. /include/boost/corosio /native /native_random_access_file.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_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP 10   #ifndef BOOST_COROSIO_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP
11   #define BOOST_COROSIO_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP 11   #define BOOST_COROSIO_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP
12   12  
13   #include <boost/corosio/random_access_file.hpp> 13   #include <boost/corosio/random_access_file.hpp>
14   #include <boost/corosio/backend.hpp> 14   #include <boost/corosio/backend.hpp>
15   15  
16   #ifndef BOOST_COROSIO_MRDOCS 16   #ifndef BOOST_COROSIO_MRDOCS
17   #if BOOST_COROSIO_HAS_EPOLL || BOOST_COROSIO_HAS_SELECT || \ 17   #if BOOST_COROSIO_HAS_EPOLL || BOOST_COROSIO_HAS_SELECT || \
18   BOOST_COROSIO_HAS_KQUEUE 18   BOOST_COROSIO_HAS_KQUEUE
19   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp> 19   #include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
20   #endif 20   #endif
21   21  
22   #if BOOST_COROSIO_HAS_IO_URING 22   #if BOOST_COROSIO_HAS_IO_URING
23   #include <boost/corosio/native/detail/io_uring/io_uring_random_access_file.hpp> 23   #include <boost/corosio/native/detail/io_uring/io_uring_random_access_file.hpp>
24   #endif 24   #endif
25   25  
26   #if BOOST_COROSIO_HAS_IOCP 26   #if BOOST_COROSIO_HAS_IOCP
27   #include <boost/corosio/native/detail/iocp/win_random_access_file_service.hpp> 27   #include <boost/corosio/native/detail/iocp/win_random_access_file_service.hpp>
28   #endif 28   #endif
29   #endif // !BOOST_COROSIO_MRDOCS 29   #endif // !BOOST_COROSIO_MRDOCS
30   30  
31   namespace boost::corosio { 31   namespace boost::corosio {
32   32  
33   /** A random-access file with devirtualized async I/O operations. 33   /** A random-access file with devirtualized async I/O operations.
34   34  
35   This class template inherits from @ref random_access_file and 35   This class template inherits from @ref random_access_file and
36   shadows `read_some_at` / `write_some_at` with versions that 36   shadows `read_some_at` / `write_some_at` with versions that
37   call the backend implementation directly, allowing the compiler 37   call the backend implementation directly, allowing the compiler
38   to inline through the entire call chain. 38   to inline through the entire call chain.
39   39  
40   Non-async operations (`open`, `close`, `size`, `resize`, 40   Non-async operations (`open`, `close`, `size`, `resize`,
41   `sync_data`, `sync_all`) remain unchanged and dispatch through 41   `sync_data`, `sync_all`) remain unchanged and dispatch through
42   the compiled library. 42   the compiled library.
43   43  
44   A `native_random_access_file` IS-A `random_access_file` and 44   A `native_random_access_file` IS-A `random_access_file` and
45   can be passed to any function expecting `random_access_file&`, 45   can be passed to any function expecting `random_access_file&`,
46   in which case virtual dispatch is used transparently. 46   in which case virtual dispatch is used transparently.
47   47  
48   @note On POSIX platforms, file I/O is dispatched to a thread 48   @note On POSIX platforms, file I/O is dispatched to a thread
49   pool regardless of the chosen reactor backend, so all three 49   pool regardless of the chosen reactor backend, so all three
50   reactor tags (`epoll`, `select`, `kqueue`) resolve to the same 50   reactor tags (`epoll`, `select`, `kqueue`) resolve to the same
51   underlying implementation. The `Backend` template parameter 51   underlying implementation. The `Backend` template parameter
52   exists for API symmetry with @ref native_tcp_socket and friends. 52   exists for API symmetry with @ref native_tcp_socket and friends.
53   The vtable savings are smaller relative to the thread-pool / 53   The vtable savings are smaller relative to the thread-pool /
54   overlapped-I/O cost than they are for socket operations. 54   overlapped-I/O cost than they are for socket operations.
55   55  
56   @tparam Backend A backend tag value (e.g., `epoll`, `iocp`). 56   @tparam Backend A backend tag value (e.g., `epoll`, `iocp`).
