TbbTsqr_FillWithZerosTask.hpp

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//
//                 Anasazi: Block Eigensolvers Package
//                 Copyright (2010) Sandia Corporation
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// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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#ifndef __TSQR_TBB_FillWithZerosTask_hpp
#define __TSQR_TBB_FillWithZerosTask_hpp

#include <tbb/task.h>
#include <TbbTsqr_Partitioner.hpp>
#include <Tsqr_SequentialTsqr.hpp>


namespace TSQR {
  namespace TBB {
    
    template< class LocalOrdinal, class Scalar >
    class FillWithZerosTask : public tbb::task {
    private:
      typedef MatView< LocalOrdinal, Scalar > mat_view;
      typedef std::pair< mat_view, mat_view > split_type;

    public:
      FillWithZerosTask (const size_t P_first, 
       const size_t P_last,
       MatView< LocalOrdinal, Scalar > C,
       const SequentialTsqr< LocalOrdinal, Scalar >& seq,
       const bool contiguous_cache_blocks = false)
  : P_first_ (P_first), 
    P_last_ (P_last), 
    C_ (C),
    seq_ (seq), 
    contiguous_cache_blocks_ (contiguous_cache_blocks)
      {}

      tbb::task* 
      execute () 
      {
  if (P_first_ > P_last_ || C_.empty())
    return NULL;
  else if (P_first_ == P_last_)
    {
      // Fill my partition with zeros.
      seq_.fill_with_zeros (C_.nrows(), C_.ncols(), C_.get(), 
          C_.lda(), contiguous_cache_blocks_);
      return NULL;
    }
  else
    {
      // "c": continuation task
      tbb::empty_task& c = *new( allocate_continuation() ) tbb::empty_task;

      // Recurse on two intervals: [P_first, P_mid] and [P_mid+1, P_last]
      const size_t P_mid = (P_first_ + P_last_) / 2;
      split_type C_split = 
        partitioner_.split (C_, P_first_, P_mid, P_last_, 
          contiguous_cache_blocks_);
      FillWithZerosTask& topTask = *new( c.allocate_child() )
        FillWithZerosTask (P_first_, P_mid, C_split.first, seq_, 
         contiguous_cache_blocks_);
      FillWithZerosTask& botTask = *new( c.allocate_child() )
        FillWithZerosTask (P_mid+1, P_last_, C_split.second, seq_, 
         contiguous_cache_blocks_);

      // Set reference count of parent (in this case, the
      // continuation task) to 2 (since 2 children -- no
      // additional task since no waiting).
      c.set_ref_count (2);
      c.spawn (botTask);
      return &topTask; // scheduler bypass optimization
    }
      }

    private:
      size_t P_first_, P_last_;
      mat_view C_;
      SequentialTsqr< LocalOrdinal, Scalar > seq_;
      Partitioner< LocalOrdinal, Scalar > partitioner_;
      bool contiguous_cache_blocks_;
    };
  } // namespace TBB
} // namespace TSQR


#endif // __TSQR_TBB_FillWithZerosTask_hpp