1//
2// detail/impl/task_io_service.ipp
3// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 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_DETAIL_IMPL_TASK_IO_SERVICE_IPP
12#define BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_IPP
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
20#if !defined(BOOST_ASIO_HAS_IOCP)
21
22#include <boost/asio/detail/event.hpp>
23#include <boost/asio/detail/limits.hpp>
24#include <boost/asio/detail/reactor.hpp>
25#include <boost/asio/detail/task_io_service.hpp>
26#include <boost/asio/detail/task_io_service_thread_info.hpp>
27
28#include <boost/asio/detail/push_options.hpp>
29
30namespace boost {
31namespace asio {
32namespace detail {
33
34struct task_io_service::task_cleanup
35{
36 ~task_cleanup()
37 {
38 if (this_thread_->private_outstanding_work > 0)
39 {
40 boost::asio::detail::increment(
41 task_io_service_->outstanding_work_,
42 this_thread_->private_outstanding_work);
43 }
44 this_thread_->private_outstanding_work = 0;
45
46 // Enqueue the completed operations and reinsert the task at the end of
47 // the operation queue.
48 lock_->lock();
49 task_io_service_->task_interrupted_ = true;
50 task_io_service_->op_queue_.push(this_thread_->private_op_queue);
51 task_io_service_->op_queue_.push(&task_io_service_->task_operation_);
52 }
53
54 task_io_service* task_io_service_;
55 mutex::scoped_lock* lock_;
56 thread_info* this_thread_;
57};
58
59struct task_io_service::work_cleanup
60{
61 ~work_cleanup()
62 {
63 if (this_thread_->private_outstanding_work > 1)
64 {
65 boost::asio::detail::increment(
66 task_io_service_->outstanding_work_,
67 this_thread_->private_outstanding_work - 1);
68 }
69 else if (this_thread_->private_outstanding_work < 1)
70 {
71 task_io_service_->work_finished();
72 }
73 this_thread_->private_outstanding_work = 0;
74
75#if defined(BOOST_ASIO_HAS_THREADS)
76 if (!this_thread_->private_op_queue.empty())
77 {
78 lock_->lock();
79 task_io_service_->op_queue_.push(this_thread_->private_op_queue);
80 }
81#endif // defined(BOOST_ASIO_HAS_THREADS)
82 }
83
84 task_io_service* task_io_service_;
85 mutex::scoped_lock* lock_;
86 thread_info* this_thread_;
87};
88
89task_io_service::task_io_service(
90 boost::asio::io_service& io_service, std::size_t concurrency_hint)
91 : boost::asio::detail::service_base<task_io_service>(io_service),
92 one_thread_(concurrency_hint == 1),
93 mutex_(),
94 task_(0),
95 task_interrupted_(true),
96 outstanding_work_(0),
97 stopped_(false),
98 shutdown_(false)
99{
100 BOOST_ASIO_HANDLER_TRACKING_INIT;
101}
102
103void task_io_service::shutdown_service()
104{
105 mutex::scoped_lock lock(mutex_);
106 shutdown_ = true;
107 lock.unlock();
108
109 // Destroy handler objects.
110 while (!op_queue_.empty())
111 {
112 operation* o = op_queue_.front();
113 op_queue_.pop();
114 if (o != &task_operation_)
115 o->destroy();
116 }
117
118 // Reset to initial state.
119 task_ = 0;
120}
121
122void task_io_service::init_task()
123{
124 mutex::scoped_lock lock(mutex_);
125 if (!shutdown_ && !task_)
126 {
127 task_ = &use_service<reactor>(this->get_io_service());
128 op_queue_.push(&task_operation_);
129 wake_one_thread_and_unlock(lock);
130 }
131}
132
133std::size_t task_io_service::run(boost::system::error_code& ec)
134{
135 ec = boost::system::error_code();
136 if (outstanding_work_ == 0)
137 {
138 stop();
139 return 0;
140 }
141
142 thread_info this_thread;
143 this_thread.private_outstanding_work = 0;
144 thread_call_stack::context ctx(this, this_thread);
145
146 mutex::scoped_lock lock(mutex_);
147
148 std::size_t n = 0;
149 for (; do_run_one(lock, this_thread, ec); lock.lock())
150 if (n != (std::numeric_limits<std::size_t>::max)())
151 ++n;
152 return n;
153}
154
155std::size_t task_io_service::run_one(boost::system::error_code& ec)
156{
157 ec = boost::system::error_code();
158 if (outstanding_work_ == 0)
159 {
160 stop();
161 return 0;
162 }
163
164 thread_info this_thread;
165 this_thread.private_outstanding_work = 0;
166 thread_call_stack::context ctx(this, this_thread);
167
168 mutex::scoped_lock lock(mutex_);
169
170 return do_run_one(lock, this_thread, ec);
171}
172
173std::size_t task_io_service::poll(boost::system::error_code& ec)
174{
175 ec = boost::system::error_code();
176 if (outstanding_work_ == 0)
177 {
178 stop();
179 return 0;
180 }
181
182 thread_info this_thread;
183 this_thread.private_outstanding_work = 0;
184 thread_call_stack::context ctx(this, this_thread);
185
186 mutex::scoped_lock lock(mutex_);
187
188#if defined(BOOST_ASIO_HAS_THREADS)
189 // We want to support nested calls to poll() and poll_one(), so any handlers
190 // that are already on a thread-private queue need to be put on to the main
191 // queue now.
