diff options
| -rw-r--r-- | base/threading/non_thread_safe.h | 9 | ||||
| -rw-r--r-- | base/threading/thread_checker.h | 30 |
2 files changed, 27 insertions, 12 deletions
diff --git a/base/threading/non_thread_safe.h b/base/threading/non_thread_safe.h index 3f60fed..da7b528 100644 --- a/base/threading/non_thread_safe.h +++ b/base/threading/non_thread_safe.h @@ -1,4 +1,4 @@ -// Copyright (c) 2011 The Chromium Authors. All rights reserved. +// Copyright (c) 2012 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. @@ -48,8 +48,13 @@ class NonThreadSafeDoNothing { // } // } // -// In Release mode, CalledOnValidThread will always return true. +// Note that base::ThreadChecker offers identical functionality to +// NonThreadSafe, but does not require inheritence. In general, it is preferable +// to have a base::ThreadChecker as a member, rather than inherit from +// NonThreadSafe. For more details about when to choose one over the other, see +// the documentation for base::ThreadChecker. // +// In Release mode, CalledOnValidThread will always return true. #ifndef NDEBUG class NonThreadSafe : public NonThreadSafeImpl { }; diff --git a/base/threading/thread_checker.h b/base/threading/thread_checker.h index 0525791..9c79958 100644 --- a/base/threading/thread_checker.h +++ b/base/threading/thread_checker.h @@ -40,24 +40,34 @@ class ThreadCheckerDoNothing { void DetachFromThread() {} }; -// Before using this class, please consider using NonThreadSafe as it -// makes it much easier to determine the nature of your class. -// // ThreadChecker is a helper class used to help verify that some methods of a -// class are called from the same thread. One can inherit from this class and -// use CalledOnValidThread() to verify. +// class are called from the same thread. It provides identical functionality to +// base::NonThreadSafe, but it is meant to be held as a member variable, rather +// than inherited from base::NonThreadSafe. +// +// While inheriting from base::NonThreadSafe may give a clear indication about +// the thread-safety of a class, it may also lead to violations of the style +// guide with regard to multiple inheritence. The choice between having a +// ThreadChecker member and inheriting from base::NonThreadSafe should be based +// on whether: +// - Derived classes need to know the thread they belong to, as opposed to +// having that functionality fully encapsulated in the base class. +// - Derived classes should be able to reassign the base class to another +// thread, via DetachFromThread. // -// Inheriting from class indicates that one must be careful when using the -// class with multiple threads. However, it is up to the class document to -// indicate how it can be used with threads. +// If neither of these are true, then having a ThreadChecker member and calling +// CalledOnValidThread is the preferable solution. // // Example: -// class MyClass : public ThreadChecker { +// class MyClass { // public: // void Foo() { -// DCHECK(CalledOnValidThread()); +// DCHECK(thread_checker_.CalledOnValidThread()); // ... (do stuff) ... // } +// +// private: +// ThreadChecker thread_checker_; // } // // In Release mode, CalledOnValidThread will always return true. |