/*
//@HEADER
// ************************************************************************
//
//                        Kokkos v. 2.0
//              Copyright (2014) Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
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// modification, are permitted provided that the following conditions are
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// 1. Redistributions of source code must retain the above copyright
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// 2. Redistributions in binary form must reproduce the above copyright
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// documentation and/or other materials provided with the distribution.
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// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
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//
// Questions? Contact  H. Carter Edwards (hcedwar@sandia.gov)
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*/

#ifndef KOKKOS_THREADS_HPP
#define KOKKOS_THREADS_HPP

#include <Kokkos_Core_fwd.hpp>

#if defined( KOKKOS_ENABLE_PTHREAD )

#include <cstddef>
#include <iosfwd>
#include <Kokkos_HostSpace.hpp>
#include <Kokkos_ScratchSpace.hpp>
#include <Kokkos_Layout.hpp>
#include <Kokkos_MemoryTraits.hpp>
#include <impl/Kokkos_Tags.hpp>

/*--------------------------------------------------------------------------*/

namespace Kokkos {
namespace Impl {
class ThreadsExec ;
} // namespace Impl
} // namespace Kokkos

/*--------------------------------------------------------------------------*/

namespace Kokkos {

/** \brief  Execution space for a pool of Pthreads or C11 threads on a CPU. */
class Threads {
public:
  //! \name Type declarations that all Kokkos devices must provide.
  //@{
  //! Tag this class as a kokkos execution space
  typedef Threads                  execution_space ;
  typedef Kokkos::HostSpace        memory_space ;

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

  typedef Kokkos::LayoutRight      array_layout ;
  typedef memory_space::size_type  size_type ;

  typedef ScratchMemorySpace< Threads >  scratch_memory_space ;


  //@}
  /*------------------------------------------------------------------------*/
  //! \name Static functions that all Kokkos devices must implement.
  //@{

  /// \brief True if and only if this method is being called in a
  ///   thread-parallel function.
  static int in_parallel();

  /** \brief  Set the device in a "sleep" state.
   *
   * This function sets the device in a "sleep" state in which it is
   * not ready for work.  This may consume less resources than if the
   * device were in an "awake" state, but it may also take time to
   * bring the device from a sleep state to be ready for work.
   *
   * \return True if the device is in the "sleep" state, else false if
   *   the device is actively working and could not enter the "sleep"
   *   state.
   */
  static bool sleep();

  /// \brief Wake the device from the 'sleep' state so it is ready for work.
  ///
  /// \return True if the device is in the "ready" state, else "false"
  ///  if the device is actively working (which also means that it's
  ///  awake).
  static bool wake();

  /// \brief Wait until all dispatched functors complete.
  ///
  /// The parallel_for or parallel_reduce dispatch of a functor may
  /// return asynchronously, before the functor completes.  This
  /// method does not return until all dispatched functors on this
  /// device have completed.
  static void fence();

  /// \brief Free any resources being consumed by the device.
  ///
  /// For the Threads device, this terminates spawned worker threads.
  static void finalize();

  /// \brief Print configuration information to the given output stream.
  static void print_configuration( std::ostream & , const bool detail = false );

  //@}
  /*------------------------------------------------------------------------*/
  /*------------------------------------------------------------------------*/
  //! \name Space-specific functions
  //@{

  /** \brief Initialize the device in the "ready to work" state.
   *
   *  The device is initialized in a "ready to work" or "awake" state.
   *  This state reduces latency and thus improves performance when
   *  dispatching work.  However, the "awake" state consumes resources
   *  even when no work is being done.  You may call sleep() to put
   *  the device in a "sleeping" state that does not consume as many
   *  resources, but it will take time (latency) to awaken the device
   *  again (via the wake()) method so that it is ready for work.
   *
   *  Teams of threads are distributed as evenly as possible across
   *  the requested number of numa regions and cores per numa region.
   *  A team will not be split across a numa region.
   *
   *  If the 'use_' arguments are not supplied the hwloc is queried
   *  to use all available cores.
   */
  static void initialize( unsigned threads_count = 0 ,
                          unsigned use_numa_count = 0 ,
                          unsigned use_cores_per_numa = 0 ,
                          bool allow_asynchronous_threadpool = false );

  static int is_initialized();

  /** \brief  Return the maximum amount of concurrency.  */
  static int concurrency();

  static Threads & instance( int = 0 );

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

  static int thread_pool_size( int depth = 0 );
#if defined( KOKKOS_ACTIVE_EXECUTION_MEMORY_SPACE_HOST )
  static int thread_pool_rank();
#else
  KOKKOS_INLINE_FUNCTION static int thread_pool_rank() { return 0 ; }
#endif

  inline static unsigned max_hardware_threads() { return thread_pool_size(0); }
  KOKKOS_INLINE_FUNCTION static unsigned hardware_thread_id() { return thread_pool_rank(); }

  //@}
  //----------------------------------------
};

} // namespace Kokkos

/*--------------------------------------------------------------------------*/

namespace Kokkos {
namespace Impl {

template<>
struct MemorySpaceAccess 
  < Kokkos::Threads::memory_space
  , Kokkos::Threads::scratch_memory_space
  >
{
  enum { assignable = false };
  enum { accessible = true };
  enum { deepcopy   = false };
};

template<>
struct VerifyExecutionCanAccessMemorySpace
  < Kokkos::Threads::memory_space
  , Kokkos::Threads::scratch_memory_space
  >
{
  enum { value = true };
  inline static void verify( void ) { }
  inline static void verify( const void * ) { }
};

} // namespace Impl
} // namespace Kokkos

/*--------------------------------------------------------------------------*/

#include <Kokkos_ExecPolicy.hpp>
#include <Kokkos_Parallel.hpp>
#include <Threads/Kokkos_ThreadsExec.hpp>
#include <Threads/Kokkos_ThreadsTeam.hpp>
#include <Threads/Kokkos_Threads_Parallel.hpp>

#include <KokkosExp_MDRangePolicy.hpp>

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

#endif /* #if defined( KOKKOS_ENABLE_PTHREAD ) */
#endif /* #define KOKKOS_THREADS_HPP */

