-
Notifications
You must be signed in to change notification settings - Fork 13
Expand file tree
/
Copy pathmutexes.html
More file actions
607 lines (486 loc) · 112 KB
/
mutexes.html
File metadata and controls
607 lines (486 loc) · 112 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
<!DOCTYPE html>
<html lang="en-US">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>C++ | Mutexes</title>
<meta name="generator" content="VuePress 1.8.2">
<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
<link rel="manifest" href="/site.webmanifest">
<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
<link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
<meta name="description" content="std::unique_lock, std::shared_lock, std::lock_guard, Strategies for lock classes: std::try_to_lock, std::adopt_lock, std::defer_lock, std::mutex, std::scoped_lock (C++ 17), Mutex Types, std::lock">
<meta property="og:site_name" content="DevTut">
<meta property="og:title" content="C++ | Mutexes">
<meta property="og:description" content="std::unique_lock, std::shared_lock, std::lock_guard, Strategies for lock classes: std::try_to_lock, std::adopt_lock, std::defer_lock, std::mutex, std::scoped_lock (C++ 17), Mutex Types, std::lock">
<meta property="og:type" content="article">
<meta property="og:url" content="/cpp/mutexes.html">
<meta property="og:image" content="/logo.png">
<meta name="twitter:title" content="C++ | Mutexes">
<meta name="twitter:description" content="std::unique_lock, std::shared_lock, std::lock_guard, Strategies for lock classes: std::try_to_lock, std::adopt_lock, std::defer_lock, std::mutex, std::scoped_lock (C++ 17), Mutex Types, std::lock">
<meta name="twitter:url" content="/cpp/mutexes.html">
<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:image" content="/logo.png">
<meta name="theme-color" content="#ffffff">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="msapplication-TileImage" content="/mstile-150x150.png">
<meta name="msapplication-TileColor" content="#da532c">
<meta name="google-site-verification" content="76_rKXgwMVIjd-axJC_1zPV9OS4mEjvtgjYOWVkAdnQ">
<link rel="preload" href="/assets/css/0.styles.60619e34.css" as="style"><link rel="preload" href="/assets/js/app.1779e102.js" as="script"><link rel="preload" href="/assets/js/3.2cfa8016.js" as="script"><link rel="preload" href="/assets/js/679.06e044ba.js" as="script">
<link rel="stylesheet" href="/assets/css/0.styles.60619e34.css">
</head>
<body>
<div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><!----> <span class="site-name">DevTut</span></a> <div class="links"><form id="search-form" role="search" class="algolia-search-wrapper search-box"><input id="algolia-search-input" class="search-query"></form> <nav class="nav-links can-hide"> <a href="https://github.com/devtut/generate" target="_blank" rel="noopener noreferrer" class="repo-link">
GitHub
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"> <a href="https://github.com/devtut/generate" target="_blank" rel="noopener noreferrer" class="repo-link">
GitHub
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav> <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>C++</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/cpp/" aria-current="page" class="sidebar-link">Disclaimer</a></li><li><a href="/cpp/getting-started-with-cpp.html" class="sidebar-link">Getting started with C++</a></li><li><a href="/cpp/literals.html" class="sidebar-link">Literals</a></li><li><a href="/cpp/operator-precedence.html" class="sidebar-link">operator precedence</a></li><li><a href="/cpp/floating-point-arithmetic.html" class="sidebar-link">Floating Point Arithmetic</a></li><li><a href="/cpp/bit-operators.html" class="sidebar-link">Bit Operators</a></li><li><a href="/cpp/bit-manipulation.html" class="sidebar-link">Bit Manipulation</a></li><li><a href="/cpp/bit-fields.html" class="sidebar-link">Bit fields</a></li><li><a href="/cpp/arrays.html" class="sidebar-link">Arrays</a></li><li><a href="/cpp/iterators.html" class="sidebar-link">Iterators</a></li><li><a href="/cpp/basic-input-output-in-c.html" class="sidebar-link">Basic input/output in c++</a></li><li><a href="/cpp/loops.html" class="sidebar-link">Loops</a></li><li><a href="/cpp/file-i-o.html" class="sidebar-link">File I/O</a></li><li><a href="/cpp/cpp-streams.html" class="sidebar-link">C++ Streams</a></li><li><a href="/cpp/stream-manipulators.html" class="sidebar-link">Stream manipulators</a></li><li><a href="/cpp/flow-control.html" class="sidebar-link">Flow Control</a></li><li><a href="/cpp/metaprogramming.html" class="sidebar-link">Metaprogramming</a></li><li><a href="/cpp/const-keyword.html" class="sidebar-link">const keyword</a></li><li><a href="/cpp/mutable-keyword.html" class="sidebar-link">mutable keyword</a></li><li><a href="/cpp/friend-keyword.html" class="sidebar-link">Friend keyword</a></li><li><a href="/cpp/type-keywords.html" class="sidebar-link">Type Keywords</a></li><li><a href="/cpp/basic-type-keywords.html" class="sidebar-link">Basic Type Keywords</a></li><li><a href="/cpp/variable-declaration-keywords.html" class="sidebar-link">Variable Declaration Keywords</a></li><li><a href="/cpp/keywords.html" class="sidebar-link">Keywords</a></li><li><a href="/cpp/returning-several-values-from-a-function.html" class="sidebar-link">Returning several values from a function</a></li><li><a href="/cpp/polymorphism.html" class="sidebar-link">Polymorphism</a></li><li><a href="/cpp/references.html" class="sidebar-link">References</a></li><li><a href="/cpp/value-and-reference-semantics.html" class="sidebar-link">Value and Reference Semantics</a></li><li><a href="/cpp/c-function-call-by-value-vs-call-by-reference.html" class="sidebar-link">C++ function "call by value" vs. "call by reference"</a></li><li><a href="/cpp/copying-vs-assignment.html" class="sidebar-link">Copying vs Assignment</a></li><li><a href="/cpp/pointers.html" class="sidebar-link">Pointers</a></li><li><a href="/cpp/pointers-to-members.html" class="sidebar-link">Pointers to members</a></li><li><a href="/cpp/the-this-pointer.html" class="sidebar-link">The This Pointer</a></li><li><a href="/cpp/smart-pointers.html" class="sidebar-link">Smart Pointers</a></li><li><a href="/cpp/classes-structures.html" class="sidebar-link">Classes/Structures</a></li><li><a href="/cpp/function-overloading.html" class="sidebar-link">Function Overloading</a></li><li><a href="/cpp/operator-overloading.html" class="sidebar-link">Operator Overloading</a></li><li><a href="/cpp/function-template-overloading.html" class="sidebar-link">Function Template Overloading</a></li><li><a href="/cpp/virtual-member-functions.html" class="sidebar-link">Virtual Member Functions</a></li><li><a href="/cpp/inline-functions.html" class="sidebar-link">Inline functions</a></li><li><a href="/cpp/special-member-functions.html" class="sidebar-link">Special Member Functions</a></li><li><a href="/cpp/non-static-member-functions.html" class="sidebar-link">Non-Static Member Functions</a></li><li><a href="/cpp/constant-class-member-functions.html" class="sidebar-link">Constant class member functions</a></li><li><a href="/cpp/c-containers.html" class="sidebar-link">C++ Containers</a></li><li><a href="/cpp/namespaces.html" class="sidebar-link">Namespaces</a></li><li><a href="/cpp/header-files.html" class="sidebar-link">Header Files</a></li><li><a href="/cpp/using-declaration.html" class="sidebar-link">Using declaration</a></li><li><a href="/cpp/std-string.html" class="sidebar-link">std::string</a></li><li><a href="/cpp/std-array.html" class="sidebar-link">std::array</a></li><li><a href="/cpp/std-vector.html" class="sidebar-link">std::vector</a></li><li><a href="/cpp/std-map.html" class="sidebar-link">std::map</a></li><li><a href="/cpp/std-optional.html" class="sidebar-link">std::optional</a></li><li><a href="/cpp/std-function-to-wrap-any-element-that-is-callable.html" class="sidebar-link">std::function: To wrap any element that is callable</a></li><li><a href="/cpp/std-forward-list.html" class="sidebar-link">std::forward_list</a></li><li><a href="/cpp/std-pair.html" class="sidebar-link">std::pair</a></li><li><a href="/cpp/std-atomics.html" class="sidebar-link">std::atomics</a></li><li><a href="/cpp/std-variant.html" class="sidebar-link">std::variant</a></li><li><a href="/cpp/std-iomanip.html" class="sidebar-link">std::iomanip</a></li><li><a href="/cpp/std-any.html" class="sidebar-link">std::any</a></li><li><a href="/cpp/std-set-and-std-multiset.html" class="sidebar-link">std::set