private boost::noncopyable
  29 {
  30 public:
  31   handler_memory()
  32     : in_use_(false)
  33   {
  34   }
  35
  36   void* allocate(std::size_t size)
  37   {
  38     if (!in_use_ && size < storage_.size)
  39     {
  40       in_use_ = true;
  41       return storage_.address();
  42     }
  43     else
  44     {
  45       return ::operator new(size);
  46     }
  47   }
  48
  49   void deallocate(void* pointer)
  50   {
  51     if (pointer == storage_.address())
  52     {
  53       in_use_ = false;
  54     }
  55     else
  56     {
  57       ::operator delete(pointer);
  58     }
  59   }
  60
  61 private:
  62   // Storage space used for handler-based custom memory allocation.
  63   boost::aligned_storage<1024> storage_;
  64
  65   // Whether the handler-based custom allocation storage has been used.
  66   bool in_use_;
  67 };
  68
  69 // The allocator to be associated with the handler objects. This allocator only
  70 // needs to satisfy the C++11 minimal allocator requirements, plus rebind when
  71 // targeting C++03.
  72 template <typename T>
  73 class handler_allocator
  74 {
  75 public:
  76   typedef T value_type;
  77
  78   explicit handler_allocator(handler_memory& mem)
  79     : memory_(mem)
  80   {
  81   }
  82
  83   template <typename U>
  84   handler_allocator(const handler_allocator<U>& other)
  85     : memory_(other.memory_)
  86   {
  87   }
  88
  89   template <typename U>
  90   struct rebind
  91   {
  92     typedef handler_allocator<U> other;
  93   };
  94
  95   bool operator==(const handler_allocator& other) const
  96   {
  97     return &memory_ == &other.memory_;
  98   }
  99
 100   bool operator!=(const handler_allocator& other) const
 101   {
 102     return &memory_ != &other.memory_;
 103   }
 104
 105   T* allocate(std::size_t n) const
 106   {
 107     return static_cast<T*>(memory_.allocate(sizeof(T) * n));
 108   }
 109
 110   void deallocate(T* p, std::size_t /*n*/) const
 111   {
 112     return memory_.deallocate(p);
 113   }
 114
 115 //private:
 116   // The underlying memory.
 117   handler_memory& memory_;
 118 };
 119
 120 // Wrapper class template for handler objects to allow handler memory
 121 // allocation to be customised. The allocator_type typedef and get_allocator()
 122 // member function are used by the asynchronous operations to obtain the
 123 // allocator. Calls to operator() are forwarded to the encapsulated handler.
 124 template <typename Handler>
 125 class custom_alloc_handler
 126 {
 127 public:
 128   typedef handler_allocator<Handler> allocator_type;
 129
 130   custom_alloc_handler(handler_memory& m, Handler h)
 131     : memory_(m),
 132       handler_(h)
 133   {
 134   }
 135
 136   allocator_type get_allocator() const
 137   {
 138     return allocator_type(memory_);
 139   }
 140
 141   template <typename Arg1>
 142   void operator()(Arg1 arg1)
 143   {
 144     handler_(arg1);
 145   }
 146
 147   template <typename Arg1, typename Arg2>
 148   void operator()(Arg1 arg1, Arg2 arg2)
 149   {
 150     handler_(arg1, arg2);
 151   }
 152
 153 private:
 154   handler_memory& memory_;
 155   Handler handler_;
 156 };
 157
 158 // Helper function to wrap a handler object to add custom allocation.
 159 template <typename Handler>
 160 inline custom_alloc_handler<Handler> make_custom_alloc_handler(
 161     handler_memory& m, Handler h)
 162 {
 163   return custom_alloc_handler<Handler>(m, h);
 164 }
 165
 166 class session
 167   : public boost::enable_shared_from_this<session>
 168 {
 169 public:
 170   session(boost::asio::io_context& io_context)
 171     : socket_(io_context)
 172   {
 173   }
 174
 175   tcp::socket& socket()
 176   {
 177     return socket_;
 178   }
 179
 180   void start()
 181   {
 182     socket_.async_read_some(boost::asio::buffer(data_),
 183         make_custom_alloc_handler(handler_memory_,
 184           boost::bind(&session::handle_read,
 185             shared_from_this(),
 186             boost::asio::placeholders::error,
 187             boost::asio::placeholders::bytes_transferred)));
 188   }
 189
 190   void handle_read(const boost::system::error_code& error,
 191       size_t bytes_transferred)
 192   {
 193     if (!error)
 194     {
 195       boost::asio::async_write(socket_,
 196           boost::asio::buffer(data_, bytes_transferred),
 197           make_custom_alloc_handler(handler_memory_,
 198             boost::bind(&session::handle_write,
 199               shared_from_this(),
 200               boost::asio::placeholders::error)));
 201     }
 202   }
 203
 204   void handle_write(const boost::system::error_code& error)
 205   {
 206     if (!error)
 207     {
 208       socket_.async_read_some(boost::asio::buffer(data_),
 209           make_custom_alloc_handler(handler_memory_,
 210             boost::bind(&session::handle_read,
 211               shared_from_this(),
 212               boost::asio::placeholders::error,
 213               boost::asio::placeholders::bytes_transferred)));
 214     }
 215   }
 216
 217 private:
 218   // The socket used to communicate with the client.
 219   tcp::socket socket_;
 220
 221   // Buffer used to store data received from the client.
 222   boost::array<char, 1024> data_;
 223
 224   // The memory to use for handler-based custom memory allocation.
 225   handler_memory handler_memory_;
 226 };
 227
 228 typedef boost::shared_ptr<session> session_ptr;
 229
 230 class server
 231 {
 232 public:
 233   server(boost::asio::io_context& io_context, short port)
 234     : io_context_(io_context),
 235       acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
 236   {
 237     session_ptr new_session(new session(io_context_));
 238     acceptor_.async_accept(new_session->socket(),
 239         boost::bind(&server::handle_accept, this, new_session,
 240           boost::asio::placeholders::error));
 241   }
 242
 243   void handle_accept(session_ptr new_session,
 244       const boost::system::error_code& error)
 245   {
 246     if (!error)
 247     {
 248       new_session->start();
 249     }
 250
 251     new_session.reset(new session(io_context_));
 252     acceptor_.async_accept(new_session->socket(),
 253         boost::bind(&server::handle_accept, this, new_session,
 254           boost::asio::placeholders::error));
 255   }
 256
 257 private:
 258   boost::asio::io_context& io_context_;
 259   tcp::acceptor acceptor_;
 260 };
 261
 262 int main(int argc, char* argv[])
 263 {
 264   try
 265   {
 266     if (argc != 2)
 267     {
 268       std::cerr << "Usage: server <port>\n";
 269       return 1;
 270     }
 271
 272     boost::asio::io_context io_context;
 273
 274     using namespace std; // For atoi.
 275     server s(io_context, atoi(argv[1]));
 276
 277     io_context.run();
 278   }
 279   catch (std::exception& e)
 280   {
 281     std::cerr << "Exception: " << e.what() << "\n";
 282   }
 283
 284   return 0;
 285 }