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1 | // |
2 | // experimental/detail/channel_service.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com) | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_EXPERIMENTAL_DETAIL_CHANNEL_SERVICE_HPP | |
12 | #define BOOST_ASIO_EXPERIMENTAL_DETAIL_CHANNEL_SERVICE_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | #include <boost/asio/associated_cancellation_slot.hpp> | |
20 | #include <boost/asio/cancellation_type.hpp> | |
21 | #include <boost/asio/detail/mutex.hpp> | |
22 | #include <boost/asio/detail/op_queue.hpp> | |
23 | #include <boost/asio/execution_context.hpp> | |
24 | #include <boost/asio/experimental/detail/channel_message.hpp> | |
25 | #include <boost/asio/experimental/detail/channel_receive_op.hpp> | |
26 | #include <boost/asio/experimental/detail/channel_send_op.hpp> | |
27 | #include <boost/asio/experimental/detail/has_signature.hpp> | |
28 | ||
29 | #include <boost/asio/detail/push_options.hpp> | |
30 | ||
31 | namespace boost { | |
32 | namespace asio { | |
33 | namespace experimental { | |
34 | namespace detail { | |
35 | ||
36 | template <typename Mutex> | |
37 | class channel_service | |
38 | : public boost::asio::detail::execution_context_service_base< | |
39 | channel_service<Mutex> > | |
40 | { | |
41 | public: | |
42 | // Possible states for a channel end. | |
43 | enum state | |
44 | { | |
45 | buffer = 0, | |
46 | waiter = 1, | |
47 | block = 2, | |
48 | closed = 3 | |
49 | }; | |
50 | ||
51 | // The base implementation type of all channels. | |
52 | struct base_implementation_type | |
53 | { | |
54 | // Default constructor. | |
55 | base_implementation_type() | |
56 | : receive_state_(block), | |
57 | send_state_(block), | |
58 | max_buffer_size_(0), | |
59 | next_(0), | |
60 | prev_(0) | |
61 | { | |
62 | } | |
63 | ||
64 | // The current state of the channel. | |
65 | state receive_state_ : 16; | |
66 | state send_state_ : 16; | |
67 | ||
68 | // The maximum number of elements that may be buffered in the channel. | |
69 | std::size_t max_buffer_size_; | |
70 | ||
71 | // The operations that are waiting on the channel. | |
72 | boost::asio::detail::op_queue<channel_operation> waiters_; | |
73 | ||
74 | // Pointers to adjacent channel implementations in linked list. | |
75 | base_implementation_type* next_; | |
76 | base_implementation_type* prev_; | |
77 | ||
78 | // The mutex type to protect the internal implementation. | |
79 | mutable Mutex mutex_; | |
80 | }; | |
81 | ||
82 | // The implementation for a specific value type. | |
83 | template <typename Traits, typename... Signatures> | |
84 | struct implementation_type; | |
85 | ||
86 | // Constructor. | |
87 | channel_service(execution_context& ctx); | |
88 | ||
89 | // Destroy all user-defined handler objects owned by the service. | |
90 | void shutdown(); | |
91 | ||
92 | // Construct a new channel implementation. | |
93 | void construct(base_implementation_type& impl, std::size_t max_buffer_size); | |
94 | ||
95 | // Destroy a channel implementation. | |
96 | template <typename Traits, typename... Signatures> | |
97 | void destroy(implementation_type<Traits, Signatures...>& impl); | |
98 | ||
99 | // Move-construct a new channel implementation. | |
100 | template <typename Traits, typename... Signatures> | |
101 | void move_construct(implementation_type<Traits, Signatures...>& impl, | |
102 | implementation_type<Traits, Signatures...>& other_impl); | |
103 | ||
104 | // Move-assign from another channel implementation. | |
105 | template <typename Traits, typename... Signatures> | |
