. /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/results.hpp> 17   #include <boost/capy/results.hpp>
18   #include <boost/capy/ex/executor_ref.hpp> 18   #include <boost/capy/ex/executor_ref.hpp>
19   #include <boost/capy/ex/await_context.hpp> 19   #include <boost/capy/ex/await_context.hpp>
20   20  
21   #include <boost/capy/continuation.hpp> 21   #include <boost/capy/continuation.hpp>
22   22  
23   #include <coroutine> 23   #include <coroutine>
24   #include <cstddef> 24   #include <cstddef>
25   #include <stop_token> 25   #include <stop_token>
26   #include <system_error> 26   #include <system_error>
27   27  
28   namespace boost::corosio { 28   namespace boost::corosio {
29   29  
30   /** Reads bytes from a stream asynchronously. 30   /** Reads bytes from a stream asynchronously.
31   31  
32   Provides the `read_some` operation via a pure virtual 32   Provides the `read_some` operation via a pure virtual
33   `do_read_some` dispatch point. Concrete classes override 33   `do_read_some` dispatch point. Concrete classes override
34   `do_read_some` to route through their implementation. 34   `do_read_some` to route through their implementation.
35   35  
36   Uses virtual inheritance from @ref io_object so that 36   Uses virtual inheritance from @ref io_object so that
37   @ref io_stream can combine this with @ref io_write_stream 37   @ref io_stream can combine this with @ref io_write_stream
38   without duplicating the `io_object` base. 38   without duplicating the `io_object` base.
39   39  
40   @par Thread Safety 40   @par Thread Safety
41   Distinct objects: Safe. 41   Distinct objects: Safe.
42   Shared objects: Unsafe. 42   Shared objects: Unsafe.
43   43  
44   @see io_write_stream, io_stream, io_object 44   @see io_write_stream, io_stream, io_object
45   */ 45   */
46   class BOOST_COROSIO_DECL io_read_stream : virtual public io_object 46   class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
47   { 47   {
48   protected: 48   protected:
49   /// Awaitable for async read operations. 49   /// Awaitable for async read operations.
50   template<class MutableBufferSequence> 50   template<class MutableBufferSequence>
51   struct read_some_awaitable 51   struct read_some_awaitable
52   : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>> 52   : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>>
53   { 53   {
54   private: 54   private:
55   friend io_read_stream; 55   friend io_read_stream;
56   56  
HITCBC 57   226544 read_some_awaitable( 57   238212 read_some_awaitable(
58   io_read_stream& ios, MutableBufferSequence buffers) noexcept 58   io_read_stream& ios, MutableBufferSequence buffers) noexcept
HITCBC 59   226544 : ios_(ios) 59   238212 : ios_(ios)
HITCBC 60   226544 , buffers_(std::move(buffers)) 60   238212 , buffers_(std::move(buffers))
61   { 61   {
HITCBC 62   226544 } 62   238212 }
63   63  
64   friend detail::bytes_op_base< 64   friend detail::bytes_op_base<
65   read_some_awaitable<MutableBufferSequence>>; 65   read_some_awaitable<MutableBufferSequence>>;
66   io_read_stream& ios_; 66   io_read_stream& ios_;
67   MutableBufferSequence buffers_; 67   MutableBufferSequence buffers_;
68   68  
69   std::coroutine_handle<> 69   std::coroutine_handle<>
HITCBC 70   226513 dispatch(capy::continuation& cont, capy::executor_ref ex) const 70   238184 dispatch(capy::continuation& cont, capy::executor_ref ex) const
71   { 71   {
HITCBC 72   453026 return ios_.do_read_some( 72   476368 return ios_.do_read_some(
HITCBC 73   679539 cont, ex, buffers_, this->token_, &this->ec_, &this->bytes_); 73   714552 cont, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
74   } 74   }
75   }; 75   };
76   76  
77   /** Dispatch a read through the concrete implementation. 77   /** Dispatch a read through the concrete implementation.
78   78  
79   @param cont Continuation to resume on completion; it lives in 79   @param cont Continuation to resume on completion; it lives in
80   the awaiting frame until then. 80   the awaiting frame until then.
