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buffered_read_stream.hpp 7.3KB

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  1. //
  2. // buffered_read_stream.hpp
  3. // ~~~~~~~~~~~~~~~~~~~~~~~~
  4. //
  5. // Copyright (c) 2003-2019 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. #ifndef ASIO_BUFFERED_READ_STREAM_HPP
  11. #define ASIO_BUFFERED_READ_STREAM_HPP
  12. #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  13. # pragma once
  14. #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  15. #include "asio/detail/config.hpp"
  16. #include <cstddef>
  17. #include "asio/async_result.hpp"
  18. #include "asio/buffered_read_stream_fwd.hpp"
  19. #include "asio/buffer.hpp"
  20. #include "asio/detail/bind_handler.hpp"
  21. #include "asio/detail/buffer_resize_guard.hpp"
  22. #include "asio/detail/buffered_stream_storage.hpp"
  23. #include "asio/detail/noncopyable.hpp"
  24. #include "asio/detail/type_traits.hpp"
  25. #include "asio/error.hpp"
  26. #include "asio/detail/push_options.hpp"
  27. namespace asio {
  28. /// Adds buffering to the read-related operations of a stream.
  29. /**
  30. * The buffered_read_stream class template can be used to add buffering to the
  31. * synchronous and asynchronous read operations of a stream.
  32. *
  33. * @par Thread Safety
  34. * @e Distinct @e objects: Safe.@n
  35. * @e Shared @e objects: Unsafe.
  36. *
  37. * @par Concepts:
  38. * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
  39. */
  40. template <typename Stream>
  41. class buffered_read_stream
  42. : private noncopyable
  43. {
  44. public:
  45. /// The type of the next layer.
  46. typedef typename remove_reference<Stream>::type next_layer_type;
  47. /// The type of the lowest layer.
  48. typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
  49. /// The type of the executor associated with the object.
  50. typedef typename lowest_layer_type::executor_type executor_type;
  51. #if defined(GENERATING_DOCUMENTATION)
  52. /// The default buffer size.
  53. static const std::size_t default_buffer_size = implementation_defined;
  54. #else
  55. ASIO_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024);
  56. #endif
  57. /// Construct, passing the specified argument to initialise the next layer.
  58. template <typename Arg>
  59. explicit buffered_read_stream(Arg& a)
  60. : next_layer_(a),
  61. storage_(default_buffer_size)
  62. {
  63. }
  64. /// Construct, passing the specified argument to initialise the next layer.
  65. template <typename Arg>
  66. buffered_read_stream(Arg& a, std::size_t buffer_size)
  67. : next_layer_(a),
  68. storage_(buffer_size)
  69. {
  70. }
  71. /// Get a reference to the next layer.
  72. next_layer_type& next_layer()
  73. {
  74. return next_layer_;
  75. }
  76. /// Get a reference to the lowest layer.
  77. lowest_layer_type& lowest_layer()
  78. {
  79. return next_layer_.lowest_layer();
  80. }
  81. /// Get a const reference to the lowest layer.
  82. const lowest_layer_type& lowest_layer() const
  83. {
  84. return next_layer_.lowest_layer();
  85. }
  86. /// Get the executor associated with the object.
  87. executor_type get_executor() ASIO_NOEXCEPT
  88. {
  89. return next_layer_.lowest_layer().get_executor();
  90. }
  91. /// Close the stream.
  92. void close()
  93. {
  94. next_layer_.close();
  95. }
  96. /// Close the stream.
  97. ASIO_SYNC_OP_VOID close(asio::error_code& ec)
  98. {
  99. next_layer_.close(ec);
  100. ASIO_SYNC_OP_VOID_RETURN(ec);
  101. }
  102. /// Write the given data to the stream. Returns the number of bytes written.
  103. /// Throws an exception on failure.
  104. template <typename ConstBufferSequence>
  105. std::size_t write_some(const ConstBufferSequence& buffers)
  106. {
  107. return next_layer_.write_some(buffers);
  108. }
  109. /// Write the given data to the stream. Returns the number of bytes written,
  110. /// or 0 if an error occurred.
  111. template <typename ConstBufferSequence>
  112. std::size_t write_some(const ConstBufferSequence& buffers,
  113. asio::error_code& ec)
  114. {
  115. return next_layer_.write_some(buffers, ec);
  116. }
  117. /// Start an asynchronous write. The data being written must be valid for the
  118. /// lifetime of the asynchronous operation.
