74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_THREADING_NON_THREAD_SAFE_H_
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#define BASE_THREADING_NON_THREAD_SAFE_H_
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// Classes deriving from NonThreadSafe may need to suppress MSVC warning 4275:
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// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
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// There is a specific macro to do it: NON_EXPORTED_BASE(), defined in
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// compiler_specific.h
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#include "base/compiler_specific.h"
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// See comment at top of thread_checker.h
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#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
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#define ENABLE_NON_THREAD_SAFE 1
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#else
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#define ENABLE_NON_THREAD_SAFE 0
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#endif
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#if ENABLE_NON_THREAD_SAFE
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#include "base/threading/non_thread_safe_impl.h"
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#endif
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namespace base {
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// Do nothing implementation of NonThreadSafe, for release mode.
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//
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// Note: You should almost always use the NonThreadSafe class to get
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// the right version of the class for your build configuration.
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class NonThreadSafeDoNothing {
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public:
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bool CalledOnValidThread() const {
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return true;
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}
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protected:
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~NonThreadSafeDoNothing() {}
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void DetachFromThread() {}
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};
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// NonThreadSafe is a helper class used to help verify that methods of a
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// class are called from the same thread. One can inherit from this class
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// and use CalledOnValidThread() to verify.
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//
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// This is intended to be used with classes that appear to be thread safe, but
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// aren't. For example, a service or a singleton like the preferences system.
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//
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// Example:
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// class MyClass : public base::NonThreadSafe {
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// public:
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// void Foo() {
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// DCHECK(CalledOnValidThread());
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// ... (do stuff) ...
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// }
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// }
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//
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// Note that base::ThreadChecker offers identical functionality to
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// NonThreadSafe, but does not require inheritence. In general, it is preferable
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// to have a base::ThreadChecker as a member, rather than inherit from
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// NonThreadSafe. For more details about when to choose one over the other, see
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// the documentation for base::ThreadChecker.
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#if ENABLE_NON_THREAD_SAFE
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typedef NonThreadSafeImpl NonThreadSafe;
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#else
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typedef NonThreadSafeDoNothing NonThreadSafe;
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#endif // ENABLE_NON_THREAD_SAFE
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#undef ENABLE_NON_THREAD_SAFE
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} // namespace base
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#endif // BASE_NON_THREAD_SAFE_H_
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