1 /* 2 Copyright (c) 2005-2021 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_null_mutex_H 18 #define __TBB_null_mutex_H 19 20 #include "detail/_config.h" 21 #include "detail/_namespace_injection.h" 22 #include "detail/_mutex_common.h" 23 24 namespace tbb { 25 namespace detail { 26 namespace d1 { 27 28 //! A mutex which does nothing 29 /** A null_mutex does no operation and simulates success. 30 @ingroup synchronization */ 31 class null_mutex { 32 public: 33 //! Constructors 34 constexpr null_mutex() noexcept = default; 35 36 //! Destructor 37 ~null_mutex() = default; 38 39 //! No Copy 40 null_mutex(const null_mutex&) = delete; 41 null_mutex& operator=(const null_mutex&) = delete; 42 43 //! Represents acquisition of a mutex. 44 class scoped_lock { 45 public: 46 //! Constructors 47 constexpr scoped_lock() noexcept = default; scoped_lock(null_mutex &)48 scoped_lock(null_mutex&) {} 49 50 //! Destructor 51 ~scoped_lock() = default; 52 53 //! No Copy 54 scoped_lock(const scoped_lock&) = delete; 55 scoped_lock& operator=(const scoped_lock&) = delete; 56 acquire(null_mutex &)57 void acquire(null_mutex&) {} try_acquire(null_mutex &)58 bool try_acquire(null_mutex&) { return true; } release()59 void release() {} 60 }; 61 62 //! Mutex traits 63 static constexpr bool is_rw_mutex = false; 64 static constexpr bool is_recursive_mutex = true; 65 static constexpr bool is_fair_mutex = true; 66 lock()67 void lock() {} try_lock()68 bool try_lock() { return true; } unlock()69 void unlock() {} 70 }; // class null_mutex 71 72 } // namespace d1 73 } // namespace detail 74 75 inline namespace v1 { 76 using detail::d1::null_mutex; 77 } // namespace v1 78 } // namespace tbb 79 80 #endif /* __TBB_null_mutex_H */ 81