1 | // |
2 | // buffered_read_stream.hpp |
3 | // ~~~~~~~~~~~~~~~~~~~~~~~~ |
4 | // |
5 | // Copyright (c) 2003-2024 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 | namespace detail { |
35 | |
36 | template <typename> class initiate_async_buffered_fill; |
37 | template <typename> class initiate_async_buffered_read_some; |
38 | |
39 | } // namespace detail |
40 | |
41 | /// Adds buffering to the read-related operations of a stream. |
42 | /** |
43 | * The buffered_read_stream class template can be used to add buffering to the |
44 | * synchronous and asynchronous read operations of a stream. |
45 | * |
46 | * @par Thread Safety |
47 | * @e Distinct @e objects: Safe.@n |
48 | * @e Shared @e objects: Unsafe. |
49 | * |
50 | * @par Concepts: |
51 | * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream. |
52 | */ |
53 | template <typename Stream> |
54 | class buffered_read_stream |
55 | : private noncopyable |
56 | { |
57 | public: |
58 | /// The type of the next layer. |
59 | typedef remove_reference_t<Stream> next_layer_type; |
60 | |
61 | /// The type of the lowest layer. |
62 | typedef typename next_layer_type::lowest_layer_type lowest_layer_type; |
63 | |
64 | /// The type of the executor associated with the object. |
65 | typedef typename lowest_layer_type::executor_type executor_type; |
66 | |
67 | #if defined(GENERATING_DOCUMENTATION) |
68 | /// The default buffer size. |
69 | static const std::size_t default_buffer_size = implementation_defined; |
70 | #else |
71 | BOOST_ASIO_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024); |
72 | #endif |
73 | |
74 | /// Construct, passing the specified argument to initialise the next layer. |
75 | template <typename Arg> |
76 | explicit buffered_read_stream(Arg&& a) |
77 | : next_layer_(static_cast<Arg&&>(a)), |
78 | storage_(default_buffer_size) |
79 | { |
80 | } |
81 | |
82 | /// Construct, passing the specified argument to initialise the next layer. |
83 | template <typename Arg> |
84 | buffered_read_stream(Arg&& a, |
85 | std::size_t buffer_size) |
86 | : next_layer_(static_cast<Arg&&>(a)), |
87 | storage_(buffer_size) |
88 | { |
89 | } |
90 | |
91 | /// Get a reference to the next layer. |
92 | next_layer_type& next_layer() |
93 | { |
94 | return next_layer_; |
95 | } |
96 | |
97 | /// Get a reference to the lowest layer. |
98 | lowest_layer_type& lowest_layer() |
99 | { |
100 | return next_layer_.lowest_layer(); |
101 | } |
102 | |
103 | /// Get a const reference to the lowest layer. |
104 | const lowest_layer_type& lowest_layer() const |
105 | { |
106 | return next_layer_.lowest_layer(); |
107 | } |
108 | |
109 | /// Get the executor associated with the object. |
110 | executor_type get_executor() noexcept |
111 | { |
112 | return next_layer_.lowest_layer().get_executor(); |
113 | } |
114 | |
115 | /// Close the stream. |
116 | void close() |
117 | { |
118 | next_layer_.close(); |
119 | } |
120 | |
121 | /// Close the stream. |
122 | BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec) |
123 | { |
124 | next_layer_.close(ec); |
125 | BOOST_ASIO_SYNC_OP_VOID_RETURN(ec); |
126 | } |
127 | |
128 | /// Write the given data to the stream. Returns the number of bytes written. |
129 | /// Throws an exception on failure. |
130 | template <typename ConstBufferSequence> |
131 | std::size_t write_some(const ConstBufferSequence& buffers) |
132 | { |
133 | return next_layer_.write_some(buffers); |
134 | } |
135 | |
136 | /// Write the given data to the stream. Returns the number of bytes written, |
137 | /// or 0 if an error occurred. |
138 | template <typename ConstBufferSequence> |
139 | std::size_t write_some(const ConstBufferSequence& buffers, |
140 | boost::system::error_code& ec) |
141 | { |
142 | return next_layer_.write_some(buffers, ec); |
143 | } |
144 | |
145 | /// Start an asynchronous write. The data being written must be valid for the |
146 | /// lifetime of the asynchronous operation. |
147 | /** |
148 | * @par Completion Signature |
149 | * @code void(boost::system::error_code, std::size_t) @endcode |
150 | */ |
151 | template <typename ConstBufferSequence, |
152 | BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, |
153 | std::size_t)) WriteHandler = default_completion_token_t<executor_type>> |
154 | auto async_write_some(const ConstBufferSequence& buffers, |
155 | WriteHandler&& handler = default_completion_token_t<executor_type>()) |
156 | -> decltype( |
157 | declval<conditional_t<true, Stream&, WriteHandler>>().async_write_some( |
158 | buffers, static_cast<WriteHandler&&>(handler))) |
159 | { |
160 | return next_layer_.async_write_some(buffers, |
161 | static_cast<WriteHandler&&>(handler)); |
162 | } |
163 | |
164 | /// Fill the buffer with some data. Returns the number of bytes placed in the |
