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// Copyright 2010 The Chromium Authors
// 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 <atomic>
#include <ostream>
#include "base/notreached.h"
#include "base/threading/platform_thread.h"
namespace base {
void DCheckAsserter::warn() {
NOTREACHED() << "Thread Collision";
}
void ThreadCollisionWarner::EnterSelf() {
// If the active thread is kInvalidThreadId 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.
PlatformThreadId current_thread_id = PlatformThread::CurrentId();
PlatformThreadId expected = kInvalidThreadId;
bool ok = valid_thread_id_.compare_exchange_strong(
expected, current_thread_id, std::memory_order_relaxed,
std::memory_order_relaxed);
if (!ok && expected != current_thread_id) {
// gotcha! a thread is trying to use the same class and that is
// not current thread.
asserter_->warn();
}
counter_.fetch_add(1, std::memory_order_relaxed);
}
void ThreadCollisionWarner::Enter() {
PlatformThreadId current_thread_id = PlatformThread::CurrentId();
PlatformThreadId expected = kInvalidThreadId;
if (!valid_thread_id_.compare_exchange_strong(expected, current_thread_id,
std::memory_order_relaxed,
std::memory_order_relaxed)) {
// gotcha! another thread is trying to use the same class.
asserter_->warn();
}
counter_.fetch_add(1, std::memory_order_relaxed);
}
void ThreadCollisionWarner::Leave() {
if (counter_.fetch_sub(1, std::memory_order_relaxed) == 1) {
valid_thread_id_.store(kInvalidThreadId, std::memory_order_relaxed);
}
}
} // namespace base
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