Kokkos_TaskScheduler.hpp

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#ifndef KOKKOS_TASKSCHEDULER_HPP
#define KOKKOS_TASKSCHEDULER_HPP

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

#include <Kokkos_Macros.hpp>
#if defined( KOKKOS_ENABLE_TASKDAG )

#include <Kokkos_Core_fwd.hpp>
#include <Kokkos_TaskScheduler_fwd.hpp>
//----------------------------------------------------------------------------

#include <Kokkos_MemoryPool.hpp>
#include <impl/Kokkos_Tags.hpp>

#include <Kokkos_Future.hpp>
#include <impl/Kokkos_TaskQueue.hpp>
#include <impl/Kokkos_SingleTaskQueue.hpp>
#include <impl/Kokkos_TaskQueueMultiple.hpp>
#include <impl/Kokkos_TaskPolicyData.hpp>
#include <impl/Kokkos_TaskTeamMember.hpp>
#include <impl/Kokkos_SimpleTaskScheduler.hpp>

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

namespace Kokkos {

namespace Impl {

template <class, class>
class TaskExec;

} // end namespace Impl


template<class ExecSpace, class QueueType>
class BasicTaskScheduler : public Impl::TaskSchedulerBase
{
public:

  using scheduler_type = BasicTaskScheduler;
  using execution_space = ExecSpace;
  using queue_type = QueueType;
  using memory_space = typename queue_type::memory_space;
  using memory_pool = typename queue_type::memory_pool;
  using specialization = Impl::TaskQueueSpecialization<BasicTaskScheduler>;
  using member_type = typename specialization::member_type;
  using team_scheduler_type = BasicTaskScheduler;
  template <class Functor>
  using runnable_task_type = Impl::Task<scheduler_type, typename Functor::value_type, Functor>;
  template <class ValueType>
  using future_type = Kokkos::BasicFuture<ValueType, BasicTaskScheduler>;
  template <class FunctorType>
  using future_type_for_functor = future_type<typename FunctorType::value_type>;

private:

  using track_type = Kokkos::Impl::SharedAllocationTracker ;
  using task_base  = Impl::TaskBase;

  track_type m_track;
  queue_type * m_queue;

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

  template <typename, typename>
  friend class Impl::TaskQueue;
  template <typename>
  friend struct Impl::TaskQueueSpecialization;
  template <typename, typename>
  friend class Impl::TaskQueueSpecializationConstrained;
  template <typename, typename>
  friend class Impl::TaskTeamMemberAdapter;
  template <typename, typename>
  friend class Impl::TaskExec;

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

  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler(
    track_type arg_track,
    queue_type* arg_queue
  )
    : m_track(std::move(arg_track)),
      m_queue(std::move(arg_queue))
  { }

  KOKKOS_INLINE_FUNCTION
  team_scheduler_type get_team_scheduler(int team_rank) const {
    return { m_track, &m_queue->get_team_queue(team_rank) };
  }

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

  KOKKOS_INLINE_FUNCTION
  static constexpr task_base* _get_task_ptr(std::nullptr_t) { return nullptr; }

  template <class ValueType>
  KOKKOS_INLINE_FUNCTION
  static constexpr task_base* _get_task_ptr(future_type<ValueType>&& f)
  {
    return f.m_task;
  }

  template< int TaskEnum , typename DepTaskType , typename FunctorType >
  KOKKOS_FUNCTION
  Kokkos::BasicFuture<typename FunctorType::value_type, scheduler_type>
  _spawn_impl(
    DepTaskType* arg_predecessor_task,
    TaskPriority arg_priority,
    typename task_base::function_type arg_function,
    typename task_base::destroy_type arg_destroy,
    FunctorType&& arg_functor
  )
  {
    using functor_future_type = future_type_for_functor<typename std::decay<FunctorType>::type>;
    using task_type = Impl::Task<BasicTaskScheduler, typename functor_future_type::value_type, FunctorType>;

