include/boost/corosio/native/detail/posix/posix_stream_file_service.hpp

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posix_stream_file_service.hpp

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1		//
2		// Copyright (c) 2026 Michael Vandeberg
3		//
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)
6		//
7		// Official repository: https://github.com/cppalliance/corosio
8		//
9
10		#ifndef BOOST_COROSIO_NATIVE_DETAIL_POSIX_POSIX_STREAM_FILE_SERVICE_HPP
11		#define BOOST_COROSIO_NATIVE_DETAIL_POSIX_POSIX_STREAM_FILE_SERVICE_HPP
12
13		#include <boost/corosio/detail/platform.hpp>
14
15		#if BOOST_COROSIO_POSIX
16
17		#include <boost/corosio/native/detail/posix/posix_stream_file.hpp>
18		#include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
19		#include <boost/corosio/detail/file_service.hpp>
20		#include <boost/corosio/detail/thread_pool.hpp>
21
22		#include <mutex>
23		#include <unordered_map>
24
25		namespace boost::corosio::detail {
26
27		/** Stream file service for POSIX backends.
28
29		Owns all posix_stream_file instances. Thread lifecycle is
30		managed by the thread_pool service (shared with resolver).
31		*/
32		class BOOST_COROSIO_DECL posix_stream_file_service final : public file_service
33		{
34		public:
35	216x	explicit posix_stream_file_service(capy::execution_context& ctx)
36	648x	: sched_(&get_scheduler(ctx))
37	216x	, pool_(ctx)
38		{
39	216x	}
40
41	432x	~posix_stream_file_service() override = default;
42
43		posix_stream_file_service(posix_stream_file_service const&) = delete;
44		posix_stream_file_service&
45		operator=(posix_stream_file_service const&) = delete;
46
47	272x	io_object::implementation* construct() override
48		{
49	272x	auto ptr = std::make_shared<posix_stream_file>(*this);
50	272x	auto* impl = ptr.get();
51
52		{
53	272x	std::lock_guard<std::mutex> lock(mutex_);
54	272x	file_list_.push_back(impl);
55	272x	file_ptrs_[impl] = std::move(ptr);
56	272x	}
57
58	272x	return impl;
59	272x	}
60
61	270x	void destroy(io_object::implementation* p) override
62		{
63	270x	auto& impl = static_cast<posix_stream_file&>(*p);
64	270x	impl.cancel();
65	270x	impl.close_file();
66	270x	destroy_impl(impl);
67	270x	}
68
69	507x	void close(io_object::handle& h) override
70		{
71	507x	if (h.get())
72		{
73	507x	auto& impl = static_cast<posix_stream_file&>(*h.get());
74	507x	impl.cancel();
75	507x	impl.close_file();
76		}
77	507x	}
78
79	255x	std::error_code open_file(
80		stream_file::implementation& impl,
81		std::filesystem::path const& path,
82		file_base::flags mode) override
83		{
84		// Unavailable in the unsafe tier: the file thread pool completes
85		// cross-thread, which the lockless scheduler cannot accept.
86	255x	if (sched_->scheduler_locking_disabled())
87	2x	return std::make_error_code(std::errc::operation_not_supported);
88	253x	return static_cast<posix_stream_file&>(impl).open_file(path, mode);
89		}
90
91	216x	void shutdown() override
92		{
93	216x	std::lock_guard<std::mutex> lock(mutex_);
94	218x	for (auto* impl = file_list_.pop_front(); impl != nullptr;
95	2x	impl = file_list_.pop_front())
96		{
97	2x	impl->cancel();
98	2x	impl->close_file();
99		}
100	216x	file_ptrs_.clear();
101	216x	}
102
103	270x	void destroy_impl(posix_stream_file& impl)
104		{
105	270x	std::lock_guard<std::mutex> lock(mutex_);
106	270x	file_list_.remove(&impl);
107	270x	file_ptrs_.erase(&impl);
108	270x	}
109
110	217x	void post(scheduler_op* op)
111		{
112	217x	sched_->post(op);
113	217x	}
114
115		void work_started() noexcept
116		{
117		sched_->work_started();
118		}
119
120		void work_finished() noexcept
121		{
122		sched_->work_finished();
123		}
124
125		/** Return the thread pool that runs this service's file work.