  119. template <typename ConstBufferSequence, typename WriteHandler>
  120. ASIO_INITFN_RESULT_TYPE(WriteHandler,
  121. void (asio::error_code, std::size_t))
  122. async_write_some(const ConstBufferSequence& buffers,
  123. ASIO_MOVE_ARG(WriteHandler) handler)
  124. {
  125. return next_layer_.async_write_some(buffers,
  126. ASIO_MOVE_CAST(WriteHandler)(handler));
  127. }
  128. /// Fill the buffer with some data. Returns the number of bytes placed in the
  129. /// buffer as a result of the operation. Throws an exception on failure.
  130. std::size_t fill();
  131. /// Fill the buffer with some data. Returns the number of bytes placed in the
  132. /// buffer as a result of the operation, or 0 if an error occurred.
  133. std::size_t fill(asio::error_code& ec);
  134. /// Start an asynchronous fill.
  135. template <typename ReadHandler>
  136. ASIO_INITFN_RESULT_TYPE(ReadHandler,
  137. void (asio::error_code, std::size_t))
  138. async_fill(ASIO_MOVE_ARG(ReadHandler) handler);
  139. /// Read some data from the stream. Returns the number of bytes read. Throws
  140. /// an exception on failure.
  141. template <typename MutableBufferSequence>
  142. std::size_t read_some(const MutableBufferSequence& buffers);
  143. /// Read some data from the stream. Returns the number of bytes read or 0 if
  144. /// an error occurred.
  145. template <typename MutableBufferSequence>
  146. std::size_t read_some(const MutableBufferSequence& buffers,
  147. asio::error_code& ec);
  148. /// Start an asynchronous read. The buffer into which the data will be read
  149. /// must be valid for the lifetime of the asynchronous operation.
  150. template <typename MutableBufferSequence, typename ReadHandler>
  151. ASIO_INITFN_RESULT_TYPE(ReadHandler,
  152. void (asio::error_code, std::size_t))
  153. async_read_some(const MutableBufferSequence& buffers,
  154. ASIO_MOVE_ARG(ReadHandler) handler);
  155. /// Peek at the incoming data on the stream. Returns the number of bytes read.
  156. /// Throws an exception on failure.
  157. template <typename MutableBufferSequence>
  158. std::size_t peek(const MutableBufferSequence& buffers);
  159. /// Peek at the incoming data on the stream. Returns the number of bytes read,
  160. /// or 0 if an error occurred.
  161. template <typename MutableBufferSequence>
  162. std::size_t peek(const MutableBufferSequence& buffers,
  163. asio::error_code& ec);
  164. /// Determine the amount of data that may be read without blocking.
  165. std::size_t in_avail()
  166. {
  167. return storage_.size();
  168. }
  169. /// Determine the amount of data that may be read without blocking.
  170. std::size_t in_avail(asio::error_code& ec)
  171. {
  172. ec = asio::error_code();
  173. return storage_.size();
  174. }
  175. private:
  176. /// Copy data out of the internal buffer to the specified target buffer.
  177. /// Returns the number of bytes copied.
  178. template <typename MutableBufferSequence>
  179. std::size_t copy(const MutableBufferSequence& buffers)
  180. {
  181. std::size_t bytes_copied = asio::buffer_copy(
  182. buffers, storage_.data(), storage_.size());
  183. storage_.consume(bytes_copied);
  184. return bytes_copied;
  185. }
  186. /// Copy data from the internal buffer to the specified target buffer, without
  187. /// removing the data from the internal buffer. Returns the number of bytes
  188. /// copied.
  189. template <typename MutableBufferSequence>
  190. std::size_t peek_copy(const MutableBufferSequence& buffers)
  191. {
  192. return asio::buffer_copy(buffers, storage_.data(), storage_.size());
  193. }
  194. /// The next layer.
  195. Stream next_layer_;
  196. // The data in the buffer.
  197. detail::buffered_stream_storage storage_;
  198. };
  199. } // namespace asio
  200. #include "asio/detail/pop_options.hpp"
  201. #include "asio/impl/buffered_read_stream.hpp"
  202. #endif // ASIO_BUFFERED_READ_STREAM_HPP