57   57  
58   @par Thread Safety 58   @par Thread Safety
59   Same as @ref random_access_file. 59   Same as @ref random_access_file.
60   60  
61   @par Example 61   @par Example
62   @code 62   @code
63   #include <boost/corosio/native/native_random_access_file.hpp> 63   #include <boost/corosio/native/native_random_access_file.hpp>
64   64  
65   native_io_context<epoll> ctx; 65   native_io_context<epoll> ctx;
66   native_random_access_file<epoll> f(ctx); 66   native_random_access_file<epoll> f(ctx);
67 - f.open("data.bin", file_base::read_only); 67 + if (auto ec = f.open("data.bin", file_base::read_only))
  68 + co_return;
68   char buf[4096]; 69   char buf[4096];
69   auto [ec, n] = co_await f.read_some_at( 70   auto [ec, n] = co_await f.read_some_at(
70   0, capy::mutable_buffer(buf, sizeof(buf))); 71   0, capy::mutable_buffer(buf, sizeof(buf)));
71   @endcode 72   @endcode
72   73  
73   @see random_access_file, epoll_t, iocp_t 74   @see random_access_file, epoll_t, iocp_t
74   */ 75   */
75   template<auto Backend> 76   template<auto Backend>
76   class native_random_access_file : public random_access_file 77   class native_random_access_file : public random_access_file
77   { 78   {
78   using backend_type = decltype(Backend); 79   using backend_type = decltype(Backend);
79   using impl_type = typename backend_type::random_access_file_type; 80   using impl_type = typename backend_type::random_access_file_type;
80   using service_type = 81   using service_type =
81   typename backend_type::random_access_file_service_type; 82   typename backend_type::random_access_file_service_type;
82   83  
HITCBC 83   4 impl_type& get_impl() noexcept 84   10 impl_type& get_impl() noexcept
84   { 85   {
HITCBC 85   4 return *static_cast<impl_type*>(h_.get()); 86   10 return *static_cast<impl_type*>(h_.get());
86   } 87   }
87   88  
88   template<class MutableBufferSequence> 89   template<class MutableBufferSequence>
89   struct native_read_at_awaitable 90   struct native_read_at_awaitable
90   { 91   {
91   native_random_access_file& self_; 92   native_random_access_file& self_;
92   std::uint64_t offset_; 93   std::uint64_t offset_;
93   MutableBufferSequence buffers_; 94   MutableBufferSequence buffers_;
94   std::stop_token token_; 95   std::stop_token token_;
95   mutable std::error_code ec_; 96   mutable std::error_code ec_;
96   mutable std::size_t bytes_transferred_ = 0; 97   mutable std::size_t bytes_transferred_ = 0;
97   98  
HITCBC 98   2 native_read_at_awaitable( 99   6 native_read_at_awaitable(
99   native_random_access_file& self, 100   native_random_access_file& self,
100   std::uint64_t offset, 101   std::uint64_t offset,
101   MutableBufferSequence buffers) noexcept 102   MutableBufferSequence buffers) noexcept
HITCBC 102   2 : self_(self) 103   6 : self_(self)
HITCBC 103   2 , offset_(offset) 104   6 , offset_(offset)
HITCBC 104   2 , buffers_(std::move(buffers)) 105   6 , buffers_(std::move(buffers))
105   { 106   {
HITCBC 106   2 } 107   6 }
107   108  
HITCBC 108   2 bool await_ready() const noexcept 109   6 bool await_ready() const noexcept
109   { 110   {
ECB 110 - 2 return token_.stop_requested(); 111 + // A pre-set ec_ means the initiator failed before
  112 + // dispatch (e.g. a closed object).