81   @param ex Executor for dispatching the completion. 81   @param ex Executor for dispatching the completion.
82   @param buffers Target buffer sequence. 82   @param buffers Target buffer sequence.
83   @param token Stop token for cancellation. 83   @param token Stop token for cancellation.
84   @param ec Output error code. 84   @param ec Output error code.
85   @param bytes Output bytes transferred. 85   @param bytes Output bytes transferred.
86   86  
87   @return Coroutine handle to resume immediately. 87   @return Coroutine handle to resume immediately.
88   */ 88   */
89   virtual std::coroutine_handle<> do_read_some( 89   virtual std::coroutine_handle<> do_read_some(
90   capy::continuation& cont, 90   capy::continuation& cont,
91   capy::executor_ref ex, 91   capy::executor_ref ex,
92   buffer_param buffers, 92   buffer_param buffers,
93   std::stop_token token, 93   std::stop_token token,
94   std::error_code* ec, 94   std::error_code* ec,
95   std::size_t* bytes) = 0; 95   std::size_t* bytes) = 0;
96   96  
97   /// Default construct; the handle is supplied through @ref io_object. 97   /// Default construct; the handle is supplied through @ref io_object.
HITCBC 98   26905 io_read_stream() noexcept = default; 98   26592 io_read_stream() noexcept = default;
99   99  
100   /// Move construct; the handle moves with @ref io_object. 100   /// Move construct; the handle moves with @ref io_object.
101   io_read_stream(io_read_stream&&) noexcept = default; 101   io_read_stream(io_read_stream&&) noexcept = default;
102   /// Move assignment is disabled; reseating a live stream is not supported. 102   /// Move assignment is disabled; reseating a live stream is not supported.
103   io_read_stream& operator=(io_read_stream&&) noexcept = delete; 103   io_read_stream& operator=(io_read_stream&&) noexcept = delete;
104   /// Copy construction is disabled; the handle is uniquely owned. 104   /// Copy construction is disabled; the handle is uniquely owned.
105   io_read_stream(io_read_stream const&) = delete; 105   io_read_stream(io_read_stream const&) = delete;
106   /// Copy assignment is disabled; the handle is uniquely owned. 106   /// Copy assignment is disabled; the handle is uniquely owned.
107   io_read_stream& operator=(io_read_stream const&) = delete; 107   io_read_stream& operator=(io_read_stream const&) = delete;
108   108  
109   public: 109   public:
110   /** Asynchronously read data from the stream. 110   /** Asynchronously read data from the stream.
111   111  
112   Suspends the calling coroutine and initiates a kernel-level 112   Suspends the calling coroutine and initiates a kernel-level
113   read. The coroutine resumes when at least one byte is read, 113   read. The coroutine resumes when at least one byte is read,
114   an error occurs, or the operation is cancelled. 114   an error occurs, or the operation is cancelled.
115   115  
116   This stream must outlive the returned awaitable. The memory 116   This stream must outlive the returned awaitable. The memory
117   referenced by @p buffers must remain valid until the operation 117   referenced by @p buffers must remain valid until the operation
118   completes. 118   completes.
119   119  
120   A closed stream completes with `errc::bad_file_descriptor`. 120   A closed stream completes with `errc::bad_file_descriptor`.
121   121  
122   @param buffers The buffer sequence to read data into. 122   @param buffers The buffer sequence to read data into.
123   123  
124   @return An awaitable yielding `(error_code, std::size_t)`. 124   @return An awaitable yielding `(error_code, std::size_t)`.
125   125  
126   @see io_stream::write_some 126   @see io_stream::write_some
127   */ 127   */
128   template<capy::MutableBufferSequence MB> 128   template<capy::MutableBufferSequence MB>
HITCBC 129   226544 [[nodiscard]] auto read_some(MB const& buffers) 129   238212 [[nodiscard]] auto read_some(MB const& buffers)
130   { 130   {
HITCBC 131   226544 return read_some_awaitable<MB>(*this, buffers); 131   238212 return read_some_awaitable<MB>(*this, buffers);
132   } 132   }
133   }; 133   };
134   134  
135   } // namespace boost::corosio 135   } // namespace boost::corosio
136   136  
137   #endif 137   #endif