1 /*
2 * Copyright 2019 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10 #include "rtc_base/synchronization/sequence_checker_internal.h"
11
12 #include <string>
13
14 #if defined(WEBRTC_MAC)
15 #include <dispatch/dispatch.h>
16 #endif
17
18 #include "rtc_base/checks.h"
19 #include "rtc_base/strings/string_builder.h"
20
21 namespace webrtc {
22 namespace webrtc_sequence_checker_internal {
23 namespace {
24 // On Mac, returns the label of the current dispatch queue; elsewhere, return
25 // null.
GetSystemQueueRef()26 const void* GetSystemQueueRef() {
27 #if defined(WEBRTC_MAC)
28 return dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL);
29 #else
30 return nullptr;
31 #endif
32 }
33
34 } // namespace
35
SequenceCheckerImpl()36 SequenceCheckerImpl::SequenceCheckerImpl()
37 : attached_(true),
38 valid_thread_(rtc::CurrentThreadRef()),
39 valid_queue_(TaskQueueBase::Current()),
40 valid_system_queue_(GetSystemQueueRef()) {}
41
IsCurrent() const42 bool SequenceCheckerImpl::IsCurrent() const {
43 const TaskQueueBase* const current_queue = TaskQueueBase::Current();
44 const rtc::PlatformThreadRef current_thread = rtc::CurrentThreadRef();
45 const void* const current_system_queue = GetSystemQueueRef();
46 MutexLock scoped_lock(&lock_);
47 if (!attached_) { // Previously detached.
48 attached_ = true;
49 valid_thread_ = current_thread;
50 valid_queue_ = current_queue;
51 valid_system_queue_ = current_system_queue;
52 return true;
53 }
54 if (valid_queue_) {
55 return valid_queue_ == current_queue;
56 }
57 if (valid_system_queue_ && valid_system_queue_ == current_system_queue) {
58 return true;
59 }
60 return rtc::IsThreadRefEqual(valid_thread_, current_thread);
61 }
62
Detach()63 void SequenceCheckerImpl::Detach() {
64 MutexLock scoped_lock(&lock_);
65 attached_ = false;
66 // We don't need to touch the other members here, they will be
67 // reset on the next call to IsCurrent().
68 }
69
70 #if RTC_DCHECK_IS_ON
ExpectationToString() const71 std::string SequenceCheckerImpl::ExpectationToString() const {
72 const TaskQueueBase* const current_queue = TaskQueueBase::Current();
73 const rtc::PlatformThreadRef current_thread = rtc::CurrentThreadRef();
74 const void* const current_system_queue = GetSystemQueueRef();
75 MutexLock scoped_lock(&lock_);
76 if (!attached_)
77 return "Checker currently not attached.";
78
79 // The format of the string is meant to compliment the one we have inside of
80 // FatalLog() (checks.cc). Example:
81 //
82 // # Expected: TQ: 0x0 SysQ: 0x7fff69541330 Thread: 0x11dcf6dc0
83 // # Actual: TQ: 0x7fa8f0604190 SysQ: 0x7fa8f0604a30 Thread: 0x700006f1a000
84 // TaskQueue doesn't match
85
86 rtc::StringBuilder message;
87 message.AppendFormat(
88 "# Expected: TQ: %p SysQ: %p Thread: %p\n"
89 "# Actual: TQ: %p SysQ: %p Thread: %p\n",
90 valid_queue_, valid_system_queue_,
91 reinterpret_cast<const void*>(valid_thread_), current_queue,
92 current_system_queue, reinterpret_cast<const void*>(current_thread));
93
94 if ((valid_queue_ || current_queue) && valid_queue_ != current_queue) {
95 message << "TaskQueue doesn't match\n";
96 } else if (valid_system_queue_ &&
97 valid_system_queue_ != current_system_queue) {
98 message << "System queue doesn't match\n";
99 } else if (!rtc::IsThreadRefEqual(valid_thread_, current_thread)) {
100 message << "Threads don't match\n";
101 }
102
103 return message.Release();
104 }
105 #endif // RTC_DCHECK_IS_ON
106
107 } // namespace webrtc_sequence_checker_internal
108 } // namespace webrtc
109