HITGNC   113 + 6 return static_cast<bool>(ec_) || token_.stop_requested();
111   } 114   }
112   115  
HITCBC 113   2 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept 116   6 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
114   { 117   {
HITCBC 115   2 if (token_.stop_requested()) 118   6 if (token_.stop_requested())
MISUBC 116   ✗ return {make_error_code(std::errc::operation_canceled), 0}; 119   ✗ return {make_error_code(std::errc::operation_canceled), 0};
HITCBC 117   2 return {ec_, bytes_transferred_}; 120   6 return {ec_, bytes_transferred_};
118   } 121   }
119   122  
HITCBC 120   2 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env) 123   6 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
121   -> std::coroutine_handle<> 124   -> std::coroutine_handle<>
122   { 125   {
HITCBC 123   2 token_ = env->stop_token; 126   6 token_ = env->stop_token;
HITCBC 124   6 return self_.get_impl().read_some_at( 127   18 return self_.get_impl().read_some_at(
HITCBC 125   2 offset_, h, env->executor, buffers_, 128   6 offset_, h, env->executor, buffers_,
HITCBC 126   6 token_, &ec_, &bytes_transferred_); 129   18 token_, &ec_, &bytes_transferred_);
127   } 130   }
128   }; 131   };
129   132  
130   template<class ConstBufferSequence> 133   template<class ConstBufferSequence>
131   struct native_write_at_awaitable 134   struct native_write_at_awaitable
132   { 135   {
133   native_random_access_file& self_; 136   native_random_access_file& self_;
134   std::uint64_t offset_; 137   std::uint64_t offset_;
135   ConstBufferSequence buffers_; 138   ConstBufferSequence buffers_;
136   std::stop_token token_; 139   std::stop_token token_;
137   mutable std::error_code ec_; 140   mutable std::error_code ec_;
138   mutable std::size_t bytes_transferred_ = 0; 141   mutable std::size_t bytes_transferred_ = 0;
139   142  
HITCBC 140   2 native_write_at_awaitable( 143   4 native_write_at_awaitable(
141   native_random_access_file& self, 144   native_random_access_file& self,
142   std::uint64_t offset, 145   std::uint64_t offset,
143   ConstBufferSequence buffers) noexcept 146   ConstBufferSequence buffers) noexcept
HITCBC 144   2 : self_(self) 147   4 : self_(self)
HITCBC 145   2 , offset_(offset) 148   4 , offset_(offset)
HITCBC 146   2 , buffers_(std::move(buffers)) 149   4 , buffers_(std::move(buffers))
147   { 150   {
HITCBC 148   2 } 151   4 }
149   152  
HITCBC 150   2 bool await_ready() const noexcept 153   4 bool await_ready() const noexcept
151   { 154   {
ECB 152 - 2 return token_.stop_requested(); 155 + // A pre-set ec_ means the initiator failed before
  156 + // dispatch (e.g. a closed object).
HITGNC   157 + 4 return static_cast<bool>(ec_) || token_.stop_requested();
153   } 158   }
154   159  
HITCBC 155   2 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept 160   4 [[nodiscard]] capy::io_result<std::size_t> await_resume() const noexcept
156   { 161   {
HITCBC 157   2 if (token_.stop_requested()) 162   4 if (token_.stop_requested())
MISUBC 158   ✗ return {make_error_code(std::errc::operation_canceled), 0}; 163   ✗ return {make_error_code(std::errc::operation_canceled), 0};
HITCBC 159   2 return {ec_, bytes_transferred_}; 164   4 return {ec_, bytes_transferred_};
160   } 165   }
161   166  
HITCBC 162   2 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env) 167   4 auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
163   -> std::coroutine_handle<> 168   -> std::coroutine_handle<>
164   { 169   {
HITCBC 165   2 token_ = env->stop_token; 170   4 token_ = env->stop_token;
HITCBC 166   6 return self_.get_impl().write_some_at( 171   12 return self_.get_impl().write_some_at(
HITCBC 167   2 offset_, h, env->executor, buffers_, 172   4 offset_, h, env->executor, buffers_,
HITCBC 168   6 token_, &ec_, &bytes_transferred_); 173   12 token_, &ec_, &bytes_transferred_);
169   } 174   }
170   }; 175   };
171   176  
172   public: 177   public:
173   /** Construct a native random-access file from an execution context. 178   /** Construct a native random-access file from an execution context.
174   179  
175   @param ctx The execution context that will own this file. 180   @param ctx The execution context that will own this file.
