86 lines
2.7 KiB
C++
86 lines
2.7 KiB
C++
// 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_THREAD_CHECKER_H_
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#define BASE_THREADING_THREAD_CHECKER_H_
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// Apart from debug builds, we also enable the thread checker in
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// builds with DCHECK_ALWAYS_ON so that trybots and waterfall bots
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// with this define will get the same level of thread checking as
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// debug bots.
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//
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// Note that this does not perfectly match situations where DCHECK is
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// enabled. For example a non-official release build may have
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// DCHECK_ALWAYS_ON undefined (and therefore ThreadChecker would be
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// disabled) but have DCHECKs enabled at runtime.
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#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
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#define ENABLE_THREAD_CHECKER 1
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#else
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#define ENABLE_THREAD_CHECKER 0
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#endif
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#if ENABLE_THREAD_CHECKER
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#include "base/threading/thread_checker_impl.h"
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#endif
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namespace base {
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// Do nothing implementation, for use in release mode.
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//
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// Note: You should almost always use the ThreadChecker class to get the
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// right version for your build configuration.
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class ThreadCheckerDoNothing {
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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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void DetachFromThread() {}
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};
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// ThreadChecker is a helper class used to help verify that some methods of a
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// class are called from the same thread. It provides identical functionality to
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// base::NonThreadSafe, but it is meant to be held as a member variable, rather
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// than inherited from base::NonThreadSafe.
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//
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// While inheriting from base::NonThreadSafe may give a clear indication about
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// the thread-safety of a class, it may also lead to violations of the style
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// guide with regard to multiple inheritence. The choice between having a
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// ThreadChecker member and inheriting from base::NonThreadSafe should be based
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// on whether:
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// - Derived classes need to know the thread they belong to, as opposed to
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// having that functionality fully encapsulated in the base class.
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// - Derived classes should be able to reassign the base class to another
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// thread, via DetachFromThread.
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//
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// If neither of these are true, then having a ThreadChecker member and calling
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// CalledOnValidThread is the preferable solution.
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//
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// Example:
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// class MyClass {
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// public:
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// void Foo() {
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// DCHECK(thread_checker_.CalledOnValidThread());
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// ... (do stuff) ...
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// }
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//
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// private:
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// ThreadChecker thread_checker_;
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// }
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//
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// In Release mode, CalledOnValidThread will always return true.
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#if ENABLE_THREAD_CHECKER
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class ThreadChecker : public ThreadCheckerImpl {
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};
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#else
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class ThreadChecker : public ThreadCheckerDoNothing {
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};
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#endif // ENABLE_THREAD_CHECKER
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#undef ENABLE_THREAD_CHECKER
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} // namespace base
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#endif // BASE_THREADING_THREAD_CHECKER_H_
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