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//                        Kokkos v. 2.0
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#ifndef KOKKOS_HBWSPACE_HPP
#define KOKKOS_HBWSPACE_HPP

#include <Kokkos_Macros.hpp>
#ifdef KOKKOS_ENABLE_HBWSPACE

#include <Kokkos_HostSpace.hpp>

namespace Kokkos {

namespace Experimental {

namespace Impl {

/// \brief Initialize lock array for arbitrary size atomics.
///
/// Arbitrary atomics are implemented using a hash table of locks
/// where the hash value is derived from the address of the
/// object for which an atomic operation is performed.
/// This function initializes the locks to zero (unset).
void init_lock_array_hbw_space();

/// \brief Aquire a lock for the address
///
/// This function tries to aquire the lock for the hash value derived
/// from the provided ptr. If the lock is successfully aquired the
/// function returns true. Otherwise it returns false.
bool lock_address_hbw_space( void* ptr );

/// \brief Release lock for the address
///
/// This function releases the lock for the hash value derived
/// from the provided ptr. This function should only be called
/// after previously successfully aquiring a lock with
/// lock_address.
void unlock_address_hbw_space( void* ptr );

} // namespace Impl

} // namespace Experimental

} // namespace Kokkos

namespace Kokkos {

namespace Experimental {

/// \class HBWSpace
/// \brief Memory management for host memory.
///
/// HBWSpace is a memory space that governs host memory.  "Host"
/// memory means the usual CPU-accessible memory.
class HBWSpace {
public:
  //! Tag this class as a kokkos memory space
  typedef HBWSpace  memory_space;
  typedef size_t     size_type;

  /// \typedef execution_space
  /// \brief Default execution space for this memory space.
  ///
  /// Every memory space has a default execution space.  This is
  /// useful for things like initializing a View (which happens in
  /// parallel using the View's default execution space).
#if defined( KOKKOS_ENABLE_DEFAULT_DEVICE_TYPE_OPENMP )
  typedef Kokkos::OpenMP    execution_space;
#elif defined( KOKKOS_ENABLE_DEFAULT_DEVICE_TYPE_THREADS )
  typedef Kokkos::Threads   execution_space;
//#elif defined( KOKKOS_ENABLE_DEFAULT_DEVICE_TYPE_QTHREADS )
//  typedef Kokkos::Qthreads  execution_space;
#elif defined( KOKKOS_ENABLE_OPENMP )
  typedef Kokkos::OpenMP    execution_space;
#elif defined( KOKKOS_ENABLE_THREADS )
  typedef Kokkos::Threads   execution_space;
//#elif defined( KOKKOS_ENABLE_QTHREADS )
//  typedef Kokkos::Qthreads  execution_space;
#elif defined( KOKKOS_ENABLE_SERIAL )
  typedef Kokkos::Serial    execution_space;
#else
#  error "At least one of the following host execution spaces must be defined: Kokkos::OpenMP, Kokkos::Threads, Kokkos::Qhreads, or Kokkos::Serial.  You might be seeing this message if you disabled the Kokkos::Serial device explicitly using the Kokkos_ENABLE_Serial:BOOL=OFF CMake option, but did not enable any of the other host execution space devices."
#endif

  //! This memory space preferred device_type
  typedef Kokkos::Device< execution_space, memory_space > device_type;

  /**\brief  Default memory space instance */
  HBWSpace();
  HBWSpace( const HBWSpace & rhs ) = default;
  HBWSpace & operator = ( const HBWSpace & ) = default;
  ~HBWSpace() = default;

  /**\brief  Non-default memory space instance to choose allocation mechansim, if available */

  enum AllocationMechanism { STD_MALLOC, POSIX_MEMALIGN, POSIX_MMAP, INTEL_MM_ALLOC };

  explicit
  HBWSpace( const AllocationMechanism & );

  /**\brief  Allocate untracked memory in the space */
  void * allocate( const size_t arg_alloc_size ) const;

  /**\brief  Deallocate untracked memory in the space */
  void deallocate( void * const arg_alloc_ptr
                 , const size_t arg_alloc_size ) const;

  /**\brief Return Name of the MemorySpace */
  static constexpr const char* name() { return "HBW"; }

private:

  AllocationMechanism  m_alloc_mech;
  friend class Kokkos::Impl::SharedAllocationRecord< Kokkos::Experimental::HBWSpace, void >;
};

} // namespace Experimental

} // namespace Kokkos

//----------------------------------------------------------------------------

namespace Kokkos {

namespace Impl {

template<>
class SharedAllocationRecord< Kokkos::Experimental::HBWSpace, void >
  : public SharedAllocationRecord< void, void >
{
private:

  friend Kokkos::Experimental::HBWSpace;

  typedef SharedAllocationRecord< void, void >  RecordBase;

