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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.
#ifndef BASE_THREADING_NON_THREAD_SAFE_H_
#define BASE_THREADING_NON_THREAD_SAFE_H_
#pragma once
#include "base/threading/thread_checker.h"
namespace base {
// A helper class used to help verify that methods of a class are
// called from the same thread. One can inherit from this class and use
// CalledOnValidThread() to verify.
//
// This is intended to be used with classes that appear to be thread safe, but
// aren't. For example, a service or a singleton like the preferences system.
//
// Example:
// class MyClass : public base::NonThreadSafe {
// public:
// void Foo() {
// DCHECK(CalledOnValidThread());
// ... (do stuff) ...
// }
// }
//
// In Release mode, CalledOnValidThread will always return true.
//
#ifndef NDEBUG
class NonThreadSafe {
public:
~NonThreadSafe();
bool CalledOnValidThread() const;
protected:
// Changes the thread that is checked for in CalledOnValidThread. The next
// call to CalledOnValidThread will attach this class to a new thread. It is
// up to the NonThreadSafe derived class to decide to expose this or not.
// This may be useful when an object may be created on one thread and then
// used exclusively on another thread.
void DetachFromThread();
private:
ThreadChecker thread_checker_;
};
#else
// Do nothing in release mode.
class NonThreadSafe {
public:
bool CalledOnValidThread() const {
return true;
}
protected:
void DetachFromThread() {}
};
#endif // NDEBUG
} // namespace base
#endif // BASE_NON_THREAD_SAFE_H_
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