106 | void move_assign(implementation_type<Traits, Signatures...>& impl, | |
107 | channel_service& other_service, | |
108 | implementation_type<Traits, Signatures...>& other_impl); | |
109 | ||
110 | // Get the capacity of the channel. | |
111 | std::size_t capacity( | |
112 | const base_implementation_type& impl) const BOOST_ASIO_NOEXCEPT; | |
113 | ||
114 | // Determine whether the channel is open. | |
115 | bool is_open(const base_implementation_type& impl) const BOOST_ASIO_NOEXCEPT; | |
116 | ||
117 | // Reset the channel to its initial state. | |
118 | template <typename Traits, typename... Signatures> | |
119 | void reset(implementation_type<Traits, Signatures...>& impl); | |
120 | ||
121 | // Close the channel. | |
122 | template <typename Traits, typename... Signatures> | |
123 | void close(implementation_type<Traits, Signatures...>& impl); | |
124 | ||
125 | // Cancel all operations associated with the channel. | |
126 | template <typename Traits, typename... Signatures> | |
127 | void cancel(implementation_type<Traits, Signatures...>& impl); | |
128 | ||
129 | // Cancel the operation associated with the channel that has the given key. | |
130 | template <typename Traits, typename... Signatures> | |
131 | void cancel_by_key(implementation_type<Traits, Signatures...>& impl, | |
132 | void* cancellation_key); | |
133 | ||
134 | // Determine whether a value can be read from the channel without blocking. | |
135 | bool ready(const base_implementation_type& impl) const BOOST_ASIO_NOEXCEPT; | |
136 | ||
137 | // Synchronously send a new value into the channel. | |
138 | template <typename Message, typename Traits, | |
139 | typename... Signatures, typename... Args> | |
140 | bool try_send(implementation_type<Traits, Signatures...>& impl, | |
141 | BOOST_ASIO_MOVE_ARG(Args)... args); | |
142 | ||
143 | // Synchronously send a number of new values into the channel. | |
144 | template <typename Message, typename Traits, | |
145 | typename... Signatures, typename... Args> | |
146 | std::size_t try_send_n(implementation_type<Traits, Signatures...>& impl, | |
147 | std::size_t count, BOOST_ASIO_MOVE_ARG(Args)... args); | |
148 | ||
149 | // Asynchronously send a new value into the channel. | |
150 | template <typename Traits, typename... Signatures, | |
151 | typename Handler, typename IoExecutor> | |
152 | void async_send(implementation_type<Traits, Signatures...>& impl, | |
153 | BOOST_ASIO_MOVE_ARG2(typename implementation_type< | |
154 | Traits, Signatures...>::payload_type) payload, | |
155 | Handler& handler, const IoExecutor& io_ex) | |
156 | { | |
157 | typename associated_cancellation_slot<Handler>::type slot | |
158 | = boost::asio::get_associated_cancellation_slot(handler); | |
159 | ||
160 | // Allocate and construct an operation to wrap the handler. | |
161 | typedef channel_send_op< | |
162 | typename implementation_type<Traits, Signatures...>::payload_type, | |
163 | Handler, IoExecutor> op; | |
164 | typename op::ptr p = { boost::asio::detail::addressof(handler), | |
165 | op::ptr::allocate(handler), 0 }; | |
166 | p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST2(typename implementation_type< | |
167 | Traits, Signatures...>::payload_type)(payload), handler, io_ex); | |
168 | ||
169 | // Optionally register for per-operation cancellation. | |
170 | if (slot.is_connected()) | |
171 | { | |
172 | p.p->cancellation_key_ = | |
173 | &slot.template emplace<op_cancellation<Traits, Signatures...> >( | |
174 | this, &impl); | |
175 | } | |
176 | ||
177 | BOOST_ASIO_HANDLER_CREATION((this->context(), *p.p, | |
178 | "channel", &impl, 0, "async_send")); | |
