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- // Copyright (c) 2010 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/threading/thread_collision_warner.h"
- #include <ostream>
- #include "base/notreached.h"
- #include "base/threading/platform_thread.h"
- namespace base {
- void DCheckAsserter::warn() {
- NOTREACHED() << "Thread Collision";
- }
- static subtle::Atomic32 CurrentThread() {
- const PlatformThreadId current_thread_id = PlatformThread::CurrentId();
- // We need to get the thread id into an atomic data type. This might be a
- // truncating conversion, but any loss-of-information just increases the
- // chance of a fault negative, not a false positive.
- const subtle::Atomic32 atomic_thread_id =
- static_cast<subtle::Atomic32>(current_thread_id);
- return atomic_thread_id;
- }
- void ThreadCollisionWarner::EnterSelf() {
- // If the active thread is 0 then I'll write the current thread ID
- // if two or more threads arrive here only one will succeed to
- // write on valid_thread_id_ the current thread ID.
- subtle::Atomic32 current_thread_id = CurrentThread();
- int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
- 0,
- current_thread_id);
- if (previous_value != 0 && previous_value != current_thread_id) {
- // gotcha! a thread is trying to use the same class and that is
- // not current thread.
- asserter_->warn();
- }
- subtle::NoBarrier_AtomicIncrement(&counter_, 1);
- }
- void ThreadCollisionWarner::Enter() {
- subtle::Atomic32 current_thread_id = CurrentThread();
- if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
- 0,
- current_thread_id) != 0) {
- // gotcha! another thread is trying to use the same class.
- asserter_->warn();
- }
- subtle::NoBarrier_AtomicIncrement(&counter_, 1);
- }
- void ThreadCollisionWarner::Leave() {
- if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {
- subtle::NoBarrier_Store(&valid_thread_id_, 0);
- }
- }
- } // namespace base
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