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_rw_mutex_H 18 #define __TBB_null_rw_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 rw mutex which does nothing 29 /** A null_rw_mutex is a rw mutex that does nothing and simulates successful operation. 30 @ingroup synchronization */ 31 class null_rw_mutex { 32 public: 33 //! Constructors 34 constexpr null_rw_mutex() noexcept = default; 35 36 //! Destructor 37 ~null_rw_mutex() = default; 38 39 //! No Copy 40 null_rw_mutex(const null_rw_mutex&) = delete; 41 null_rw_mutex& operator=(const null_rw_mutex&) = delete; 42 43 //! Represents acquisition of a mutex. 44 class scoped_lock { 45 public: 46 //! Constructors 47 constexpr scoped_lock() noexcept = default; 48 scoped_lock(null_rw_mutex&, bool = true) {} 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 57 void acquire(null_rw_mutex&, bool = true) {} 58 bool try_acquire(null_rw_mutex&, bool = true) { return true; } release()59 void release() {} upgrade_to_writer()60 bool upgrade_to_writer() { return true; } downgrade_to_reader()61 bool downgrade_to_reader() { return true; } 62 is_writer()63 bool is_writer() const { return true; } 64 }; 65 66 //! Mutex traits 67 static constexpr bool is_rw_mutex = true; 68 static constexpr bool is_recursive_mutex = true; 69 static constexpr bool is_fair_mutex = true; 70 lock()71 void lock() {} try_lock()72 bool try_lock() { return true; } unlock()73 void unlock() {} lock_shared()74 void lock_shared() {} try_lock_shared()75 bool try_lock_shared() { return true; } unlock_shared()76 void unlock_shared() {} 77 }; // class null_rw_mutex 78 79 } // namespace d1 80 } // namespace detail 81 82 inline namespace v1 { 83 using detail::d1::null_rw_mutex; 84 } // namespace v1 85 } // namespace tbb 86 87 #endif /* __TBB_null_rw_mutex_H */ 88