  SharedAllocationRecord( const SharedAllocationRecord & ) = delete;
  SharedAllocationRecord & operator = ( const SharedAllocationRecord & ) = delete;

  static void deallocate( RecordBase * );

  /**\brief  Root record for tracked allocations from this HBWSpace instance */
  static RecordBase s_root_record;

  const Kokkos::Experimental::HBWSpace m_space;

protected:

  ~SharedAllocationRecord();
  SharedAllocationRecord() = default;

  SharedAllocationRecord( const Kokkos::Experimental::HBWSpace & arg_space
                        , const std::string                    & arg_label
                        , const size_t                           arg_alloc_size
                        , const RecordBase::function_type        arg_dealloc = & deallocate
                        );

public:

  inline
  std::string get_label() const
    {
      return std::string( RecordBase::head()->m_label );
    }

  KOKKOS_INLINE_FUNCTION static
  SharedAllocationRecord * allocate( const Kokkos::Experimental::HBWSpace & arg_space
                                   , const std::string                    & arg_label
                                   , const size_t                           arg_alloc_size
                                   )
    {
#if defined( KOKKOS_ACTIVE_EXECUTION_MEMORY_SPACE_HOST )
      return new SharedAllocationRecord( arg_space, arg_label, arg_alloc_size );
#else
      return (SharedAllocationRecord *) 0;
#endif
    }

  /**\brief  Allocate tracked memory in the space */
  static
  void * allocate_tracked( const Kokkos::Experimental::HBWSpace & arg_space
                         , const std::string                    & arg_label
                         , const size_t                           arg_alloc_size );

  /**\brief  Reallocate tracked memory in the space */
  static
  void * reallocate_tracked( void * const arg_alloc_ptr
                           , const size_t arg_alloc_size );

  /**\brief  Deallocate tracked memory in the space */
  static
  void deallocate_tracked( void * const arg_alloc_ptr );

  static SharedAllocationRecord * get_record( void * arg_alloc_ptr );

  static void print_records( std::ostream &, const Kokkos::Experimental::HBWSpace &, bool detail = false );
};

} // namespace Impl

} // namespace Kokkos

//----------------------------------------------------------------------------

namespace Kokkos {

namespace Impl {

static_assert( Kokkos::Impl::MemorySpaceAccess< Kokkos::Experimental::HBWSpace, Kokkos::Experimental::HBWSpace >::assignable, "" );

template<>
struct MemorySpaceAccess< Kokkos::HostSpace, Kokkos::Experimental::HBWSpace > {
  enum { assignable = true };
  enum { accessible = true };
  enum { deepcopy   = true };
};

template<>
struct MemorySpaceAccess< Kokkos::Experimental::HBWSpace, Kokkos::HostSpace > {
  enum { assignable = false };
  enum { accessible = true };
  enum { deepcopy   = true };
};

} // namespace Impl

} // namespace Kokkos

//----------------------------------------------------------------------------

namespace Kokkos {

namespace Impl {

template< class ExecutionSpace >
struct DeepCopy< Experimental::HBWSpace, Experimental::HBWSpace, ExecutionSpace > {
  DeepCopy( void * dst, const void * src, size_t n ) {
    memcpy( dst, src, n );
  }

  DeepCopy( const ExecutionSpace& exec, void * dst, const void * src, size_t n ) {
    exec.fence();
    memcpy( dst, src, n );
  }
};

template< class ExecutionSpace >
struct DeepCopy< HostSpace, Experimental::HBWSpace, ExecutionSpace > {
  DeepCopy( void * dst, const void * src, size_t n ) {
    memcpy( dst, src, n );
  }

  DeepCopy( const ExecutionSpace& exec, void * dst, const void * src, size_t n ) {
    exec.fence();
    memcpy( dst, src, n );
  }
};

template< class ExecutionSpace >
struct DeepCopy< Experimental::HBWSpace, HostSpace, ExecutionSpace > {
  DeepCopy( void * dst, const void * src, size_t n ) {
    memcpy( dst, src, n );
  }

  DeepCopy( const ExecutionSpace& exec, void * dst, const void * src, size_t n ) {
    exec.fence();
    memcpy( dst, src, n );
  }
};

} // namespace Impl

} // namespace Kokkos

namespace Kokkos {

namespace Impl {

template<>
struct VerifyExecutionCanAccessMemorySpace< Kokkos::HostSpace, Kokkos::Experimental::HBWSpace >
{
  enum { value = true };
  inline static void verify( void ) { }
  inline static void verify( const void * ) { }
};

template<>
struct VerifyExecutionCanAccessMemorySpace< Kokkos::Experimental::HBWSpace, Kokkos::HostSpace >
{
  enum { value = true };
  inline static void verify( void ) { }
  inline static void verify( const void * ) { }
};

} // namespace Impl

} // namespace Kokkos

#endif
#endif // #define KOKKOS_HBWSPACE_HPP

