memory.hpp

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/*
  Copyright (c) 2014, Randolph Voorhies, Shane Grant
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
      * Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.
      * Neither the name of cereal nor the
        names of its contributors may be used to endorse or promote products
        derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL RANDOLPH VOORHIES OR SHANE GRANT BE LIABLE FOR ANY
  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CEREAL_TYPES_SHARED_PTR_HPP_
#define CEREAL_TYPES_SHARED_PTR_HPP_

#include <cereal/cereal.hpp>
#include <memory>
#include <cstring>

namespace cereal
{
  namespace memory_detail
  {

    template<class T>
    struct PtrWrapper
    {
      PtrWrapper(T && p) : ptr(std::forward<T>(p)) {}
      T & ptr;

      PtrWrapper & operator=( PtrWrapper const & ) = delete;
    };


    template<class T> inline
    PtrWrapper<T> make_ptr_wrapper(T && t)
    {
      return {std::forward<T>(t)};
    }


    template <class Archive, class T>
    struct LoadAndConstructLoadWrapper
    {
      LoadAndConstructLoadWrapper( T * ptr ) :
        construct( ptr )
      { }

      inline void CEREAL_SERIALIZE_FUNCTION_NAME( Archive & ar )
      {
        ::cereal::detail::Construct<T, Archive>::load_andor_construct( ar, construct );
      }

      ::cereal::construct<T> construct;
    };


    template <class T>
    class EnableSharedStateHelper
    {
      // typedefs for parent type and storage type
      using BaseType = typename ::cereal::traits::get_shared_from_this_base<T>::type;
      using ParentType = std::enable_shared_from_this<BaseType>;
      using StorageType = typename std::aligned_storage<sizeof(ParentType)>::type;

      public:

        inline EnableSharedStateHelper( T * ptr ) :
          itsPtr( static_cast<ParentType *>( ptr ) ),
          itsState()
        {
          std::memcpy( &itsState, itsPtr, sizeof(ParentType) );
        }

        inline ~EnableSharedStateHelper()
        {
          std::memcpy( itsPtr, &itsState, sizeof(ParentType) );
        }

      private:
        ParentType * itsPtr;
        StorageType itsState;
    }; // end EnableSharedStateHelper


    template <class Archive, class T> inline
    void loadAndConstructSharedPtr( Archive & ar, T * ptr, std::true_type /* has_shared_from_this */ )
    {
      memory_detail::LoadAndConstructLoadWrapper<Archive, T> loadWrapper( ptr );
      memory_detail::EnableSharedStateHelper<T> state( ptr );

      // let the user perform their initialization
      ar( CEREAL_NVP_("data", loadWrapper) );
    }


    template <class Archive, class T> inline
    void loadAndConstructSharedPtr( Archive & ar, T * ptr, std::false_type /* has_shared_from_this */ )
    {
      memory_detail::LoadAndConstructLoadWrapper<Archive, T> loadWrapper( ptr );
      ar( CEREAL_NVP_("data", loadWrapper) );
    }
  } // end namespace memory_detail

  template <class Archive, class T> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_SAVE_FUNCTION_NAME( Archive & ar, std::shared_ptr<T> const & ptr )
  {
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( ptr )) );
  }

  template <class Archive, class T> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, std::shared_ptr<T> & ptr )
  {
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( ptr )) );
  }

  template <class Archive, class T> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_SAVE_FUNCTION_NAME( Archive & ar, std::weak_ptr<T> const & ptr )
  {
    auto const sptr = ptr.lock();
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( sptr )) );
  }

  template <class Archive, class T> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, std::weak_ptr<T> & ptr )
  {
    std::shared_ptr<T> sptr;
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( sptr )) );
    ptr = sptr;
  }

  template <class Archive, class T, class D> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_SAVE_FUNCTION_NAME( Archive & ar, std::unique_ptr<T, D> const & ptr )
  {
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( ptr )) );
  }

  template <class Archive, class T, class D> inline
  typename std::enable_if<!std::is_polymorphic<T>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, std::unique_ptr<T, D> & ptr )
  {
    ar( CEREAL_NVP_("ptr_wrapper", memory_detail::make_ptr_wrapper( ptr )) );
  }

