. /include/boost/corosio /tcp_acceptor.hpp
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1   // 1   //
2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com) 2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   // Copyright (c) 2026 Steve Gerbino 3   // Copyright (c) 2026 Steve Gerbino
4   // Copyright (c) 2026 Michael Vandeberg 4   // Copyright (c) 2026 Michael Vandeberg
5   // 5   //
6   // Distributed under the Boost Software License, Version 1.0. (See accompanying 6   // Distributed under the Boost Software License, Version 1.0. (See accompanying
7   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 7   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8   // 8   //
9   // Official repository: https://github.com/cppalliance/corosio 9   // Official repository: https://github.com/cppalliance/corosio
10   // 10   //
11   11  
12   #ifndef BOOST_COROSIO_TCP_ACCEPTOR_HPP 12   #ifndef BOOST_COROSIO_TCP_ACCEPTOR_HPP
13   #define BOOST_COROSIO_TCP_ACCEPTOR_HPP 13   #define BOOST_COROSIO_TCP_ACCEPTOR_HPP
14   14  
15   #include <boost/corosio/family.hpp> 15   #include <boost/corosio/family.hpp>
16   #include <boost/corosio/detail/config.hpp> 16   #include <boost/corosio/detail/config.hpp>
17   #include <boost/corosio/detail/except.hpp> 17   #include <boost/corosio/detail/except.hpp>
18   #include <boost/corosio/detail/native_handle.hpp> 18   #include <boost/corosio/detail/native_handle.hpp>
19   #include <boost/corosio/detail/op_base.hpp> 19   #include <boost/corosio/detail/op_base.hpp>
20   #include <boost/corosio/wait_type.hpp> 20   #include <boost/corosio/wait_type.hpp>
21   #include <boost/corosio/io/io_object.hpp> 21   #include <boost/corosio/io/io_object.hpp>
22   #include <boost/capy/io_result.hpp> 22   #include <boost/capy/io_result.hpp>
23   #include <boost/corosio/endpoint.hpp> 23   #include <boost/corosio/endpoint.hpp>
24   #include <boost/corosio/tcp_socket.hpp> 24   #include <boost/corosio/tcp_socket.hpp>
25   #include <boost/capy/ex/executor_ref.hpp> 25   #include <boost/capy/ex/executor_ref.hpp>
26   #include <boost/capy/ex/execution_context.hpp> 26   #include <boost/capy/ex/execution_context.hpp>
27   #include <boost/capy/ex/io_env.hpp> 27   #include <boost/capy/ex/io_env.hpp>
28   #include <boost/capy/concept/executor.hpp> 28   #include <boost/capy/concept/executor.hpp>
29   29  
30   #include <system_error> 30   #include <system_error>
31   31  
32   #include <concepts> 32   #include <concepts>
33   #include <coroutine> 33   #include <coroutine>
34   #include <cstddef> 34   #include <cstddef>
35   #include <stop_token> 35   #include <stop_token>
36   #include <type_traits> 36   #include <type_traits>
37   37  
38   namespace boost::corosio { 38   namespace boost::corosio {
39   39  
40   /** Accepts inbound TCP connections, from a coroutine. 40   /** Accepts inbound TCP connections, from a coroutine.
41   41  
42   This class provides asynchronous TCP accept operations that return 42   This class provides asynchronous TCP accept operations that return
43   awaitable types. The acceptor binds to a local endpoint and listens 43   awaitable types. The acceptor binds to a local endpoint and listens
44   for incoming connections. 44   for incoming connections.
45   45  
46   Each accept operation participates in the affine awaitable protocol, 46   Each accept operation participates in the affine awaitable protocol,
47   ensuring coroutines resume on the correct executor. 47   ensuring coroutines resume on the correct executor.
48   48  
49   @par Thread Safety 49   @par Thread Safety
50   Distinct objects: Safe.@n 50   Distinct objects: Safe.@n
51   Shared objects: Unsafe. An acceptor must not have concurrent accept 51   Shared objects: Unsafe. An acceptor must not have concurrent accept
52   operations. 52   operations.
53   53  
54   @par Semantics 54   @par Semantics
55   Wraps the platform TCP listener. Operations dispatch to 55   Wraps the platform TCP listener. Operations dispatch to
56   OS accept APIs via the `io_context` reactor. 56   OS accept APIs via the `io_context` reactor.
57   57  
58   @par Example 58   @par Example
59   @par !example convenience_construction 59   @par !example convenience_construction
60   60  
61   @par Example 61   @par Example
62   @par !example fine_grained_setup 62   @par !example fine_grained_setup
63   */ 63   */
64   class BOOST_COROSIO_DECL tcp_acceptor : public io_object 64   class BOOST_COROSIO_DECL tcp_acceptor : public io_object
65   { 65   {
66   struct wait_awaitable : detail::void_op_base<wait_awaitable> 66   struct wait_awaitable : detail::void_op_base<wait_awaitable>
67   { 67   {
68   private: 68   private:
69   friend tcp_acceptor; 69   friend tcp_acceptor;
70   70  
HITCBC 71   28 wait_awaitable(tcp_acceptor& acc, wait_type w) noexcept 71   28 wait_awaitable(tcp_acceptor& acc, wait_type w) noexcept
HITCBC 72   56 : acc_(acc) 72   56 : acc_(acc)
HITCBC 73   28 , w_(w) 73   28 , w_(w)
74   { 74   {
HITCBC 75   28 } 75   28 }
76   76  
77   friend detail::void_op_base<wait_awaitable>; 77   friend detail::void_op_base<wait_awaitable>;
78   78  
79   tcp_acceptor& acc_; 79   tcp_acceptor& acc_;
80   wait_type w_; 80   wait_type w_;
81   81  
82   std::coroutine_handle<> 82   std::coroutine_handle<>
HITCBC 83   24 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const 83   24 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
84   { 84   {
HITCBC 85   24 return acc_.get().wait(h, ex, w_, token_, &ec_); 85   24 return acc_.get().wait(h, ex, w_, token_, &ec_);
86   } 86   }
87   }; 87   };
88   88  
89   struct accept_awaitable : detail::void_op_base<accept_awaitable> 89   struct accept_awaitable : detail::void_op_base<accept_awaitable>
90   { 90   {
91   private: 91   private:
92   friend tcp_acceptor; 92   friend tcp_acceptor;
93   friend detail::void_op_base<accept_awaitable>; 93   friend detail::void_op_base<accept_awaitable>;