    //----------------------------------------
    // Give single-thread back-ends an opportunity to clear
    // queue of ready tasks before allocating a new task

    // TODO @tasking @optimization DSH re-enable this, maybe?
    // specialization::iff_single_thread_recursive_execute(scheduler);

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

    functor_future_type f ;

    // Allocate task from memory pool

    const size_t alloc_size =
      m_queue->template spawn_allocation_size< FunctorType >();

    void* task_storage = m_queue->allocate(alloc_size);

    if (task_storage) {

      // Placement new construction
      // Reference count starts at two:
      //   +1 for the matching decrement when task is complete
      //   +1 for the future
      f.m_task = new (task_storage) task_type( std::forward<FunctorType>(arg_functor) );

      f.m_task->m_apply      = arg_function;
      //f.m_task->m_destroy    = arg_destroy;
      f.m_task->m_queue      = m_queue;
      f.m_task->m_next       = arg_predecessor_task;
      f.m_task->m_ref_count  = 2;
      f.m_task->m_alloc_size = alloc_size;
      f.m_task->m_task_type  = TaskEnum;
      f.m_task->m_priority   = (int16_t)arg_priority;

      Kokkos::memory_fence();

      // The dependence (if any) is processed immediately
      // within the schedule function, as such the dependence's
      // reference count does not need to be incremented for
      // the assignment.

      m_queue->schedule_runnable( f.m_task );
      // This task may be updated or executed at any moment,
      // even during the call to 'schedule'.
    }

    return f;

  }

public:


  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler() : m_track(), m_queue(0) {}

  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler( BasicTaskScheduler && rhs ) noexcept
    : m_track(rhs.m_track),  // probably should be a move, but this is deprecated code anyway
      m_queue(std::move(rhs.m_queue))
  { }

  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler( BasicTaskScheduler const & rhs )
    : m_track(rhs.m_track),
      m_queue(rhs.m_queue)
  { }

  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler& operator=(BasicTaskScheduler&& rhs) noexcept
  {
    m_track = rhs.m_track;  // probably should be a move, but this is deprecated code anyway
    m_queue = std::move(rhs.m_queue);
    return *this;
  }

  KOKKOS_INLINE_FUNCTION
  BasicTaskScheduler& operator=(BasicTaskScheduler const& rhs)
  {
    m_track = rhs.m_track;
    m_queue = rhs.m_queue;
    return *this;
  }

  explicit BasicTaskScheduler(memory_pool const & arg_memory_pool) noexcept
    : m_track(), m_queue(0)
    {
      typedef Kokkos::Impl::SharedAllocationRecord
        < memory_space , typename queue_type::Destroy >
          record_type ;

      record_type * record =
        record_type::allocate( memory_space()
                             , "TaskQueue"
                             , sizeof(queue_type)
                             );

      m_queue = new( record->data() ) queue_type( arg_memory_pool );

      record->m_destroy.m_queue = m_queue ;

      m_track.assign_allocated_record_to_uninitialized( record );
    }

  BasicTaskScheduler( memory_space const & arg_memory_space
               , size_t const mempool_capacity
               , unsigned const mempool_min_block_size  // = 1u << 6
               , unsigned const mempool_max_block_size  // = 1u << 10
               , unsigned const mempool_superblock_size // = 1u << 12
               )
    : BasicTaskScheduler( memory_pool( arg_memory_space
                                , mempool_capacity
                                , mempool_min_block_size
                                , mempool_max_block_size
                                , mempool_superblock_size ) )
    {}

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

  KOKKOS_INLINE_FUNCTION
  queue_type& queue() const noexcept {
    KOKKOS_EXPECTS(m_queue != nullptr);
    return *m_queue;
  }

  KOKKOS_INLINE_FUNCTION
  memory_pool * memory() const noexcept
    { return m_queue ? &( m_queue->m_memory ) : (memory_pool*) 0 ; }