176   */ 181   */
HITCBC 177   10 explicit native_random_access_file(capy::execution_context& ctx) 182   12 explicit native_random_access_file(capy::execution_context& ctx)
HITCBC 178   10 : random_access_file(create_handle<service_type>(ctx)) 183   12 : random_access_file(create_handle<service_type>(ctx))
179   { 184   {
HITCBC 180   10 } 185   12 }
181   186  
182   /** Construct a native random-access file from an executor. 187   /** Construct a native random-access file from an executor.
183   188  
184   @param ex The executor whose context will own this file. 189   @param ex The executor whose context will own this file.
185   */ 190   */
186   template<class Ex> 191   template<class Ex>
187   requires(!std::same_as< 192   requires(!std::same_as<
188   std::remove_cvref_t<Ex>, 193   std::remove_cvref_t<Ex>,
189   native_random_access_file>) && 194   native_random_access_file>) &&
190   capy::Executor<Ex> 195   capy::Executor<Ex>
191   explicit native_random_access_file(Ex const& ex) 196   explicit native_random_access_file(Ex const& ex)
192   : native_random_access_file(ex.context()) 197   : native_random_access_file(ex.context())
193   { 198   {
194   } 199   }
195   200  
196   /// Move construct. 201   /// Move construct.
197   native_random_access_file(native_random_access_file&&) noexcept = default; 202   native_random_access_file(native_random_access_file&&) noexcept = default;
198   203  
199   /// Move assign. 204   /// Move assign.
200   native_random_access_file& 205   native_random_access_file&
201   operator=(native_random_access_file&&) noexcept = default; 206   operator=(native_random_access_file&&) noexcept = default;
202   207  
203   native_random_access_file(native_random_access_file const&) = delete; 208   native_random_access_file(native_random_access_file const&) = delete;
204   native_random_access_file& 209   native_random_access_file&
205   operator=(native_random_access_file const&) = delete; 210   operator=(native_random_access_file const&) = delete;
206   211  
207   /** Asynchronously read at the given offset. 212   /** Asynchronously read at the given offset.
208   213  
209   Calls the backend implementation directly, bypassing virtual 214   Calls the backend implementation directly, bypassing virtual
210   dispatch. Otherwise identical to @ref random_access_file::read_some_at. 215   dispatch. Otherwise identical to @ref random_access_file::read_some_at.
211   */ 216   */
212   template<capy::MutableBufferSequence MB> 217   template<capy::MutableBufferSequence MB>
HITCBC 213 - 2 auto read_some_at(std::uint64_t offset, MB const& buffers) 218 + 6 [[nodiscard]] auto read_some_at(std::uint64_t offset, MB const& buffers)
214   { 219   {
HITCBC 215   2 return native_read_at_awaitable<MB>(*this, offset, buffers); 220   6 return native_read_at_awaitable<MB>(*this, offset, buffers);
216   } 221   }
217   222  
218   /** Asynchronously write at the given offset. 223   /** Asynchronously write at the given offset.
219   224  
220   Calls the backend implementation directly, bypassing virtual 225   Calls the backend implementation directly, bypassing virtual
221   dispatch. Otherwise identical to @ref random_access_file::write_some_at. 226   dispatch. Otherwise identical to @ref random_access_file::write_some_at.
222   */ 227   */
223   template<capy::ConstBufferSequence CB> 228   template<capy::ConstBufferSequence CB>
HITCBC 224 - 2 auto write_some_at(std::uint64_t offset, CB const& buffers) 229 + 4 [[nodiscard]] auto write_some_at(std::uint64_t offset, CB const& buffers)
225   { 230   {
HITCBC 226   2 return native_write_at_awaitable<CB>(*this, offset, buffers); 231   4 return native_write_at_awaitable<CB>(*this, offset, buffers);
227   } 232   }
228   }; 233   };
229   234  
230   } // namespace boost::corosio 235   } // namespace boost::corosio
231   236  
232   #endif // BOOST_COROSIO_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP 237   #endif // BOOST_COROSIO_NATIVE_NATIVE_RANDOM_ACCESS_FILE_HPP