and std::multiset</a></li><li><a href="/cpp/std-integer-sequence.html" class="sidebar-link">std::integer_sequence</a></li><li><a href="/cpp/using-std-unordered-map.html" class="sidebar-link">Using std::unordered_map</a></li><li><a href="/cpp/standard-library-algorithms.html" class="sidebar-link">Standard Library Algorithms</a></li><li><a href="/cpp/the-iso-c-standard.html" class="sidebar-link">The ISO C++ Standard</a></li><li><a href="/cpp/inline-variables.html" class="sidebar-link">Inline variables</a></li><li><a href="/cpp/random-number-generation.html" class="sidebar-link">Random number generation</a></li><li><a href="/cpp/date-and-time-using-chrono-header.html" class="sidebar-link">Date and time using header</a></li><li><a href="/cpp/sorting.html" class="sidebar-link">Sorting</a></li><li><a href="/cpp/enumeration.html" class="sidebar-link">Enumeration</a></li><li><a href="/cpp/iteration.html" class="sidebar-link">Iteration</a></li><li><a href="/cpp/regular-expressions.html" class="sidebar-link">Regular expressions</a></li><li><a href="/cpp/implementation-defined-behavior.html" class="sidebar-link">Implementation-defined behavior</a></li><li><a href="/cpp/exceptions.html" class="sidebar-link">Exceptions</a></li><li><a href="/cpp/lambdas.html" class="sidebar-link">Lambdas</a></li><li><a href="/cpp/value-categories.html" class="sidebar-link">Value Categories</a></li><li><a href="/cpp/preprocessor.html" class="sidebar-link">Preprocessor</a></li><li><a href="/cpp/data-structures-in-c.html" class="sidebar-link">Data Structures in C++</a></li><li><a href="/cpp/templates.html" class="sidebar-link">Templates</a></li><li><a href="/cpp/expression-templates.html" class="sidebar-link">Expression templates</a></li><li><a href="/cpp/curiously-recurring-template-pattern-crtp.html" class="sidebar-link">Curiously Recurring Template Pattern (CRTP)</a></li><li><a href="/cpp/threading.html" class="sidebar-link">Threading</a></li><li><a href="/cpp/thread-synchronization-structures.html" class="sidebar-link">Thread synchronization structures</a></li><li><a href="/cpp/the-rule-of-three-five-and-zero.html" class="sidebar-link">The Rule of Three, Five, And Zero</a></li><li><a href="/cpp/raii-resource-acquisition-is-initialization.html" class="sidebar-link">RAII: Resource Acquisition Is Initialization</a></li><li><a href="/cpp/rtti-run-time-type-information.html" class="sidebar-link">RTTI: Run-Time Type Information</a></li><li><a href="/cpp/mutexes.html" aria-current="page" class="active sidebar-link">Mutexes</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#std-unique-lock-std-shared-lock-std-lock-guard" class="sidebar-link">std::uniquelock, std::sharedlock, std::lock_guard</a></li><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#strategies-for-lock-classes-std-try-to-lock-std-adopt-lock-std-defer-lock" class="sidebar-link">Strategies for lock classes: std::trytolock, std::adoptlock, std::deferlock</a></li><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#std-mutex" class="sidebar-link">std::mutex</a></li><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#std-scoped-lock-c-17" class="sidebar-link">std::scoped_lock (C++ 17)</a></li><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#mutex-types" class="sidebar-link">Mutex Types</a></li><li class="sidebar-sub-header"><a href="/cpp/mutexes.html#std-lock" class="sidebar-link">std::lock</a></li></ul></li><li><a href="/cpp/recursive-mutex.html" class="sidebar-link">Recursive Mutex</a></li><li><a href="/cpp/semaphore.html" class="sidebar-link">Semaphore</a></li><li><a href="/cpp/futures-and-promises.html" class="sidebar-link">Futures and Promises</a></li><li><a href="/cpp/atomic-types.html" class="sidebar-link">Atomic Types</a></li><li><a href="/cpp/type-erasure.html" class="sidebar-link">Type Erasure</a></li><li><a href="/cpp/explicit-type-conversions.html" class="sidebar-link">Explicit type conversions</a></li><li><a href="/cpp/unnamed-types.html" class="sidebar-link">Unnamed types</a></li><li><a href="/cpp/type-traits.html" class="sidebar-link">Type Traits</a></li><li><a href="/cpp/return-type-covariance.html" class="sidebar-link">Return Type Covariance</a></li><li><a href="/cpp/layout-of-object-types.html" class="sidebar-link">Layout of object types</a></li><li><a href="/cpp/type-inference.html" class="sidebar-link">Type Inference</a></li><li><a href="/cpp/typedef-and-type-aliases.html" class="sidebar-link">Typedef and type aliases</a></li><li><a href="/cpp/type-deduction.html" class="sidebar-link">type deduction</a></li><li><a href="/cpp/trailing-return-type.html" class="sidebar-link">Trailing return type</a></li><li><a href="/cpp/alignment.html" class="sidebar-link">Alignment</a></li><li><a href="/cpp/perfect-forwarding.html" class="sidebar-link">Perfect Forwarding</a></li><li><a href="/cpp/decltype.html" class="sidebar-link">decltype</a></li><li><a href="/cpp/sfinae-substitution-failure-is-not-an-error.html" class="sidebar-link">SFINAE (Substitution Failure Is Not An Error)</a></li><li><a href="/cpp/undefined-behavior.html" class="sidebar-link">Undefined Behavior</a></li><li><a href="/cpp/overload-resolution.html" class="sidebar-link">Overload resolution</a></li><li><a href="/cpp/move-semantics.html" class="sidebar-link">Move Semantics</a></li><li><a href="/cpp/pimpl-idiom.html" class="sidebar-link">Pimpl Idiom</a></li><li><a href="/cpp/auto.html" class="sidebar-link">auto</a></li><li><a href="/cpp/copy-elision.html" class="sidebar-link">Copy Elision</a></li><li><a href="/cpp/fold-expressions.html" class="sidebar-link">Fold Expressions</a></li><li><a href="/cpp/unions.html" class="sidebar-link">Unions</a></li><li><a href="/cpp/design-pattern-implementation-in-c.html" class="sidebar-link">Design pattern implementation in C++</a></li><li><a href="/cpp/singleton-design-pattern.html" class="sidebar-link">Singleton Design Pattern</a></li><li><a href="/cpp/user-defined-literals.html" class="sidebar-link">User-Defined Literals</a></li><li><a href="/cpp/memory-management.html" class="sidebar-link">Memory management</a></li><li><a href="/cpp/c-11-memory-model.html" class="sidebar-link">C++11 Memory Model</a></li><li><a href="/cpp/scopes.html" class="sidebar-link">Scopes</a></li><li><a href="/cpp/static-assert.html" class="sidebar-link">static_assert</a></li><li><a href="/cpp/constexpr.html" class="sidebar-link">constexpr</a></li><li><a href="/cpp/one-definition-rule-odr.html" class="sidebar-link">One Definition Rule (ODR)</a></li><li><a href="/cpp/unspecified-behavior.html" class="sidebar-link">Unspecified behavior</a></li><li><a href="/cpp/argument-dependent-name-lookup.html" class="sidebar-link">Argument Dependent Name Lookup</a></li><li><a href="/cpp/attributes.html" class="sidebar-link">Attributes</a></li><li><a href="/cpp/recursion-in-c.html" class="sidebar-link">Recursion in C++</a></li><li><a href="/cpp/arithmitic-metaprogramming.html" class="sidebar-link">Arithmitic Metaprogramming</a></li><li><a href="/cpp/callable-objects.html" class="sidebar-link">Callable Objects</a></li><li><a href="/cpp/client-server-examples.html" class="sidebar-link">Client server examples</a></li><li><a href="/cpp/const-correctness.html" class="sidebar-link">Const Correctness</a></li><li><a href="/cpp/parameter-packs.html" class="sidebar-link">Parameter packs</a></li><li><a href="/cpp/build-systems.html" class="sidebar-link">Build Systems</a></li><li><a href="/cpp/concurrency-with-openmp.html" class="sidebar-link">Concurrency With OpenMP</a></li><li><a href="/cpp/resource-management.html" class="sidebar-link">Resource Management</a></li><li><a href="/cpp/storage-class-specifiers.html" class="sidebar-link">Storage class specifiers</a></li><li><a href="/cpp/linkage-specifications.html" class="sidebar-link">Linkage specifications</a></li><li><a href="/cpp/digit-separators.html" class="sidebar-link">Digit separators</a></li><li><a href="/cpp/c-incompatibilities.html" class="sidebar-link">C incompatibilities</a></li><li><a href="/cpp/side-by-side-comparisons-of-classic-c-examples-solved-via-c-vs-c-11-vs-c-14-vs-c-17.html" class="sidebar-link">Side by Side Comparisons of classic C++ examples solved via C++ vs C++11 vs C++14 vs C++17</a></li><li><a href="/cpp/compiling-and-building.html" class="sidebar-link">Compiling and Building</a></li><li><a href="/cpp/common-compile-linker-errors-gcc.html" class="sidebar-link">Common compile/linker errors (GCC)</a></li><li><a href="/cpp/more-undefined-behaviors-in-c.html" class="sidebar-link">More undefined behaviors in C++</a></li><li><a href="/cpp/unit-testing-in-c.html" class="sidebar-link">Unit Testing in C++</a></li><li><a href="/cpp/c-debugging-and-debug-prevention-tools-techniques.html" class="sidebar-link">C++ Debugging and Debug-prevention Tools & Techniques</a></li><li><a href="/cpp/optimization-in-c.html" class="sidebar-link">Optimization in C++</a></li><li><a href="/cpp/optimization.html" class="sidebar-link">Optimization</a></li><li><a href="/cpp/profiling.html" class="sidebar-link">Profiling</a></li><li><a href="/cpp/refactoring-techniques.html" class="sidebar-link">Refactoring Techniques</a></li><li><a href="/cpp/internationalization-in-c.html" class="sidebar-link">Internationalization in C++</a></li><li><a href="/cpp/contributors.html" class="sidebar-link">The Contributors</a></li></ul></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="mutexes"><a href="#mutexes" class="header-anchor">#</a> Mutexes</h1> <h2 id="std-unique-lock-std-shared-lock-std-lock-guard"><a href="#std-unique-lock-std-shared-lock-std-lock-guard" class="header-anchor">#</a> std::unique_lock, std::shared_lock, std::lock_guard</h2> <p>Used for the RAII style acquiring of try locks, timed try locks and recursive locks.