192 if (one_thread_)
193 if (thread_info* outer_thread_info = ctx.next_by_key())
194 op_queue_.push(outer_thread_info->private_op_queue);
195#endif // defined(BOOST_ASIO_HAS_THREADS)
196
197 std::size_t n = 0;
198 for (; do_poll_one(lock, this_thread, ec); lock.lock())
199 if (n != (std::numeric_limits<std::size_t>::max)())
200 ++n;
201 return n;
202}
203
204std::size_t task_io_service::poll_one(boost::system::error_code& ec)
205{
206 ec = boost::system::error_code();
207 if (outstanding_work_ == 0)
208 {
209 stop();
210 return 0;
211 }
212
213 thread_info this_thread;
214 this_thread.private_outstanding_work = 0;
215 thread_call_stack::context ctx(this, this_thread);
216
217 mutex::scoped_lock lock(mutex_);
218
219#if defined(BOOST_ASIO_HAS_THREADS)
220 // We want to support nested calls to poll() and poll_one(), so any handlers
221 // that are already on a thread-private queue need to be put on to the main
222 // queue now.
223 if (one_thread_)
224 if (thread_info* outer_thread_info = ctx.next_by_key())
225 op_queue_.push(outer_thread_info->private_op_queue);
226#endif // defined(BOOST_ASIO_HAS_THREADS)
227
228 return do_poll_one(lock, this_thread, ec);
229}
230
231void task_io_service::stop()
232{
233 mutex::scoped_lock lock(mutex_);
234 stop_all_threads(lock);
235}
236
237bool task_io_service::stopped() const
238{
239 mutex::scoped_lock lock(mutex_);
240 return stopped_;
241}
242
243void task_io_service::reset()
244{
245 mutex::scoped_lock lock(mutex_);
246 stopped_ = false;
247}
248
249void task_io_service::post_immediate_completion(
250 task_io_service::operation* op, bool is_continuation)
251{
252#if defined(BOOST_ASIO_HAS_THREADS)
253 if (one_thread_ || is_continuation)
254 {
255 if (thread_info* this_thread = thread_call_stack::contains(this))
256 {
257 ++this_thread->private_outstanding_work;
258 this_thread->private_op_queue.push(op);
259 return;
260 }
261 }
262#else // defined(BOOST_ASIO_HAS_THREADS)
263 (void)is_continuation;
264#endif // defined(BOOST_ASIO_HAS_THREADS)
265
266 work_started();
267 mutex::scoped_lock lock(mutex_);
268 op_queue_.push(op);
269 wake_one_thread_and_unlock(lock);
270}
271
272void task_io_service::post_deferred_completion(task_io_service::operation* op)
273{
274#if defined(BOOST_ASIO_HAS_THREADS)
275 if (one_thread_)
276 {
277 if (thread_info* this_thread = thread_call_stack::contains(this))
278 {
279 this_thread->private_op_queue.push(op);
280 return;
281 }
282 }
283#endif // defined(BOOST_ASIO_HAS_THREADS)
284
285 mutex::scoped_lock lock(mutex_);
286 op_queue_.push(op);
287 wake_one_thread_and_unlock(lock);
288}
289
290void task_io_service::post_deferred_completions(
291 op_queue<task_io_service::operation>& ops)
292{
293 if (!ops.empty())
294 {
295#if defined(BOOST_ASIO_HAS_THREADS)
296 if (one_thread_)
297 {
298 if (thread_info* this_thread = thread_call_stack::contains(this))
299 {
300 this_thread->private_op_queue.push(ops);
301 return;
302 }
303 }
304#endif // defined(BOOST_ASIO_HAS_THREADS)
305
306 mutex::scoped_lock lock(mutex_);
307 op_queue_.push(ops);
308 wake_one_thread_and_unlock(lock);
309 }
310}
311
312void task_io_service::do_dispatch(
313 task_io_service::operation* op)
314{
315 work_started();
316 mutex::scoped_lock lock(mutex_);
317 op_queue_.push(op);
318 wake_one_thread_and_unlock(lock);
319}
320
321void task_io_service::abandon_operations(
322 op_queue<task_io_service::operation>& ops)
323{
324 op_queue<task_io_service::operation> ops2;
325 ops2.push(ops);
326}
327
328std::size_t task_io_service::do_run_one(mutex::scoped_lock& lock,
329 task_io_service::thread_info& this_thread,
330 const boost::system::error_code& ec)
331{
332 while (!stopped_)
333 {
334 if (!op_queue_.empty())
335 {
336 // Prepare to execute first handler from queue.
