. /include/boost/corosio /io /io_read_stream.hpp
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1   // 1   //
2   // Copyright (c) 2026 Steve Gerbino 2   // Copyright (c) 2026 Steve Gerbino
3   // 3   //
4   // Distributed under the Boost Software License, Version 1.0. (See accompanying 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) 5   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   // 6   //
7   // Official repository: https://github.com/cppalliance/corosio 7   // Official repository: https://github.com/cppalliance/corosio
8   // 8   //
9   9  
10   #ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP 10   #ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP
11   #define BOOST_COROSIO_IO_IO_READ_STREAM_HPP 11   #define BOOST_COROSIO_IO_IO_READ_STREAM_HPP
12   12  
13   #include <boost/corosio/detail/config.hpp> 13   #include <boost/corosio/detail/config.hpp>
14   #include <boost/corosio/detail/op_base.hpp> 14   #include <boost/corosio/detail/op_base.hpp>
15   #include <boost/corosio/io/io_object.hpp> 15   #include <boost/corosio/io/io_object.hpp>
16   #include <boost/corosio/detail/buffer_param.hpp> 16   #include <boost/corosio/detail/buffer_param.hpp>
17   #include <boost/capy/io_result.hpp> 17   #include <boost/capy/io_result.hpp>
18   #include <boost/capy/ex/executor_ref.hpp> 18   #include <boost/capy/ex/executor_ref.hpp>
19   #include <boost/capy/ex/io_env.hpp> 19   #include <boost/capy/ex/io_env.hpp>
20   20  
21   #include <coroutine> 21   #include <coroutine>
22   #include <cstddef> 22   #include <cstddef>
23   #include <stop_token> 23   #include <stop_token>
24   #include <system_error> 24   #include <system_error>
25   25  
26   namespace boost::corosio { 26   namespace boost::corosio {
27   27  
28 - /** Reads bytes from a stream asynchronously. 28 + /** Abstract base for streams that support async reads.
29   29  
30   Provides the `read_some` operation via a pure virtual 30   Provides the `read_some` operation via a pure virtual
31   `do_read_some` dispatch point. Concrete classes override 31   `do_read_some` dispatch point. Concrete classes override
32   `do_read_some` to route through their implementation. 32   `do_read_some` to route through their implementation.
33   33  
34   Uses virtual inheritance from @ref io_object so that 34   Uses virtual inheritance from @ref io_object so that
35   @ref io_stream can combine this with @ref io_write_stream 35   @ref io_stream can combine this with @ref io_write_stream
36   without duplicating the `io_object` base. 36   without duplicating the `io_object` base.
37   37  
38   @par Thread Safety 38   @par Thread Safety
39   Distinct objects: Safe. 39   Distinct objects: Safe.
40   Shared objects: Unsafe. 40   Shared objects: Unsafe.
41   41  
42   @see io_write_stream, io_stream, io_object 42   @see io_write_stream, io_stream, io_object
43   */ 43   */
44   class BOOST_COROSIO_DECL io_read_stream : virtual public io_object 44   class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
45   { 45   {
46   protected: 46   protected:
47   /// Awaitable for async read operations. 47   /// Awaitable for async read operations.
48   template<class MutableBufferSequence> 48   template<class MutableBufferSequence>
49   struct read_some_awaitable 49   struct read_some_awaitable
50   : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>> 50   : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>>
51   { 51   {
52 - private: 52 + io_read_stream& ios_;
53 - friend io_read_stream; 53 + MutableBufferSequence buffers_;
54   54  
HITCBC 55   210587 read_some_awaitable( 55   220780 read_some_awaitable(
56   io_read_stream& ios, MutableBufferSequence buffers) noexcept 56   io_read_stream& ios, MutableBufferSequence buffers) noexcept
HITCBC 57   210587 : ios_(ios) 57   220780 : ios_(ios)
HITCBC 58   210587 , buffers_(std::move(buffers)) 58   220780 , buffers_(std::move(buffers))
59   { 59   {
HITCBC 60   210587 } 60   220780 }
61 - friend detail::bytes_op_base<  
62 - read_some_awaitable<MutableBufferSequence>>;  
63 - io_read_stream& ios_;  
64 - MutableBufferSequence buffers_;  
65 -  
66   61  
67   std::coroutine_handle<> 62   std::coroutine_handle<>
HITCBC 68   210578 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const 63   220771 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
69   { 64   {
HITCBC 70   421156 return ios_.do_read_some( 65   441542 return ios_.do_read_some(
HITCBC 71   631734 h, ex, buffers_, this->token_, &this->ec_, &this->bytes_); 66   662313 h, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
72   } 67   }
73   }; 68   };
74   69  
75   /** Dispatch a read through the concrete implementation. 70   /** Dispatch a read through the concrete implementation.
