lock_free_spmc_ring_buffer.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2022 the Initial Developer.
 *  All Rights Reserved.
 *  
 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
 *  others to use your version of this file under the CPAL, indicate your decision by 
 *  deleting the provisions above and replace them with the notice and other 
 *  provisions required by the GPL License. If you do not delete the provisions above,
 *  a recipient may use your version of this file under either the CPAL or the GPL.
 *  
 *  *** END LICENSE INFORMATION ***
 */
 
#pragma once
 
#include "stde_common.h"
#include "../util/non_copyable.h"
#include "../util/atomic.h"
 
namespace lass
{
namespace stde
{
namespace impl
{
 
class lock_free_spmc_ring_buffer_base: util::NonCopyable
{
public:
 
    bool empty() const;
    bool full() const;
 
protected:
 
    lock_free_spmc_ring_buffer_base(size_t capacity);
    ~lock_free_spmc_ring_buffer_base() = default;
 
    typedef num::Tuint32 index_type;
 
    struct alignas(8) tagged_index_t
    {
        tagged_index_t() noexcept {}
        tagged_index_t(index_type index, index_type tag) : index(index), tag(tag) {}
        index_type index = 0;
        index_type tag = 0;
 
        static bool empty(tagged_index_t head, tagged_index_t tail) { return head.index == tail.index && head.tag == tail.tag; }
        static bool full(tagged_index_t head, tagged_index_t tail) { return head.index == tail.index && head.tag != tail.tag; }
    };
 
    
    tagged_index_t next_index(tagged_index_t index) const;
 
    alignas(LASS_LOCK_FREE_ALIGNMENT) std::atomic<tagged_index_t> head_;
    alignas(LASS_LOCK_FREE_ALIGNMENT) std::atomic<tagged_index_t> tail_;
    const index_type ring_size_;
 
private:
 
    static_assert(sizeof(tagged_index_t) == 8, "tagged_index_t should be 8-bytes");
 
    static size_t enforce_valid_size(size_t size);
 
};
 
 
 
template<typename T>
class lock_free_spmc_value_ring_buffer: private lock_free_spmc_ring_buffer_base
{
public:
    typedef T value_type;
 
    lock_free_spmc_value_ring_buffer(size_t capacity);
    ~lock_free_spmc_value_ring_buffer() = default;
 
    bool try_push(const value_type& x);
    bool try_push(value_type&& x);
    template <class... Args> bool try_emplace(Args&&... args);
    bool try_pop(value_type& x);
 
    using lock_free_spmc_ring_buffer_base::empty;
    using lock_free_spmc_ring_buffer_base::full;
 
private:
 
    std::vector< std::atomic<value_type> > ring_;
};
 
 
template
<
    typename T,
    typename FixedAllocator = util::AllocatorConcurrentFreeList<>
>
class lock_free_spmc_object_ring_buffer: private lock_free_spmc_ring_buffer_base
{
public:
    typedef T value_type;
 
    lock_free_spmc_object_ring_buffer(size_t capacity);
    ~lock_free_spmc_object_ring_buffer();
 
    bool try_push(const value_type& x);
    bool try_push(value_type&& x);
    template <class... Args> bool try_emplace(Args&&... args);
    bool try_pop(value_type& x);
 
    using lock_free_spmc_ring_buffer_base::empty;
    using lock_free_spmc_ring_buffer_base::full;
 
private:
 
    FixedAllocator value_allocator_;
    std::vector< std::atomic<T*> > ring_;
};
 
}
 
template<typename T>
using lock_free_spmc_ring_buffer = typename std::conditional<
        std::is_trivially_copy_constructible<T>::value,
        impl::lock_free_spmc_value_ring_buffer<T>,
        impl::lock_free_spmc_object_ring_buffer<T>
    >::type;
 
}
 
}
 
#include "lock_free_spmc_ring_buffer.inl"
 
// EOF