94   94  
95   tcp_acceptor& acc_; 95   tcp_acceptor& acc_;
96   tcp_socket& peer_; 96   tcp_socket& peer_;
97   mutable io_object::implementation* peer_impl_ = nullptr; 97   mutable io_object::implementation* peer_impl_ = nullptr;
98   98  
HITCBC 99   4518 accept_awaitable(tcp_acceptor& acc, tcp_socket& peer) noexcept 99   4532 accept_awaitable(tcp_acceptor& acc, tcp_socket& peer) noexcept
HITCBC 100   9036 : acc_(acc) 100   9064 : acc_(acc)
HITCBC 101   4518 , peer_(peer) 101   4532 , peer_(peer)
102   { 102   {
HITCBC 103   4518 } 103   4532 }
104   104  
105   std::coroutine_handle<> 105   std::coroutine_handle<>
HITCBC 106   4514 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const 106   4528 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
107   { 107   {
HITCBC 108   13542 return acc_.get().accept( 108   13584 return acc_.get().accept(
HITCBC 109   13542 h, ex, this->token_, &this->ec_, &peer_impl_); 109   13584 h, ex, this->token_, &this->ec_, &peer_impl_);
110   } 110   }
111   111  
112   public: 112   public:
HITCBC 113   4508 [[nodiscard]] capy::io_result<> await_resume() const noexcept 113   4522 [[nodiscard]] capy::io_result<> await_resume() const noexcept
114   { 114   {
HITCBC 115   4508 if (!this->ec_ && peer_impl_) 115   4522 if (!this->ec_ && peer_impl_)
HITCBC 116   4413 peer_.h_.reset(peer_impl_); 116   4427 peer_.h_.reset(peer_impl_);
HITCBC 117   4508 return {this->ec_}; 117   4522 return {this->ec_};
118   } 118   }
119   }; 119   };
120   120  
121   struct accept_value_awaitable : detail::void_op_base<accept_value_awaitable> 121   struct accept_value_awaitable : detail::void_op_base<accept_value_awaitable>
122   { 122   {
123   private: 123   private:
124   friend tcp_acceptor; 124   friend tcp_acceptor;
125   friend detail::void_op_base<accept_value_awaitable>; 125   friend detail::void_op_base<accept_value_awaitable>;
126   126  
127   tcp_acceptor& acc_; 127   tcp_acceptor& acc_;
128   mutable io_object::implementation* peer_impl_ = nullptr; 128   mutable io_object::implementation* peer_impl_ = nullptr;
129   129  
HITCBC 130   33 explicit accept_value_awaitable(tcp_acceptor& acc) noexcept : acc_(acc) 130   33 explicit accept_value_awaitable(tcp_acceptor& acc) noexcept : acc_(acc)
131   { 131   {
HITCBC 132   33 } 132   33 }
133   133  
134   std::coroutine_handle<> 134   std::coroutine_handle<>
HITCBC 135   29 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const 135   29 dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
136   { 136   {
HITCBC 137   87 return acc_.get().accept( 137   87 return acc_.get().accept(
HITCBC 138   87 h, ex, this->token_, &this->ec_, &peer_impl_); 138   87 h, ex, this->token_, &this->ec_, &peer_impl_);
139   } 139   }
140   140  
141   public: 141   public:
HITCBC 142   33 [[nodiscard]] capy::io_result<tcp_socket> await_resume() noexcept 142   33 [[nodiscard]] capy::io_result<tcp_socket> await_resume() noexcept
143   { 143   {
144   // The peer is built only on success: error paths must not 144   // The peer is built only on success: error paths must not
145   // touch acc_.context(), which a moved-from acceptor lacks. 145   // touch acc_.context(), which a moved-from acceptor lacks.
HITCBC 146   33 if (this->ec_ || !peer_impl_) 146   33 if (this->ec_ || !peer_impl_)
HITCBC 147   6 return {this->ec_, tcp_socket()}; 147   6 return {this->ec_, tcp_socket()};
148   148  
HITCBC 149   27 tcp_socket peer(acc_.context()); 149   27 tcp_socket peer(acc_.context());
HITCBC 150   27 peer.h_.reset(peer_impl_); 150   27 peer.h_.reset(peer_impl_);
HITCBC 151   27 return {this->ec_, std::move(peer)}; 151   27 return {this->ec_, std::move(peer)};
HITCBC 152   27 } 152   27 }
153   }; 153   };
154   154  
155   public: 155   public:
156   /** Closes the acceptor if open, cancelling any pending operations. 156   /** Closes the acceptor if open, cancelling any pending operations.
157   */ 157   */
158   ~tcp_acceptor() override; 158   ~tcp_acceptor() override;
159   159  
160   /** Construct an acceptor from an execution context. 160   /** Construct an acceptor from an execution context.
161   161  
162   @param ctx The execution context that owns this acceptor. 162   @param ctx The execution context that owns this acceptor.
163   */ 163   */
164   explicit tcp_acceptor(capy::execution_context& ctx); 164   explicit tcp_acceptor(capy::execution_context& ctx);
165   165  
166   /** Convenience constructor: open + configure + bind + listen. 166   /** Convenience constructor: open + configure + bind + listen.
167   167  
168   Creates a fully bound listening acceptor in a single 168   Creates a fully bound listening acceptor in a single
169   expression, throwing the codes the piecewise `open()` + 169   expression, throwing the codes the piecewise `open()` +
170   `set_option()` + `bind()` + `listen()` path reports. The 170   `set_option()` + `bind()` + `listen()` path reports. The
171   address family is deduced from @p ep. 171   address family is deduced from @p ep.
172   172  
173   Before binding, the constructor configures address reuse so a 173   Before binding, the constructor configures address reuse so a
174   server can rebind its port immediately after a restart. It 174   server can rebind its port immediately after a restart. It
175   sets `SO_REUSEADDR` on POSIX and `SO_EXCLUSIVEADDRUSE` on 175   sets `SO_REUSEADDR` on POSIX and `SO_EXCLUSIVEADDRUSE` on
176   Windows. Windows does not use `SO_REUSEADDR` because it 176   Windows. Windows does not use `SO_REUSEADDR` because it
177   instead grants other sockets bind-over rights. A second 177   instead grants other sockets bind-over rights. A second
178   listener on an occupied endpoint therefore throws 178   listener on an occupied endpoint therefore throws
179   `errc::address_in_use` on every platform. 179   `errc::address_in_use` on every platform.
