1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/ipc/chromium/src/base/thread_collision_warner.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,64 @@
1.4 +// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#include "base/thread_collision_warner.h"
1.9 +
1.10 +#include "base/logging.h"
1.11 +#include "base/platform_thread.h"
1.12 +
1.13 +namespace base {
1.14 +
1.15 +void DCheckAsserter::warn() {
1.16 + NOTREACHED() << "Thread Collision";
1.17 +}
1.18 +
1.19 +static subtle::Atomic32 CurrentThread() {
1.20 + const PlatformThreadId current_thread_id = PlatformThread::CurrentId();
1.21 + // We need to get the thread id into an atomic data type. This might be a
1.22 + // truncating conversion, but any loss-of-information just increases the
1.23 + // chance of a fault negative, not a false positive.
1.24 + const subtle::Atomic32 atomic_thread_id =
1.25 + static_cast<subtle::Atomic32>(current_thread_id);
1.26 +
1.27 + return atomic_thread_id;
1.28 +}
1.29 +
1.30 +void ThreadCollisionWarner::EnterSelf() {
1.31 + // If the active thread is 0 then I'll write the current thread ID
1.32 + // if two or more threads arrive here only one will succeed to
1.33 + // write on valid_thread_id_ the current thread ID.
1.34 + subtle::Atomic32 current_thread_id = CurrentThread();
1.35 +
1.36 + int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
1.37 + 0,
1.38 + current_thread_id);
1.39 + if (previous_value != 0 && previous_value != current_thread_id) {
1.40 + // gotcha! a thread is trying to use the same class and that is
1.41 + // not current thread.
1.42 + asserter_->warn();
1.43 + }
1.44 +
1.45 + subtle::NoBarrier_AtomicIncrement(&counter_, 1);
1.46 +}
1.47 +
1.48 +void ThreadCollisionWarner::Enter() {
1.49 + subtle::Atomic32 current_thread_id = CurrentThread();
1.50 +
1.51 + if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
1.52 + 0,
1.53 + current_thread_id) != 0) {
1.54 + // gotcha! another thread is trying to use the same class.
1.55 + asserter_->warn();
1.56 + }
1.57 +
1.58 + subtle::NoBarrier_AtomicIncrement(&counter_, 1);
1.59 +}
1.60 +
1.61 +void ThreadCollisionWarner::Leave() {
1.62 + if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {
1.63 + subtle::NoBarrier_Store(&valid_thread_id_, 0);
1.64 + }
1.65 +}
1.66 +
1.67 +} // namespace base