  // ######################################################################
  // Pointer wrapper implementations follow below


  template <class Archive, class T> inline
  void CEREAL_SAVE_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::shared_ptr<T> const &> const & wrapper )
  {
    auto & ptr = wrapper.ptr;

    uint32_t id = ar.registerSharedPointer( ptr.get() );
    ar( CEREAL_NVP_("id", id) );

    if( id & detail::msb_32bit )
    {
      ar( CEREAL_NVP_("data", *ptr) );
    }
  }


  template <class Archive, class T> inline
  typename std::enable_if<traits::has_load_and_construct<T, Archive>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::shared_ptr<T> &> & wrapper )
  {
    auto & ptr = wrapper.ptr;

    uint32_t id;

    ar( CEREAL_NVP_("id", id) );

    if( id & detail::msb_32bit )
    {
      // Storage type for the pointer - since we can't default construct this type,
      // we'll allocate it using std::aligned_storage and use a custom deleter
      using ST = typename std::aligned_storage<sizeof(T)>::type;

      // Valid flag - set to true once construction finishes
      //  This prevents us from calling the destructor on
      //  uninitialized data.
      auto valid = std::make_shared<bool>( false );

      // Allocate our storage, which we will treat as
      //  uninitialized until initialized with placement new
      ptr.reset( reinterpret_cast<T *>( new ST() ),
          [=]( T * t )
          {
            if( valid )
              t->~T();

            delete reinterpret_cast<ST *>( t );
          } );

      // Register the pointer
      ar.registerSharedPointer( id, ptr );

      // Perform the actual loading and allocation
      memory_detail::loadAndConstructSharedPtr( ar, ptr.get(), typename ::cereal::traits::has_shared_from_this<T>::type() );

      // Mark pointer as valid (initialized)
      *valid = true;
    }
    else
      ptr = std::static_pointer_cast<T>(ar.getSharedPointer(id));
  }


  template <class Archive, class T> inline
  typename std::enable_if<!traits::has_load_and_construct<T, Archive>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::shared_ptr<T> &> & wrapper )
  {
    auto & ptr = wrapper.ptr;

    uint32_t id;

    ar( CEREAL_NVP_("id", id) );

    if( id & detail::msb_32bit )
    {
      ptr.reset( detail::Construct<T, Archive>::load_andor_construct() );
      ar.registerSharedPointer( id, ptr );
      ar( CEREAL_NVP_("data", *ptr) );
    }
    else
      ptr = std::static_pointer_cast<T>(ar.getSharedPointer(id));
  }


  template <class Archive, class T, class D> inline
  void CEREAL_SAVE_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::unique_ptr<T, D> const &> const & wrapper )
  {
    auto & ptr = wrapper.ptr;

    // unique_ptr get one byte of metadata which signifies whether they were a nullptr
    // 0 == nullptr
    // 1 == not null

    if( !ptr )
      ar( CEREAL_NVP_("valid", uint8_t(0)) );
    else
    {
      ar( CEREAL_NVP_("valid", uint8_t(1)) );
      ar( CEREAL_NVP_("data", *ptr) );
    }
  }


  template <class Archive, class T, class D> inline
  typename std::enable_if<traits::has_load_and_construct<T, Archive>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::unique_ptr<T, D> &> & wrapper )
  {
    uint8_t isValid;
    ar( CEREAL_NVP_("valid", isValid) );

    auto & ptr = wrapper.ptr;

    if( isValid )
    {
      // Storage type for the pointer - since we can't default construct this type,
      // we'll allocate it using std::aligned_storage
      using ST = typename std::aligned_storage<sizeof(T)>::type;

      // Allocate storage - note the ST type so that deleter is correct if
      //                    an exception is thrown before we are initialized
      std::unique_ptr<ST> stPtr( new ST() );

      // Use wrapper to enter into "data" nvp of ptr_wrapper
      memory_detail::LoadAndConstructLoadWrapper<Archive, T> loadWrapper( reinterpret_cast<T *>( stPtr.get() ) );

      // Initialize storage
      ar( CEREAL_NVP_("data", loadWrapper) );

      // Transfer ownership to correct unique_ptr type
      ptr.reset( reinterpret_cast<T *>( stPtr.release() ) );
    }
    else
      ptr.reset( nullptr );
  }


  template <class Archive, class T, class D> inline
  typename std::enable_if<!traits::has_load_and_construct<T, Archive>::value, void>::type
  CEREAL_LOAD_FUNCTION_NAME( Archive & ar, memory_detail::PtrWrapper<std::unique_ptr<T, D> &> & wrapper )
  {
    uint8_t isValid;
    ar( CEREAL_NVP_("valid", isValid) );

    auto & ptr = wrapper.ptr;

    if( isValid )
    {
      ptr.reset( detail::Construct<T, Archive>::load_andor_construct() );
      ar( CEREAL_NVP_( "data", *ptr ) );
    }
    else
    {
      ptr.reset( nullptr );
    }
  }
} // namespace cereal

#endif // CEREAL_TYPES_SHARED_PTR_HPP_