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comparison: ipc/chromium/src/base/thread_collision_warner.cc
ipc/chromium/src/base/thread_collision_warner.cc
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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/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 |