180   180  
181   @param ctx The execution context that owns this acceptor. 181   @param ctx The execution context that owns this acceptor.
182   @param ep The local endpoint to bind to. 182   @param ep The local endpoint to bind to.
183   @param backlog The maximum pending connection queue length. 183   @param backlog The maximum pending connection queue length.
184   184  
185   @throws std::system_error on open, configuration, bind, or 185   @throws std::system_error on open, configuration, bind, or
186   listen failure. 186   listen failure.
187   */ 187   */
188   tcp_acceptor(capy::execution_context& ctx, endpoint ep, int backlog = 128); 188   tcp_acceptor(capy::execution_context& ctx, endpoint ep, int backlog = 128);
189   189  
190   /** Construct an acceptor from an executor. 190   /** Construct an acceptor from an executor.
191   191  
192   The acceptor is associated with the executor's context. `Ex` 192   The acceptor is associated with the executor's context. `Ex`
193   must satisfy `capy::Executor`. 193   must satisfy `capy::Executor`.
194   194  
195   @param ex The executor whose context owns the acceptor. 195   @param ex The executor whose context owns the acceptor.
196   */ 196   */
197   template<class Ex> 197   template<class Ex>
198   requires(!std::same_as<std::remove_cvref_t<Ex>, tcp_acceptor>) && 198   requires(!std::same_as<std::remove_cvref_t<Ex>, tcp_acceptor>) &&
199   capy::Executor<Ex> 199   capy::Executor<Ex>
HITCBC 200   1 explicit tcp_acceptor(Ex const& ex) : tcp_acceptor(ex.context()) 200   1 explicit tcp_acceptor(Ex const& ex) : tcp_acceptor(ex.context())
201   { 201   {
HITCBC 202   1 } 202   1 }
203   203  
204   /** Convenience constructor from an executor. 204   /** Convenience constructor from an executor.
205   205  
206   Creates a fully bound listening acceptor in a single 206   Creates a fully bound listening acceptor in a single
207   expression, throwing the codes the piecewise `open()` + 207   expression, throwing the codes the piecewise `open()` +
208   `set_option()` + `bind()` + `listen()` path reports. The 208   `set_option()` + `bind()` + `listen()` path reports. The
209   address family is deduced from @p ep. 209   address family is deduced from @p ep.
210   210  
211   Before binding, the constructor configures address reuse so a 211   Before binding, the constructor configures address reuse so a
212   server can rebind its port immediately after a restart. It 212   server can rebind its port immediately after a restart. It
213   sets `SO_REUSEADDR` on POSIX and `SO_EXCLUSIVEADDRUSE` on 213   sets `SO_REUSEADDR` on POSIX and `SO_EXCLUSIVEADDRUSE` on
214   Windows. Windows does not use `SO_REUSEADDR` because it 214   Windows. Windows does not use `SO_REUSEADDR` because it
215   instead grants other sockets bind-over rights. A second 215   instead grants other sockets bind-over rights. A second
216   listener on an occupied endpoint therefore throws 216   listener on an occupied endpoint therefore throws
217   `errc::address_in_use` on every platform. 217   `errc::address_in_use` on every platform.
218   218  
219   `Ex` must satisfy `capy::Executor`. 219   `Ex` must satisfy `capy::Executor`.
220   220  
221   @param ex The executor whose context owns the acceptor. 221   @param ex The executor whose context owns the acceptor.
222   @param ep The local endpoint to bind to. 222   @param ep The local endpoint to bind to.
223   @param backlog The maximum pending connection queue length. 223   @param backlog The maximum pending connection queue length.
224   224  
225   @throws std::system_error on open, configuration, bind, or 225   @throws std::system_error on open, configuration, bind, or
226   listen failure. 226   listen failure.
227   */ 227   */
228   template<class Ex> 228   template<class Ex>
229   requires capy::Executor<Ex> 229   requires capy::Executor<Ex>
230   tcp_acceptor(Ex const& ex, endpoint ep, int backlog = 128) 230   tcp_acceptor(Ex const& ex, endpoint ep, int backlog = 128)
231   : tcp_acceptor(ex.context(), ep, backlog) 231   : tcp_acceptor(ex.context(), ep, backlog)
232   { 232   {
233   } 233   }
234   234  
235   /** Transfers ownership of the acceptor resources. 235   /** Transfers ownership of the acceptor resources.
236   236  
237   @param other The acceptor to move from. 237   @param other The acceptor to move from.
238   238  
239   @pre No awaitables returned by @p other's methods exist. 239   @pre No awaitables returned by @p other's methods exist.
240   @pre The execution context associated with @p other must 240   @pre The execution context associated with @p other must
241   outlive this acceptor. 241   outlive this acceptor.
242   */ 242   */
HITCBC 243   9 tcp_acceptor(tcp_acceptor&& other) noexcept : io_object(std::move(other)) {} 243   9 tcp_acceptor(tcp_acceptor&& other) noexcept : io_object(std::move(other)) {}
244   244  
245   /** Closes any existing acceptor and transfers ownership. 245   /** Closes any existing acceptor and transfers ownership.
246   246  
247   @param other The acceptor to move from. 247   @param other The acceptor to move from.
248   248  
249   @pre No awaitables returned by either `*this` or @p other's 249   @pre No awaitables returned by either `*this` or @p other's
250   methods exist. 250   methods exist.
251   @pre The execution context associated with @p other must 251   @pre The execution context associated with @p other must
252   outlive this acceptor. 252   outlive this acceptor.
253   253  
254   @return Reference to this acceptor. 254   @return Reference to this acceptor.
255   */ 255   */
HITCBC 256   3 tcp_acceptor& operator=(tcp_acceptor&& other) noexcept 256   3 tcp_acceptor& operator=(tcp_acceptor&& other) noexcept
257   { 257   {
HITCBC 258   3 if (this != &other) 258   3 if (this != &other)
259   { 259   {
HITCBC 260   3 close(); 260   3 close();
HITCBC 261   3 h_ = std::move(other.h_); 261   3 h_ = std::move(other.h_);
262   } 262   }
HITCBC 263   3 return *this; 263   3 return *this;
264   } 264   }
265   265  
266   /// Copy construction is disabled; the handle is uniquely owned. 266   /// Copy construction is disabled; the handle is uniquely owned.