165 | /// buffer as a result of the operation. Throws an exception on failure. |
166 | std::size_t fill(); |
167 | |
168 | /// Fill the buffer with some data. Returns the number of bytes placed in the |
169 | /// buffer as a result of the operation, or 0 if an error occurred. |
170 | std::size_t fill(boost::system::error_code& ec); |
171 | |
172 | /// Start an asynchronous fill. |
173 | /** |
174 | * @par Completion Signature |
175 | * @code void(boost::system::error_code, std::size_t) @endcode |
176 | */ |
177 | template < |
178 | BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, |
179 | std::size_t)) ReadHandler = default_completion_token_t<executor_type>> |
180 | auto async_fill( |
181 | ReadHandler&& handler = default_completion_token_t<executor_type>()) |
182 | -> decltype( |
183 | async_initiate<ReadHandler, |
184 | void (boost::system::error_code, std::size_t)>( |
185 | declval<detail::initiate_async_buffered_fill<Stream>>(), |
186 | handler, declval<detail::buffered_stream_storage*>())); |
187 | |
188 | /// Read some data from the stream. Returns the number of bytes read. Throws |
189 | /// an exception on failure. |
190 | template <typename MutableBufferSequence> |
191 | std::size_t read_some(const MutableBufferSequence& buffers); |
192 | |
193 | /// Read some data from the stream. Returns the number of bytes read or 0 if |
194 | /// an error occurred. |
195 | template <typename MutableBufferSequence> |
196 | std::size_t read_some(const MutableBufferSequence& buffers, |
197 | boost::system::error_code& ec); |
198 | |
199 | /// Start an asynchronous read. The buffer into which the data will be read |
200 | /// must be valid for the lifetime of the asynchronous operation. |
201 | /** |
202 | * @par Completion Signature |
203 | * @code void(boost::system::error_code, std::size_t) @endcode |
204 | */ |
205 | template <typename MutableBufferSequence, |
206 | BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code, |
207 | std::size_t)) ReadHandler = default_completion_token_t<executor_type>> |
208 | auto async_read_some(const MutableBufferSequence& buffers, |
209 | ReadHandler&& handler = default_completion_token_t<executor_type>()) |
210 | -> decltype( |
211 | async_initiate<ReadHandler, |
212 | void (boost::system::error_code, std::size_t)>( |
213 | declval<detail::initiate_async_buffered_read_some<Stream>>(), |
214 | handler, declval<detail::buffered_stream_storage*>(), buffers)); |
215 | |
216 | /// Peek at the incoming data on the stream. Returns the number of bytes read. |
217 | /// Throws an exception on failure. |
218 | template <typename MutableBufferSequence> |
219 | std::size_t peek(const MutableBufferSequence& buffers); |
220 | |
221 | /// Peek at the incoming data on the stream. Returns the number of bytes read, |
222 | /// or 0 if an error occurred. |
223 | template <typename MutableBufferSequence> |
224 | std::size_t peek(const MutableBufferSequence& buffers, |
225 | boost::system::error_code& ec); |
226 | |
227 | /// Determine the amount of data that may be read without blocking. |
228 | std::size_t in_avail() |
229 | { |
230 | return storage_.size(); |
231 | } |
232 | |
233 | /// Determine the amount of data that may be read without blocking. |
234 | std::size_t in_avail(boost::system::error_code& ec) |
235 | { |
236 | ec = boost::system::error_code(); |
237 | return storage_.size(); |
238 | } |
239 | |
240 | private: |
241 | /// Copy data out of the internal buffer to the specified target buffer. |
242 | /// Returns the number of bytes copied. |
243 | template <typename MutableBufferSequence> |
244 | std::size_t copy(const MutableBufferSequence& buffers) |
245 | { |
246 | std::size_t bytes_copied = boost::asio::buffer_copy( |
247 | buffers, storage_.data(), storage_.size()); |
248 | storage_.consume(count: bytes_copied); |
249 | return bytes_copied; |
250 | } |
251 | |
252 | /// Copy data from the internal buffer to the specified target buffer, without |
253 | /// removing the data from the internal buffer. Returns the number of bytes |
254 | /// copied. |
255 | template <typename MutableBufferSequence> |
256 | std::size_t peek_copy(const MutableBufferSequence& buffers) |
257 | { |
258 | return boost::asio::buffer_copy(buffers, storage_.data(), storage_.size()); |
259 | } |
260 | |
261 | /// The next layer. |
262 | Stream next_layer_; |
263 | |
264 | // The data in the buffer. |
265 | detail::buffered_stream_storage storage_; |
266 | }; |
267 | |
268 | } // namespace asio |
269 | } // namespace boost |
270 | |
271 | #include <boost/asio/detail/pop_options.hpp> |
272 | |
273 | #include <boost/asio/impl/buffered_read_stream.hpp> |
274 | |
275 | #endif // BOOST_ASIO_BUFFERED_READ_STREAM_HPP |
276 | |