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_IO_PULL_FROM_HPP
11 : #define BOOST_CAPY_IO_PULL_FROM_HPP
12 :
13 : #include <boost/capy/detail/config.hpp>
14 : #include <boost/capy/buffers.hpp>
15 : #include <boost/capy/cond.hpp>
16 : #include <boost/capy/concept/buffer_sink.hpp>
17 : #include <boost/capy/concept/read_source.hpp>
18 : #include <boost/capy/concept/read_stream.hpp>
19 : #include <boost/capy/io_task.hpp>
20 :
21 : #include <cstddef>
22 : #include <span>
23 :
24 : namespace boost {
25 : namespace capy {
26 :
27 : /** Transfer data from a ReadSource to a BufferSink.
28 :
29 : This function reads data from the source directly into the sink's
30 : internal buffers using the callee-owns-buffers model. The sink
31 : provides writable buffers via `prepare()`, the source reads into
32 : them, and the sink commits the data. When the source signals EOF,
33 : `commit_eof()` is called on the sink to finalize the transfer.
34 :
35 : @tparam Src The source type, must satisfy @ref ReadSource.
36 : @tparam Sink The sink type, must satisfy @ref BufferSink.
37 :
38 : @param source The source to read data from.
39 : @param sink The sink to write data to.
40 :
41 : @return A task that yields `(std::error_code, std::size_t)`.
42 : On success, `ec` is default-constructed (no error) and `n` is
43 : the total number of bytes transferred. On error, `ec` contains
44 : the error code and `n` is the total number of bytes transferred
45 : before the error.
46 :
47 : @par Example
48 : @code
49 : task<void> transfer_body(ReadSource auto& source, BufferSink auto& sink)
50 : {
51 : auto [ec, n] = co_await pull_from(source, sink);
52 : if (ec)
53 : {
54 : // Handle error
55 : }
56 : // n bytes were transferred
57 : }
58 : @endcode
59 :
60 : @see ReadSource, BufferSink, push_to
61 : */
62 : template<ReadSource Src, BufferSink Sink>
63 : io_task<std::size_t>
64 HIT 136 : pull_from(Src& source, Sink& sink)
65 : {
66 : mutable_buffer dst_arr[detail::max_iovec_];
67 : std::size_t total = 0;
68 :
69 : for(;;)
70 : {
71 : auto dst_bufs = sink.prepare(dst_arr);
72 : if(dst_bufs.empty())
73 : {
74 : // No buffer space available; commit nothing to flush
75 : auto [flush_ec] = co_await sink.commit(0);
76 : if(flush_ec)
77 : co_return {flush_ec, total};
78 : continue;
79 : }
80 :
81 : auto [ec, n] = co_await source.read(
82 : std::span<mutable_buffer const>(dst_bufs));
83 :
84 : auto [commit_ec] = co_await sink.commit(n);
85 : total += n;
86 :
87 : if(commit_ec)
88 : co_return {commit_ec, total};
89 :
90 : if(ec == cond::eof)
91 : {
92 : auto [eof_ec] = co_await sink.commit_eof(0);
93 : co_return {eof_ec, total};
94 : }
95 :
96 : if(ec)
97 : co_return {ec, total};
98 : }
99 272 : }
100 :
101 : /** Transfer data from a ReadStream to a BufferSink.
102 :
103 : This function reads data from the stream directly into the sink's
104 : internal buffers using the callee-owns-buffers model. The sink
105 : provides writable buffers via `prepare()`, the stream reads into
106 : them using `read_some()`, and the sink commits the data. When the
107 : stream signals EOF, `commit_eof()` is called on the sink to
108 : finalize the transfer.
109 :
110 : This overload handles partial reads from the stream, committing
111 : data incrementally as it arrives. It loops until EOF is encountered
112 : or an error occurs.
113 :
114 : @tparam Src The source type, must satisfy @ref ReadStream.
115 : @tparam Sink The sink type, must satisfy @ref BufferSink.
116 :
117 : @param source The stream to read data from.
118 : @param sink The sink to write data to.
119 :
120 : @return A task that yields `(std::error_code, std::size_t)`.
121 : On success, `ec` is default-constructed (no error) and `n` is
122 : the total number of bytes transferred. On error, `ec` contains
123 : the error code and `n` is the total number of bytes transferred
124 : before the error.
125 :
126 : @par Example
127 : @code
128 : task<void> transfer_body(ReadStream auto& stream, BufferSink auto& sink)
129 : {
130 : auto [ec, n] = co_await pull_from(stream, sink);
131 : if (ec)
132 : {
133 : // Handle error
134 : }
135 : // n bytes were transferred
136 : }
137 : @endcode
138 :
139 : @see ReadStream, BufferSink, push_to
140 : */
141 : template<ReadStream Src, BufferSink Sink>
142 : requires (!ReadSource<Src>)
143 : io_task<std::size_t>
144 226 : pull_from(Src& source, Sink& sink)
145 : {
146 : mutable_buffer dst_arr[detail::max_iovec_];
147 : std::size_t total = 0;
148 :
149 : for(;;)
150 : {
151 : // Prepare destination buffers from the sink
152 : auto dst_bufs = sink.prepare(dst_arr);
153 : if(dst_bufs.empty())
154 : {
155 : // No buffer space available; commit nothing to flush
156 : auto [flush_ec] = co_await sink.commit(0);
157 : if(flush_ec)
158 : co_return {flush_ec, total};
159 : continue;
160 : }
161 :
162 : // Read data from the stream into the sink's buffers
163 : auto [ec, n] = co_await source.read_some(
164 : std::span<mutable_buffer const>(dst_bufs));
165 :
166 : auto [commit_ec] = co_await sink.commit(n);
167 : total += n;
168 :
169 : if(commit_ec)
170 : co_return {commit_ec, total};
171 :
172 : if(ec == cond::eof)
173 : {
174 : auto [eof_ec] = co_await sink.commit_eof(0);
175 : co_return {eof_ec, total};
176 : }
177 :
178 : // Check for other errors
179 : if(ec)
180 : co_return {ec, total};
181 : }
182 452 : }
183 :
184 : } // namespace capy
185 : } // namespace boost
186 :
187 : #endif
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