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include/boost/capy/read.hpp

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read.hpp
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boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::contingent_read_stream, boost::capy::mutable_buffer>(boost::capy::contingent_read_stream&, boost::capy::mutable_buffer) :95 4x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::mutable_buffer>(boost::capy::test::read_stream&, boost::capy::mutable_buffer) :95 22x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, std::array<boost::capy::mutable_buffer, 2ul> >(boost::capy::test::read_stream&, std::array<boost::capy::mutable_buffer, 2ul>) :95 34x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::stream, boost::capy::mutable_buffer>(boost::capy::test::stream&, boost::capy::mutable_buffer) :95 38x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&>(boost::capy::test::read_stream&, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&, unsigned long) :171 50x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::circular_dynamic_buffer&>(boost::capy::test::read_stream&, boost::capy::circular_dynamic_buffer&, unsigned long) :171 30x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_source, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&>(boost::capy::test::read_source&, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&, unsigned long) :252 30x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_source, boost::capy::circular_dynamic_buffer&>(boost::capy::test::read_source&, boost::capy::circular_dynamic_buffer&, unsigned long) :252 24x 100.0% 44.0%
Line TLA Hits Source Code
1 //
2 // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // Official repository: https://github.com/cppalliance/capy
8 //
9
10 #ifndef BOOST_CAPY_READ_HPP
11 #define BOOST_CAPY_READ_HPP
12
13 #include <boost/capy/detail/config.hpp>
14 #include <boost/capy/cond.hpp>
15 #include <boost/capy/io_task.hpp>
16 #include <boost/capy/buffers.hpp>
17 #include <boost/capy/buffers/buffer_slice.hpp>
18 #include <boost/capy/concept/dynamic_buffer.hpp>
19 #include <boost/capy/concept/read_source.hpp>
20 #include <boost/capy/concept/read_stream.hpp>
21 #include <system_error>
22
23 #include <cstddef>
24
25 namespace boost {
26 namespace capy {
27
28 /** Read data from a stream until the buffer sequence is full.
29
30 @par Await-effects
31
32 Reads data from `stream` via awaiting `stream.read_some` repeatedly
33 until:
34
35 @li either the entire buffer sequence @c buffers is filled,
36 @li or a contingency occurs.
37
38 If `buffer_size(buffers) == 0` then no awaiting `stream.read_some`
39 is performed. This is not a contingency.
40
41 @par Await-returns
42 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
43
44 Upon a contingency, `n` represents the number of bytes read so far,
45 inclusive of the last partial read.
46
47 Contingencies:
48
49 @li The first contingency reported from awaiting @c stream.read_some
50 while `buffers` is not yet filled. A contingency that accompanies
51 the read which fills `buffers` is not reported: a completed
52 transfer is a success.
53
54 Notable conditions:
55
56 @li @c cond::canceled — Operation was cancelled,
57 @li @c cond::eof — Stream reached end before `buffers` was filled.
58
59 @par Await-postcondition
60 If `n == buffer_size(buffers)` the transfer completed and `ec` is
61 success; otherwise `ec` is set.
62
63 @param stream The stream to read from. If the lifetime of `stream` ends
64 before the coroutine finishes, the behavior is undefined.
65
66 @param buffers The buffer sequence to fill. If the lifetime of the buffer
67 sequence represented by `buffers` ends before the coroutine finishes, the behavior is undefined.
68
69
70 @par Remarks
71 Supports _IoAwaitable cancellation_.
72
73
74 @par Example
75
76 @code
77 capy::task<> process_message(capy::ReadStream auto& stream)
78 {
79 std::vector<char> header(16); // known header size for some protocol
80 auto [ec, n] = co_await capy::read(stream, capy::mutable_buffer(header));
81 if (ec == capy::cond::eof)
82 co_return; // Connection closed
83 if (ec)
84 throw std::system_error(ec);
85
86 // at this point `header` contains exactly 16 bytes
87 }
88 @endcode
89
90 @see ReadStream, MutableBufferSequence
91 */
92 template <typename S, typename MB>
93 requires ReadStream<S> && MutableBufferSequence<MB>
94 auto
95 98x read(S& stream, MB buffers) ->
96 io_task<std::size_t>
97 {
98 auto consuming = buffer_slice(buffers);
99 std::size_t const total_size = buffer_size(buffers);
100 std::size_t total_read = 0;
101
102 while(total_read < total_size)
103 {
104 auto [ec, n] = co_await stream.read_some(consuming.data());
105 consuming.remove_prefix(n);
106 total_read += n;
107 // A contingency that still completed the transfer is a success:
108 // report it only when the buffer was not filled.
109 if(ec && total_read < total_size)
110 co_return {ec, total_read};
111 }
112
113 co_return {{}, total_read};
114 196x }
115
116 /** Read all data from a stream into a dynamic buffer.