267   tcp_acceptor(tcp_acceptor const&) = delete; 267   tcp_acceptor(tcp_acceptor const&) = delete;
268   /// Copy assignment is disabled; the handle is uniquely owned. 268   /// Copy assignment is disabled; the handle is uniquely owned.
269   tcp_acceptor& operator=(tcp_acceptor const&) = delete; 269   tcp_acceptor& operator=(tcp_acceptor const&) = delete;
270   270  
271   /** Create the acceptor socket without binding or listening. 271   /** Create the acceptor socket without binding or listening.
272   272  
273   Creates a TCP socket with dual-stack enabled for IPv6. 273   Creates a TCP socket with dual-stack enabled for IPv6.
274   Does not set SO_REUSEADDR. Call `set_option` explicitly 274   Does not set SO_REUSEADDR. Call `set_option` explicitly
275   if needed. 275   if needed.
276   276  
277   If the acceptor is already open, this function is a no-op. 277   If the acceptor is already open, this function is a no-op.
278   278  
279   Failures such as descriptor exhaustion are normal runtime 279   Failures such as descriptor exhaustion are normal runtime
280   conditions and are reported through the returned error code. 280   conditions and are reported through the returned error code.
281   281  
282   @param f The address family (IPv4 or IPv6). Defaults to 282   @param f The address family (IPv4 or IPv6). Defaults to
283   `family::v4`. 283   `family::v4`.
284   284  
285   @par Example 285   @par Example
286   @par !example open 286   @par !example open
287   287  
288   @see bind, listen 288   @see bind, listen
289   289  
290   @return The error code, empty on success. 290   @return The error code, empty on success.
291   */ 291   */
292   [[nodiscard]] std::error_code open(family f = family::v4) noexcept; 292   [[nodiscard]] std::error_code open(family f = family::v4) noexcept;
293   293  
294   /** Bind to a local endpoint. 294   /** Bind to a local endpoint.
295   295  
296   The acceptor must be open. Binds the socket to @p ep and 296   The acceptor must be open. Binds the socket to @p ep and
297   caches the resolved local endpoint (useful when port 0 is 297   caches the resolved local endpoint (useful when port 0 is
298   used to request an ephemeral port). 298   used to request an ephemeral port).
299   299  
300   @param ep The local endpoint to bind to. 300   @param ep The local endpoint to bind to.
301   301  
302   @return An error code indicating success or the reason for 302   @return An error code indicating success or the reason for
303   failure. 303   failure.
304   304  
305   @par Error Conditions 305   @par Error Conditions
306   @li `errc::address_in_use`: The endpoint is already in use. 306   @li `errc::address_in_use`: The endpoint is already in use.
307   @li `errc::address_not_available`: The address is not available 307   @li `errc::address_not_available`: The address is not available
308   on any local interface. 308   on any local interface.
309   @li `errc::permission_denied`: Insufficient privileges to bind 309   @li `errc::permission_denied`: Insufficient privileges to bind
310   to the endpoint (e.g., privileged port). 310   to the endpoint (e.g., privileged port).
311   @li `errc::bad_file_descriptor`: The acceptor is not open. 311   @li `errc::bad_file_descriptor`: The acceptor is not open.
312   */ 312   */
313   [[nodiscard]] std::error_code bind(endpoint ep) noexcept; 313   [[nodiscard]] std::error_code bind(endpoint ep) noexcept;
314   314  
315   /** Start listening for incoming connections. 315   /** Start listening for incoming connections.
316   316  
317   The acceptor must be open and bound. Registers the acceptor 317   The acceptor must be open and bound. Registers the acceptor
318   with the platform reactor. 318   with the platform reactor.
319   319  
320   @param backlog The maximum length of the queue of pending 320   @param backlog The maximum length of the queue of pending
321   connections. Defaults to 128. 321   connections. Defaults to 128.
322   322  
323   @return An error code indicating success or the reason for 323   @return An error code indicating success or the reason for
324   failure. 324   failure.
325   325  
326   A closed acceptor reports `errc::bad_file_descriptor`. 326   A closed acceptor reports `errc::bad_file_descriptor`.
327   */ 327   */
328   [[nodiscard]] std::error_code listen(int backlog = 128) noexcept; 328   [[nodiscard]] std::error_code listen(int backlog = 128) noexcept;
329   329  
330   /** Close the acceptor. 330   /** Close the acceptor.
331   331  
332   Releases acceptor resources. Any pending operations complete 332   Releases acceptor resources. Any pending operations complete
333   with `errc::operation_canceled`. 333   with `errc::operation_canceled`.
334   */ 334   */
335   void close() noexcept; 335   void close() noexcept;
336   336  
337   /** Check if the acceptor is listening. 337   /** Check if the acceptor is listening.
338   338  
339   @return `true` if the acceptor is open and listening. 339   @return `true` if the acceptor is open and listening.
340   */ 340   */
HITCBC 341   8811 bool is_open() const noexcept 341   8825 bool is_open() const noexcept
342   { 342   {
HITCBC 343   8811 return h_ && get().is_open(); 343   8825 return h_ && get().is_open();
344   } 344   }
345   345  
346   /** Initiate an asynchronous accept operation. 346   /** Initiate an asynchronous accept operation.
347   347  
348   Accepts an incoming connection and initializes the provided 348   Accepts an incoming connection and initializes the provided
349   socket with the new connection. The acceptor must be listening 349   socket with the new connection. The acceptor must be listening
350   before calling this function. 350   before calling this function.
351   351  
352   The operation supports cancellation via `std::stop_token` through 352   The operation supports cancellation via `std::stop_token` through
353   the affine awaitable protocol. If the associated stop token is 353   the affine awaitable protocol. If the associated stop token is
354   triggered, the operation completes immediately with 354   triggered, the operation completes immediately with
355   `errc::operation_canceled`. 355   `errc::operation_canceled`.
356   356  
357   @param peer The socket to receive the accepted connection. Any 357   @param peer The socket to receive the accepted connection. Any
358   existing connection on this socket is closed. 358   existing connection on this socket is closed.
359   359  
360   @return An awaitable that completes with `io_result<>`. 360   @return An awaitable that completes with `io_result<>`.
361   Returns success on successful accept, or an error code on 361   Returns success on successful accept, or an error code on
362   failure including: 362   failure including:
363   - `operation_canceled`: Cancelled via stop_token or cancel(). 363   - `operation_canceled`: Cancelled via stop_token or cancel().
