queue_spsc_atomic.h

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/******************************************************************************
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
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#ifndef ETL_SPSC_QUEUE_ATOMIC_INCLUDED
#define ETL_SPSC_QUEUE_ATOMIC_INCLUDED
 
#include "platform.h"
#include "alignment.h"
#include "atomic.h"
#include "integral_limits.h"
#include "memory_model.h"
#include "parameter_type.h"
#include "placement_new.h"
#include "utility.h"
 
#include <stddef.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::get_next_index;
    using base_t::read;
    using base_t::Reserved;
    using base_t::write;
 
    //*************************************************************************
    //*************************************************************************
    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;
} // namespace etl
 
#endif
 
#endif