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_TEST_WRITE_SINK_HPP
11 : #define BOOST_CAPY_TEST_WRITE_SINK_HPP
12 :
13 : #include <boost/capy/detail/config.hpp>
14 : #include <boost/capy/buffers.hpp>
15 : #include <boost/capy/buffers/buffer_copy.hpp>
16 : #include <boost/capy/buffers/make_buffer.hpp>
17 : #include <boost/capy/coro.hpp>
18 : #include <boost/capy/ex/executor_ref.hpp>
19 : #include <boost/capy/io_result.hpp>
20 : #include <boost/capy/error.hpp>
21 : #include <boost/capy/test/fuse.hpp>
22 :
23 : #include <algorithm>
24 : #include <stop_token>
25 : #include <string>
26 : #include <string_view>
27 :
28 : namespace boost {
29 : namespace capy {
30 : namespace test {
31 :
32 : /** A mock sink for testing write operations.
33 :
34 : Use this to verify code that performs complete writes without needing
35 : real I/O. Call @ref write to write data, then @ref data to retrieve
36 : what was written. The associated @ref fuse enables error injection
37 : at controlled points.
38 :
39 : Unlike @ref write_stream which provides partial writes via `write_some`,
40 : this class satisfies the @ref WriteSink concept by providing complete
41 : writes and EOF signaling.
42 :
43 : @par Thread Safety
44 : Not thread-safe.
45 :
46 : @par Example
47 : @code
48 : fuse f;
49 : write_sink ws( f );
50 :
51 : auto r = f.armed( [&]( fuse& ) -> task<void> {
52 : auto [ec, n] = co_await ws.write(
53 : const_buffer( "Hello", 5 ) );
54 : if( ec )
55 : co_return;
56 : auto [ec2] = co_await ws.write_eof();
57 : if( ec2 )
58 : co_return;
59 : // ws.data() returns "Hello"
60 : } );
61 : @endcode
62 :
63 : @see fuse, WriteSink
64 : */
65 : class write_sink
66 : {
67 : fuse* f_;
68 : std::string data_;
69 : std::string expect_;
70 : std::size_t max_write_size_;
71 : bool eof_called_ = false;
72 :
73 : std::error_code
74 172 : consume_match_() noexcept
75 : {
76 172 : if(data_.empty() || expect_.empty())
77 172 : return {};
78 0 : std::size_t const n = (std::min)(data_.size(), expect_.size());
79 0 : if(std::string_view(data_.data(), n) !=
80 0 : std::string_view(expect_.data(), n))
81 0 : return error::test_failure;
82 0 : data_.erase(0, n);
83 0 : expect_.erase(0, n);
84 0 : return {};
85 : }
86 :
87 : public:
88 : /** Construct a write sink.
89 :
90 : @param f The fuse used to inject errors during writes.
91 :
92 : @param max_write_size Maximum bytes transferred per write.
93 : Use to simulate chunked delivery.
94 : */
95 236 : explicit write_sink(
96 : fuse& f,
97 : std::size_t max_write_size = std::size_t(-1)) noexcept
98 236 : : f_(&f)
99 236 : , max_write_size_(max_write_size)
100 : {
101 236 : }
102 :
103 : /// Return the written data as a string view.
104 : std::string_view
105 38 : data() const noexcept
106 : {
107 38 : return data_;
108 : }
109 :
110 : /** Set the expected data for subsequent writes.
111 :
112 : Stores the expected data and immediately tries to match
113 : against any data already written. Matched data is consumed
114 : from both buffers.
115 :
116 : @param sv The expected data.
117 :
118 : @return An error if existing data does not match.
119 : */
120 : std::error_code
121 : expect(std::string_view sv)
122 : {
123 : expect_.assign(sv);
124 : return consume_match_();
125 : }
126 :
127 : /// Return the number of bytes written.
128 : std::size_t
129 2 : size() const noexcept
130 : {
131 2 : return data_.size();
132 : }
133 :
134 : /// Return whether write_eof has been called.
135 : bool
136 36 : eof_called() const noexcept
137 : {
138 36 : return eof_called_;
139 : }
140 :
141 : /// Clear all data and reset state.
142 : void
143 : clear() noexcept
144 : {
145 : data_.clear();
146 : expect_.clear();
147 : eof_called_ = false;
148 : }
149 :
150 : /** Asynchronously write data to the sink.
151 :
152 : Transfers all bytes from the provided const buffer sequence to
153 : the internal buffer. Before every write, the attached @ref fuse
154 : is consulted to possibly inject an error for testing fault
155 : scenarios. The returned `std::size_t` is the number of bytes
156 : transferred.
157 :
158 : @par Effects
159 : On success, appends the written bytes to the internal buffer.
160 : If an error is injected by the fuse, the internal buffer remains
161 : unchanged.
162 :
163 : @par Exception Safety
164 : No-throw guarantee.
165 :
166 : @param buffers The const buffer sequence containing data to write.
167 :
168 : @return An awaitable yielding `(error_code,std::size_t)`.