</p> <p><code>std::unique_lock</code> allows for exclusive ownership of mutexes.</p> <p><code>std::shared_lock</code> allows for shared ownership of mutexes. Several threads can hold <code>std::shared_locks</code> on a <code>std::shared_mutex</code>. Available from C++ 14.</p> <p><code>std::lock_guard</code> is a lightweight alternative to <code>std::unique_lock</code> and <code>std::shared_lock</code>.</p> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><unordered_map></span></span>
<span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><mutex></span></span>
<span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><shared_mutex></span></span>
<span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><thread></span></span>
<span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><string></span></span>
<span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string"><iostream></span></span>
<span class="token keyword">class</span> <span class="token class-name">PhoneBook</span> <span class="token punctuation">{</span>
<span class="token keyword">public</span><span class="token operator">:</span>
std<span class="token double-colon punctuation">::</span>string <span class="token function">getPhoneNo</span><span class="token punctuation">(</span> <span class="token keyword">const</span> std<span class="token double-colon punctuation">::</span>string <span class="token operator">&</span> name <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>shared_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>shared_timed_mutex<span class="token operator">></span> <span class="token function">l</span><span class="token punctuation">(</span>_protect<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">auto</span> it <span class="token operator">=</span> _phonebook<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span> name <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> it <span class="token operator">!=</span> _phonebook<span class="token punctuation">.</span><span class="token function">end</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token operator">*</span>it<span class="token punctuation">)</span><span class="token punctuation">.</span>second<span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token string">""</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">addPhoneNo</span> <span class="token punctuation">(</span> <span class="token keyword">const</span> std<span class="token double-colon punctuation">::</span>string <span class="token operator">&</span> name<span class="token punctuation">,</span> <span class="token keyword">const</span> std<span class="token double-colon punctuation">::</span>string <span class="token operator">&</span> phone <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>shared_timed_mutex<span class="token operator">></span> <span class="token function">l</span><span class="token punctuation">(</span>_protect<span class="token punctuation">)</span><span class="token punctuation">;</span>
_phonebook<span class="token punctuation">[</span>name<span class="token punctuation">]</span> <span class="token operator">=</span> phone<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span>shared_timed_mutex _protect<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>unordered_map<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>string<span class="token punctuation">,</span>std<span class="token double-colon punctuation">::</span>string<span class="token operator">></span> _phonebook<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre></div><h2 id="strategies-for-lock-classes-std-try-to-lock-std-adopt-lock-std-defer-lock"><a href="#strategies-for-lock-classes-std-try-to-lock-std-adopt-lock-std-defer-lock" class="header-anchor">#</a> Strategies for lock classes: std::try_to_lock, std::adopt_lock, std::defer_lock</h2> <p>When creating a std::unique_lock, there are three different locking strategies to choose from: <code>std::try_to_lock</code>, <code>std::defer_lock</code> and <code>std::adopt_lock</code></p> <ol><li><code>std::try_to_lock</code> allows for trying a lock without blocking:</li></ol> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>atomic_int temp <span class="token punctuation">{</span><span class="token number">0</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>mutex _mutex<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>thread <span class="token function">t</span><span class="token punctuation">(</span> <span class="token punctuation">[</span><span class="token operator">&</span><span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">while</span><span class="token punctuation">(</span> temp<span class="token operator">!=</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_for</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">seconds</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span> _mutex<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>try_to_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span><span class="token punctuation">(</span>lock<span class="token punctuation">.</span><span class="token function">owns_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token comment">//do something</span>
temp<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span> <span class="token boolean">true</span> <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_for</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">seconds</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock</span><span class="token punctuation">(</span> _mutex<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>try_to_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span><span class="token punctuation">(</span>lock<span class="token punctuation">.</span><span class="token function">owns_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>temp <span class="token operator"><</span> INT_MAX<span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token operator">++</span>temp<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> temp <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre></div><li>`std::defer_lock` allows for creating a lock structure without acquiring the lock. When locking more than one mutex, there is a window of
opportunity for a deadlock if two function callers try to acquire the
locks at the same time:</li> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock1</span><span class="token punctuation">(</span>_mutex1<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>defer_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock2</span><span class="token punctuation">(</span>_mutex2<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>defer_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
lock1<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
lock2<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// deadlock here</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> "Locked<span class="token operator">!</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
<span class="token comment">//...</span>
<span class="token punctuation">}</span>
</code></pre></div><p>With the following code, whatever happens in
