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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/thread_collision_warner.h" | |
6 | |
7 #include "base/logging.h" | |
8 #include "base/threading/platform_thread.h" | |
9 | |
10 namespace base { | |
11 | |
12 void DCheckAsserter::warn() { | |
13 NOTREACHED() << "Thread Collision"; | |
14 } | |
15 | |
16 static subtle::Atomic32 CurrentThread() { | |
17 const PlatformThreadId current_thread_id = PlatformThread::CurrentId(); | |
18 // We need to get the thread id into an atomic data type. This might be a | |
19 // truncating conversion, but any loss-of-information just increases the | |
20 // chance of a fault negative, not a false positive. | |
21 const subtle::Atomic32 atomic_thread_id = | |
22 static_cast<subtle::Atomic32>(current_thread_id); | |
23 | |
24 return atomic_thread_id; | |
25 } | |
26 | |
27 void ThreadCollisionWarner::EnterSelf() { | |
28 // If the active thread is 0 then I'll write the current thread ID | |
29 // if two or more threads arrive here only one will succeed to | |
30 // write on valid_thread_id_ the current thread ID. | |
31 subtle::Atomic32 current_thread_id = CurrentThread(); | |
32 | |
33 int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_, | |
34 0, | |
35 current_thread_id); | |
36 if (previous_value != 0 && previous_value != current_thread_id) { | |
37 // gotcha! a thread is trying to use the same class and that is | |
38 // not current thread. | |
39 asserter_->warn(); | |
40 } | |
41 | |
42 subtle::NoBarrier_AtomicIncrement(&counter_, 1); | |
43 } | |
44 | |
45 void ThreadCollisionWarner::Enter() { | |
46 subtle::Atomic32 current_thread_id = CurrentThread(); | |
47 | |
48 if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_, | |
49 0, | |
50 current_thread_id) != 0) { | |
51 // gotcha! another thread is trying to use the same class. | |
52 asserter_->warn(); | |
53 } | |
54 | |
55 subtle::NoBarrier_AtomicIncrement(&counter_, 1); | |
56 } | |
57 | |
58 void ThreadCollisionWarner::Leave() { | |
59 if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) { | |
60 subtle::NoBarrier_Store(&valid_thread_id_, 0); | |
61 } | |
62 } | |
63 | |
64 } // namespace base | |
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