337 operation* o = op_queue_.front();
338 op_queue_.pop();
339 bool more_handlers = (!op_queue_.empty());
340
341 if (o == &task_operation_)
342 {
343 task_interrupted_ = more_handlers;
344
345 if (more_handlers && !one_thread_)
346 wakeup_event_.unlock_and_signal_one(lock);
347 else
348 lock.unlock();
349
350 task_cleanup on_exit = { this, &lock, &this_thread };
351 (void)on_exit;
352
353 // Run the task. May throw an exception. Only block if the operation
354 // queue is empty and we're not polling, otherwise we want to return
355 // as soon as possible.
356 task_->run(!more_handlers, this_thread.private_op_queue);
357 }
358 else
359 {
360 std::size_t task_result = o->task_result_;
361
362 if (more_handlers && !one_thread_)
363 wake_one_thread_and_unlock(lock);
364 else
365 lock.unlock();
366
367 // Ensure the count of outstanding work is decremented on block exit.
368 work_cleanup on_exit = { this, &lock, &this_thread };
369 (void)on_exit;
370
371 // Complete the operation. May throw an exception. Deletes the object.
372 o->complete(*this, ec, task_result);
373
374 return 1;
375 }
376 }
377 else
378 {
379 wakeup_event_.clear(lock);
380 wakeup_event_.wait(lock);
381 }
382 }
383
384 return 0;
385}
386
387std::size_t task_io_service::do_poll_one(mutex::scoped_lock& lock,
388 task_io_service::thread_info& this_thread,
389 const boost::system::error_code& ec)
390{
391 if (stopped_)
392 return 0;
393
394 operation* o = op_queue_.front();
395 if (o == &task_operation_)
396 {
397 op_queue_.pop();
398 lock.unlock();
399
400 {
401 task_cleanup c = { this, &lock, &this_thread };
402 (void)c;
403
404 // Run the task. May throw an exception. Only block if the operation
405 // queue is empty and we're not polling, otherwise we want to return
406 // as soon as possible.
407 task_->run(false, this_thread.private_op_queue);
408 }
409
410 o = op_queue_.front();
411 if (o == &task_operation_)
412 {
413 wakeup_event_.maybe_unlock_and_signal_one(lock);
414 return 0;
415 }
416 }
417
418 if (o == 0)
419 return 0;
420
421 op_queue_.pop();
422 bool more_handlers = (!op_queue_.empty());
423
424 std::size_t task_result = o->task_result_;
425
426 if (more_handlers && !one_thread_)
427 wake_one_thread_and_unlock(lock);
428 else
429 lock.unlock();
430
431 // Ensure the count of outstanding work is decremented on block exit.
432 work_cleanup on_exit = { this, &lock, &this_thread };
433 (void)on_exit;
434
435 // Complete the operation. May throw an exception. Deletes the object.
436 o->complete(*this, ec, task_result);
437
438 return 1;
439}
440
441void task_io_service::stop_all_threads(
442 mutex::scoped_lock& lock)
443{
444 stopped_ = true;
445 wakeup_event_.signal_all(lock);
446
447 if (!task_interrupted_ && task_)
448 {
449 task_interrupted_ = true;
450 task_->interrupt();
451 }
452}
453
454void task_io_service::wake_one_thread_and_unlock(
455 mutex::scoped_lock& lock)
456{
457 if (!wakeup_event_.maybe_unlock_and_signal_one(lock))
458 {
459 if (!task_interrupted_ && task_)
460 {
461 task_interrupted_ = true;
462 task_->interrupt();
463 }
464 lock.unlock();
465 }
466}
467
468} // namespace detail
469} // namespace asio
470} // namespace boost
471
472#include <boost/asio/detail/pop_options.hpp>
473
474#endif // !defined(BOOST_ASIO_HAS_IOCP)
475
476#endif // BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_IPP
477