the function, the locks are acquired and released in appropriate order:</p> <div class="language- extra-class"><pre class="language-text"><code>
{
std::unique_lock<std::mutex> lock1(_mutex1, std::defer_lock);
std::unique_lock<std::mutex> lock2(_mutex2, std::defer_lock);
std::lock(lock1,lock2); // no deadlock possible
std::cout << "Locked! << std::endl;
//...
}
</code></pre></div><ol><li><code>std::adopt_lock</code> does not attempt to lock a second time if the calling thread currently owns the lock.</li></ol> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock1</span><span class="token punctuation">(</span>_mutex1<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>adopt_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>unique_lock<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>mutex<span class="token operator">></span> <span class="token function">lock2</span><span class="token punctuation">(</span>_mutex2<span class="token punctuation">,</span> std<span class="token double-colon punctuation">::</span>adopt_lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> "Locked<span class="token operator">!</span> <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
<span class="token comment">//...</span>
<span class="token punctuation">}</span>
</code></pre></div><p>Something to keep in mind is that std::adopt_lock is not a substitute for recursive mutex usage. When the lock goes out of scope the mutex is <strong>released</strong>.</p> <h2 id="std-mutex"><a href="#std-mutex" class="header-anchor">#</a> std::mutex</h2> <p>std::mutex is a simple, non-recursive synchronization structure that is used to protect data which is accessed by multiple threads.</p> <div class="language- extra-class"><pre class="language-text"><code>
std::atomic_int temp{0};
std::mutex _mutex;
std::thread t( [&](){
while( temp!= -1){
std::this_thread::sleep_for(std::chrono::seconds(5));
std::unique_lock<std::mutex> lock( _mutex);
temp=0;
}
});
while ( true )
{
std::this_thread::sleep_for(std::chrono::milliseconds(1));
std::unique_lock<std::mutex> lock( _mutex, std::try_to_lock);
if ( temp < INT_MAX )
temp++;
cout << temp << endl;
}
</code></pre></div><h2 id="std-scoped-lock-c-17"><a href="#std-scoped-lock-c-17" class="header-anchor">#</a> std::scoped_lock (C++ 17)</h2> <p><code>std::scoped_lock</code> provides RAII style semantics for owning one more mutexes, combined with the lock avoidance algorithms used by <code>std::lock</code>. When <code>std::scoped_lock</code> is destroyed, mutexes are released in the reverse order from which they where acquired.</p> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>scoped_lock lock<span class="token punctuation">{</span>_mutex1<span class="token punctuation">,</span>_mutex2<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token comment">//do something</span>
<span class="token punctuation">}</span>
</code></pre></div><h2 id="mutex-types"><a href="#mutex-types" class="header-anchor">#</a> Mutex Types</h2> <p>C++1x offers a selection of mutex classes:</p> <ul><li><a href="http://stackoverflow.com/documentation/c%2B%2B/9895/mutexes/30441/stdmutex#t=201705100643590643715" target="_blank" rel="noopener noreferrer">std::mutex<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a> - offers simple locking functionality.</li> <li>std::timed_mutex - offers try_to_lock functionality</li> <li><a href="http://stackoverflow.com/documentation/c%2B%2B/9929/recursive-mutex/30442/stdrecursive-mutex#t=201705100822554334632" target="_blank" rel="noopener noreferrer">std::recursive_mutex<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a> - allows recursive locking by the same thread.</li> <li>std::shared_mutex, std::shared_timed_mutex - offers shared and unique lock functionality.</li></ul> <h2 id="std-lock"><a href="#std-lock" class="header-anchor">#</a> std::lock</h2> <p><code>std::lock</code> uses deadlock avoidance algorithms to lock one or more mutexes. If an exception is thrown during a call to lock multiple objects, <code>std::lock</code> unlocks the successfully locked objects before re-throwing the exception.</p> <div class="language-cpp extra-class"><pre class="language-cpp"><code>std<span class="token double-colon punctuation">::</span><span class="token function">lock</span><span class="token punctuation">(</span>_mutex1<span class="token punctuation">,</span> _mutex2<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div><h4 id="remarks"><a href="#remarks" class="header-anchor">#</a> Remarks</h4> <h3 id="it-is-better-to-use-std-shared-mutex-than-std-shared-timed-mutex"><a href="#it-is-better-to-use-std-shared-mutex-than-std-shared-timed-mutex" class="header-anchor">#</a> It is better to use <strong>std::shared_mutex</strong> than <strong>std::shared_timed_mutex</strong>.</h3> <p><strong>The performance difference is more than double.</strong></p> <p>If you want to use RWLock, you will find that there are two options.<br>
It is std::shared_mutex and shared_timed_mutex.<br>
you may think std::shared_timed_mutex is just the version 'std::shared_mutex + time method'.</p> <p><strong>But the implementation is totally different.</strong></p> <h3 id="the-code-below-is-msvc14-1-implementation-of-std-shared-mutex"><a href="#the-code-below-is-msvc14-1-implementation-of-std-shared-mutex" class="header-anchor">#</a> The code below is MSVC14.1 implementation of std::shared_mutex.</h3> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token keyword">class</span> <span class="token class-name">shared_mutex</span>
<span class="token punctuation">{</span>
<span class="token keyword">public</span><span class="token operator">:</span>
<span class="token keyword">typedef</span> _Smtx_t <span class="token operator">*</span> native_handle_type<span class="token punctuation">;</span>
<span class="token function">shared_mutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token operator">:</span> <span class="token function">_Myhandle</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// default construct</span>
<span class="token punctuation">}</span>
<span class="token operator">~</span><span class="token function">shared_mutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// destroy the object</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// lock exclusive</span>
<span class="token function">_Smtx_lock_exclusive</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">bool</span> <span class="token function">try_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// try to lock exclusive</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">_Smtx_try_lock_exclusive</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// unlock exclusive</span>
<span class="token function">_Smtx_unlock_exclusive</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// lock non-exclusive</span>
<span class="token function">_Smtx_lock_shared</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">bool</span> <span class="token function">try_lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">_Smtx_try_lock_shared</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">unlock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// unlock non-exclusive</span>
<span class="token function">_Smtx_unlock_shared</span><span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
native_handle_type <span class="token function">native_handle</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// get native handle</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token operator">&</span>_Myhandle<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">shared_mutex</span><span class="token punctuation">(</span><span class="token keyword">const</span> shared_mutex<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
shared_mutex<span class="token operator">&</span> <span class="token keyword">operator</span><span class="token operator">=</span><span class="token punctuation">(</span><span class="token keyword">const</span> shared_mutex<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
<span class="token keyword">private</span><span class="token operator">:</span>
_Smtx_t _Myhandle<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">void</span> __cdecl <span class="token function">_Smtx_lock_exclusive</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* lock shared mutex exclusively */</span>
<span class="token function">AcquireSRWLockExclusive</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> __cdecl <span class="token function">_Smtx_lock_shared</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* lock shared mutex non-exclusively */</span>
