queue_spsc_atomic.h

Go to the documentation of this file.

 
/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2018 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
 
#ifndef ETL_SPSC_QUEUE_ATOMIC_INCLUDED
#define ETL_SPSC_QUEUE_ATOMIC_INCLUDED
 
#include "platform.h"
#include "alignment.h"
#include "parameter_type.h"
#include "atomic.h"
#include "memory_model.h"
#include "integral_limits.h"
#include "utility.h"
#include "placement_new.h"
 
#include <stddef.h>
#include <stdint.h>
 
#if ETL_HAS_ATOMIC
 
namespace etl
{
  template <size_t Memory_Model = etl::memory_model::MEMORY_MODEL_LARGE>
  class queue_spsc_atomic_base
  {
  public:

    typedef typename etl::size_type_lookup<Memory_Model>::type size_type;
 
    //*************************************************************************
    //*************************************************************************
    bool empty() const
    {
      return read.load(etl::memory_order_acquire) == write.load(etl::memory_order_acquire);
    }
 
    //*************************************************************************
    //*************************************************************************
    bool full() const
    {
      size_type next_index = get_next_index(write.load(etl::memory_order_acquire), Reserved);
 
      return (next_index == read.load(etl::memory_order_acquire));
    }
 
    //*************************************************************************
    //*************************************************************************
    size_type size() const
    {
      size_type write_index = write.load(etl::memory_order_acquire);
      size_type read_index = read.load(etl::memory_order_acquire);
 
      size_type n;
 
      if (write_index >= read_index)
      {
        n = write_index - read_index;
      }
      else
      {
        n = Reserved - read_index + write_index;
      }
 
      return n;
    }
 
    //*************************************************************************
    //*************************************************************************
    size_type available() const
    {
      return Reserved - size() - 1;
    }
 
    //*************************************************************************
    //*************************************************************************
    size_type capacity() const
    {
      return Reserved - 1;
    }
 
    //*************************************************************************
    //*************************************************************************
    size_type max_size() const
    {
      return Reserved - 1;
    }
 
  protected:
 
    queue_spsc_atomic_base(size_type reserved_)
      : write(0),
        read(0),
        Reserved(reserved_)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    static size_type get_next_index(size_type index, size_type maximum)
    {
      ++index;
 
      if (index == maximum) ETL_UNLIKELY
      {
        index = 0;
      }
 
      return index;
    }
 
    etl::atomic<size_type> write; 
    etl::atomic<size_type> read;  
    const size_type Reserved;     
 
  private:
 
    //*************************************************************************
    //*************************************************************************
#if defined(ETL_POLYMORPHIC_SPSC_QUEUE_ATOMIC) || defined(ETL_POLYMORPHIC_CONTAINERS)
  public:
    virtual ~queue_spsc_atomic_base()
    {
    }
#else
  protected:
    ~queue_spsc_atomic_base()
    {
    }
#endif
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename T, const size_t Memory_Model = etl::memory_model::MEMORY_MODEL_LARGE>
  class iqueue_spsc_atomic : public queue_spsc_atomic_base<Memory_Model>
  {
  private:
 
    typedef typename etl::queue_spsc_atomic_base<Memory_Model> base_t;
 
  public:
 
    typedef T                          value_type;      
    typedef T&                         reference;       
    typedef const T&                   const_reference; 
#if ETL_USING_CPP11
    typedef T&&                        rvalue_reference;
#endif
    typedef typename base_t::size_type size_type;       
 
    using base_t::write;
    using base_t::read;
    using base_t::Reserved;
    using base_t::get_next_index;
 
    //*************************************************************************
    //*************************************************************************
    bool push(const_reference value)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(value);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
 
#if ETL_USING_CPP11 && ETL_NOT_USING_STLPORT && !defined(ETL_QUEUE_ATOMIC_FORCE_CPP03_IMPLEMENTATION)
    //*************************************************************************
    //*************************************************************************
    bool push(rvalue_reference value)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(etl::move(value));
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
#endif
 
#if ETL_USING_CPP11 && ETL_NOT_USING_STLPORT && !defined(ETL_QUEUE_ATOMIC_FORCE_CPP03_IMPLEMENTATION)
    //*************************************************************************
    //*************************************************************************
    template <typename ... Args>
    bool emplace(Args&&... args)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(etl::forward<Args>(args)...);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
#else
    //*************************************************************************
    //*************************************************************************
    bool emplace()
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T();
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T1>
    bool emplace(const T1& value1)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(value1);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T1, typename T2>
    bool emplace(const T1& value1, const T2& value2)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(value1, value2);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T1, typename T2, typename T3>
    bool emplace(const T1& value1, const T2& value2, const T3& value3)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(value1, value2, value3);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T1, typename T2, typename T3, typename T4>
    bool emplace(const T1& value1, const T2& value2, const T3& value3, const T4& value4)
    {
      size_type write_index = write.load(etl::memory_order_relaxed);
      size_type next_index  = get_next_index(write_index, Reserved);
 