126
127		The pool's service is created on first use, so this can fail
128		where a plain accessor could not. Its workers start later, on
129		the first post, and a thread the system refuses there is
130		reported by that post rather than thrown here.
131
132		@throws std::bad_alloc If the service cannot be allocated.
133
134		@return The context's shared blocking-I/O pool.
135
136		@see thread_pool_ref::get
137		*/
138	225x	thread_pool& pool()
139		{
140	225x	return pool_.get();
141		}
142
143		private:
144		scheduler* sched_;
145		thread_pool_ref pool_;
146		std::mutex mutex_;
147		intrusive_list<posix_stream_file> file_list_;
148		std::unordered_map<posix_stream_file*, std::shared_ptr<posix_stream_file>>
149		file_ptrs_;
150		};
151
152		// ---------------------------------------------------------------------------
153		// posix_stream_file inline implementations (require complete service type)
154		// ---------------------------------------------------------------------------
155
156		inline std::coroutine_handle<>
157	152x	posix_stream_file::read_some(
158		std::coroutine_handle<> h,
159		capy::executor_ref ex,
160		buffer_param param,
161		std::stop_token token,
162		std::error_code* ec,
163		std::size_t* bytes_out)
164		{
165	152x	auto& op = read_op_;
166	152x	op.reset();
167	152x	op.is_read = true;
168
169		// Closed-object contract outranks the zero-length no-op.
170	152x	if (fd_ < 0)
171		{
172	6x	*ec = make_error_code(std::errc::bad_file_descriptor);
173	6x	*bytes_out = 0;
174	6x	op.cont.h = h;
175	6x	return dispatch_coro(ex, op.cont);
176		}
177
178	146x	capy::mutable_buffer bufs[max_buffers];
179	146x	op.iovec_count = static_cast<int>(param.copy_to(bufs, max_buffers));
180
181	146x	if (op.iovec_count == 0)
182		{
183	2x	*ec = {};
184	2x	*bytes_out = 0;
185	2x	op.cont.h = h;
186	2x	return dispatch_coro(ex, op.cont);
187		}
188
189	288x	for (int i = 0; i < op.iovec_count; ++i)
190		{
191	144x	op.iovecs[i].iov_base = bufs[i].data();
192	144x	op.iovecs[i].iov_len = bufs[i].size();
193		}
194
195	144x	op.h = h;
196	144x	op.ex = ex;
197	144x	op.ec_out = ec;
198	144x	op.bytes_out = bytes_out;
199	144x	op.start(token);
200
201	144x	op.ex.on_work_started();
202
203	144x	read_pool_op_.file_ = this;
204	144x	read_pool_op_.ref_ = this->shared_from_this();
205	144x	read_pool_op_.func_ = &posix_stream_file::do_read_work;
206	144x	if (auto pec = svc_.pool().post(&read_pool_op_))
207		{
208		// The pool is shutting down, or the system refused it a thread.
209		// Nothing of this read went cross-thread, so it answers here
210		// like the closed-descriptor and zero-length exits above rather
211		// than through a completion the scheduler has to carry back.
212	6x	read_pool_op_.ref_.reset();
213	6x	op.stop_cb.reset();
214	6x	op.ex.on_work_finished();
215	6x	*ec = pec;
216	6x	*bytes_out = 0;
217	6x	op.cont.h = h;
218	6x	return dispatch_coro(ex, op.cont);
219		}
220	138x	return std::noop_coroutine();
221		}
222
223		inline void
224	138x	posix_stream_file::do_read_work(pool_work_item* w) noexcept
225		{
226	138x	auto* pw = static_cast<pool_op*>(w);
227	138x	auto* self = pw->file_;
228	138x	auto& op = self->read_op_;
229
230	138x	if (!op.cancelled.load(std::memory_order_acquire))
231		{
232		ssize_t n;
233		do
234		{
235	240x	n = ::preadv(
236	120x	self->fd_, op.iovecs, op.iovec_count,
237	120x	static_cast<off_t>(self->offset_));
238		}
239	120x	while (n < 0 && errno == EINTR);
240
241	120x	if (n >= 0)
242		{
243	113x	op.errn = 0;
244	113x	op.bytes_transferred = static_cast<std::size_t>(n);
245	113x	self->offset_ += static_cast<std::uint64_t>(n);
246		}
247		else
248		{
249	7x	op.errn = errno;
250	7x	op.bytes_transferred = 0;
251		}
252		}
253
254	138x	op.impl_ptr = std::move(pw->ref_);
255	138x	self->svc_.post(&op);
256	138x	}
257
258		inline std::coroutine_handle<>
259	89x	posix_stream_file::write_some(
260		std::coroutine_handle<> h,
261		capy::executor_ref ex,
262		buffer_param param,
263		std::stop_token token,
264		std::error_code* ec,
265		std::size_t* bytes_out)
266		{
267	89x	auto& op = write_op_;
268	89x	op.reset();
269	89x	op.is_read = false;
270
271		// Closed-object contract outranks the zero-length no-op.