  //----------------------------------------
  template< typename FunctorType >
  KOKKOS_FUNCTION
  size_t spawn_allocation_size() const
    { return m_queue->template spawn_allocation_size< FunctorType >(); }

  KOKKOS_FUNCTION
  size_t when_all_allocation_size( int narg ) const
    { return m_queue->when_all_allocation_size( narg ); }


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

  template <int TaskEnum, typename DepFutureType, typename FunctorType>
  KOKKOS_FUNCTION static
  Kokkos::BasicFuture<typename FunctorType::value_type, scheduler_type>
  spawn(
    Impl::TaskPolicyWithScheduler<TaskEnum, scheduler_type, DepFutureType>&& arg_policy,
    typename task_base::function_type arg_function,
    typename task_base::destroy_type arg_destroy,
    FunctorType&& arg_functor
  )
  {
    return std::move(arg_policy.scheduler()).template _spawn_impl<TaskEnum>(
      _get_task_ptr(std::move(arg_policy.predecessor())),
      arg_policy.priority(),
      arg_function,
      arg_destroy,
      std::forward<FunctorType>(arg_functor)
    );
  }

  template <int TaskEnum, typename DepFutureType, typename FunctorType>
  KOKKOS_FUNCTION
  future_type_for_functor<typename std::decay<FunctorType>::type>
  spawn(
    Impl::TaskPolicyWithPredecessor<TaskEnum, DepFutureType>&& arg_policy,
    FunctorType&& arg_functor
  )
  {
    using task_type = runnable_task_type<FunctorType>;
    typename task_type::function_type const ptr = task_type::apply;
    typename task_type::destroy_type const dtor = task_type::destroy;

    return _spawn_impl<TaskEnum>(
      _get_task_ptr(std::move(arg_policy).predecessor()),
      arg_policy.priority(),
      ptr, dtor,
      std::forward<FunctorType>(arg_functor)
    );
  }

  template<typename FunctorType, typename ValueType, typename Scheduler>
  KOKKOS_FUNCTION static
  void
  respawn(
    FunctorType* arg_self,
    BasicFuture<ValueType,Scheduler> const & arg_dependence,
    TaskPriority  const & arg_priority
  ) {
    // Precondition: task is in Executing state

    using value_type  = typename FunctorType::value_type ;
    using task_type = Impl::Task<BasicTaskScheduler, value_type, FunctorType>;

    task_type * const task = static_cast< task_type * >( arg_self );

    task->m_priority = static_cast<int>(arg_priority);

    task->add_dependence( arg_dependence.m_task );

    // Postcondition: task is in Executing-Respawn state
  }

  template< typename FunctorType >
  KOKKOS_FUNCTION static
  void
  respawn(
    FunctorType* arg_self,
    BasicTaskScheduler const &,
    TaskPriority  const & arg_priority
  )
  {
    // Precondition: task is in Executing state

    using value_type = typename FunctorType::value_type;
    using task_type = Impl::Task<BasicTaskScheduler, value_type, FunctorType>;

    task_type * const task = static_cast< task_type * >( arg_self );

    task->m_priority = static_cast<int>(arg_priority);

    task->add_dependence( (task_base*) 0 );

    // Postcondition: task is in Executing-Respawn state
  }

  //----------------------------------------
  template<typename ValueType>
  KOKKOS_FUNCTION
  BasicFuture< void, scheduler_type >
  when_all(BasicFuture<ValueType, BasicTaskScheduler> const arg[], int narg)
  {

    future_type<void> f ;

    if ( narg ) {

      queue_type* q = m_queue;

