TLA Line data Source code
1 : //
2 : // Copyright (c) 2026 Steve Gerbino
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/corosio
8 : //
9 :
10 : #ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP
11 : #define BOOST_COROSIO_IO_IO_READ_STREAM_HPP
12 :
13 : #include <boost/corosio/detail/config.hpp>
14 : #include <boost/corosio/detail/op_base.hpp>
15 : #include <boost/corosio/io/io_object.hpp>
16 : #include <boost/corosio/detail/buffer_param.hpp>
17 : #include <boost/capy/results.hpp>
18 : #include <boost/capy/ex/executor_ref.hpp>
19 : #include <boost/capy/ex/await_context.hpp>
20 :
21 : #include <boost/capy/continuation.hpp>
22 :
23 : #include <coroutine>
24 : #include <cstddef>
25 : #include <stop_token>
26 : #include <system_error>
27 :
28 : namespace boost::corosio {
29 :
30 : /** Reads bytes from a stream asynchronously.
31 :
32 : Provides the `read_some` operation via a pure virtual
33 : `do_read_some` dispatch point. Concrete classes override
34 : `do_read_some` to route through their implementation.
35 :
36 : Uses virtual inheritance from @ref io_object so that
37 : @ref io_stream can combine this with @ref io_write_stream
38 : without duplicating the `io_object` base.
39 :
40 : @par Thread Safety
41 : Distinct objects: Safe.
42 : Shared objects: Unsafe.
43 :
44 : @see io_write_stream, io_stream, io_object
45 : */
46 : class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
47 : {
48 : protected:
49 : /// Awaitable for async read operations.
50 : template<class MutableBufferSequence>
51 : struct read_some_awaitable
52 : : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>>
53 : {
54 : private:
55 : friend io_read_stream;
56 :
57 HIT 238212 : read_some_awaitable(
58 : io_read_stream& ios, MutableBufferSequence buffers) noexcept
59 238212 : : ios_(ios)
60 238212 : , buffers_(std::move(buffers))
61 : {
62 238212 : }
63 :
64 : friend detail::bytes_op_base<
65 : read_some_awaitable<MutableBufferSequence>>;
66 : io_read_stream& ios_;
67 : MutableBufferSequence buffers_;
68 :
69 : std::coroutine_handle<>
70 238184 : dispatch(capy::continuation& cont, capy::executor_ref ex) const
71 : {
72 476368 : return ios_.do_read_some(
73 714552 : cont, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
74 : }
75 : };
76 :
77 : /** Dispatch a read through the concrete implementation.
78 :
79 : @param cont Continuation to resume on completion; it lives in
80 : the awaiting frame until then.
81 : @param ex Executor for dispatching the completion.
82 : @param buffers Target buffer sequence.
83 : @param token Stop token for cancellation.
84 : @param ec Output error code.
85 : @param bytes Output bytes transferred.
86 :
87 : @return Coroutine handle to resume immediately.
88 : */
89 : virtual std::coroutine_handle<> do_read_some(
90 : capy::continuation& cont,
91 : capy::executor_ref ex,
92 : buffer_param buffers,
93 : std::stop_token token,
94 : std::error_code* ec,
95 : std::size_t* bytes) = 0;
96 :
97 : /// Default construct; the handle is supplied through @ref io_object.
98 26592 : io_read_stream() noexcept = default;
99 :
100 : /// Move construct; the handle moves with @ref io_object.
101 : io_read_stream(io_read_stream&&) noexcept = default;
102 : /// Move assignment is disabled; reseating a live stream is not supported.
103 : io_read_stream& operator=(io_read_stream&&) noexcept = delete;
104 : /// Copy construction is disabled; the handle is uniquely owned.
105 : io_read_stream(io_read_stream const&) = delete;
106 : /// Copy assignment is disabled; the handle is uniquely owned.
107 : io_read_stream& operator=(io_read_stream const&) = delete;
108 :
109 : public:
110 : /** Asynchronously read data from the stream.
111 :
112 : Suspends the calling coroutine and initiates a kernel-level
113 : read. The coroutine resumes when at least one byte is read,
114 : an error occurs, or the operation is cancelled.
115 :
116 : This stream must outlive the returned awaitable. The memory
117 : referenced by @p buffers must remain valid until the operation
118 : completes.
119 :
120 : A closed stream completes with `errc::bad_file_descriptor`.
121 :
122 : @param buffers The buffer sequence to read data into.
123 :
124 : @return An awaitable yielding `(error_code, std::size_t)`.
125 :
126 : @see io_stream::write_some
127 : */
128 : template<capy::MutableBufferSequence MB>
129 238212 : [[nodiscard]] auto read_some(MB const& buffers)
130 : {
131 238212 : return read_some_awaitable<MB>(*this, buffers);
132 : }
133 : };
134 :
135 : } // namespace boost::corosio
136 :
137 : #endif
|