169 :
170 : @see fuse
171 : */
172 : template<ConstBufferSequence CB>
173 : auto
174 254 : write(CB buffers)
175 : {
176 : struct awaitable
177 : {
178 : write_sink* self_;
179 : CB buffers_;
180 :
181 254 : bool await_ready() const noexcept { return true; }
182 :
183 0 : void await_suspend(
184 : coro,
185 : executor_ref,
186 : std::stop_token) const noexcept
187 : {
188 0 : }
189 :
190 : io_result<std::size_t>
191 254 : await_resume()
192 : {
193 254 : auto ec = self_->f_->maybe_fail();
194 213 : if(ec)
195 41 : return {ec, 0};
196 :
197 172 : std::size_t n = buffer_size(buffers_);
198 172 : n = (std::min)(n, self_->max_write_size_);
199 172 : if(n == 0)
200 0 : return {{}, 0};
201 :
202 172 : std::size_t const old_size = self_->data_.size();
203 172 : self_->data_.resize(old_size + n);
204 172 : buffer_copy(make_buffer(
205 172 : self_->data_.data() + old_size, n), buffers_, n);
206 :
207 172 : ec = self_->consume_match_();
208 172 : if(ec)
209 0 : return {ec, n};
210 :
211 172 : return {{}, n};
212 : }
213 : };
214 254 : return awaitable{this, buffers};
215 : }
216 :
217 : /** Asynchronously write data to the sink with optional EOF.
218 :
219 : Transfers all bytes from the provided const buffer sequence to
220 : the internal buffer, optionally signaling end-of-stream. Before
221 : every write, the attached @ref fuse is consulted to possibly
222 : inject an error for testing fault scenarios. The returned
223 : `std::size_t` is the number of bytes transferred.
224 :
225 : @par Effects
226 : On success, appends the written bytes to the internal buffer.
227 : If `eof` is `true`, marks the sink as finalized.
228 : If an error is injected by the fuse, the internal buffer remains
229 : unchanged.
230 :
231 : @par Exception Safety
232 : No-throw guarantee.
233 :
234 : @param buffers The const buffer sequence containing data to write.
235 : @param eof If true, signals end-of-stream after writing.
236 :
237 : @return An awaitable yielding `(error_code,std::size_t)`.
238 :
239 : @see fuse
240 : */
241 : template<ConstBufferSequence CB>
242 : auto
243 0 : write(CB buffers, bool eof)
244 : {
245 : struct awaitable
246 : {
247 : write_sink* self_;
248 : CB buffers_;
249 : bool eof_;
250 :
251 0 : bool await_ready() const noexcept { return true; }
252 :
253 0 : void await_suspend(
254 : coro,
255 : executor_ref,
256 : std::stop_token) const noexcept
257 : {
258 0 : }
259 :
260 : io_result<std::size_t>
261 0 : await_resume()
262 : {
263 0 : auto ec = self_->f_->maybe_fail();
264 0 : if(ec)
265 0 : return {ec, 0};
266 :
267 0 : std::size_t n = buffer_size(buffers_);
268 0 : n = (std::min)(n, self_->max_write_size_);
269 0 : if(n > 0)
270 : {
271 0 : std::size_t const old_size = self_->data_.size();
272 0 : self_->data_.resize(old_size + n);
273 0 : buffer_copy(make_buffer(
274 0 : self_->data_.data() + old_size, n), buffers_, n);
275 :
276 0 : ec = self_->consume_match_();
277 0 : if(ec)
278 0 : return {ec, n};
279 : }
280 :
281 0 : if(eof_)
282 0 : self_->eof_called_ = true;
283 :
284 0 : return {{}, n};
285 : }
286 : };
287 0 : return awaitable{this, buffers, eof};
288 : }
289 :
290 : /** Signal end-of-stream.
291 :
292 : Marks the sink as finalized, indicating no more data will be
293 : written. Before signaling, the attached @ref fuse is consulted
294 : to possibly inject an error for testing fault scenarios.
295 :
296 : @par Effects
297 : On success, marks the sink as finalized.
298 : If an error is injected by the fuse, the state remains unchanged.
299 :
300 : @par Exception Safety
301 : No-throw guarantee.
302 :
303 : @return An awaitable yielding `(error_code)`.
304 :
305 : @see fuse
306 : */
307 : auto
308 68 : write_eof()
309 : {
310 : struct awaitable
311 : {
312 : write_sink* self_;
313 :
314 68 : bool await_ready() const noexcept { return true; }
315 :
316 0 : void await_suspend(
317 : coro,
318 : executor_ref,
319 : std::stop_token) const noexcept
320 : {
321 0 : }
322 :
323 : io_result<>
324 68 : await_resume()
325 : {
326 68 : auto ec = self_->f_->maybe_fail();
327 50 : if(ec)
328 18 : return {ec};
329 :
330 32 : self_->eof_called_ = true;
331 32 : return {};
332 : }
333 : };
334 68 : return awaitable{this};
335 : }
336 : };
337 :
338 : } // test
339 : } // capy
340 : } // boost
341 :
342 : #endif
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