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1cd8e15942
MemoryPool maintains a free list of pre-allocated entries stored in a libcds MPMC Queue. In contrast to LocklessAllocator, it's a lot faster, less (and less complex) code to maintain for us and it doesn't fail when it's full.
95 lines
1.9 KiB
C++
95 lines
1.9 KiB
C++
/*
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* LocklessList.h - list with lockless push and pop
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*
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* Copyright (c) 2016 Javier Serrano Polo <javier@jasp.net>
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*
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* This file is part of LMMS - https://lmms.io
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program (see COPYING); if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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*/
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#ifndef LOCKLESS_LIST_H
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#define LOCKLESS_LIST_H
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#include "MemoryPool.h"
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#include <atomic>
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template<typename T>
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class LocklessList
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{
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public:
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struct Element
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{
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T value;
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Element * next;
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} ;
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LocklessList( size_t size ) :
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m_first(nullptr),
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m_allocator(new MemoryPool<Element>(size))
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{
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}
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~LocklessList()
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{
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delete m_allocator;
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}
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void push( T value )
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{
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Element * e = m_allocator->allocate();
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e->value = value;
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e->next = m_first.load(std::memory_order_relaxed);
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while (!m_first.compare_exchange_weak(e->next, e,
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std::memory_order_release,
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std::memory_order_relaxed))
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{
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// Empty loop (compare_exchange_weak updates e->next)
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}
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}
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Element * popList()
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{
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return m_first.exchange(nullptr);
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}
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Element * first()
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{
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return m_first.load(std::memory_order_acquire);
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}
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void setFirst( Element * e )
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{
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m_first.store(e, std::memory_order_release);
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}
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void free( Element * e )
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{
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m_allocator->destroy( e );
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}
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private:
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std::atomic<Element*> m_first;
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MemoryPool<Element> * m_allocator;
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} ;
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#endif
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