ceph/src/boost/boost/asio/buffered_read_stream.hpp

   1 //
   2 // buffered_read_stream.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2022 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 #ifndef BOOST_ASIO_BUFFERED_READ_STREAM_HPP
  12 #define BOOST_ASIO_BUFFERED_READ_STREAM_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/config.hpp>
  19 #include <cstddef>
  20 #include <boost/asio/async_result.hpp>
  21 #include <boost/asio/buffered_read_stream_fwd.hpp>
  22 #include <boost/asio/buffer.hpp>
  23 #include <boost/asio/detail/bind_handler.hpp>
  24 #include <boost/asio/detail/buffer_resize_guard.hpp>
  25 #include <boost/asio/detail/buffered_stream_storage.hpp>
  26 #include <boost/asio/detail/noncopyable.hpp>
  27 #include <boost/asio/detail/type_traits.hpp>
  28 #include <boost/asio/error.hpp>
  29
  30 #include <boost/asio/detail/push_options.hpp>
  31
  32 namespace boost {
  33 namespace asio {
  34
  35 /// Adds buffering to the read-related operations of a stream.
  36 /**
  37  * The buffered_read_stream class template can be used to add buffering to the
  38  * synchronous and asynchronous read operations of a stream.
  39  *
  40  * @par Thread Safety
  41  * @e Distinct @e objects: Safe.@n
  42  * @e Shared @e objects: Unsafe.
  43  *
  44  * @par Concepts:
  45  * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
  46  */
  47 template <typename Stream>
  48 class buffered_read_stream
  49   : private noncopyable
  50 {
  51 public:
  52   /// The type of the next layer.
  53   typedef typename remove_reference<Stream>::type next_layer_type;
  54
  55   /// The type of the lowest layer.
  56   typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
  57
  58   /// The type of the executor associated with the object.
  59   typedef typename lowest_layer_type::executor_type executor_type;
  60
  61 #if defined(GENERATING_DOCUMENTATION)
  62   /// The default buffer size.
  63   static const std::size_t default_buffer_size = implementation_defined;
  64 #else
  65   BOOST_ASIO_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024);
  66 #endif
  67
  68   /// Construct, passing the specified argument to initialise the next layer.
  69   template <typename Arg>
  70   explicit buffered_read_stream(Arg& a)
  71     : next_layer_(a),
  72       storage_(default_buffer_size)
  73   {
  74   }
  75
  76   /// Construct, passing the specified argument to initialise the next layer.
  77   template <typename Arg>
  78   buffered_read_stream(Arg& a, std::size_t buffer_size)
  79     : next_layer_(a),
  80       storage_(buffer_size)
  81   {
  82   }
  83
  84   /// Get a reference to the next layer.
  85   next_layer_type& next_layer()
  86   {
  87     return next_layer_;
  88   }
  89
  90   /// Get a reference to the lowest layer.
  91   lowest_layer_type& lowest_layer()
  92   {
  93     return next_layer_.lowest_layer();
  94   }
  95
  96   /// Get a const reference to the lowest layer.
  97   const lowest_layer_type& lowest_layer() const
  98   {
  99     return next_layer_.lowest_layer();
 100   }
 101
 102   /// Get the executor associated with the object.
 103   executor_type get_executor() BOOST_ASIO_NOEXCEPT
 104   {
 105     return next_layer_.lowest_layer().get_executor();
 106   }
 107
 108   /// Close the stream.
 109   void close()
 110   {
 111     next_layer_.close();
 112   }
 113
 114   /// Close the stream.
 115   BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
 116   {
 117     next_layer_.close(ec);
 118     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 119   }
 120
 121   /// Write the given data to the stream. Returns the number of bytes written.
 122   /// Throws an exception on failure.
 123   template <typename ConstBufferSequence>
 124   std::size_t write_some(const ConstBufferSequence& buffers)
 125   {
 126     return next_layer_.write_some(buffers);
 127   }
 128
 129   /// Write the given data to the stream. Returns the number of bytes written,
 130   /// or 0 if an error occurred.
 131   template <typename ConstBufferSequence>
 132   std::size_t write_some(const ConstBufferSequence& buffers,
 133       boost::system::error_code& ec)
 134   {
 135     return next_layer_.write_some(buffers, ec);
 136   }
 137
 138   /// Start an asynchronous write. The data being written must be valid for the
 139   /// lifetime of the asynchronous operation.
