158 lines
3.3 KiB
C++
158 lines
3.3 KiB
C++
#ifndef _DETHREADSAFERINGBUFFER_HPP
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#define _DETHREADSAFERINGBUFFER_HPP
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/*-------------------------------------------------------------------------
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* drawElements C++ Base Library
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* -----------------------------
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*
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* Copyright 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*//*!
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* \file
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* \brief Thread-safe ring buffer template.
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*//*--------------------------------------------------------------------*/
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#include "deDefs.hpp"
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#include "deMutex.hpp"
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#include "deSemaphore.hpp"
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#include <vector>
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namespace de
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{
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void ThreadSafeRingBuffer_selfTest (void);
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/** Thread-safe ring buffer template. */
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template <typename T>
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class ThreadSafeRingBuffer
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{
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public:
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ThreadSafeRingBuffer (size_t size);
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~ThreadSafeRingBuffer (void) {}
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void pushFront (const T& elem);
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bool tryPushFront (const T& elem);
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T popBack (void);
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bool tryPopBack (T& dst);
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protected:
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void pushFrontInternal (const T& elem);
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T popBackInternal (void);
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const size_t m_size;
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std::vector<T> m_elements;
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size_t m_front;
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size_t m_back;
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Mutex m_writeMutex;
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Mutex m_readMutex;
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Semaphore m_fill;
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Semaphore m_empty;
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};
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// ThreadSafeRingBuffer implementation.
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template <typename T>
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ThreadSafeRingBuffer<T>::ThreadSafeRingBuffer (size_t size)
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: m_size (size+1)
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, m_elements (m_size)
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, m_front (0)
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, m_back (0)
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, m_fill (0)
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, m_empty ((int)size)
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{
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// Semaphores currently only support INT_MAX
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DE_ASSERT(size > 0 && size < 0x7fffffff);
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}
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template <typename T>
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inline void ThreadSafeRingBuffer<T>::pushFrontInternal (const T& elem)
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{
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m_elements[m_front] = elem;
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m_front = (m_front + 1) % m_size;
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}
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template <typename T>
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inline T ThreadSafeRingBuffer<T>::popBackInternal ()
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{
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const size_t ndx = m_back;
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m_back = (m_back + 1) % m_size;
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return m_elements[ndx];
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}
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template <typename T>
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void ThreadSafeRingBuffer<T>::pushFront (const T& elem)
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{
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m_writeMutex.lock();
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m_empty.decrement();
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pushFrontInternal(elem);
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m_fill.increment();
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m_writeMutex.unlock();
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}
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template <typename T>
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bool ThreadSafeRingBuffer<T>::tryPushFront (const T& elem)
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{
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if (!m_writeMutex.tryLock())
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return false;
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const bool success = m_empty.tryDecrement();
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if (success)
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{
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pushFrontInternal(elem);
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m_fill.increment();
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}
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m_writeMutex.unlock();
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return success;
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}
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template <typename T>
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T ThreadSafeRingBuffer<T>::popBack ()
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{
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m_readMutex.lock();
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m_fill.decrement();
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T elem = popBackInternal();
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m_empty.increment();
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m_readMutex.unlock();
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return elem;
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}
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template <typename T>
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bool ThreadSafeRingBuffer<T>::tryPopBack (T& dst)
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{
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if (!m_readMutex.tryLock())
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return false;
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bool success = m_fill.tryDecrement();
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if (success)
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{
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dst = popBackInternal();
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m_empty.increment();
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}
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m_readMutex.unlock();
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return success;
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}
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} // de
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#endif // _DETHREADSAFERINGBUFFER_HPP
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