      if (next_index != read.load(etl::memory_order_acquire))
      {
        ::new (&p_buffer[write_index]) T(value1, value2, value3, value4);
 
        write.store(next_index, etl::memory_order_release);
 
        return true;
      }
 
      // Queue is full.
      return false;
    }
#endif
 
    //*************************************************************************
    //*************************************************************************
    bool front(reference value)
    {
      size_type read_index = read.load(etl::memory_order_relaxed);
 
      if (read_index == write.load(etl::memory_order_acquire))
      {
        // Queue is empty
        return false;
      }
 
      value = p_buffer[read_index];
 
      return true;
    }
 
    //*************************************************************************
    //*************************************************************************
    bool pop(reference value)
    {
      size_type read_index = read.load(etl::memory_order_relaxed);
 
      if (read_index == write.load(etl::memory_order_acquire))
      {
        // Queue is empty
        return false;
      }
 
      size_type next_index = get_next_index(read_index, Reserved);
 
#if ETL_USING_CPP11 && ETL_NOT_USING_STLPORT && !defined(ETL_QUEUE_LOCKABLE_FORCE_CPP03_IMPLEMENTATION)
      value = etl::move(p_buffer[read_index]);
#else
      value = p_buffer[read_index];
#endif
 
      p_buffer[read_index].~T();
 
      read.store(next_index, etl::memory_order_release);
 
      return true;
    }
 
    //*************************************************************************
    //*************************************************************************
    bool pop()
    {
      size_type read_index = read.load(etl::memory_order_relaxed);
 
      if (read_index == write.load(etl::memory_order_acquire))
      {
        // Queue is empty
        return false;
      }
 
      size_type next_index = get_next_index(read_index, Reserved);
 
      p_buffer[read_index].~T();
 
      read.store(next_index, etl::memory_order_release);
 
      return true;
    }
 
    //*************************************************************************
    //*************************************************************************
    reference front()
    {
      size_type read_index = read.load(etl::memory_order_relaxed);
 
      return p_buffer[read_index];
    }
 
    //*************************************************************************
    //*************************************************************************
    const_reference front() const
    {
      size_type read_index = read.load(etl::memory_order_relaxed);
 
      return p_buffer[read_index];
    }
 
    //*************************************************************************
    //*************************************************************************
    void clear()
    {
      if ETL_IF_CONSTEXPR(etl::is_trivially_destructible<T>::value)
      {
        write = 0;
        read  = 0;
      }
      else
      {
        while (pop())
        {
          // Do nothing.
        }
      }
    }
 
  protected:
 
    //*************************************************************************
    //*************************************************************************
    iqueue_spsc_atomic(T* p_buffer_, size_type reserved_)
      : base_t(reserved_),
        p_buffer(p_buffer_)
    {
    }
 
  private:
 
    // Disable copy construction and assignment.
    iqueue_spsc_atomic(const iqueue_spsc_atomic&) ETL_DELETE;
    iqueue_spsc_atomic& operator =(const iqueue_spsc_atomic&) ETL_DELETE;
 
#if ETL_USING_CPP11
    iqueue_spsc_atomic(iqueue_spsc_atomic&&) = delete;
    iqueue_spsc_atomic& operator =(iqueue_spsc_atomic&&) = delete;
#endif
 
    T* p_buffer; 
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename T, size_t Size, const size_t Memory_Model = etl::memory_model::MEMORY_MODEL_LARGE>
  class queue_spsc_atomic : public iqueue_spsc_atomic<T, Memory_Model>
  {
  private:
 
    typedef typename etl::iqueue_spsc_atomic<T, Memory_Model> base_t;
 
  public:
 
    typedef typename base_t::size_type size_type;
 
  private:
 
    static ETL_CONSTANT size_type Reserved_Size = size_type(Size + 1);
 
  public:
 
    ETL_STATIC_ASSERT((Size <= (etl::integral_limits<size_type>::max - 1)), "Size too large for memory model");
 
    static ETL_CONSTANT size_type MAX_SIZE = size_type(Size);
 
    //*************************************************************************
    //*************************************************************************
    queue_spsc_atomic()
      : base_t(reinterpret_cast<T*>(&buffer[0]), Reserved_Size)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    ~queue_spsc_atomic()
    {
      base_t::clear();
    }
 
  private:

    typename etl::aligned_storage<sizeof(T), etl::alignment_of<T>::value>::type buffer[Reserved_Size];
  };
 
  template <typename T, size_t Size, const size_t Memory_Model>
  ETL_CONSTANT typename queue_spsc_atomic<T, Size, Memory_Model>::size_type queue_spsc_atomic<T, Size, Memory_Model>::MAX_SIZE;
}
 
#endif
 
#endif