 140   /**
 141    * @par Completion Signature
 142    * @code void(boost::system::error_code, std::size_t) @endcode
 143    */
 144   template <typename ConstBufferSequence,
 145       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
 146         std::size_t)) WriteHandler
 147           BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)>
 148   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(WriteHandler,
 149       void (boost::system::error_code, std::size_t))
 150   async_write_some(const ConstBufferSequence& buffers,
 151       BOOST_ASIO_MOVE_ARG(WriteHandler) handler
 152         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(executor_type))
 153   {
 154     return next_layer_.async_write_some(buffers,
 155         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
 156   }
 157
 158   /// Fill the buffer with some data. Returns the number of bytes placed in the
 159   /// buffer as a result of the operation. Throws an exception on failure.
 160   std::size_t fill();
 161
 162   /// Fill the buffer with some data. Returns the number of bytes placed in the
 163   /// buffer as a result of the operation, or 0 if an error occurred.
 164   std::size_t fill(boost::system::error_code& ec);
 165
 166   /// Start an asynchronous fill.
 167   /**
 168    * @par Completion Signature
 169    * @code void(boost::system::error_code, std::size_t) @endcode
 170    */
 171   template <
 172       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
 173         std::size_t)) ReadHandler
 174           BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)>
 175   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
 176       void (boost::system::error_code, std::size_t))
 177   async_fill(
 178       BOOST_ASIO_MOVE_ARG(ReadHandler) handler
 179         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(executor_type));
 180
 181   /// Read some data from the stream. Returns the number of bytes read. Throws
 182   /// an exception on failure.
 183   template <typename MutableBufferSequence>
 184   std::size_t read_some(const MutableBufferSequence& buffers);
 185
 186   /// Read some data from the stream. Returns the number of bytes read or 0 if
 187   /// an error occurred.
 188   template <typename MutableBufferSequence>
 189   std::size_t read_some(const MutableBufferSequence& buffers,
 190       boost::system::error_code& ec);
 191
 192   /// Start an asynchronous read. The buffer into which the data will be read
 193   /// must be valid for the lifetime of the asynchronous operation.
 194   /**
 195    * @par Completion Signature
 196    * @code void(boost::system::error_code, std::size_t) @endcode
 197    */
 198   template <typename MutableBufferSequence,
 199       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
 200         std::size_t)) ReadHandler
 201           BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(executor_type)>
 202   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
 203       void (boost::system::error_code, std::size_t))
 204   async_read_some(const MutableBufferSequence& buffers,
 205       BOOST_ASIO_MOVE_ARG(ReadHandler) handler
 206         BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(executor_type));
 207
 208   /// Peek at the incoming data on the stream. Returns the number of bytes read.
 209   /// Throws an exception on failure.
 210   template <typename MutableBufferSequence>
 211   std::size_t peek(const MutableBufferSequence& buffers);
 212
 213   /// Peek at the incoming data on the stream. Returns the number of bytes read,
 214   /// or 0 if an error occurred.
 215   template <typename MutableBufferSequence>
 216   std::size_t peek(const MutableBufferSequence& buffers,
 217       boost::system::error_code& ec);
 218
 219   /// Determine the amount of data that may be read without blocking.
 220   std::size_t in_avail()
 221   {
 222     return storage_.size();
 223   }
 224
 225   /// Determine the amount of data that may be read without blocking.
 226   std::size_t in_avail(boost::system::error_code& ec)
 227   {
 228     ec = boost::system::error_code();
 229     return storage_.size();
 230   }
 231
 232 private:
 233   /// Copy data out of the internal buffer to the specified target buffer.
 234   /// Returns the number of bytes copied.
 235   template <typename MutableBufferSequence>
 236   std::size_t copy(const MutableBufferSequence& buffers)
 237   {
 238     std::size_t bytes_copied = boost::asio::buffer_copy(
 239         buffers, storage_.data(), storage_.size());
 240     storage_.consume(bytes_copied);
 241     return bytes_copied;
 242   }
 243
 244   /// Copy data from the internal buffer to the specified target buffer, without
 245   /// removing the data from the internal buffer. Returns the number of bytes
 246   /// copied.
 247   template <typename MutableBufferSequence>
 248   std::size_t peek_copy(const MutableBufferSequence& buffers)
 249   {
 250     return boost::asio::buffer_copy(buffers, storage_.data(), storage_.size());
 251   }
 252
 253   /// The next layer.
 254   Stream next_layer_;
 255
 256   // The data in the buffer.
 257   detail::buffered_stream_storage storage_;
 258 };
 259
 260 } // namespace asio
 261 } // namespace boost
 262
 263 #include <boost/asio/detail/pop_options.hpp>
 264
 265 #include <boost/asio/impl/buffered_read_stream.hpp>
 266
 267 #endif // BOOST_ASIO_BUFFERED_READ_STREAM_HPP