364   Check `ec == cond::canceled` for portable comparison. 364   Check `ec == cond::canceled` for portable comparison.
365   365  
366   A closed acceptor completes with `errc::bad_file_descriptor`. 366   A closed acceptor completes with `errc::bad_file_descriptor`.
367   367  
368   @pre The peer socket must be associated with the same execution context. 368   @pre The peer socket must be associated with the same execution context.
369   369  
370   Both this acceptor and @p peer must outlive the returned 370   Both this acceptor and @p peer must outlive the returned
371   awaitable. 371   awaitable.
372   372  
373   @par Example 373   @par Example
374   @par !example accept_into_a_reused_socket 374   @par !example accept_into_a_reused_socket
375   375  
376   @see accept() 376   @see accept()
377   */ 377   */
HITCBC 378   4518 [[nodiscard]] auto accept(tcp_socket& peer) 378   4532 [[nodiscard]] auto accept(tcp_socket& peer)
379   { 379   {
HITCBC 380   4518 accept_awaitable aw(*this, peer); 380   4532 accept_awaitable aw(*this, peer);
HITCBC 381   4518 if (!is_open()) 381   4532 if (!is_open())
HITCBC 382   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor); 382   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor);
HITCBC 383   4518 return aw; 383   4532 return aw;
384   } 384   }
385   385  
386   /** Initiate an asynchronous accept operation, returning the peer. 386   /** Initiate an asynchronous accept operation, returning the peer.
387   387  
388   Accepts an incoming connection and returns a newly constructed 388   Accepts an incoming connection and returns a newly constructed
389   socket for it, associated with this acceptor's execution context. 389   socket for it, associated with this acceptor's execution context.
390   The acceptor must be listening before calling this function. 390   The acceptor must be listening before calling this function.
391   391  
392   The caller does not pre-construct the peer socket. The returned 392   The caller does not pre-construct the peer socket. The returned
393   socket shares this acceptor's execution context. 393   socket shares this acceptor's execution context.
394   394  
395   The operation supports cancellation via `std::stop_token` through 395   The operation supports cancellation via `std::stop_token` through
396   the affine awaitable protocol. If the associated stop token is 396   the affine awaitable protocol. If the associated stop token is
397   triggered, the operation completes immediately with 397   triggered, the operation completes immediately with
398   `errc::operation_canceled`. 398   `errc::operation_canceled`.
399   399  
400   @return An awaitable that completes with `io_result<tcp_socket>`. 400   @return An awaitable that completes with `io_result<tcp_socket>`.
401   On success the payload is the connected peer socket; on failure 401   On success the payload is the connected peer socket; on failure
402   (including cancellation) the error code is set and the payload 402   (including cancellation) the error code is set and the payload
403   socket is unconnected. Errors include: 403   socket is unconnected. Errors include:
404   - `operation_canceled`: Cancelled via stop_token or cancel(). 404   - `operation_canceled`: Cancelled via stop_token or cancel().
405   Check `ec == cond::canceled` for portable comparison. 405   Check `ec == cond::canceled` for portable comparison.
406   406  
407   A closed acceptor completes with `errc::bad_file_descriptor`. 407   A closed acceptor completes with `errc::bad_file_descriptor`.
408   On failure the returned socket is default-constructed and 408   On failure the returned socket is default-constructed and
409   may only be destroyed or assigned. 409   may only be destroyed or assigned.
410   410  
411   @pre This acceptor must outlive the returned awaitable. 411   @pre This acceptor must outlive the returned awaitable.
412   412  
413   @par Example 413   @par Example
414   @par !example accept_returning_a_new_socket 414   @par !example accept_returning_a_new_socket
415   415  
416   @see accept(tcp_socket&) 416   @see accept(tcp_socket&)
417   */ 417   */
HITCBC 418   33 [[nodiscard]] auto accept() 418   33 [[nodiscard]] auto accept()
419   { 419   {
HITCBC 420   33 accept_value_awaitable aw(*this); 420   33 accept_value_awaitable aw(*this);
HITCBC 421   33 if (!is_open()) 421   33 if (!is_open())
HITCBC 422   4 aw.ec_ = make_error_code(std::errc::bad_file_descriptor); 422   4 aw.ec_ = make_error_code(std::errc::bad_file_descriptor);
HITCBC 423   33 return aw; 423   33 return aw;
424   } 424   }
425   425  
426   /** Wait for an incoming connection or readiness condition. 426   /** Wait for an incoming connection or readiness condition.
427   427  
428   Suspends until the listen socket is ready in the 428   Suspends until the listen socket is ready in the
429   requested direction, or an error condition is reported. 429   requested direction, or an error condition is reported.
430   For `wait_type::read`, completion signals that a 430   For `wait_type::read`, completion signals that a
431   subsequent @ref accept succeeds without blocking. A 431   subsequent @ref accept succeeds without blocking. A
432   connection already queued when the wait begins completes 432   connection already queued when the wait begins completes
433   it immediately. No connection is consumed. 433   it immediately. No connection is consumed.
434   434  
435   @note `wait_type::write` is not usable on an acceptor: 435   @note `wait_type::write` is not usable on an acceptor:
436   writability carries no meaning for a listening socket, so 436   writability carries no meaning for a listening socket, so
437   the wait fails with `errc::operation_not_supported` on 437   the wait fails with `errc::operation_not_supported` on
438   every backend. 438   every backend.
439   439  
440   @param w The wait direction. 440   @param w The wait direction.
441   441  
442   @return An awaitable that completes with `io_result<>`. 442   @return An awaitable that completes with `io_result<>`.
443   443  
444   A closed acceptor completes with `errc::bad_file_descriptor`. 444   A closed acceptor completes with `errc::bad_file_descriptor`.
445   445  
446   @pre This acceptor must outlive the returned awaitable. 446   @pre This acceptor must outlive the returned awaitable.
447   */ 447   */
HITCBC 448   28 [[nodiscard]] auto wait(wait_type w) 448   28 [[nodiscard]] auto wait(wait_type w)
449   { 449   {
HITCBC 450   28 wait_awaitable aw(*this, w); 450   28 wait_awaitable aw(*this, w);
HITCBC 451   28 if (!is_open()) 451   28 if (!is_open())
HITCBC 452   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor); 452   2 aw.ec_ = make_error_code(std::errc::bad_file_descriptor);
HITCBC 453   28 return aw; 453   28 return aw;
454   } 454   }
455   455  
456   /** Cancel any pending asynchronous operations. 456   /** Cancel any pending asynchronous operations.