<span class="token function">AcquireSRWLockShared</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">int</span> __cdecl <span class="token function">_Smtx_try_lock_exclusive</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* try to lock shared mutex exclusively */</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">TryAcquireSRWLockExclusive</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">int</span> __cdecl <span class="token function">_Smtx_try_lock_shared</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* try to lock shared mutex non-exclusively */</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">TryAcquireSRWLockShared</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> __cdecl <span class="token function">_Smtx_unlock_exclusive</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* unlock exclusive shared mutex */</span>
<span class="token function">ReleaseSRWLockExclusive</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> __cdecl <span class="token function">_Smtx_unlock_shared</span><span class="token punctuation">(</span>_Smtx_t <span class="token operator">*</span> smtx<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">/* unlock non-exclusive shared mutex */</span>
<span class="token function">ReleaseSRWLockShared</span><span class="token punctuation">(</span><span class="token generic-function"><span class="token function">reinterpret_cast</span><span class="token generic class-name"><span class="token operator"><</span>PSRWLOCK<span class="token operator">></span></span></span><span class="token punctuation">(</span>smtx<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><p>You can see that std::shared_mutex is implemented in Windows Slim Reader/Write Locks(<a href="https://msdn.microsoft.com/ko-kr/library/windows/desktop/aa904937(v=vs.85).aspx" target="_blank" rel="noopener noreferrer">https://msdn.microsoft.com/ko-kr/library/windows/desktop/aa904937(v=vs.85).aspx)<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a>)</p> <p>Now Let's look at the implementation of std::shared_timed_mutex.</p> <h3 id="the-code-below-is-msvc14-1-implementation-of-std-shared-timed-mutex"><a href="#the-code-below-is-msvc14-1-implementation-of-std-shared-timed-mutex" class="header-anchor">#</a> The code below is MSVC14.1 implementation of std::shared_timed_mutex.</h3> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token keyword">class</span> <span class="token class-name">shared_timed_mutex</span>
<span class="token punctuation">{</span>
<span class="token keyword">typedef</span> <span class="token keyword">unsigned</span> <span class="token keyword">int</span> _Read_cnt_t<span class="token punctuation">;</span>
<span class="token keyword">static</span> <span class="token keyword">constexpr</span> _Read_cnt_t _Max_readers <span class="token operator">=</span> <span class="token function">_Read_cnt_t</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">public</span><span class="token operator">:</span>
<span class="token function">shared_timed_mutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token operator">:</span> <span class="token function">_Mymtx</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">_Read_queue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">_Write_queue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token function">_Readers</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">_Writing</span><span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// default construct</span>
<span class="token punctuation">}</span>
<span class="token operator">~</span><span class="token function">shared_timed_mutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span> _NOEXCEPT
<span class="token punctuation">{</span> <span class="token comment">// destroy the object</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// lock exclusive</span>
unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>_Writing<span class="token punctuation">)</span>
_Write_queue<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
_Writing <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token number">0</span> <span class="token operator"><</span> _Readers<span class="token punctuation">)</span>
_Read_queue<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// wait for writing, no readers</span>
<span class="token punctuation">}</span>
<span class="token keyword">bool</span> <span class="token function">try_lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock exclusive</span>
lock_guard<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>_Writing <span class="token operator">||</span> <span class="token number">0</span> <span class="token operator"><</span> _Readers<span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">else</span>
<span class="token punctuation">{</span> <span class="token comment">// set writing, no readers</span>
_Writing <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">template</span><span class="token operator"><</span><span class="token keyword">class</span> <span class="token class-name">_Rep</span><span class="token punctuation">,</span>
<span class="token keyword">class</span> <span class="token class-name">_Period</span><span class="token operator">></span>
<span class="token keyword">bool</span> <span class="token function">try_lock_for</span><span class="token punctuation">(</span>
<span class="token keyword">const</span> chrono<span class="token double-colon punctuation">::</span>duration<span class="token operator"><</span>_Rep<span class="token punctuation">,</span> _Period<span class="token operator">></span><span class="token operator">&</span> _Rel_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock for duration</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">try_lock_until</span><span class="token punctuation">(</span>chrono<span class="token double-colon punctuation">::</span>steady_clock<span class="token double-colon punctuation">::</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span> _Rel_time<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">template</span><span class="token operator"><</span><span class="token keyword">class</span> <span class="token class-name">_Clock</span><span class="token punctuation">,</span>
<span class="token keyword">class</span> <span class="token class-name">_Duration</span><span class="token operator">></span>
<span class="token keyword">bool</span> <span class="token function">try_lock_until</span><span class="token punctuation">(</span>
<span class="token keyword">const</span> chrono<span class="token double-colon punctuation">::</span>time_point<span class="token operator"><</span>_Clock<span class="token punctuation">,</span> _Duration<span class="token operator">></span><span class="token operator">&</span> _Abs_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock until time point</span>
<span class="token keyword">auto</span> _Not_writing <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token keyword">this</span><span class="token punctuation">]</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Writing<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">auto</span> _Zero_readers <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token keyword">this</span><span class="token punctuation">]</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token punctuation">(</span>_Readers <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Write_queue<span class="token punctuation">.</span><span class="token function">wait_until</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">,</span> _Abs_time<span class="token punctuation">,</span> _Not_writing<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
_Writing <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Read_queue<span class="token punctuation">.</span><span class="token function">wait_until</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">,</span> _Abs_time<span class="token punctuation">,</span> _Zero_readers<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// timeout, leave writing state</span>
_Writing <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
_Lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// unlock before notifying, for efficiency</span>
_Write_queue<span class="token punctuation">.</span><span class="token function">notify_all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// unlock exclusive</span>
