etl/include/etl/shared_message.h

///\file

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

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

Copyright(c) 2020 jwellbelove

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

#ifndef ETL_SHARED_MESSAGE_INCLUDED
#define ETL_SHARED_MESSAGE_INCLUDED

#include "platform.h"
#include "reference_counted_message_pool.h"
#include "reference_counted_message.h"

//*****************************************************************************
/// A wrapper for reference counted messages.
/// Contains pointers to a pool owner and a message defined with a ref count type.
//*****************************************************************************
namespace etl
{
  class shared_message
  {
  public:

    //*************************************************************************
    /// Constructor
    /// \param owner_   A reference to the owner pool.
    /// \param pmessage A reference to the message allocated from the pool.
    //*************************************************************************
    shared_message(etl::ireference_counted_message& message_, etl::ireference_counted_message_pool& owner_)
      : p_rcmessage_owner(&owner_)
      , p_rcmessage(&message_)
    {
      p_rcmessage->get_reference_counter().set_reference_count(1U);
    }

    //*************************************************************************
    /// Constructor

    /// \param pmessage A reference to the message allocated from the pool.
    //*************************************************************************
    shared_message(etl::ireference_counted_message& message_)
      : p_rcmessage_owner(ETL_NULLPTR)
      , p_rcmessage(&message_)
    {
      p_rcmessage->get_reference_counter().set_reference_count(1U);
    }

    //*************************************************************************
    /// Copy constructor
    //*************************************************************************
    shared_message(const shared_message& other)
      : p_rcmessage_owner(other.p_rcmessage_owner)
      , p_rcmessage(other.p_rcmessage)
    {
      p_rcmessage->get_reference_counter().increment_reference_count();
    }

    //*************************************************************************
    /// Copy assignment operator
    //*************************************************************************
    shared_message& operator =(const shared_message& other)
    {
      if (&other != this)
      {
        // Deal with the current message.
        if (p_rcmessage->get_reference_counter().decrement_reference_count() == 0U)
        {
          if (p_rcmessage_owner != ETL_NULLPTR)
          {
            p_rcmessage_owner->release(p_rcmessage);
          }
        }

        // Copy over the new one.
        p_rcmessage_owner = other.p_rcmessage_owner;
        p_rcmessage       = other.p_rcmessage;
        p_rcmessage->get_reference_counter().increment_reference_count();
       }

      return *this;
    }

    //*************************************************************************
    /// Destructor
    /// Returns the message back to the pool it it is the last copy.
    //*************************************************************************
    ~shared_message()
    {
      if (p_rcmessage->get_reference_counter().decrement_reference_count() == 0U)
      {       
        if (is_owned())
        {
          p_rcmessage_owner->release(p_rcmessage);
        }
      }
    }

    //*************************************************************************
    /// Get a const reference to the contained message.
    //*************************************************************************
    const etl::imessage& get_message() const
    {
      return p_rcmessage->get_message();
    }

    //*************************************************************************
    /// Get the current reference count for this shared message.
    //*************************************************************************
    uint32_t get_reference_count() const
    {
      return p_rcmessage->get_reference_counter().get_reference_count();
    }

  private:

    //*************************************************************************
    /// Returns <b>true</b> if the internal reference counted message is owned by a pool.
    //*************************************************************************
    bool is_owned() const
    {
      return (p_rcmessage_owner != ETL_NULLPTR);
    }

    shared_message() ETL_DELETE;

    etl::ireference_counted_message_pool* p_rcmessage_owner;
    etl::ireference_counted_message*      p_rcmessage;
  };

  //*****************************************************************************
  /// A wrapper for reference counted messages.
  /// Contains pointers to a pool owner and a message defined with a ref count type.
  //*****************************************************************************
  template <typename TPool, typename TMessage>
  etl::shared_message make_shared_message(TPool& owner, const TMessage& message)
  {
    etl::ireference_counted_message* p_rcmessage = owner.allocate(message);
    return etl::shared_message(*p_rcmessage, owner);
  }

#if ETL_CPP11_SUPPORTED
  //*****************************************************************************
  /// A wrapper for reference counted messages.
  /// Contains pointers to a pool owner and a message defined with a ref count type.
  //*****************************************************************************
  template <typename TMessage, typename TPool, typename... TArgs>
  etl::shared_message make_shared_message(TPool& owner, TArgs&&... args)
  {
    etl::ireference_counted_message* p_rcmessage = owner.allocate<TMessage>(etl::forward<TArgs>(args)...);
    return etl::shared_message(*p_rcmessage, owner);
  }
#endif
}

#endif