io_service.html
28.4 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>io_service</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../index.html" title="Asio">
<link rel="up" href="../reference.html" title="Reference">
<link rel="prev" href="io_context__work/_work.html" title="io_context::work::~work">
<link rel="next" href="ip__address.html" title="ip::address">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="io_context__work/_work.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="ip__address.html"><img src="../../next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.io_service"></a><a class="link" href="io_service.html" title="io_service">io_service</a>
</h3></div></div></div>
<p>
<a class="indexterm" name="asio.indexterm.io_service"></a>
Typedef for backwards compatibility.
</p>
<pre class="programlisting">typedef io_context io_service;
</pre>
<h5>
<a name="asio.reference.io_service.h0"></a>
<span><a name="asio.reference.io_service.types"></a></span><a class="link" href="io_service.html#asio.reference.io_service.types">Types</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context__basic_executor_type.html" title="io_context::basic_executor_type"><span class="bold"><strong>basic_executor_type</strong></span></a>
</p>
</td>
<td>
<p>
Executor implementation type used to submit functions to an io_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__service.html" title="io_context::service"><span class="bold"><strong>service</strong></span></a>
</p>
</td>
<td>
<p>
Base class for all io_context services.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand.html" title="io_context::strand"><span class="bold"><strong>strand</strong></span></a>
</p>
</td>
<td>
<p>
Provides serialised handler execution.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__work.html" title="io_context::work"><span class="bold"><strong>work</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use executor_work_guard.) Class to inform the io_context
when it has work to do.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/count_type.html" title="io_context::count_type"><span class="bold"><strong>count_type</strong></span></a>
</p>
</td>
<td>
<p>
The type used to count the number of handlers executed by the context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/executor_type.html" title="io_context::executor_type"><span class="bold"><strong>executor_type</strong></span></a>
</p>
</td>
<td>
<p>
Executor used to submit functions to an io_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/fork_event.html" title="io_context::fork_event"><span class="bold"><strong>fork_event</strong></span></a>
</p>
</td>
<td>
<p>
Fork-related event notifications.
</p>
</td>
</tr>
</tbody>
</table></div>
<h5>
<a name="asio.reference.io_service.h1"></a>
<span><a name="asio.reference.io_service.member_functions"></a></span><a class="link" href="io_service.html#asio.reference.io_service.member_functions">Member
Functions</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context/dispatch.html" title="io_context::dispatch"><span class="bold"><strong>dispatch</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use asio::dispatch().) Request the io_context to invoke
the given handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/get_executor.html" title="io_context::get_executor"><span class="bold"><strong>get_executor</strong></span></a>
</p>
</td>
<td>
<p>
Obtains the executor associated with the io_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/io_context.html" title="io_context::io_context"><span class="bold"><strong>io_context</strong></span></a> <span class="silver">[constructor]</span>
</p>
</td>
<td>
<p>
Constructor.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/notify_fork.html" title="io_context::notify_fork"><span class="bold"><strong>notify_fork</strong></span></a>
</p>
</td>
<td>
<p>
Notify the execution_context of a fork-related event.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/poll.html" title="io_context::poll"><span class="bold"><strong>poll</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop to execute ready
handlers. <br> <span class="silver"> —</span><br> (Deprecated: Use non-error_code overload.)
Run the io_context object's event processing loop to execute ready
handlers.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/poll_one.html" title="io_context::poll_one"><span class="bold"><strong>poll_one</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop to execute one
ready handler. <br> <span class="silver"> —</span><br> (Deprecated: Use non-error_code overload.)
Run the io_context object's event processing loop to execute one
ready handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/post.html" title="io_context::post"><span class="bold"><strong>post</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use asio::post().) Request the io_context to invoke
the given handler and return immediately.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/reset.html" title="io_context::reset"><span class="bold"><strong>reset</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use restart().) Reset the io_context in preparation
for a subsequent run() invocation.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/restart.html" title="io_context::restart"><span class="bold"><strong>restart</strong></span></a>
</p>
</td>
<td>
<p>
Restart the io_context in preparation for a subsequent run() invocation.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run.html" title="io_context::run"><span class="bold"><strong>run</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop. <br> <span class="silver"> —</span><br>
(Deprecated: Use non-error_code overload.) Run the io_context object's
event processing loop.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run_for.html" title="io_context::run_for"><span class="bold"><strong>run_for</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop for a specified
duration.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run_one.html" title="io_context::run_one"><span class="bold"><strong>run_one</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop to execute at
most one handler. <br> <span class="silver"> —</span><br> (Deprecated: Use non-error_code
overlaod.) Run the io_context object's event processing loop to
execute at most one handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run_one_for.html" title="io_context::run_one_for"><span class="bold"><strong>run_one_for</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop for a specified
duration to execute at most one handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run_one_until.html" title="io_context::run_one_until"><span class="bold"><strong>run_one_until</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop until a specified
time to execute at most one handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/run_until.html" title="io_context::run_until"><span class="bold"><strong>run_until</strong></span></a>
</p>
</td>
<td>
<p>
Run the io_context object's event processing loop until a specified
time.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/stop.html" title="io_context::stop"><span class="bold"><strong>stop</strong></span></a>
</p>
</td>
<td>
<p>
Stop the io_context object's event processing loop.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/stopped.html" title="io_context::stopped"><span class="bold"><strong>stopped</strong></span></a>
</p>
</td>
<td>
<p>
Determine whether the io_context object has been stopped.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/wrap.html" title="io_context::wrap"><span class="bold"><strong>wrap</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use asio::bind_executor().) Create a new handler that
automatically dispatches the wrapped handler on the io_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/_io_context.html" title="io_context::~io_context"><span class="bold"><strong>~io_context</strong></span></a> <span class="silver">[destructor]</span>
</p>
</td>
<td>
<p>
Destructor.