457   457  
458   Accept and wait transfer no bytes, so a cancellation always wins: 458   Accept and wait transfer no bytes, so a cancellation always wins:
459   an operation reports `errc::operation_canceled` even when it had 459   an operation reports `errc::operation_canceled` even when it had
460   already succeeded when the cancellation landed. Check 460   already succeeded when the cancellation landed. Check
461   `ec == cond::canceled` for portable comparison. 461   `ec == cond::canceled` for portable comparison.
462   */ 462   */
463   void cancel() noexcept; 463   void cancel() noexcept;
464   464  
465   /** Get the native socket handle. 465   /** Get the native socket handle.
466   466  
467   Returns the underlying platform-specific socket descriptor. 467   Returns the underlying platform-specific socket descriptor.
468   On POSIX systems this is an `int` file descriptor. 468   On POSIX systems this is an `int` file descriptor.
469   On Windows this is a `SOCKET` handle. 469   On Windows this is a `SOCKET` handle.
470   470  
471   @return The native socket handle, or -1/INVALID_SOCKET if not open. 471   @return The native socket handle, or -1/INVALID_SOCKET if not open.
472   472  
473   @pre None. May be called on closed acceptors. 473   @pre None. May be called on closed acceptors.
474   */ 474   */
475   native_handle_type native_handle() const noexcept; 475   native_handle_type native_handle() const noexcept;
476   476  
477   /** Assign an existing native socket to this acceptor. 477   /** Assign an existing native socket to this acceptor.
478   478  
479   Adopts a listening socket created outside the library. The 479   Adopts a listening socket created outside the library. The
480   socket may come from a service manager, be inherited, or be 480   socket may come from a service manager, be inherited, or be
481   created natively. Adoption registers the socket with the 481   created natively. Adoption registers the socket with the
482   backend. The socket must be a listening stream socket in the 482   backend. The socket must be a listening stream socket in the
483   `AF_INET` or `AF_INET6` family. 483   `AF_INET` or `AF_INET6` family.
484   Adoption never alters the descriptor's flags or options: on 484   Adoption never alters the descriptor's flags or options: on
485   POSIX the fd must already be non-blocking, and on Windows the 485   POSIX the fd must already be non-blocking, and on Windows the
486   socket must be overlapped-capable. 486   socket must be overlapped-capable.
487   487  
488   Adoption does not verify listen state; @ref accept reports the 488   Adoption does not verify listen state; @ref accept reports the
489   error if the socket is not listening. 489   error if the socket is not listening.
490   490  
491   If this object is already open, pending operations complete 491   If this object is already open, pending operations complete
492   with `errc::operation_canceled` and the held socket is 492   with `errc::operation_canceled` and the held socket is
493   closed before the new one is adopted. 493   closed before the new one is adopted.
494   494  
495   @par Exception Safety 495   @par Exception Safety
496   Strong guarantee on validation failure: the object is 496   Strong guarantee on validation failure: the object is
497   unchanged. If backend registration fails, the object either 497   unchanged. If backend registration fails, the object either
498   retains its previous socket or is left closed, depending on 498   retains its previous socket or is left closed, depending on
499   the backend. In all failure cases the caller retains 499   the backend. In all failure cases the caller retains
500   ownership of `fd`. 500   ownership of `fd`.
501   501  
502   @param fd The native socket to adopt. On success the object 502   @param fd The native socket to adopt. On success the object
503   owns it and closes it. 503   owns it and closes it.
504   504  
505   @return The error code, empty on success. Validation and 505   @return The error code, empty on success. Validation and
506   registration failures are normal runtime conditions when 506   registration failures are normal runtime conditions when
507   adopting foreign descriptors. 507   adopting foreign descriptors.
508   */ 508   */
509   [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept; 509   [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept;
510   510  
511   /** Release ownership of the native socket handle. 511   /** Release ownership of the native socket handle.
512   512  
513   Deregisters the socket from the backend and cancels pending 513   Deregisters the socket from the backend and cancels pending
514   operations without closing the descriptor. The caller takes 514   operations without closing the descriptor. The caller takes
515   ownership of the returned handle. 515   ownership of the returned handle.
516   516  
517   @return The native handle. 517   @return The native handle.
518   518  
519   @throws std::system_error `errc::bad_file_descriptor` if the 519   @throws std::system_error `errc::bad_file_descriptor` if the
520   acceptor is not open. 520   acceptor is not open.
521   521  
522   @post is_open() == false 522   @post is_open() == false
523   */ 523   */
524   native_handle_type release(); 524   native_handle_type release();
525   525  
526   /** Get the local endpoint of the acceptor. 526   /** Get the local endpoint of the acceptor.
527   527  
528   Returns the local address and port to which the acceptor is bound. 528   Returns the local address and port to which the acceptor is bound.
529   This is useful when binding to port 0 (ephemeral port) to discover 529   This is useful when binding to port 0 (ephemeral port) to discover
530   the OS-assigned port number. The endpoint is cached when bind() 530   the OS-assigned port number. The endpoint is cached when bind()
531   is called. 531   is called.
532   532  
533   @return The local endpoint, or a default endpoint (0.0.0.0:0) if 533   @return The local endpoint, or a default endpoint (0.0.0.0:0) if
534   the acceptor is not open. 534   the acceptor is not open.
535   535  
536   @par Thread Safety 536   @par Thread Safety
537   The cached endpoint value is set during bind() and cleared 537   The cached endpoint value is set during bind() and cleared
538   during close(). This function may be called concurrently with 538   during close(). This function may be called concurrently with
539   accept operations, but must not be called concurrently with 539   accept operations, but must not be called concurrently with
540   bind() or close(). 540   bind() or close().
541   */ 541   */
542   endpoint local_endpoint() const noexcept; 542   endpoint local_endpoint() const noexcept;
543   543  
544   /** Set a socket option on the acceptor. 544   /** Set a socket option on the acceptor.
545   545  
546   Applies a type-safe socket option to the underlying listening 546   Applies a type-safe socket option to the underlying listening
547   socket. The socket must be open (via `open()` or `listen()`). 547   socket. The socket must be open (via `open()` or `listen()`).