272	89x	if (fd_ < 0)
273		{
274	6x	*ec = make_error_code(std::errc::bad_file_descriptor);
275	6x	*bytes_out = 0;
276	6x	op.cont.h = h;
277	6x	return dispatch_coro(ex, op.cont);
278		}
279
280	83x	capy::mutable_buffer bufs[max_buffers];
281	83x	op.iovec_count = static_cast<int>(param.copy_to(bufs, max_buffers));
282
283	83x	if (op.iovec_count == 0)
284		{
285	2x	*ec = {};
286	2x	*bytes_out = 0;
287	2x	op.cont.h = h;
288	2x	return dispatch_coro(ex, op.cont);
289		}
290
291	162x	for (int i = 0; i < op.iovec_count; ++i)
292		{
293	81x	op.iovecs[i].iov_base = bufs[i].data();
294	81x	op.iovecs[i].iov_len = bufs[i].size();
295		}
296
297	81x	op.h = h;
298	81x	op.ex = ex;
299	81x	op.ec_out = ec;
300	81x	op.bytes_out = bytes_out;
301	81x	op.start(token);
302
303	81x	op.ex.on_work_started();
304
305	81x	write_pool_op_.file_ = this;
306	81x	write_pool_op_.ref_ = this->shared_from_this();
307	81x	write_pool_op_.func_ = &posix_stream_file::do_write_work;
308	81x	if (auto pec = svc_.pool().post(&write_pool_op_))
309		{
310		// The pool is shutting down, or the system refused it a thread.
311		// Nothing of this write went cross-thread, so it answers here
312		// like the closed-descriptor and zero-length exits above rather
313		// than through a completion the scheduler has to carry back.
314	2x	write_pool_op_.ref_.reset();
315	2x	op.stop_cb.reset();
316	2x	op.ex.on_work_finished();
317	2x	*ec = pec;
318	2x	*bytes_out = 0;
319	2x	op.cont.h = h;
320	2x	return dispatch_coro(ex, op.cont);
321		}
322	79x	return std::noop_coroutine();
323		}
324
325		inline void
326	79x	posix_stream_file::do_write_work(pool_work_item* w) noexcept
327		{
328	79x	auto* pw = static_cast<pool_op*>(w);
329	79x	auto* self = pw->file_;
330	79x	auto& op = self->write_op_;
331
332	79x	if (!op.cancelled.load(std::memory_order_acquire))
333		{
334		ssize_t n;
335		do
336		{
337	58x	n = ::pwritev(
338	29x	self->fd_, op.iovecs, op.iovec_count,
339	29x	static_cast<off_t>(self->offset_));
340		}
341	29x	while (n < 0 && errno == EINTR);
342
343	29x	if (n >= 0)
344		{
345	22x	op.errn = 0;
346	22x	op.bytes_transferred = static_cast<std::size_t>(n);
347	22x	self->offset_ += static_cast<std::uint64_t>(n);
348		}
349		else
350		{
351	7x	op.errn = errno;
352	7x	op.bytes_transferred = 0;
353		}
354		}
355
356	79x	op.impl_ptr = std::move(pw->ref_);
357	79x	self->svc_.post(&op);
358	79x	}
359
360		} // namespace boost::corosio::detail
361
362		#endif // BOOST_COROSIO_POSIX
363
364		#endif // BOOST_COROSIO_NATIVE_DETAIL_POSIX_POSIX_STREAM_FILE_SERVICE_HPP
365