scatter_message.icc

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#ifndef _RHEOLEF_SCATTER_MESSAGE_ICC
#define _RHEOLEF_SCATTER_MESSAGE_ICC
//
// create distributed to sequential scatter context
// inspirated from petsc-2.0/vpscat.c: VecScatterCreate_PtoS(...)
//
#include "rheolef/compiler.h"
 
#ifdef _RHEOLEF_HAVE_MPI
#include "rheolef/scatter_message.h"
#include "rheolef/msg_left_permutation_apply.h"
#include "rheolef/msg_right_permutation_apply.h"
 
namespace rheolef {
 
// =================================================================================
// part 1: init
// =================================================================================
// case of multi-valued data:
// called after the scatter_message<Container,false> scatter is finished:
// => the size of each object to transmit is known
template<class Container>
void
scatter_message<Container,true>::multi_init ()
{
  // ----------------------------------------------
  // 1) count the total message size
  // ----------------------------------------------
  size_type n_data = base::n_data();
  _ptr.resize (n_data+1);
  _ptr [0] = 0;
  for (size_type i = 0; i < n_data; i++) {
    size_type size_i = base::_values [i];
    _ptr [i+1] = _ptr[i] + size_i;
  }
  size_type n_multi_data = _ptr[n_data];
 
  // ----------------------------------------------
  // 2) resize & fill multi_{values,indices} arrays
  // ----------------------------------------------
  _multi_values.resize  (n_multi_data);
#ifdef TO_CLEAN
  _multi_indices.resize (n_multi_data);
  typename std::vector<size_type>::const_iterator p = base::_indices.begin();
  std::vector<size_type> ip (n_data);
  for (size_type i = 0; i < n_data; i++) {
    ip[p[i]] = i;
  }
  // y[p[i]] == x[i] <==> x[ip[j]] == y[j]      
  // yptr[j]... yptr[j+1]-1 = range of multi-valued y[j]==x[i], j=p[i]
  std::vector<size_type> yptr (n_data+1);
  yptr [0] = 0;
  for (size_type j = 0; j < n_data; j++) {
    size_type size_j = base::_values [ip[j]];
    yptr[j+1] = yptr[j] + size_j;
  }
  for (size_type i = 0; i < n_data; i++) {
    size_type size_i = base::_values [i];
    size_type j = _ptr[i];
    for (size_type k = 0; k < size_i; j++) {
      _multi_indices [yptr[j]+k] = _ptr[i] + k;
    }
  }
#endif // TO_CLEAN
  // --------------------------------------------
  // 3) eliminate zero-sized multi-messages
  // --------------------------------------------
  // some values could asked for send/receive could be empty set, so 
  // the multi_nproc of send/receive could be < nproc for sizes
  // => check for empty messages, i.e. with zero-sized multi-valued containers(set,list,..)
  //    and MPI waits infinitely for empty messages to arrive...
  size_type nproc = base::_procs.size();
  std::vector<size_type> msg_size (nproc, 0);
  size_type multi_nproc = 0;
  for (size_type iproc = 0; iproc < nproc; iproc++) {
    for (size_type   i = base::_starts[iproc],
                last_i = base::_starts[iproc+1]; i < last_i; i++) {
      size_type size_i = base::_values [i];
      msg_size[iproc] += size_i;
    }
    if (msg_size[iproc] != 0) {
      multi_nproc++;
    }
  }
  // --------------------------------------------
  // 4) resize & fill multi_{procs,starts} arrays
  // --------------------------------------------
  _multi_procs.resize   (multi_nproc);
  _multi_starts.resize  (multi_nproc+1);
  _multi_irecv2base_irecv.resize  (multi_nproc);
  _multi_starts [0] = 0;
  for (size_type iproc = 0, multi_iproc = 0; iproc < nproc; iproc++) {
    if (msg_size[iproc] == 0) continue;
    _multi_procs  [multi_iproc]   = base::_procs [iproc];
    _multi_starts [multi_iproc+1] = _multi_starts [multi_iproc] + msg_size[iproc]; 
    _multi_irecv2base_irecv [multi_iproc] = iproc;
    multi_iproc++;
  }
}
// =================================================================================
// part 2: load and store
// =================================================================================
// values[i] = x[indices[i]], i=[0..n_data[
template<class Container>
template<class InputIterator>
void
scatter_message<Container,false>::load_values (InputIterator x)
{
   msg_right_permutation_apply (
     _indices.begin(),
     _indices.end(),
     x,
     _values.begin());
}
// the same with multi-valued data:
template<class Container>
template<class InputIterator>
void
scatter_message<Container,true>::load_values (InputIterator x)
{
  for (size_type i = 0, n_data = base::_indices.size(), z = 0; i < n_data; i++) {
    size_type pi = base::_indices[i];
    for (typename value_type::const_iterator first = x[pi].begin(), last = x[pi].end(); first != last; first++, z++) {
      _multi_values [z] = *first;
    }
  }
}
// y[indices[i]] = value[i], i=[start(i_recv)..starts(i_recv+1)[
template<class Container>
template<class OutputIterator, class SetOp>
void
scatter_message<Container,false>::store_values (OutputIterator y, size_type i_recv, SetOp op) const
{
  msg_left_permutation_apply (
    _values.begin()  + _starts[i_recv],
    op,
    _indices.begin() + _starts[i_recv],
    _indices.begin() + _starts[i_recv+1],
    y);
}
// the same with multi-valued data:
template<class Container>
template<class OutputIterator, class SetOp>
void
scatter_message<Container,true>::store_values (OutputIterator y, size_type i_multi_recv, SetOp op) const
{
  size_type i_recv = _multi_irecv2base_irecv [i_multi_recv];
  for (size_type i = base::_starts[i_recv], n_data = base::_starts[i_recv+1]; i < n_data; i++) {
    size_type pi = base::_indices[i];
    for (size_type z = _ptr[i], last_z = _ptr[i+1]; z < last_z; z++) {
      y[pi] += _multi_values [z];
    }
  }
}
 
} // namespace rheolef
#endif // _RHEOLEF_HAVE_MPI
#endif // _RHEOLEF_SCATTER_MESSAGE_ICC