</p>
</td>
</tr>
</tbody>
</table></div>
<h5>
<a name="asio.reference.io_service.h2"></a>
<span><a name="asio.reference.io_service.protected_member_functions"></a></span><a class="link" href="io_service.html#asio.reference.io_service.protected_member_functions">Protected
Member Functions</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context/destroy.html" title="io_context::destroy"><span class="bold"><strong>destroy</strong></span></a>
</p>
</td>
<td>
<p>
Destroys all services in the context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/shutdown.html" title="io_context::shutdown"><span class="bold"><strong>shutdown</strong></span></a>
</p>
</td>
<td>
<p>
Shuts down all services in the context.
</p>
</td>
</tr>
</tbody>
</table></div>
<h5>
<a name="asio.reference.io_service.h3"></a>
<span><a name="asio.reference.io_service.friends"></a></span><a class="link" href="io_service.html#asio.reference.io_service.friends">Friends</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context/add_service.html" title="io_context::add_service"><span class="bold"><strong>add_service</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use make_service().) Add a service object to the execution_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/has_service.html" title="io_context::has_service"><span class="bold"><strong>has_service</strong></span></a>
</p>
</td>
<td>
<p>
Determine if an execution_context contains a specified service
type.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/make_service.html" title="io_context::make_service"><span class="bold"><strong>make_service</strong></span></a>
</p>
</td>
<td>
<p>
Creates a service object and adds it to the execution_context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context/use_service.html" title="io_context::use_service"><span class="bold"><strong>use_service</strong></span></a>
</p>
</td>
<td>
<p>
<br> <span class="silver"> —</span><br> Obtain the service object corresponding to the given
type.
</p>
</td>
</tr>
</tbody>
</table></div>
<p>
The <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
class provides the core I/O functionality for users of the asynchronous I/O
objects, including:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<code class="computeroutput">asio::ip::tcp::socket</code>
</li>
<li class="listitem">
<code class="computeroutput">asio::ip::tcp::acceptor</code>
</li>
<li class="listitem">
<code class="computeroutput">asio::ip::udp::socket</code>
</li>
<li class="listitem">
<a class="link" href="deadline_timer.html" title="deadline_timer"><code class="computeroutput">deadline_timer</code></a>.
</li>
</ul></div>
<p>
The <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
class also includes facilities intended for developers of custom asynchronous
services.
</p>
<h5>
<a name="asio.reference.io_service.h4"></a>
<span><a name="asio.reference.io_service.thread_safety"></a></span><a class="link" href="io_service.html#asio.reference.io_service.thread_safety">Thread
Safety</a>
</h5>
<p>
<span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
</p>
<p>
<span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Safe, with the
specific exceptions of the <code class="computeroutput">restart()</code> and <code class="computeroutput">notify_fork()</code>
functions. Calling <code class="computeroutput">restart()</code> while there are unfinished <code class="computeroutput">run()</code>,
<code class="computeroutput">run_one()</code>, <code class="computeroutput">run_for()</code>, <code class="computeroutput">run_until()</code>,
<code class="computeroutput">poll()</code> or <code class="computeroutput">poll_one()</code> calls results in undefined
behaviour. The <code class="computeroutput">notify_fork()</code> function should not be called while
any <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
function, or any function on an I/O object that is associated with the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>, is being
called in another thread.
</p>
<h5>
<a name="asio.reference.io_service.h5"></a>
<span><a name="asio.reference.io_service.synchronous_and_asynchronous_operations"></a></span><a class="link" href="io_service.html#asio.reference.io_service.synchronous_and_asynchronous_operations">Synchronous
and asynchronous operations</a>
</h5>
<p>
Synchronous operations on I/O objects implicitly run the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
object for an individual operation. The <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
functions <code class="computeroutput">run()</code>, <code class="computeroutput">run_one()</code>, <code class="computeroutput">run_for()</code>,
<code class="computeroutput">run_until()</code>, <code class="computeroutput">poll()</code> or <code class="computeroutput">poll_one()</code>
must be called for the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
to perform asynchronous operations on behalf of a C++ program. Notification
that an asynchronous operation has completed is delivered by invocation of
the associated handler. Handlers are invoked only by a thread that is currently
calling any overload of <code class="computeroutput">run()</code>, <code class="computeroutput">run_one()</code>, <code class="computeroutput">run_for()</code>,
<code class="computeroutput">run_until()</code>, <code class="computeroutput">poll()</code> or <code class="computeroutput">poll_one()</code>
for the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>.