179 | ||
180 | start_send_op(impl, p.p); | |
181 | p.v = p.p = 0; | |
182 | } | |
183 | ||
184 | // Synchronously receive a value from the channel. | |
185 | template <typename Traits, typename... Signatures, typename Handler> | |
186 | bool try_receive(implementation_type<Traits, Signatures...>& impl, | |
187 | BOOST_ASIO_MOVE_ARG(Handler) handler); | |
188 | ||
189 | // Asynchronously send a new value into the channel. | |
190 | // Asynchronously receive a value from the channel. | |
191 | template <typename Traits, typename... Signatures, | |
192 | typename Handler, typename IoExecutor> | |
193 | void async_receive(implementation_type<Traits, Signatures...>& impl, | |
194 | Handler& handler, const IoExecutor& io_ex) | |
195 | { | |
196 | typename associated_cancellation_slot<Handler>::type slot | |
197 | = boost::asio::get_associated_cancellation_slot(handler); | |
198 | ||
199 | // Allocate and construct an operation to wrap the handler. | |
200 | typedef channel_receive_op< | |
201 | typename implementation_type<Traits, Signatures...>::payload_type, | |
202 | Handler, IoExecutor> op; | |
203 | typename op::ptr p = { boost::asio::detail::addressof(handler), | |
204 | op::ptr::allocate(handler), 0 }; | |
205 | p.p = new (p.v) op(handler, io_ex); | |
206 | ||
207 | // Optionally register for per-operation cancellation. | |
208 | if (slot.is_connected()) | |
209 | { | |
210 | p.p->cancellation_key_ = | |
211 | &slot.template emplace<op_cancellation<Traits, Signatures...> >( | |
212 | this, &impl); | |
213 | } | |
214 | ||
215 | BOOST_ASIO_HANDLER_CREATION((this->context(), *p.p, | |
216 | "channel", &impl, 0, "async_receive")); | |
217 | ||
218 | start_receive_op(impl, p.p); | |
219 | p.v = p.p = 0; | |
220 | } | |
221 | ||
222 | private: | |
223 | // Helper function object to handle a closed notification. | |
224 | template <typename Payload, typename Signature> | |
225 | struct complete_receive | |
226 | { | |
227 | explicit complete_receive(channel_receive<Payload>* op) | |
228 | : op_(op) | |
229 | { | |
230 | } | |
231 | ||
232 | template <typename... Args> | |
233 | void operator()(BOOST_ASIO_MOVE_ARG(Args)... args) | |
234 | { | |
235 | op_->complete( | |
236 | channel_message<Signature>(0, | |
237 | BOOST_ASIO_MOVE_CAST(Args)(args)...)); | |
238 | } | |
239 | ||
240 | channel_receive<Payload>* op_; | |
241 | }; | |
242 | ||
243 | // Destroy a base channel implementation. | |
244 | void base_destroy(base_implementation_type& impl); | |
245 | ||
246 | // Helper function to start an asynchronous put operation. | |
247 | template <typename Traits, typename... Signatures> | |
248 | void start_send_op(implementation_type<Traits, Signatures...>& impl, | |
249 | channel_send<typename implementation_type< | |
250 | Traits, Signatures...>::payload_type>* send_op); | |
251 | ||
252 | // Helper function to start an asynchronous get operation. | |
253 | template <typename Traits, typename... Signatures> | |
254 | void start_receive_op(implementation_type<Traits, Signatures...>& impl, | |
255 | channel_receive<typename implementation_type< | |
256 | Traits, Signatures...>::payload_type>* receive_op); | |
257 | ||
258 | // Helper class used to implement per-operation cancellation. | |
259 | template <typename Traits, typename... Signatures> | |
260 | class op_cancellation | |
261 | { | |
262 | public: | |
263 | op_cancellation(channel_service* s, | |
264 | implementation_type<Traits, Signatures...>* impl) | |
265 | : service_(s), | |
266 | impl_(impl) | |
267 | { | |
268 | } | |
269 | ||
270 | void operator()(cancellation_type_t type) | |
271 | { | |