      //BasicTaskScheduler const* scheduler_ptr = nullptr;

      for ( int i = 0 ; i < narg ; ++i ) {
        task_base * const t = arg[i].m_task ;
        if ( nullptr != t ) {
          // Increment reference count to track subsequent assignment.
          Kokkos::atomic_increment( &(t->m_ref_count) );
          if(q != static_cast< queue_type const* >(t->m_queue)) {
            Kokkos::abort("Kokkos when_all Futures must be in the same scheduler" );
          }
        }
      }

      if ( q != 0 ) { // this should probably handle the queue == 0 case, but this is deprecated code anyway

        size_t const alloc_size = q->when_all_allocation_size( narg );

        f.m_task =
          reinterpret_cast< task_base * >( q->allocate( alloc_size ) );
        //f.m_scheduler = *scheduler_ptr;

        if ( f.m_task ) {

          // Reference count starts at two:
          // +1 to match decrement when task completes
          // +1 for the future

          new( f.m_task ) task_base();

          f.m_task->m_queue = q;
          f.m_task->m_ref_count = 2 ;
          f.m_task->m_alloc_size = static_cast<int32_t>(alloc_size);
          f.m_task->m_dep_count = narg ;
          f.m_task->m_task_type = task_base::Aggregate ;

          // Assign dependences, reference counts were already incremented

          task_base * volatile * const dep =
            f.m_task->aggregate_dependences();

          for ( int i = 0 ; i < narg ; ++i ) { dep[i] = arg[i].m_task ; }

          Kokkos::memory_fence();

          q->schedule_aggregate( f.m_task );
          // this when_all may be processed at any moment
        }
      }
    }

    return f ;
  }

  template < class F >
  KOKKOS_FUNCTION
  BasicFuture< void, scheduler_type >
  when_all( int narg , F const func )
    {
      using input_type  = decltype( func(0) );

      static_assert( is_future< input_type >::value
                   , "Functor must return a Kokkos::Future" );

      future_type<void> f ;

      if ( 0 == narg ) return f ;

      size_t const alloc_size = m_queue->when_all_allocation_size( narg );

      f.m_task =
        reinterpret_cast< task_base * >( m_queue->allocate( alloc_size ) );

      if ( f.m_task ) {

        // Reference count starts at two:
        // +1 to match decrement when task completes
        // +1 for the future

        new( f.m_task ) task_base();
        //f.m_scheduler = *this;

        //f.m_task->m_scheduler = &f.m_scheduler;
        f.m_task->m_queue = m_queue;
        f.m_task->m_ref_count = 2 ;
        f.m_task->m_alloc_size = static_cast<int32_t>(alloc_size);
        f.m_task->m_dep_count = narg ;
        f.m_task->m_task_type = task_base::Aggregate ;
        //f.m_task->m_apply = nullptr;
        //f.m_task->m_destroy = nullptr;

        // Assign dependences, reference counts were already incremented

        task_base * volatile * const dep =
          f.m_task->aggregate_dependences();

        for ( int i = 0 ; i < narg ; ++i ) {
          const input_type arg_f = func(i);
          if ( 0 != arg_f.m_task ) {

            // Not scheduled, so task scheduler is not yet set
            //if ( m_queue != static_cast< BasicTaskScheduler const * >( arg_f.m_task->m_scheduler )->m_queue ) {
            //  Kokkos::abort("Kokkos when_all Futures must be in the same scheduler" );
            //}
            // Increment reference count to track subsequent assignment.
            Kokkos::atomic_increment( &(arg_f.m_task->m_ref_count) );
            dep[i] = arg_f.m_task ;
          }
        }

        Kokkos::memory_fence();

        m_queue->schedule_aggregate( f.m_task );
        // this when_all may be processed at any moment
      }
      return f ;
    }

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

  KOKKOS_INLINE_FUNCTION
  int allocation_capacity() const noexcept
    { return m_queue->m_memory.capacity(); }

  KOKKOS_INLINE_FUNCTION
  int allocated_task_count() const noexcept
    { return m_queue->m_count_alloc ; }

  KOKKOS_INLINE_FUNCTION
  int allocated_task_count_max() const noexcept
    { return m_queue->m_max_alloc ; }

  KOKKOS_INLINE_FUNCTION
  long allocated_task_count_accum() const noexcept
    { return m_queue->m_accum_alloc ; }

