LocklessAllocator.h

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/*
 * LocklessAllocator.h - allocator with lockless alloc and free
 *
 * Copyright (c) 2016 Javier Serrano Polo <javier@jasp.net>
 *
 * This file is part of LMMS - https://lmms.io
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA.
 *
 */
 
#ifndef LMMS_LOCKLESS_ALLOCATOR_H
#define LMMS_LOCKLESS_ALLOCATOR_H
 
#include <atomic>
#include <cstddef>
 
 
namespace lmms
{
 
 
class LocklessAllocator
{
public:
    LocklessAllocator( size_t nmemb, size_t size );
    virtual ~LocklessAllocator();
    void * alloc();
    void free( void * ptr );
 
 
private:
    char * m_pool;
    size_t m_capacity;
    size_t m_elementSize;
 
    std::atomic_int * m_freeState;
    size_t m_freeStateSets;
 
    std::atomic_size_t m_available;
    std::atomic_size_t m_startIndex;
 
} ;
 
 
 
 
template<typename T>
class LocklessAllocatorT : private LocklessAllocator
{
public:
    LocklessAllocatorT( size_t nmemb ) :
        LocklessAllocator( nmemb, sizeof( T ) )
    {
    }
 
    ~LocklessAllocatorT() override = default;
 
    T * alloc()
    {
        return (T *)LocklessAllocator::alloc();
    }
 
    void free( T * ptr )
    {
        LocklessAllocator::free( ptr );
    }
 
} ;
 
 
} // namespace lmms
 
#endif // LMMS_LOCKLESS_ALLOCATOR_H