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Issue 2877023002: Move webrtc/{base => rtc_base} (Closed)
Patch Set: update presubmit.py and DEPS include rules Created 3 years, 5 months ago
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1 /*
2 * Copyright (c) 2016 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
11 #include "webrtc/base/race_checker.h"
12
13 namespace rtc {
14
15 RaceChecker::RaceChecker() {}
16
17 // Note that the implementation here is in itself racy, but we pretend it does
18 // not matter because we want this useful in release builds without having to
19 // pay the cost of using atomics. A race hitting the race checker is likely to
20 // cause access_count_ to diverge from zero and therefore cause the ThreadRef
21 // comparison to fail, signaling a race, although it may not be in the exact
22 // spot where a race *first* appeared in the code we're trying to protect. There
23 // is also a chance that an actual race is missed, however the probability of
24 // that has been considered small enough to be an acceptable trade off.
25 bool RaceChecker::Acquire() const {
26 const PlatformThreadRef current_thread = CurrentThreadRef();
27 // Set new accessing thread if this is a new use.
28 if (access_count_++ == 0)
29 accessing_thread_ = current_thread;
30 // If this is being used concurrently this check will fail for the second
31 // thread entering since it won't set the thread. Recursive use of checked
32 // methods are OK since the accessing thread remains the same.
33 const PlatformThreadRef accessing_thread = accessing_thread_;
34 return IsThreadRefEqual(accessing_thread, current_thread);
35 }
36
37 void RaceChecker::Release() const {
38 --access_count_;
39 }
40
41 namespace internal {
42 RaceCheckerScope::RaceCheckerScope(const RaceChecker* race_checker)
43 : race_checker_(race_checker), race_check_ok_(race_checker->Acquire()) {}
44
45 bool RaceCheckerScope::RaceDetected() const {
46 return !race_check_ok_;
47 }
48
49 RaceCheckerScope::~RaceCheckerScope() {
50 race_checker_->Release();
51 }
52
53 } // namespace internal
54 } // namespace rtc
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