548   This is useful for setting options between `open()` and 548   This is useful for setting options between `open()` and
549   `listen()`, such as `socket_option::reuse_port`. 549   `listen()`, such as `socket_option::reuse_port`.
550   550  
551   @par Example 551   @par Example
552   @par !example set_option 552   @par !example set_option
553   553  
554   @param opt The option to set. 554   @param opt The option to set.
555   555  
556   @throws std::system_error `errc::bad_file_descriptor` if the 556   @throws std::system_error `errc::bad_file_descriptor` if the
557   acceptor is not open; otherwise thrown on failure. 557   acceptor is not open; otherwise thrown on failure.
558   */ 558   */
559   template<class Option> 559   template<class Option>
HITCBC 560   605 void set_option(Option const& opt) 560   605 void set_option(Option const& opt)
561   { 561   {
HITCBC 562   605 if (!is_open()) 562   605 if (!is_open())
HITCBC 563   2 detail::throw_system_error( 563   2 detail::throw_system_error(
HITCBC 564   4 make_error_code(std::errc::bad_file_descriptor), 564   4 make_error_code(std::errc::bad_file_descriptor),
565   "tcp_acceptor::set_option"); 565   "tcp_acceptor::set_option");
HITCBC 566   603 auto const fam = get().family(); 566   603 auto const fam = get().family();
HITCBC 567   603 std::error_code ec = get().set_option( 567   603 std::error_code ec = get().set_option(
568   opt.level(fam), opt.name(fam), opt.data(fam), opt.size(fam)); 568   opt.level(fam), opt.name(fam), opt.data(fam), opt.size(fam));
HITCBC 569   603 if (ec) 569   603 if (ec)
HITCBC 570   8 detail::throw_system_error(ec, "tcp_acceptor::set_option"); 570   8 detail::throw_system_error(ec, "tcp_acceptor::set_option");
HITCBC 571   595 } 571   595 }
572   572  
573   /** Get a socket option from the acceptor. 573   /** Get a socket option from the acceptor.
574   574  
575   Retrieves the current value of a type-safe socket option. 575   Retrieves the current value of a type-safe socket option.
576   576  
577   @par Example 577   @par Example
578   @par !example get_option 578   @par !example get_option
579   579  
580   @return The current option value. 580   @return The current option value.
581   581  
582   @throws std::system_error `errc::bad_file_descriptor` if the 582   @throws std::system_error `errc::bad_file_descriptor` if the
583   acceptor is not open; otherwise thrown on failure. 583   acceptor is not open; otherwise thrown on failure.
584   */ 584   */
585   template<class Option> 585   template<class Option>
HITCBC 586   23 Option get_option() const 586   23 Option get_option() const
587   { 587   {
HITCBC 588   23 if (!is_open()) 588   23 if (!is_open())
HITCBC 589   2 detail::throw_system_error( 589   2 detail::throw_system_error(
HITCBC 590   4 make_error_code(std::errc::bad_file_descriptor), 590   4 make_error_code(std::errc::bad_file_descriptor),
591   "tcp_acceptor::get_option"); 591   "tcp_acceptor::get_option");
HITCBC 592   21 Option opt{}; 592   21 Option opt{};
HITCBC 593   21 auto const fam = get().family(); 593   21 auto const fam = get().family();
HITCBC 594   21 std::size_t sz = opt.size(fam); 594   21 std::size_t sz = opt.size(fam);
595   std::error_code ec = 595   std::error_code ec =
HITCBC 596   21 get().get_option(opt.level(fam), opt.name(fam), opt.data(fam), &sz); 596   21 get().get_option(opt.level(fam), opt.name(fam), opt.data(fam), &sz);
HITCBC 597   21 if (ec) 597   21 if (ec)
HITCBC 598   8 detail::throw_system_error(ec, "tcp_acceptor::get_option"); 598   8 detail::throw_system_error(ec, "tcp_acceptor::get_option");
HITCBC 599   13 opt.resize(fam, sz); 599   13 opt.resize(fam, sz);
HITCBC 600   13 return opt; 600   13 return opt;
601   } 601   }
602   602  
603   /** Define backend hooks for TCP acceptor operations. 603   /** Define backend hooks for TCP acceptor operations.
604   604  
605   Platform backends derive from this to implement 605   Platform backends derive from this to implement
606   accept, endpoint query, open-state checks, cancellation, 606   accept, endpoint query, open-state checks, cancellation,
607   and socket-option management. 607   and socket-option management.
608   */ 608   */
609   struct implementation : io_object::implementation 609   struct implementation : io_object::implementation
610   { 610   {
611   /** Initiate an asynchronous accept operation. 611   /** Initiate an asynchronous accept operation.
612   612  
613   @param h Coroutine handle to resume on completion. 613   @param h Coroutine handle to resume on completion.
614   @param ex Executor for dispatching the completion. 614   @param ex Executor for dispatching the completion.
615   @param token Stop token for cancellation. 615   @param token Stop token for cancellation.
616   @param ec Output error code. 616   @param ec Output error code.
617   @param impl_out Output implementation for the accepted peer. 617   @param impl_out Output implementation for the accepted peer.
618   618  
619   @return Coroutine handle to resume immediately. 619   @return Coroutine handle to resume immediately.
620   */ 620   */
621   virtual std::coroutine_handle<> accept( 621   virtual std::coroutine_handle<> accept(
622   std::coroutine_handle<> h, 622   std::coroutine_handle<> h,
623   capy::executor_ref ex, 623   capy::executor_ref ex,
624   std::stop_token token, 624   std::stop_token token,
625   std::error_code* ec, 625   std::error_code* ec,
626   io_object::implementation** impl_out) = 0; 626   io_object::implementation** impl_out) = 0;
627   627  
628   /** Initiate an asynchronous wait for acceptor readiness. 628   /** Initiate an asynchronous wait for acceptor readiness.
629   629  
630   Completes when the listen socket becomes ready for 630   Completes when the listen socket becomes ready for
631   the specified direction (typically `wait_type::read` 631   the specified direction (typically `wait_type::read`
632   for an incoming connection), or an error condition is 632   for an incoming connection), or an error condition is
633   reported. No connection is consumed. 633   reported. No connection is consumed.
634   634  
635   @param h Coroutine handle to resume on completion. 635   @param h Coroutine handle to resume on completion.
636   @param ex Executor for dispatching the completion. 636   @param ex Executor for dispatching the completion.
637   @param w The direction to wait on. 637   @param w The direction to wait on.