<span class="token punctuation">{</span> <span class="token comment">// unlock before notifying, for efficiency</span>
lock_guard<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
_Writing <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
_Write_queue<span class="token punctuation">.</span><span class="token function">notify_all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// lock non-exclusive</span>
unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>_Writing <span class="token operator">||</span> _Readers <span class="token operator">==</span> _Max_readers<span class="token punctuation">)</span>
_Write_queue<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>_Readers<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">bool</span> <span class="token function">try_lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive</span>
lock_guard<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>_Writing <span class="token operator">||</span> _Readers <span class="token operator">==</span> _Max_readers<span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">else</span>
<span class="token punctuation">{</span> <span class="token comment">// count another reader</span>
<span class="token operator">++</span>_Readers<span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">template</span><span class="token operator"><</span><span class="token keyword">class</span> <span class="token class-name">_Rep</span><span class="token punctuation">,</span>
<span class="token keyword">class</span> <span class="token class-name">_Period</span><span class="token operator">></span>
<span class="token keyword">bool</span> <span class="token function">try_lock_shared_for</span><span class="token punctuation">(</span>
<span class="token keyword">const</span> chrono<span class="token double-colon punctuation">::</span>duration<span class="token operator"><</span>_Rep<span class="token punctuation">,</span> _Period<span class="token operator">></span><span class="token operator">&</span> _Rel_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive for relative time</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">try_lock_shared_until</span><span class="token punctuation">(</span>_Rel_time
<span class="token operator">+</span> chrono<span class="token double-colon punctuation">::</span>steady_clock<span class="token double-colon punctuation">::</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">template</span><span class="token operator"><</span><span class="token keyword">class</span> <span class="token class-name">_Time</span><span class="token operator">></span>
<span class="token keyword">bool</span> <span class="token function">_Try_lock_shared_until</span><span class="token punctuation">(</span>_Time _Abs_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive until absolute time</span>
<span class="token keyword">auto</span> _Can_acquire <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token keyword">this</span><span class="token punctuation">]</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Writing <span class="token operator">&&</span> _Readers <span class="token operator"><</span> _Max_readers<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
unique_lock<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Write_queue<span class="token punctuation">.</span><span class="token function">wait_until</span><span class="token punctuation">(</span>_Lock<span class="token punctuation">,</span> _Abs_time<span class="token punctuation">,</span> _Can_acquire<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>_Readers<span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">template</span><span class="token operator"><</span><span class="token keyword">class</span> <span class="token class-name">_Clock</span><span class="token punctuation">,</span>
<span class="token keyword">class</span> <span class="token class-name">_Duration</span><span class="token operator">></span>
<span class="token keyword">bool</span> <span class="token function">try_lock_shared_until</span><span class="token punctuation">(</span>
<span class="token keyword">const</span> chrono<span class="token double-colon punctuation">::</span>time_point<span class="token operator"><</span>_Clock<span class="token punctuation">,</span> _Duration<span class="token operator">></span><span class="token operator">&</span> _Abs_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive until absolute time</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">_Try_lock_shared_until</span><span class="token punctuation">(</span>_Abs_time<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">bool</span> <span class="token function">try_lock_shared_until</span><span class="token punctuation">(</span><span class="token keyword">const</span> xtime <span class="token operator">*</span>_Abs_time<span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// try to lock non-exclusive until absolute time</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token function">_Try_lock_shared_until</span><span class="token punctuation">(</span>_Abs_time<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">unlock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span> <span class="token comment">// unlock non-exclusive</span>
_Read_cnt_t _Local_readers<span class="token punctuation">;</span>
<span class="token keyword">bool</span> _Local_writing<span class="token punctuation">;</span>
<span class="token punctuation">{</span> <span class="token comment">// unlock before notifying, for efficiency</span>
lock_guard<span class="token operator"><</span>mutex<span class="token operator">></span> <span class="token function">_Lock</span><span class="token punctuation">(</span>_Mymtx<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">--</span>_Readers<span class="token punctuation">;</span>
_Local_readers <span class="token operator">=</span> _Readers<span class="token punctuation">;</span>
_Local_writing <span class="token operator">=</span> _Writing<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>_Local_writing <span class="token operator">&&</span> _Local_readers <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span>
_Read_queue<span class="token punctuation">.</span><span class="token function">notify_one</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>_Local_writing <span class="token operator">&&</span> _Local_readers <span class="token operator">==</span> _Max_readers <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">)</span>
_Write_queue<span class="token punctuation">.</span><span class="token function">notify_all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">shared_timed_mutex</span><span class="token punctuation">(</span><span class="token keyword">const</span> shared_timed_mutex<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
shared_timed_mutex<span class="token operator">&</span> <span class="token keyword">operator</span><span class="token operator">=</span><span class="token punctuation">(</span><span class="token keyword">const</span> shared_timed_mutex<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
<span class="token keyword">private</span><span class="token operator">:</span>
mutex _Mymtx<span class="token punctuation">;</span>
condition_variable _Read_queue<span class="token punctuation">,</span> _Write_queue<span class="token punctuation">;</span>
_Read_cnt_t _Readers<span class="token punctuation">;</span>
<span class="token keyword">bool</span> _Writing<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">class</span> <span class="token class-name">stl_condition_variable_win7</span> <span class="token keyword">final</span> <span class="token operator">:</span> <span class="token keyword">public</span> stl_condition_variable_interface
<span class="token punctuation">{</span>
<span class="token keyword">public</span><span class="token operator">:</span>
<span class="token function">stl_condition_variable_win7</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
<span class="token function">__crtInitializeConditionVariable</span><span class="token punctuation">(</span><span class="token operator">&</span>m_condition_variable<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token operator">~</span><span class="token function">stl_condition_variable_win7</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