272 | if (!!(type & | |
273 | (cancellation_type::terminal | |
274 | | cancellation_type::partial | |
275 | | cancellation_type::total))) | |
276 | { | |
277 | service_->cancel_by_key(*impl_, this); | |
278 | } | |
279 | } | |
280 | ||
281 | private: | |
282 | channel_service* service_; | |
283 | implementation_type<Traits, Signatures...>* impl_; | |
284 | }; | |
285 | ||
286 | // Mutex to protect access to the linked list of implementations. | |
287 | boost::asio::detail::mutex mutex_; | |
288 | ||
289 | // The head of a linked list of all implementations. | |
290 | base_implementation_type* impl_list_; | |
291 | }; | |
292 | ||
293 | // The implementation for a specific value type. | |
294 | template <typename Mutex> | |
295 | template <typename Traits, typename... Signatures> | |
296 | struct channel_service<Mutex>::implementation_type : base_implementation_type | |
297 | { | |
298 | // The traits type associated with the channel. | |
299 | typedef typename Traits::template rebind<Signatures...>::other traits_type; | |
300 | ||
301 | // Type of an element stored in the buffer. | |
302 | typedef typename conditional< | |
303 | has_signature< | |
304 | typename traits_type::receive_cancelled_signature, | |
305 | Signatures... | |
306 | >::value, | |
307 | typename conditional< | |
308 | has_signature< | |
309 | typename traits_type::receive_closed_signature, | |
310 | Signatures... | |
311 | >::value, | |
312 | channel_payload<Signatures...>, | |
313 | channel_payload< | |
314 | Signatures..., | |
315 | typename traits_type::receive_closed_signature | |
316 | > | |
317 | >::type, | |
318 | typename conditional< | |
319 | has_signature< | |
320 | typename traits_type::receive_closed_signature, | |
321 | Signatures..., | |
322 | typename traits_type::receive_cancelled_signature | |
323 | >::value, | |
324 | channel_payload< | |
325 | Signatures..., | |
326 | typename traits_type::receive_cancelled_signature | |
327 | >, | |
328 | channel_payload< | |
329 | Signatures..., | |
330 | typename traits_type::receive_cancelled_signature, | |
331 | typename traits_type::receive_closed_signature | |
332 | > | |
333 | >::type | |
334 | >::type payload_type; | |
335 | ||
336 | // Move from another buffer. | |
337 | void buffer_move_from(implementation_type& other) | |
338 | { | |
339 | buffer_ = BOOST_ASIO_MOVE_CAST( | |
340 | typename traits_type::template container< | |
341 | payload_type>::type)(other.buffer_); | |
342 | other.buffer_clear(); | |
343 | } | |
344 | ||
345 | // Get number of buffered elements. | |
346 | std::size_t buffer_size() const | |
347 | { | |
348 | return buffer_.size(); | |
349 | } | |
350 | ||
351 | // Push a new value to the back of the buffer. | |
352 | void buffer_push(payload_type payload) | |
353 | { | |
354 | buffer_.push_back(BOOST_ASIO_MOVE_CAST(payload_type)(payload)); | |
355 | } | |
356 | ||
357 | // Push new values to the back of the buffer. | |
358 | std::size_t buffer_push_n(std::size_t count, payload_type payload) | |
359 | { | |
360 | std::size_t i = 0; | |
361 | for (; i < count && buffer_.size() < this->max_buffer_size_; ++i) | |
362 | buffer_.push_back(payload); | |
363 | return i; | |
364 | } | |
365 | ||
366 | // Get the element at the front of the buffer. | |
367 | payload_type buffer_front() | |
368 | { | |
369 | return BOOST_ASIO_MOVE_CAST(payload_type)(buffer_.front()); | |
370 | } | |
371 | ||
372 | // Pop a value from the front of the buffer. | |
373 | void buffer_pop() | |
374 | { | |
375 | buffer_.pop_front(); | |
376 | } | |
377 | ||
378 | // Clear all buffered values. | |
379 | void buffer_clear() | |
