TLA Line data 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 :
51 : Notable conditions:
52 :
53 : @li @c cond::canceled — Operation was cancelled,
54 : @li @c cond::eof — Stream reached end before `buffers` was filled.
55 :
56 : @par Await-postcondition
57 : `ec || n == buffer_size(buffers)`.
58 :
59 : @param stream The stream to read from. If the lifetime of `stream` ends
60 : before the coroutine finishes, the behavior is undefined.
61 :
62 : @param buffers The buffer sequence to fill. If the lifetime of the buffer
63 : sequence represented by `buffers` ends before the coroutine finishes, the behavior is undefined.
64 :
65 :
66 : @par Remarks
67 : Supports _IoAwaitable cancellation_.
68 :
69 :
70 : @par Example
71 :
72 : @code
73 : capy::task<> process_message(capy::ReadStream auto& stream)
74 : {
75 : std::vector<char> header(16); // known header size for some protocol
76 : auto [ec, n] = co_await capy::read(stream, capy::mutable_buffer(header));
77 : if (ec == capy::cond::eof)
78 : co_return; // Connection closed
79 : if (ec)
80 : throw std::system_error(ec);
81 :
82 : // at this point `header` contains exactly 16 bytes
83 : }
84 : @endcode
85 :
86 : @see ReadStream, MutableBufferSequence
87 : */
88 : template <typename S, typename MB>
89 : requires ReadStream<S> && MutableBufferSequence<MB>
90 : auto
91 HIT 94 : read(S& stream, MB buffers) ->
92 : io_task<std::size_t>
93 : {
94 : auto consuming = buffer_slice(buffers);
95 : std::size_t const total_size = buffer_size(buffers);
96 : std::size_t total_read = 0;
97 :
98 : while(total_read < total_size)
99 : {
100 : auto [ec, n] = co_await stream.read_some(consuming.data());
101 : consuming.remove_prefix(n);
102 : total_read += n;
103 : if(ec)
104 : co_return {ec, total_read};
105 : }
106 :
107 : co_return {{}, total_read};
108 188 : }
109 :
110 : /** Read all data from a stream into a dynamic buffer.
111 :
112 : @par Await-effects
113 :
114 : Reads data from `stream` via awaiting `stream.read_some` repeatedly
115 : and appending the results to `dynbuf`,
116 : until a contingency occurs.
117 :
118 : Data is appended using prepare/commit semantics.
119 : The buffer grows with 1.5x factor when filled.
120 :
121 : @par Await-returns
122 :
123 : An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
124 :
125 : `n` represents the total number of bytes read,
126 : inclusive of the last partial read.
127 :
128 : Contingencies:
129 :
130 : @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
131 :
132 : @par Await-throws
133 : `std::bad_alloc` when append to `dynbuf` fails.
134 :
135 : @param stream The stream to read from. If the lifetime of `stream` ends
136 : before the coroutine finishes, the behavior is undefined.
137 :
138 : @param dynbuf The dynamic buffer to append data to. If the lifetime of the buffer
139 : sequence represented by `dynbuf` ends before the coroutine finishes, the behavior is undefined.
140 :
141 : @param initial_amount Initial bytes to prepare (default 2048).
142 :
143 :
144 : @par Remarks
145 : Supports _IoAwaitable cancellation_.
146 :
147 : @par Example
148 :
149 : @code
150 : capy::task<std::string> read_body(capy::ReadStream auto& stream)
151 : {
152 : std::string body;
153 : auto [ec, n] = co_await capy::read(stream, capy::dynamic_buffer(body));
154 : if (ec)
155 : throw std::system_error(ec);
156 : return body;
157 : }
158 : @endcode
159 :
160 : @see read_some, ReadStream, DynamicBufferParam
161 : */
162 : template <typename S, typename DB>
163 : requires ReadStream<S> && DynamicBufferParam<DB>
164 : auto
165 80 : read(
166 : S& stream,
167 : DB&& dynbuf,
168 : std::size_t initial_amount = 2048) ->
169 : io_task<std::size_t>
170 : {
171 : std::size_t amount = initial_amount;
172 : std::size_t total_read = 0;
173 : for(;;)
174 : {
175 : auto mb = dynbuf.prepare(amount);
176 : auto const mb_size = buffer_size(mb);
177 : auto [ec, n] = co_await stream.read_some(mb);
178 : dynbuf.commit(n);
179 : total_read += n;
180 : if(ec == cond::eof)
181 : co_return {{}, total_read};
182 : if(ec)
183 : co_return {ec, total_read};
184 : if(n == mb_size)
185 : amount = amount / 2 + amount;
186 : }
187 160 : }
188 :
189 : /** Read all data from a source into a dynamic buffer.
190 :
191 : @par Await-effects
192 :
193 : Reads data from `stream` by calling `source.read` repeatedly
194 : and appending it to `dynbuf` until a contingency occurs.
195 : The last, potenitally partial, read is also appended.
196 :
197 : Data is appended using prepare/commit semantics.
198 : The buffer grows with 1.5x factor when filled.
199 :
200 : @par Await-returns
201 :
202 : An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
203 :
204 : `n` represents the total number of bytes read,
205 : inclusive of the last partial read.
206 :
207 :
208 : Contingencies:
209 :
210 : @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
211 :
212 : @par Await-throws
213 :
214 : `std::bad_alloc` when append to `dynbuf` fails.
215 :
216 : @param source The source to read from. If the lifetime of `source` ends
217 : before the coroutine finishes, the behavior is undefined.
218 :
219 : @param dynbuf The dynamic buffer to append data to. If the lifetime of the
220 : buffer sequence represented by `dynbuf` ends before the coroutine finishes,
221 : the behavior is undefined.
222 :
223 : @param initial_amount Initial bytes to prepare (default 2048).
224 :
225 : @par Remarks
226 : Supports _IoAwaitable cancellation_.
227 :
228 : @par Example
229 :
230 : @code
231 : capy::task<std::string> read_body(capy::ReadSource auto& source)
232 : {
233 : std::string body;
234 : auto [ec, n] = co_await capy::read(source, capy::dynamic_buffer(body));
235 : if (ec)
236 : throw std::system_error(ec);
237 : return body;
238 : }
239 : @endcode
240 :
241 : @see ReadSource, DynamicBufferParam
242 : */
243 : template <typename S, typename DB>
244 : requires ReadSource<S> && DynamicBufferParam<DB>
245 : auto
246 54 : read(
247 : S& source,
248 : DB&& dynbuf,
249 : std::size_t initial_amount = 2048) ->
250 : io_task<std::size_t>
251 : {
252 : std::size_t amount = initial_amount;
253 : std::size_t total_read = 0;
254 : for(;;)
255 : {
256 : auto mb = dynbuf.prepare(amount);
257 : auto const mb_size = buffer_size(mb);
258 : auto [ec, n] = co_await source.read(mb);
259 : dynbuf.commit(n);
260 : total_read += n;
261 : if(ec == cond::eof)
262 : co_return {{}, total_read};
263 : if(ec)
264 : co_return {ec, total_read};
265 : if(n == mb_size)
266 : amount = amount / 2 + amount; // 1.5x growth
267 : }
268 108 : }
269 :
270 : } // namespace capy
271 : } // namespace boost
272 :
273 : #endif
|
