fsfw/contrib/fsfw_contrib/etl-20.39.4/include/etl/queue_spsc_atomic.h

///\file

/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com

Copyright(c) 2018 John Wellbelove

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******************************************************************************/

#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:

    /// The type used for determining the size of queue.
    typedef typename etl::size_type_lookup<MEMORY_MODEL>::type size_type;

    //*************************************************************************
    /// Is the queue empty?
    /// Accurate from the 'pop' thread.
    /// 'Not empty' is a guess from the 'push' thread.
    //*************************************************************************
    bool empty() const
    {
      return read.load(etl::memory_order_acquire) == write.load(etl::memory_order_acquire);
    }

    //*************************************************************************
    /// Is the queue full?
    /// Accurate from the 'push' thread.
    /// 'Not full' is a guess from the 'pop' thread.
    //*************************************************************************
    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));
    }

    //*************************************************************************
    /// How many items in the queue?
    /// Due to concurrency, this is a guess.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// How much free space available in the queue.
    /// Due to concurrency, this is a guess.
    //*************************************************************************
    size_type available() const
    {
      return RESERVED - size() - 1;
    }

    //*************************************************************************
    /// How many items can the queue hold.
    //*************************************************************************
    size_type capacity() const
    {
      return RESERVED - 1;
    }

    //*************************************************************************
    /// How many items can the queue hold.
    //*************************************************************************
    size_type max_size() const
    {
      return RESERVED - 1;
    }

  protected:

    queue_spsc_atomic_base(size_type reserved_)
      : write(0),
        read(0),
        RESERVED(reserved_)
    {
    }

    //*************************************************************************
    /// Calculate the next index.
    //*************************************************************************
    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; ///< Where to input new data.
    etl::atomic<size_type> read;  ///< Where to get the oldest data.
    const size_type RESERVED;     ///< The maximum number of items in the queue.

  private:

    //*************************************************************************
    /// Destructor.
    //*************************************************************************
#if defined(ETL_POLYMORPHIC_SPSC_QUEUE_ATOMIC) || defined(ETL_POLYMORPHIC_CONTAINERS)
  public:
    virtual ~queue_spsc_atomic_base()
    {
    }
#else
  protected:
    ~queue_spsc_atomic_base()
    {
    }
#endif
  };

  //***************************************************************************
  ///\ingroup queue_spsc_atomic
  ///\brief This is the base for all queue_spscs that contain a particular type.
  ///\details Normally a reference to this type will be taken from a derived queue_spsc.
  ///\code
  /// etl::queue_spsc_atomic<int, 10> myQueue;
  /// etl::iqueue_spsc_atomic<int>& iQueue = myQueue;
  ///\endcode
  /// This queue supports concurrent access by one producer and one consumer.
  /// \tparam T The type of value that the queue_spsc_atomic holds.
  //***************************************************************************
  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;      ///< The type stored in the queue.
    typedef T&                         reference;       ///< A reference to the type used in the queue.
    typedef const T&                   const_reference; ///< A const reference to the type used in the queue.
#if ETL_USING_CPP11
    typedef T&&                        rvalue_reference;///< An rvalue_reference to the type used in the queue.
#endif
    typedef typename base_t::size_type size_type;       ///< The type used for determining the size of the queue.

    using base_t::write;
    using base_t::read;
    using base_t::RESERVED;
    using base_t::get_next_index;

    //*************************************************************************
    /// Push a value to the queue.
    //*************************************************************************
    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)
    //*************************************************************************
    /// Push a value to the queue.
    //*************************************************************************
    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)
    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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
    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    //*************************************************************************
    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

    //*************************************************************************
    /// Peek the next value in the queue without removing it.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Pop a value from the queue.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Pop a value from the queue and discard.
    //*************************************************************************
    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;
    }

    //*************************************************************************
    /// Peek a value from the front of the queue.
    //*************************************************************************
    reference front()
    {
      size_type read_index = read.load(etl::memory_order_relaxed);

      return p_buffer[read_index];
    }

    //*************************************************************************
    /// Peek a value from the front of the queue.
    //*************************************************************************
    const_reference front() const
    {
      size_type read_index = read.load(etl::memory_order_relaxed);

      return p_buffer[read_index];
    }

    //*************************************************************************
    /// Clear the queue.
    /// Must be called from thread that pops the queue or when there is no
    /// possibility of concurrent access.
    //*************************************************************************
    void clear()
    {
      while (pop())
      {
        // Do nothing.
      }
    }

  protected:

    //*************************************************************************
    /// The constructor that is called from derived classes.
    //*************************************************************************
    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; ///< The internal buffer.
  };

  //***************************************************************************
  ///\ingroup queue_spsc
  /// A fixed capacity spsc queue.
  /// This queue supports concurrent access by one producer and one consumer.
  /// \tparam T            The type this queue should support.
  /// \tparam SIZE         The maximum capacity of the queue.
  /// \tparam MEMORY_MODEL The memory model for the queue. Determines the type of the internal counter variables.
  //***************************************************************************
  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);

    //*************************************************************************
    /// Default constructor.
    //*************************************************************************
    queue_spsc_atomic()
      : base_t(reinterpret_cast<T*>(&buffer[0]), RESERVED_SIZE)
    {
    }

    //*************************************************************************
    /// Destructor.
    //*************************************************************************
    ~queue_spsc_atomic()
    {
      base_t::clear();
    }

  private:

    /// The uninitialised buffer of T used in the queue_spsc.
    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