<span class="token function">stl_condition_variable_win7</span><span class="token punctuation">(</span><span class="token keyword">const</span> stl_condition_variable_win7<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
stl_condition_variable_win7<span class="token operator">&</span> <span class="token keyword">operator</span><span class="token operator">=</span><span class="token punctuation">(</span><span class="token keyword">const</span> stl_condition_variable_win7<span class="token operator">&</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token keyword">delete</span><span class="token punctuation">;</span>
<span class="token keyword">virtual</span> <span class="token keyword">void</span> <span class="token function">destroy</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">override</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
<span class="token keyword">virtual</span> <span class="token keyword">void</span> <span class="token function">wait</span><span class="token punctuation">(</span>stl_critical_section_interface <span class="token operator">*</span>lock<span class="token punctuation">)</span> <span class="token keyword">override</span>
<span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>stl_condition_variable_win7<span class="token double-colon punctuation">::</span><span class="token function">wait_for</span><span class="token punctuation">(</span>lock<span class="token punctuation">,</span> INFINITE<span class="token punctuation">)</span><span class="token punctuation">)</span>
std<span class="token double-colon punctuation">::</span><span class="token function">terminate</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">virtual</span> <span class="token keyword">bool</span> <span class="token function">wait_for</span><span class="token punctuation">(</span>stl_critical_section_interface <span class="token operator">*</span>lock<span class="token punctuation">,</span> <span class="token keyword">unsigned</span> <span class="token keyword">int</span> timeout<span class="token punctuation">)</span> <span class="token keyword">override</span>
<span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token function">__crtSleepConditionVariableSRW</span><span class="token punctuation">(</span><span class="token operator">&</span>m_condition_variable<span class="token punctuation">,</span> <span class="token generic-function"><span class="token function">static_cast</span><span class="token generic class-name"><span class="token operator"><</span>stl_critical_section_win7 <span class="token operator">*</span><span class="token operator">></span></span></span><span class="token punctuation">(</span>lock<span class="token punctuation">)</span><span class="token operator">-></span><span class="token function">native_handle</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> timeout<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">virtual</span> <span class="token keyword">void</span> <span class="token function">notify_one</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">override</span>
<span class="token punctuation">{</span>
<span class="token function">__crtWakeConditionVariable</span><span class="token punctuation">(</span><span class="token operator">&</span>m_condition_variable<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">virtual</span> <span class="token keyword">void</span> <span class="token function">notify_all</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">override</span>
<span class="token punctuation">{</span>
<span class="token function">__crtWakeAllConditionVariable</span><span class="token punctuation">(</span><span class="token operator">&</span>m_condition_variable<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">private</span><span class="token operator">:</span>
CONDITION_VARIABLE m_condition_variable<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre></div><p>You can see that std::shared_timed_mutex is implemented in std::condition_value.</p> <p>This is a huge difference.</p> <p>So Let's check the performance of two of them.</p> <p><a href="https://i.stack.imgur.com/xdKwe.png" target="_blank" rel="noopener noreferrer"><img src="https://i.stack.imgur.com/xdKwe.png" alt="TEST RESULTS"><span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></p> <p>This is the result of read/write test for 1000 millisecond.</p> <h3 id="std-shared-mutex-processed-read-write-over-2-times-more-than-std-shared-timed-mutex"><a href="#std-shared-mutex-processed-read-write-over-2-times-more-than-std-shared-timed-mutex" class="header-anchor">#</a> std::shared_mutex processed read/write <strong>over 2 times</strong> more than std::shared_timed_mutex.</h3> <p>In this example, the read / write ratio is the same, but the read rate is more frequent than the write rate in real.<br>
Therefore, the performance difference can be larger.</p> <p>the code below is the code in this example.</p> <div class="language-cpp extra-class"><pre class="language-cpp"><code><span class="token keyword">void</span> <span class="token function">useSTLSharedMutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>shared_mutex shared_mtx_lock<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>vector<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>thread<span class="token operator">></span> readThreads<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>vector<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>thread<span class="token operator">></span> writeThreads<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>list<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> data <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">volatile</span> <span class="token keyword">bool</span> exit <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>atomic<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">readProcessedCnt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>atomic<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">writeProcessedCnt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">unsigned</span> <span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> std<span class="token double-colon punctuation">::</span>thread<span class="token double-colon punctuation">::</span><span class="token function">hardware_concurrency</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
readThreads<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span><span class="token function">thread</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token operator">&</span>data<span class="token punctuation">,</span> <span class="token operator">&</span>exit<span class="token punctuation">,</span> <span class="token operator">&</span>shared_mtx_lock<span class="token punctuation">,</span> <span class="token operator">&</span>readProcessedCnt<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>list<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> mydata<span class="token punctuation">;</span>
<span class="token keyword">int</span> localProcessCnt <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
mydata<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>data<span class="token punctuation">.</span><span class="token function">back</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>localProcessCnt<span class="token punctuation">;</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">unlock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>exit<span class="token punctuation">)</span>
<span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span><span class="token function">atomic_fetch_add</span><span class="token punctuation">(</span><span class="token operator">&</span>readProcessedCnt<span class="token punctuation">,</span> localProcessCnt<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
writeThreads<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span><span class="token function">thread</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token operator">&</span>data<span class="token punctuation">,</span> <span class="token operator">&</span>exit<span class="token punctuation">,</span> <span class="token operator">&</span>shared_mtx_lock<span class="token punctuation">,</span> <span class="token operator">&</span>writeProcessedCnt<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">int</span> localProcessCnt <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
