1 /* 2 Copyright (c) 2021 Intel Corporation 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 #ifndef __TBB_mutex_H 18 #define __TBB_mutex_H 19 20 #if __TBB_PREVIEW_MUTEXES 21 22 #include "detail/_namespace_injection.h" 23 #include "detail/_utils.h" 24 #include "detail/_scoped_lock.h" 25 #include "detail/_waitable_atomic.h" 26 #include "detail/_mutex_common.h" 27 #include "profiling.h" 28 29 namespace tbb { 30 namespace detail { 31 namespace d1 { 32 33 class mutex { 34 public: 35 //! Constructors 36 mutex() { 37 create_itt_sync(this, "tbb::mutex", ""); 38 }; 39 40 //! Destructor 41 ~mutex() { 42 __TBB_ASSERT(!my_flag.load(std::memory_order_relaxed), "destruction of an acquired mutex"); 43 } 44 45 //! No Copy 46 mutex(const mutex&) = delete; 47 mutex& operator=(const mutex&) = delete; 48 49 using scoped_lock = unique_scoped_lock<mutex>; 50 51 //! Mutex traits 52 static constexpr bool is_rw_mutex = false; 53 static constexpr bool is_recursive_mutex = false; 54 static constexpr bool is_fair_mutex = false; 55 56 //! Acquire lock 57 /** Spin if the lock is taken */ 58 void lock() { 59 call_itt_notify(prepare, this); 60 while (!try_lock()) { 61 my_flag.wait(true, /* context = */ 0, std::memory_order_relaxed); 62 } 63 } 64 65 //! Try acquiring lock (non-blocking) 66 /** Return true if lock acquired; false otherwise. */ 67 bool try_lock() { 68 bool result = !my_flag.load(std::memory_order_relaxed) && !my_flag.exchange(true); 69 if (result) { 70 call_itt_notify(acquired, this); 71 } 72 return result; 73 } 74 75 //! Release lock 76 void unlock() { 77 call_itt_notify(releasing, this); 78 // We need Write Read memory barrier before notify that reads the waiter list. 79 // In C++ only full fence covers this type of barrier. 80 my_flag.exchange(false); 81 my_flag.notify_one_relaxed(); 82 } 83 84 private: 85 waitable_atomic<bool> my_flag{0}; 86 }; // class mutex 87 88 } // namespace d1 89 } // namespace detail 90 91 inline namespace v1 { 92 using detail::d1::mutex; 93 } // namespace v1 94 95 } // namespace tbb 96 97 #endif /* __TBB_PREVIEW_MUTEXES */ 98 99 #endif // __TBB_mutex_H 100