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

  template<class S, class Q>
  friend
  void wait(Kokkos::BasicTaskScheduler<S, Q> const&);

};

} // namespace Kokkos

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

namespace Kokkos {

//----------------------------------------------------------------------------
// Construct a TaskTeam execution policy

template <class T, class Scheduler>
Impl::TaskPolicyWithPredecessor<
  Impl::TaskType::TaskTeam,
  Kokkos::BasicFuture<T, Scheduler>
>
KOKKOS_INLINE_FUNCTION
TaskTeam(
  Kokkos::BasicFuture<T, Scheduler> arg_future,
  TaskPriority arg_priority = TaskPriority::Regular
)
{
  return { std::move(arg_future), arg_priority };
}

template <class Scheduler>
Impl::TaskPolicyWithScheduler<
  Impl::TaskType::TaskTeam, Scheduler
>
KOKKOS_INLINE_FUNCTION
TaskTeam(
  Scheduler arg_scheduler,
  typename std::enable_if<
    Kokkos::is_scheduler<Scheduler>::value,
    TaskPriority
  >::type arg_priority = TaskPriority::Regular
)
{
  return { std::move(arg_scheduler), arg_priority };
}

template<
  class Scheduler,
  class PredecessorFuture
>
Impl::TaskPolicyWithScheduler<
  Kokkos::Impl::TaskType::TaskTeam,
  Scheduler,
  PredecessorFuture
>
KOKKOS_INLINE_FUNCTION
TaskTeam(
  Scheduler arg_scheduler,
  PredecessorFuture arg_future,
  typename std::enable_if<
    Kokkos::is_scheduler<Scheduler>::value
      && Kokkos::is_future<PredecessorFuture>::value,
    TaskPriority
  >::type arg_priority = TaskPriority::Regular
)
{
  static_assert(
    std::is_same<typename PredecessorFuture::scheduler_type, Scheduler>::value,
    "Can't create a task policy from a scheduler and a future from a different scheduler"
  );

  return { std::move(arg_scheduler), std::move(arg_future), arg_priority };
}

// Construct a TaskSingle execution policy

template <class T, class Scheduler>
Impl::TaskPolicyWithPredecessor<
  Impl::TaskType::TaskSingle,
  Kokkos::BasicFuture<T, Scheduler>
>
KOKKOS_INLINE_FUNCTION
TaskSingle(
  Kokkos::BasicFuture<T, Scheduler> arg_future,
  TaskPriority arg_priority = TaskPriority::Regular
)
{
  return { std::move(arg_future), arg_priority };
}

template <class Scheduler>
Impl::TaskPolicyWithScheduler<
  Impl::TaskType::TaskSingle, Scheduler
>
KOKKOS_INLINE_FUNCTION
TaskSingle(
  Scheduler arg_scheduler,
  typename std::enable_if<
    Kokkos::is_scheduler<Scheduler>::value,
    TaskPriority
  >::type arg_priority = TaskPriority::Regular
)
{
  return { std::move(arg_scheduler), arg_priority };
}

template<
  class Scheduler,
  class PredecessorFuture
>
Impl::TaskPolicyWithScheduler<
  Kokkos::Impl::TaskType::TaskSingle,
  Scheduler,
  PredecessorFuture
>
KOKKOS_INLINE_FUNCTION
TaskSingle(
  Scheduler arg_scheduler,
  PredecessorFuture arg_future,
  typename std::enable_if<
    Kokkos::is_scheduler<Scheduler>::value
      && Kokkos::is_future<PredecessorFuture>::value,
    TaskPriority
  >::type arg_priority = TaskPriority::Regular
)
{
  static_assert(
    std::is_same<typename PredecessorFuture::scheduler_type, Scheduler>::value,
    "Can't create a task policy from a scheduler and a future from a different scheduler"
  );