</p>
<h5>
<a name="asio.reference.io_service.h6"></a>
<span><a name="asio.reference.io_service.effect_of_exceptions_thrown_from_handlers"></a></span><a class="link" href="io_service.html#asio.reference.io_service.effect_of_exceptions_thrown_from_handlers">Effect
of exceptions thrown from handlers</a>
</h5>
<p>
If an exception is thrown from a handler, the exception is allowed to propagate
through the throwing thread's invocation of <code class="computeroutput">run()</code>, <code class="computeroutput">run_one()</code>,
<code class="computeroutput">run_for()</code>, <code class="computeroutput">run_until()</code>, <code class="computeroutput">poll()</code> or
<code class="computeroutput">poll_one()</code>. No other threads that are calling any of these functions
are affected. It is then the responsibility of the application to catch the
exception.
</p>
<p>
After the exception has been caught, the <code class="computeroutput">run()</code>, <code class="computeroutput">run_one()</code>,
<code class="computeroutput">run_for()</code>, <code class="computeroutput">run_until()</code>, <code class="computeroutput">poll()</code> or
<code class="computeroutput">poll_one()</code> call may be restarted <span class="emphasis"><em>without</em></span>
the need for an intervening call to <code class="computeroutput">restart()</code>. This allows the
thread to rejoin the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
object's thread pool without impacting any other threads in the pool.
</p>
<p>
For example:
</p>
<pre class="programlisting">asio::io_context io_context;
...
for (;;)
{
try
{
io_context.run();
break; // run() exited normally
}
catch (my_exception& e)
{
// Deal with exception as appropriate.
}
}
</pre>
<h5>
<a name="asio.reference.io_service.h7"></a>
<span><a name="asio.reference.io_service.submitting_arbitrary_tasks_to_the_io_context"></a></span><a class="link" href="io_service.html#asio.reference.io_service.submitting_arbitrary_tasks_to_the_io_context">Submitting
arbitrary tasks to the io_context</a>
</h5>
<p>
To submit functions to the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>,
use the <a class="link" href="dispatch.html" title="dispatch"><code class="computeroutput">dispatch</code></a>
, <a class="link" href="post.html" title="post"><code class="computeroutput">post</code></a> or <a class="link" href="defer.html" title="defer"><code class="computeroutput">defer</code></a>
free functions.
</p>
<p>
For example:
</p>
<pre class="programlisting">void my_task()
{
...
}
...
asio::io_context io_context;
// Submit a function to the io_context.
asio::post(io_context, my_task);
// Submit a lambda object to the io_context.
asio::post(io_context,
[]()
{
...
});
// Run the io_context until it runs out of work.
io_context.run();
</pre>
<h5>
<a name="asio.reference.io_service.h8"></a>
<span><a name="asio.reference.io_service.stopping_the_io_context_from_running_out_of_work"></a></span><a class="link" href="io_service.html#asio.reference.io_service.stopping_the_io_context_from_running_out_of_work">Stopping
the io_context from running out of work</a>
</h5>
<p>
Some applications may need to prevent an <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
object's <code class="computeroutput">run()</code> call from returning when there is no more work
to do. For example, the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
may be being run in a background thread that is launched prior to the application's
asynchronous operations. The <code class="computeroutput">run()</code> call may be kept running
by creating an executor that tracks work against the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>:
</p>
<pre class="programlisting">asio::io_context io_context;
auto work = asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
...
</pre>
<p>
If using C++03, which lacks automatic variable type deduction, you may compute
the return type of the require call:
</p>
<pre class="programlisting">asio::io_context io_context;
typename asio::require_result<
asio::io_context::executor_type,
asio::exeution::outstanding_work_t::tracked_t>
work = asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
...
</pre>
<p>
or store the result in the type-erasing executor wrapper, any_io_executor:
</p>
<pre class="programlisting">asio::io_context io_context;
asio::any_io_executor work
= asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
...
</pre>
<p>
To effect a shutdown, the application will then need to call the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
object's <code class="computeroutput">stop()</code> member function. This will cause the <a class="link" href="io_context.html" title="io_context"><code class="computeroutput">io_context</code></a>
<code class="computeroutput">run()</code> call to return as soon as possible, abandoning unfinished
operations and without permitting ready handlers to be dispatched.
</p>
<p>
Alternatively, if the application requires that all operations and handlers
be allowed to finish normally, store the work-tracking executor in an any_io_executor
object, so that it may be explicitly reset.
</p>
<pre class="programlisting">asio::io_context io_context;
asio::any_io_executor work
= asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
...
work = asio::any_io_executor(); // Allow run() to exit.
</pre>
<h5>
<a name="asio.reference.io_service.h9"></a>
<span><a name="asio.reference.io_service.requirements"></a></span><a class="link" href="io_service.html#asio.reference.io_service.requirements">Requirements</a>
</h5>
<p>
<span class="emphasis"><em>Header: </em></span><code class="literal">asio/io_service.hpp</code>
</p>
<p>
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M.
Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="io_context__work/_work.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="ip__address.html"><img src="../../next.png" alt="Next"></a>
</div>
</body>
</html>