1 #ifndef _DESEMAPHORE_HPP 2 #define _DESEMAPHORE_HPP 3 /*------------------------------------------------------------------------- 4 * drawElements C++ Base Library 5 * ----------------------------- 6 * 7 * Copyright 2014 The Android Open Source Project 8 * 9 * Licensed under the Apache License, Version 2.0 (the "License"); 10 * you may not use this file except in compliance with the License. 11 * You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, software 16 * distributed under the License is distributed on an "AS IS" BASIS, 17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 18 * See the License for the specific language governing permissions and 19 * limitations under the License. 20 * 21 *//*! 22 * \file 23 * \brief deSemaphore C++ wrapper. 24 *//*--------------------------------------------------------------------*/ 25 26 #include "deDefs.hpp" 27 #include "deSemaphore.h" 28 29 namespace de 30 { 31 32 /*--------------------------------------------------------------------*//*! 33 * \brief Semaphore 34 * 35 * Semaphore provides standard semaphore functionality. 36 * 37 * Semaphore is thread-safe counter that can be used to control access 38 * to a set of resources. The count can be incremented and decremented. 39 * When decrementing causes counter to reach negative value, it will 40 * block until increment has been called from an another thread. 41 *//*--------------------------------------------------------------------*/ 42 class Semaphore 43 { 44 public: 45 Semaphore (int initialValue, deUint32 flags = 0); 46 ~Semaphore (void); 47 48 void increment (void) throw(); 49 void decrement (void) throw(); 50 bool tryDecrement (void) throw(); 51 52 private: 53 Semaphore (const Semaphore& other); // Not allowed! 54 Semaphore& operator= (const Semaphore& other); // Not allowed! 55 56 deSemaphore m_semaphore; 57 }; 58 59 // Inline implementations. 60 61 /*--------------------------------------------------------------------*//*! 62 * \brief Increment semaphore count. 63 * 64 * Incremeting increases semaphore value by 1. If a value is currently 65 * negative (there is a thread waiting in decrement) the waiting thread 66 * will be resumed. 67 * 68 * Incrementing semaphore will never block. 69 *//*--------------------------------------------------------------------*/ 70 inline void Semaphore::increment (void) throw() 71 { 72 deSemaphore_increment(m_semaphore); 73 } 74 75 /*--------------------------------------------------------------------*//*! 76 * \brief Decrement semaphore count. 77 * 78 * Decrementing decreases semaphore value by 1. If resulting value is negative 79 * (only -1 is possible) decrement() will block until the value is again 0 80 * (increment() has been called). 81 * 82 * If there is an another thread waiting in decrement(), the current thread 83 * will block until other thread(s) have been resumed. 84 *//*--------------------------------------------------------------------*/ 85 inline void Semaphore::decrement (void) throw() 86 { 87 deSemaphore_decrement(m_semaphore); 88 } 89 90 /*--------------------------------------------------------------------*//*! 91 * \brief Try to decrement semaphore value. 92 * \return true if decrementing was successful without blocking, false 93 * otherwise 94 * 95 * This function will never block, i.e. it will return false if decrementing 96 * semaphore counter would result in negative value or there is already 97 * one or more threads waiting for this semaphore. 98 *//*--------------------------------------------------------------------*/ 99 inline bool Semaphore::tryDecrement (void) throw() 100 { 101 return deSemaphore_tryDecrement(m_semaphore) == DE_TRUE; 102 } 103 104 } // de 105 106 #endif // _DESEMAPHORE_HPP 107