data<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span><span class="token function">rand</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>localProcessCnt<span class="token punctuation">;</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>exit<span class="token punctuation">)</span>
<span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span><span class="token function">atomic_fetch_add</span><span class="token punctuation">(</span><span class="token operator">&</span>writeProcessedCnt<span class="token punctuation">,</span> localProcessCnt<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_for</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">milliseconds</span><span class="token punctuation">(</span>MAIN_WAIT_MILLISECONDS<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
exit <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">auto</span> <span class="token operator">&</span>r <span class="token operator">:</span> readThreads<span class="token punctuation">)</span>
r<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">auto</span> <span class="token operator">&</span>w <span class="token operator">:</span> writeThreads<span class="token punctuation">)</span>
w<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"STLSharedMutex READ : "</span> <span class="token operator"><<</span> readProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"STLSharedMutex WRITE : "</span> <span class="token operator"><<</span> writeProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"TOTAL READ&WRITE : "</span> <span class="token operator"><<</span> readProcessedCnt <span class="token operator">+</span> writeProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">void</span> <span class="token function">useSTLSharedTimedMutex</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>shared_timed_mutex shared_mtx_lock<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>vector<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>thread<span class="token operator">></span> readThreads<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>vector<span class="token operator"><</span>std<span class="token double-colon punctuation">::</span>thread<span class="token operator">></span> writeThreads<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>list<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> data <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">volatile</span> <span class="token keyword">bool</span> exit <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>atomic<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">readProcessedCnt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>atomic<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> <span class="token function">writeProcessedCnt</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">unsigned</span> <span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> std<span class="token double-colon punctuation">::</span>thread<span class="token double-colon punctuation">::</span><span class="token function">hardware_concurrency</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
readThreads<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span><span class="token function">thread</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token operator">&</span>data<span class="token punctuation">,</span> <span class="token operator">&</span>exit<span class="token punctuation">,</span> <span class="token operator">&</span>shared_mtx_lock<span class="token punctuation">,</span> <span class="token operator">&</span>readProcessedCnt<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
std<span class="token double-colon punctuation">::</span>list<span class="token operator"><</span><span class="token keyword">int</span><span class="token operator">></span> mydata<span class="token punctuation">;</span>
<span class="token keyword">int</span> localProcessCnt <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">lock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
mydata<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>data<span class="token punctuation">.</span><span class="token function">back</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>localProcessCnt<span class="token punctuation">;</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">unlock_shared</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>exit<span class="token punctuation">)</span>
<span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span><span class="token function">atomic_fetch_add</span><span class="token punctuation">(</span><span class="token operator">&</span>readProcessedCnt<span class="token punctuation">,</span> localProcessCnt<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
writeThreads<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span><span class="token function">thread</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token operator">&</span>data<span class="token punctuation">,</span> <span class="token operator">&</span>exit<span class="token punctuation">,</span> <span class="token operator">&</span>shared_mtx_lock<span class="token punctuation">,</span> <span class="token operator">&</span>writeProcessedCnt<span class="token punctuation">]</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">int</span> localProcessCnt <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
data<span class="token punctuation">.</span><span class="token function">push_back</span><span class="token punctuation">(</span><span class="token function">rand</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token operator">++</span>localProcessCnt<span class="token punctuation">;</span>
shared_mtx_lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>exit<span class="token punctuation">)</span>
<span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span><span class="token function">atomic_fetch_add</span><span class="token punctuation">(</span><span class="token operator">&</span>writeProcessedCnt<span class="token punctuation">,</span> localProcessCnt<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
std<span class="token double-colon punctuation">::</span>this_thread<span class="token double-colon punctuation">::</span><span class="token function">sleep_for</span><span class="token punctuation">(</span>std<span class="token double-colon punctuation">::</span>chrono<span class="token double-colon punctuation">::</span><span class="token function">milliseconds</span><span class="token punctuation">(</span>MAIN_WAIT_MILLISECONDS<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
exit <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">auto</span> <span class="token operator">&</span>r <span class="token operator">:</span> readThreads<span class="token punctuation">)</span>
r<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">auto</span> <span class="token operator">&</span>w <span class="token operator">:</span> writeThreads<span class="token punctuation">)</span>
w<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"STLSharedTimedMutex READ : "</span> <span class="token operator"><<</span> readProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"STLSharedTimedMutex WRITE : "</span> <span class="token operator"><<</span> writeProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
std<span class="token double-colon punctuation">::</span>cout <span class="token operator"><<</span> <span class="token string">"TOTAL READ&WRITE : "</span> <span class="token operator"><<</span> readProcessedCnt <span class="token operator">+</span> writeProcessedCnt <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl <span class="token operator"><<</span> std<span class="token double-colon punctuation">::</span>endl<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div></div> <footer class="page-edit"><div class="edit-link"><a href="https://github.com/devtut/generate/edit/master/docs/cpp/mutexes.md" target="_blank" rel="noopener noreferrer">Edit this page on GitHub</a> <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></div> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev">
←
<a href="/cpp/rtti-run-time-type-information.html" class="prev">
RTTI: Run-Time Type Information
</a></span> <span class="next"><a href="/cpp/recursive-mutex.html">
Recursive Mutex
</a>
→
</span></p></div> </main></div><div class="global-ui"><!----></div></div>
<script src="/assets/js/app.1779e102.js" defer></script><script src="/assets/js/3.2cfa8016.js" defer></script><script src="/assets/js/679.06e044ba.js" defer></script>
</body>
</html>