76   71  
77   @param h Coroutine handle to resume on completion. 72   @param h Coroutine handle to resume on completion.
78   @param ex Executor for dispatching the completion. 73   @param ex Executor for dispatching the completion.
79   @param buffers Target buffer sequence. 74   @param buffers Target buffer sequence.
80   @param token Stop token for cancellation. 75   @param token Stop token for cancellation.
81   @param ec Output error code. 76   @param ec Output error code.
82   @param bytes Output bytes transferred. 77   @param bytes Output bytes transferred.
83   78  
84   @return Coroutine handle to resume immediately. 79   @return Coroutine handle to resume immediately.
85   */ 80   */
86   virtual std::coroutine_handle<> do_read_some( 81   virtual std::coroutine_handle<> do_read_some(
87 - std::coroutine_handle<> h, 82 + std::coroutine_handle<>,
88 - capy::executor_ref ex, 83 + capy::executor_ref,
89 - buffer_param buffers, 84 + buffer_param,
90 - std::stop_token token, 85 + std::stop_token,
91 - std::error_code* ec, 86 + std::error_code*,
92 - std::size_t* bytes) = 0; 87 + std::size_t*) = 0;
93 - /// Default construct; the handle is supplied through @ref io_object.  
94   88  
HITCBC 95   10475 io_read_stream() noexcept = default; 89   10243 io_read_stream() noexcept = default;
96   90  
97 - /// Move construct; the handle moves with @ref io_object. 91 + io_read_stream(io_read_stream&&) noexcept = default;
98 - io_read_stream(io_read_stream&&) noexcept = default;  
99 - /// Move assignment is disabled; reseating a live stream is not supported.  
100   io_read_stream& operator=(io_read_stream&&) noexcept = delete; 92   io_read_stream& operator=(io_read_stream&&) noexcept = delete;
101 - /// Copy construction is disabled; the handle is uniquely owned. 93 + io_read_stream(io_read_stream const&) = delete;
102 - io_read_stream(io_read_stream const&) = delete; 94 + io_read_stream& operator=(io_read_stream const&) = delete;
103 - /// Copy assignment is disabled; the handle is uniquely owned.  
104 - io_read_stream& operator=(io_read_stream const&) = delete;  
105   95  
106   public: 96   public:
107   /** Asynchronously read data from the stream. 97   /** Asynchronously read data from the stream.
108   98  
109   Suspends the calling coroutine and initiates a kernel-level 99   Suspends the calling coroutine and initiates a kernel-level
110   read. The coroutine resumes when at least one byte is read, 100   read. The coroutine resumes when at least one byte is read,
111   an error occurs, or the operation is cancelled. 101   an error occurs, or the operation is cancelled.
112   102  
113   This stream must outlive the returned awaitable. The memory 103   This stream must outlive the returned awaitable. The memory
114   referenced by @p buffers must remain valid until the operation 104   referenced by @p buffers must remain valid until the operation
115   completes. 105   completes.
116   106  
117   A closed stream completes with `errc::bad_file_descriptor`. 107   A closed stream completes with `errc::bad_file_descriptor`.
118   108  
119   @param buffers The buffer sequence to read data into. 109   @param buffers The buffer sequence to read data into.
120   110  
121   @return An awaitable yielding `(error_code, std::size_t)`. 111   @return An awaitable yielding `(error_code, std::size_t)`.
122   112  
123   @see io_stream::write_some 113   @see io_stream::write_some
124   */ 114   */
125   template<capy::MutableBufferSequence MB> 115   template<capy::MutableBufferSequence MB>
HITCBC 126   210587 [[nodiscard]] auto read_some(MB const& buffers) 116   220780 [[nodiscard]] auto read_some(MB const& buffers)
127   { 117   {
HITCBC 128   210587 return read_some_awaitable<MB>(*this, buffers); 118   220780 return read_some_awaitable<MB>(*this, buffers);
129   } 119   }
130   }; 120   };
131   121  
132   } // namespace boost::corosio 122   } // namespace boost::corosio
133   123  
134   #endif 124   #endif