638   @param token Stop token for cancellation. 638   @param token Stop token for cancellation.
639   @param ec Output error code. 639   @param ec Output error code.
640   640  
641   @return Coroutine handle to resume immediately. 641   @return Coroutine handle to resume immediately.
642   */ 642   */
643   virtual std::coroutine_handle<> wait( 643   virtual std::coroutine_handle<> wait(
644   std::coroutine_handle<> h, 644   std::coroutine_handle<> h,
645   capy::executor_ref ex, 645   capy::executor_ref ex,
646   wait_type w, 646   wait_type w,
647   std::stop_token token, 647   std::stop_token token,
648   std::error_code* ec) = 0; 648   std::error_code* ec) = 0;
649   649  
650   /** Returns the cached local endpoint. 650   /** Returns the cached local endpoint.
651   651  
652   @return The cached local endpoint. 652   @return The cached local endpoint.
653   */ 653   */
654   virtual endpoint local_endpoint() const noexcept = 0; 654   virtual endpoint local_endpoint() const noexcept = 0;
655   655  
656   /** Return true if the acceptor has a kernel resource open. 656   /** Return true if the acceptor has a kernel resource open.
657   657  
658   @return true if the acceptor has a kernel resource open. 658   @return true if the acceptor has a kernel resource open.
659   */ 659   */
660   virtual bool is_open() const noexcept = 0; 660   virtual bool is_open() const noexcept = 0;
661   661  
662   /** Return the native handle, or the platform sentinel if closed. 662   /** Return the native handle, or the platform sentinel if closed.
663   663  
664   @return The native handle, or the platform sentinel if closed. 664   @return The native handle, or the platform sentinel if closed.
665   */ 665   */
666   virtual native_handle_type native_handle() const noexcept = 0; 666   virtual native_handle_type native_handle() const noexcept = 0;
667   667  
668   /** Return the socket's address family. 668   /** Return the socket's address family.
669   669  
670   Socket options render for this family. 670   Socket options render for this family.
671   671  
672   @return The socket's address family. 672   @return The socket's address family.
673   */ 673   */
674   virtual corosio::family family() const noexcept = 0; 674   virtual corosio::family family() const noexcept = 0;
675   675  
676   /** Release and return the native handle without closing. 676   /** Release and return the native handle without closing.
677   677  
678   @return The native handle. 678   @return The native handle.
679   */ 679   */
680   virtual native_handle_type release_socket() noexcept = 0; 680   virtual native_handle_type release_socket() noexcept = 0;
681   681  
682   /** Cancel any pending asynchronous operations. 682   /** Cancel any pending asynchronous operations.
683   683  
684   Accept and wait transfer no bytes, so a cancellation always 684   Accept and wait transfer no bytes, so a cancellation always
685   wins: an operation reports `operation_canceled` even when it 685   wins: an operation reports `operation_canceled` even when it
686   had already succeeded when the cancellation landed. 686   had already succeeded when the cancellation landed.
687   */ 687   */
688   virtual void cancel() noexcept = 0; 688   virtual void cancel() noexcept = 0;
689   689  
690   /** Set a socket option. 690   /** Set a socket option.
691   691  
692   @param level The protocol level. 692   @param level The protocol level.
693   @param optname The option name. 693   @param optname The option name.
694   @param data Pointer to the option value. 694   @param data Pointer to the option value.
695   @param size Size of the option value in bytes. 695   @param size Size of the option value in bytes.
696   @return Error code on failure, empty on success. 696   @return Error code on failure, empty on success.
697   */ 697   */
698   virtual std::error_code set_option( 698   virtual std::error_code set_option(
699   int level, 699   int level,
700   int optname, 700   int optname,
701   void const* data, 701   void const* data,
702   std::size_t size) noexcept = 0; 702   std::size_t size) noexcept = 0;
703   703  
704   /** Get a socket option. 704   /** Get a socket option.
705   705  
706   @param level The protocol level. 706   @param level The protocol level.
707   @param optname The option name. 707   @param optname The option name.
708   @param data Pointer to receive the option value. 708   @param data Pointer to receive the option value.
709   @param size On entry, the size of the buffer. On exit, 709   @param size On entry, the size of the buffer. On exit,
710   the size of the option value. 710   the size of the option value.
711   @return Error code on failure, empty on success. 711   @return Error code on failure, empty on success.
712   */ 712   */
713   virtual std::error_code 713   virtual std::error_code
714   get_option(int level, int optname, void* data, std::size_t* size) 714   get_option(int level, int optname, void* data, std::size_t* size)
715   const noexcept = 0; 715   const noexcept = 0;
716   }; 716   };
717   717  
718   protected: 718   protected:
719   /** Adopt an existing handle. 719   /** Adopt an existing handle.
720   720  
721   @param h The handle the acceptor takes ownership of. 721   @param h The handle the acceptor takes ownership of.
722   */ 722   */
HITCBC 723   35 explicit tcp_acceptor(handle h) noexcept : io_object(std::move(h)) {} 723   35 explicit tcp_acceptor(handle h) noexcept : io_object(std::move(h)) {}
724   724  
725   /** Transfer the accepted peer implementation to the peer socket. 725   /** Transfer the accepted peer implementation to the peer socket.
726   726  
727   @param peer The socket that receives the transferred implementation. 727   @param peer The socket that receives the transferred implementation.
728   @param impl The accepted peer implementation, or null to do nothing. 728   @param impl The accepted peer implementation, or null to do nothing.
729   */ 729   */
730   static void 730   static void
HITCBC 731   17 reset_peer_impl(tcp_socket& peer, io_object::implementation* impl) noexcept 731   17 reset_peer_impl(tcp_socket& peer, io_object::implementation* impl) noexcept
732   { 732   {
HITCBC 733   17 if (impl) 733   17 if (impl)
HITCBC 734   17 peer.h_.reset(impl); 734   17 peer.h_.reset(impl);
HITCBC 735   17 } 735   17 }
736   736  
737   private: 737   private:
HITCBC 738   15200 inline implementation& get() const noexcept 738   15228 inline implementation& get() const noexcept
739   { 739   {
HITCBC 740   15200 return *static_cast<implementation*>(h_.get()); 740   15228 return *static_cast<implementation*>(h_.get());
741   } 741   }
742   }; 742   };
743   743  
744   } // namespace boost::corosio 744   } // namespace boost::corosio
745   745  
746   #endif 746   #endif