  return { std::move(arg_scheduler), std::move(arg_future), arg_priority };
}

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

template<int TaskEnum, typename Scheduler, typename DepFutureType, typename FunctorType>
typename Scheduler::template future_type_for_functor<typename std::decay<FunctorType>::type>
host_spawn(
  Impl::TaskPolicyWithScheduler<TaskEnum, Scheduler, DepFutureType> arg_policy,
  FunctorType&& arg_functor
) {
  using scheduler_type = Scheduler;
  using task_type =
    typename scheduler_type::template runnable_task_type<FunctorType>;

  static_assert(
    TaskEnum == Impl::TaskType::TaskTeam || TaskEnum == Impl::TaskType::TaskSingle,
    "Kokkos host_spawn requires TaskTeam or TaskSingle"
  );

  // May be spawning a Cuda task, must use the specialization
  // to query on-device function pointer.
  typename task_type::function_type ptr;
  typename task_type::destroy_type dtor;
  Kokkos::Impl::TaskQueueSpecialization< scheduler_type >::
    template get_function_pointer< task_type >(ptr, dtor);

  return scheduler_type::spawn(
    std::move(arg_policy), ptr, dtor, std::forward<FunctorType>(arg_functor)
  );
}

template<int TaskEnum, typename Scheduler, typename DepFutureType, typename FunctorType>
typename Scheduler::template future_type_for_functor<typename std::decay<FunctorType>::type>
KOKKOS_INLINE_FUNCTION
task_spawn(
  Impl::TaskPolicyWithScheduler<TaskEnum, Scheduler, DepFutureType> arg_policy,
  FunctorType&& arg_functor
)
{
  using scheduler_type = Scheduler;

  using task_type =
    typename scheduler_type::template runnable_task_type<FunctorType>;

 #if defined( KOKKOS_ACTIVE_EXECUTION_MEMORY_SPACE_HOST ) && \
     defined( KOKKOS_ENABLE_CUDA )

   static_assert( ! std::is_same< Kokkos::Cuda , typename Scheduler::execution_space >::value
                , "Error calling Kokkos::task_spawn for Cuda space within Host code" );

 #endif

  static_assert(
    TaskEnum == Impl::TaskType::TaskTeam || TaskEnum == Impl::TaskType::TaskSingle,
    "Kokkos task_spawn requires TaskTeam or TaskSingle"
  );

  typename task_type::function_type const ptr = task_type::apply ;
  typename task_type::destroy_type const dtor = task_type::destroy ;

  return scheduler_type::spawn(std::move(arg_policy), ptr, dtor,
    std::forward<FunctorType>(arg_functor)
  );
}

template< typename FunctorType , typename T >
void
KOKKOS_INLINE_FUNCTION
respawn( FunctorType         * arg_self
       , T             const & arg
       , TaskPriority  const & arg_priority = TaskPriority::Regular
       )
{
  static_assert( Kokkos::is_future<T>::value ||
                 Kokkos::is_scheduler<T>::value
               , "Kokkos respawn argument must be Future or TaskScheduler" );

  T::scheduler_type::respawn(
    arg_self , arg , arg_priority
  );
}

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

//template<typename ValueType, typename Scheduler>
//KOKKOS_INLINE_FUNCTION
//BasicFuture<void, Scheduler>
//when_all(BasicFuture<ValueType, Scheduler> const arg[], int narg)
//{
//  return BasicFuture<void, Scheduler>::scheduler_type::when_all(arg, narg);
//}

//----------------------------------------------------------------------------
// Wait for all runnable tasks to complete

template<class ExecSpace, class QueueType>
inline
void wait(BasicTaskScheduler<ExecSpace, QueueType> const& scheduler)
{
  using scheduler_type = BasicTaskScheduler<ExecSpace, QueueType>;
  scheduler_type::specialization::execute(scheduler);
  //scheduler.m_queue->execute();
}

} // namespace Kokkos

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

// END OLD CODE

#endif /* #if defined( KOKKOS_ENABLE_TASKDAG ) */
#endif /* #ifndef KOKKOS_TASKSCHEDULER_HPP */