380 | { | |
381 | buffer_.clear(); | |
382 | } | |
383 | ||
384 | private: | |
385 | // Buffered values. | |
386 | typename traits_type::template container<payload_type>::type buffer_; | |
387 | }; | |
388 | ||
389 | // The implementation for a void value type. | |
390 | template <typename Mutex> | |
391 | template <typename Traits, typename R> | |
392 | struct channel_service<Mutex>::implementation_type<Traits, R()> | |
393 | : channel_service::base_implementation_type | |
394 | { | |
395 | // The traits type associated with the channel. | |
396 | typedef typename Traits::template rebind<R()>::other traits_type; | |
397 | ||
398 | // Type of an element stored in the buffer. | |
399 | typedef typename conditional< | |
400 | has_signature< | |
401 | typename traits_type::receive_cancelled_signature, | |
402 | R() | |
403 | >::value, | |
404 | typename conditional< | |
405 | has_signature< | |
406 | typename traits_type::receive_closed_signature, | |
407 | R() | |
408 | >::value, | |
409 | channel_payload<R()>, | |
410 | channel_payload< | |
411 | R(), | |
412 | typename traits_type::receive_closed_signature | |
413 | > | |
414 | >::type, | |
415 | typename conditional< | |
416 | has_signature< | |
417 | typename traits_type::receive_closed_signature, | |
418 | R(), | |
419 | typename traits_type::receive_cancelled_signature | |
420 | >::value, | |
421 | channel_payload< | |
422 | R(), | |
423 | typename traits_type::receive_cancelled_signature | |
424 | >, | |
425 | channel_payload< | |
426 | R(), | |
427 | typename traits_type::receive_cancelled_signature, | |
428 | typename traits_type::receive_closed_signature | |
429 | > | |
430 | >::type | |
431 | >::type payload_type; | |
432 | ||
433 | // Construct with empty buffer. | |
434 | implementation_type() | |
435 | : buffer_(0) | |
436 | { | |
437 | } | |
438 | ||
439 | // Move from another buffer. | |
440 | void buffer_move_from(implementation_type& other) | |
441 | { | |
442 | buffer_ = other.buffer_; | |
443 | other.buffer_ = 0; | |
444 | } | |
445 | ||
446 | // Get number of buffered elements. | |
447 | std::size_t buffer_size() const | |
448 | { | |
449 | return buffer_; | |
450 | } | |
451 | ||
452 | // Push a new value to the back of the buffer. | |
453 | void buffer_push(payload_type) | |
454 | { | |
455 | ++buffer_; | |
456 | } | |
457 | ||
458 | // Push new values to the back of the buffer. | |
459 | std::size_t buffer_push_n(std::size_t count, payload_type) | |
460 | { | |
461 | std::size_t available = this->max_buffer_size_ - buffer_; | |
462 | count = (count < available) ? count : available; | |
463 | buffer_ += count; | |
464 | return count; | |
465 | } | |
466 | ||
467 | // Get the element at the front of the buffer. | |
468 | payload_type buffer_front() | |
469 | { | |
470 | return payload_type(channel_message<R()>(0)); | |
471 | } | |
472 | ||
473 | // Pop a value from the front of the buffer. | |
474 | void buffer_pop() | |
475 | { | |
476 | --buffer_; | |
477 | } | |
478 | ||
479 | // Clear all values from the buffer. | |
480 | void buffer_clear() | |
481 | { | |
482 | buffer_ = 0; | |
483 | } | |
484 | ||
485 | private: | |
486 | // Number of buffered "values". | |
487 | std::size_t buffer_; | |
488 | }; | |
489 | ||
490 | } // namespace detail | |
491 | } // namespace experimental | |
492 | } // namespace asio | |
493 | } // namespace boost | |
494 | ||
495 | #include <boost/asio/detail/pop_options.hpp> | |
496 | ||
497 | #include <boost/asio/experimental/detail/impl/channel_service.hpp> | |
498 | ||
499 | #endif // BOOST_ASIO_EXPERIMENTAL_DETAIL_CHANNEL_SERVICE_HPP |