117
118 @par Await-effects
119
120 Reads data from `stream` via awaiting `stream.read_some` repeatedly
121 and appending the results to `dynbuf`,
122 until a contingency occurs.
123
124 Data is appended using prepare/commit semantics.
125 The buffer grows with 1.5x factor when filled.
126
127 @par Await-returns
128
129 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
130
131 `n` represents the total number of bytes read,
132 inclusive of the last partial read.
133
134 Contingencies:
135
136 @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
137
138 @par Await-throws
139 `std::bad_alloc` when append to `dynbuf` fails.
140
141 @param stream The stream to read from. If the lifetime of `stream` ends
142 before the coroutine finishes, the behavior is undefined.
143
144 @param dynbuf The dynamic buffer to append data to. If the lifetime of the buffer
145 sequence represented by `dynbuf` ends before the coroutine finishes, the behavior is undefined.
146
147 @param initial_amount Initial bytes to prepare (default 2048).
148
149
150 @par Remarks
151 Supports _IoAwaitable cancellation_.
152
153 @par Example
154
155 @code
156 capy::task<std::string> read_body(capy::ReadStream auto& stream)
157 {
158 std::string body;
159 auto [ec, n] = co_await capy::read(stream, capy::dynamic_buffer(body));
160 if (ec)
161 throw std::system_error(ec);
162 return body;
163 }
164 @endcode
165
166 @see read_some, ReadStream, DynamicBufferParam
167 */
168 template <typename S, typename DB>
169 requires ReadStream<S> && DynamicBufferParam<DB>
170 auto
171 80x read(
172 S& stream,
173 DB&& dynbuf,
174 std::size_t initial_amount = 2048) ->
175 io_task<std::size_t>
176 {
177 std::size_t amount = initial_amount;
178 std::size_t total_read = 0;
179 for(;;)
180 {
181 auto mb = dynbuf.prepare(amount);
182 auto const mb_size = buffer_size(mb);
183 auto [ec, n] = co_await stream.read_some(mb);
184 dynbuf.commit(n);
185 total_read += n;
186 if(ec == cond::eof)
187 co_return {{}, total_read};
188 if(ec)
189 co_return {ec, total_read};
190 if(n == mb_size)
191 amount = amount / 2 + amount;
192 }
193 160x }
194
195 /** Read all data from a source into a dynamic buffer.
196
197 @par Await-effects
198
199 Reads data from `stream` by calling `source.read` repeatedly
200 and appending it to `dynbuf` until a contingency occurs.
201 The last, potenitally partial, read is also appended.
202
203 Data is appended using prepare/commit semantics.
204 The buffer grows with 1.5x factor when filled.
205
206 @par Await-returns
207
208 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
209
210 `n` represents the total number of bytes read,
211 inclusive of the last partial read.
212
213
214 Contingencies:
215
216 @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
217
218 @par Await-throws
219
220 `std::bad_alloc` when append to `dynbuf` fails.
221
222 @param source The source to read from. If the lifetime of `source` ends
223 before the coroutine finishes, the behavior is undefined.
224
225 @param dynbuf The dynamic buffer to append data to. If the lifetime of the
226 buffer sequence represented by `dynbuf` ends before the coroutine finishes,
227 the behavior is undefined.
228
229 @param initial_amount Initial bytes to prepare (default 2048).
230
231 @par Remarks
232 Supports _IoAwaitable cancellation_.
233
234 @par Example
235
236 @code
237 capy::task<std::string> read_body(capy::ReadSource auto& source)
238 {
239 std::string body;
240 auto [ec, n] = co_await capy::read(source, capy::dynamic_buffer(body));
241 if (ec)
242 throw std::system_error(ec);
243 return body;
244 }
245 @endcode
246
247 @see ReadSource, DynamicBufferParam
248 */
249 template <typename S, typename DB>
250 requires ReadSource<S> && DynamicBufferParam<DB>
251 auto
252 54x read(
253 S& source,
254 DB&& dynbuf,
255 std::size_t initial_amount = 2048) ->
256 io_task<std::size_t>
257 {
258 std::size_t amount = initial_amount;
259 std::size_t total_read = 0;
260 for(;;)
261 {
262 auto mb = dynbuf.prepare(amount);
263 auto const mb_size = buffer_size(mb);
264 auto [ec, n] = co_await source.read(mb);
265 dynbuf.commit(n);
266 total_read += n;
267 if(ec == cond::eof)
268 co_return {{}, total_read};
269 if(ec)
270 co_return {ec, total_read};
271 if(n == mb_size)
272 amount = amount / 2 + amount; // 1.5x growth
273 }
274 108x }
275
276 } // namespace capy
277 } // namespace boost
278
279 #endif
280