1 #ifndef _DETHREADSAFERINGBUFFER_HPP 2 #define _DETHREADSAFERINGBUFFER_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 Thread-safe ring buffer template. 24 *//*--------------------------------------------------------------------*/ 25 26 #include "deDefs.hpp" 27 #include "deMutex.hpp" 28 #include "deSemaphore.hpp" 29 30 namespace de 31 { 32 33 void ThreadSafeRingBuffer_selfTest (void); 34 35 /** Thread-safe ring buffer template. */ 36 template <typename T> 37 class ThreadSafeRingBuffer 38 { 39 public: 40 ThreadSafeRingBuffer (int size); ~ThreadSafeRingBuffer(void)41 ~ThreadSafeRingBuffer (void) {} 42 43 void pushFront (const T& elem); 44 bool tryPushFront (const T& elem); 45 T popBack (void); 46 bool tryPopBack (T& dst); 47 48 protected: 49 void pushFrontInternal (const T& elem); 50 T popBackInternal (void); 51 52 int m_front; 53 int m_back; 54 T* m_buffer; 55 int m_size; 56 57 Mutex m_writeMutex; 58 Mutex m_readMutex; 59 60 Semaphore m_fill; 61 Semaphore m_empty; 62 }; 63 64 // ThreadSafeRingBuffer implementation. 65 66 template <typename T> ThreadSafeRingBuffer(int size)67ThreadSafeRingBuffer<T>::ThreadSafeRingBuffer (int size) 68 : m_front (0) 69 , m_back (0) 70 , m_size (size+1) 71 , m_fill (0) 72 , m_empty (size) 73 { 74 DE_ASSERT(size > 0); 75 m_buffer = new T[m_size]; 76 } 77 78 template <typename T> pushFrontInternal(const T & elem)79inline void ThreadSafeRingBuffer<T>::pushFrontInternal (const T& elem) 80 { 81 m_buffer[m_front] = elem; 82 m_front = (m_front + 1) % m_size; 83 } 84 85 template <typename T> popBackInternal()86inline T ThreadSafeRingBuffer<T>::popBackInternal () 87 { 88 int ndx = m_back; 89 m_back = (m_back + 1) % m_size; 90 return m_buffer[ndx]; 91 } 92 93 template <typename T> pushFront(const T & elem)94void ThreadSafeRingBuffer<T>::pushFront (const T& elem) 95 { 96 m_writeMutex.lock(); 97 m_empty.decrement(); 98 pushFrontInternal(elem); 99 m_fill.increment(); 100 m_writeMutex.unlock(); 101 } 102 103 template <typename T> tryPushFront(const T & elem)104bool ThreadSafeRingBuffer<T>::tryPushFront (const T& elem) 105 { 106 if (!m_writeMutex.tryLock()) 107 return false; 108 bool success = m_empty.tryDecrement(); 109 if (success) 110 { 111 pushFrontInternal(elem); 112 m_fill.increment(); 113 } 114 m_writeMutex.unlock(); 115 return success; 116 } 117 118 template <typename T> popBack()119T ThreadSafeRingBuffer<T>::popBack () 120 { 121 m_readMutex.lock(); 122 m_fill.decrement(); 123 T elem = popBackInternal(); 124 m_empty.increment(); 125 m_readMutex.unlock(); 126 return elem; 127 } 128 129 template <typename T> tryPopBack(T & dst)130bool ThreadSafeRingBuffer<T>::tryPopBack (T& dst) 131 { 132 if (!m_readMutex.tryLock()) 133 return false; 134 135 bool success = m_fill.tryDecrement(); 136 137 if (success) 138 { 139 dst = popBackInternal(); 140 m_empty.increment(); 141 } 142 143 m_readMutex.unlock(); 144 145 return success; 146 } 147 148 } // de 149 150 #endif // _DETHREADSAFERINGBUFFER_HPP 151