| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // A class for checking that the current thread is/isn't the same as an initial |
| // thread. |
| |
| #ifndef LIB_FXL_SYNCHRONIZATION_THREAD_CHECKER_H_ |
| #define LIB_FXL_SYNCHRONIZATION_THREAD_CHECKER_H_ |
| |
| #include "lib/fxl/build_config.h" |
| |
| #include <pthread.h> |
| |
| #include "lib/fxl/logging.h" |
| #include "lib/fxl/macros.h" |
| #include "lib/fxl/synchronization/thread_annotations.h" |
| |
| namespace fxl { |
| |
| // A simple class that records the identity of the thread that it was created |
| // on, and at later points can tell if the current thread is the same as its |
| // creation thread. This class is thread-safe. |
| // |
| // Note: Unlike Chromium's |base::ThreadChecker|, this is *not* Debug-only (so |
| // #ifdef it out if you want something Debug-only). (Rationale: Having a |
| // |CalledOnValidThread()| that lies in Release builds seems bad. Moreover, |
| // there's a small space cost to having even an empty class. ) |
| // |
| // In addition to providing an explicity check of the current thread, |
| // |ThreadChecker| commplies with BasicLockable, checking the current thread |
| // when |lock| is called. This allows static thread safety analysis to be used |
| // to ensure that resources are accessed in a context that is checked (at debug |
| // runtime) to ensure that it's running on the correct thread: |
| // |
| // class MyClass { |
| // public: |
| // void Foo() { |
| // std::lock_guard<fxl::ThreadChecker> locker(thread_checker_); |
| // resource_ = 0; |
| // } |
| // private: |
| // mutable fxl::ThreadChecker thread_checker_; |
| // int resource_ FXL_GUARDED_BY(thread_checker_); |
| // } |
| // |
| // Note: |lock| checks the thread in debug builds only. |
| // |
| class FXL_CAPABILITY("mutex") ThreadChecker final { |
| public: |
| ThreadChecker() : self_(pthread_self()) {} |
| ~ThreadChecker() {} |
| |
| // Returns true if the current thread is the thread this object was created |
| // on and false otherwise. |
| bool IsCreationThreadCurrent() const { |
| return !!pthread_equal(pthread_self(), self_); |
| } |
| |
| void lock() FXL_ACQUIRE() { |
| FXL_DCHECK(IsCreationThreadCurrent()); |
| } |
| |
| void unlock() FXL_RELEASE() {} |
| |
| private: |
| const pthread_t self_; |
| |
| FXL_DISALLOW_COPY_AND_ASSIGN(ThreadChecker); |
| }; |
| |
| #ifndef NDEBUG |
| #define FXL_DECLARE_THREAD_CHECKER(c) fxl::ThreadChecker c |
| #define FXL_DCHECK_CREATION_THREAD_IS_CURRENT(c) \ |
| FXL_DCHECK((c).IsCreationThreadCurrent()) |
| #else |
| #define FXL_DECLARE_THREAD_CHECKER(c) |
| #define FXL_DCHECK_CREATION_THREAD_IS_CURRENT(c) ((void)0) |
| #endif |
| |
| } // namespace fxl |
| |
| #endif // LIB_FXL_SYNCHRONIZATION_THREAD_CHECKER_H_ |