reduce.cpp

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// @HEADER
// *****************************************************************************
//                    Teuchos: Common Tools Package
//
// Copyright 2004 NTESS and the Teuchos contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#include "Teuchos_ConfigDefs.hpp"
#include "Teuchos_DefaultComm.hpp"
#include "Teuchos_CommHelpers.hpp"
#ifdef HAVE_TEUCHOS_MPI
#  include "Teuchos_DefaultMpiComm.hpp"
#endif // HAVE_TEUCHOS_MPI
#include "Teuchos_UnitTestHarness.hpp"


template<class PacketType>
bool
testReduceSum (bool& success, std::ostream& out,
               const int root, const Teuchos::Comm<int>& comm)
{
  using Teuchos::reduce;
  using Teuchos::TypeNameTraits;
  using std::endl;
  typedef PacketType packet_type;

  // Teuchos constructs the output stream such that it only prints on
  // Process 0 anyway.
  out << "Testing Teuchos::reduce<int, " << TypeNameTraits<packet_type>::name ()
      << "> with reductType = REDUCE_SUM and root = " << root << endl;

  const packet_type ZERO = Teuchos::ScalarTraits<packet_type>::zero ();
  const packet_type ONE = Teuchos::ScalarTraits<packet_type>::one ();
  const int count = 10;
  packet_type sendBuf[10];
  packet_type recvBuf[10];
  for (int i = 0; i < count; ++i) {
    sendBuf[i] = ONE;
    recvBuf[i] = ZERO;
  }
  const Teuchos::EReductionType reductType = Teuchos::REDUCE_SUM;
  reduce<int, packet_type> (sendBuf, recvBuf, count, reductType, root, comm);

  // Don't trust that any other Teuchos communicator wrapper functions
  // work here.  Instead, if building with MPI, use raw MPI.  If not
  // building with MPI, first test that comm has only one process,
  // then assume this in the test.

#ifdef HAVE_TEUCHOS_MPI
  using Teuchos::MpiComm;
  int err = MPI_SUCCESS;

  const MpiComm<int>* mpiComm = dynamic_cast<const MpiComm<int>* > (&comm);
  TEUCHOS_TEST_FOR_EXCEPTION
    (mpiComm == NULL, std::logic_error, "Building with MPI, but default "
     "communicator is not a Teuchos::MpiComm!");
  MPI_Comm rawMpiComm = * (mpiComm->getRawMpiComm ());

  // Use a barrier to make sure that every process got this far.
  err = MPI_Barrier (rawMpiComm);
  TEUCHOS_TEST_FOR_EXCEPTION
    (err != MPI_SUCCESS, std::logic_error, "MPI_Barrier failed!");

  // Recompute using MPI.  Use an all-reduce to simplify the test.
  packet_type sendBuf2[10];
  packet_type recvBuf2[10];
  for (int i = 0; i < count; ++i) {
    sendBuf2[i] = ONE;
    recvBuf2[i] = ZERO;
  }
  // FIXME (14 Jul 2015) Need to get the MPI_Datatype right for PacketType.
  MPI_Datatype rawMpiType;
  if (typeid (packet_type) == typeid (short)) {
    rawMpiType = MPI_SHORT;
  } else if (typeid (packet_type) == typeid (unsigned short)) {
    rawMpiType = MPI_UNSIGNED_SHORT;
  } else if (typeid (packet_type) == typeid (int)) {
    rawMpiType = MPI_INT;
  } else if (typeid (packet_type) == typeid (unsigned int)) {
    rawMpiType = MPI_UNSIGNED;
  } else if (typeid (packet_type) == typeid (long)) {
    rawMpiType = MPI_LONG;
  } else if (typeid (packet_type) == typeid (unsigned long)) {
    rawMpiType = MPI_UNSIGNED_LONG;
  } else if (typeid (packet_type) == typeid (long long)) {
    rawMpiType = MPI_LONG_LONG;
  } else if (typeid (packet_type) == typeid (unsigned long long)) {
    rawMpiType = MPI_UNSIGNED_LONG_LONG;
  } else if (typeid (packet_type) == typeid (float)) {
    rawMpiType = MPI_FLOAT;
  } else if (typeid (packet_type) == typeid (double)) {
    rawMpiType = MPI_DOUBLE;
  } else {
    TEUCHOS_TEST_FOR_EXCEPTION
      (true, std::logic_error, "Unimplemented conversion from PacketType = "
       << TypeNameTraits<packet_type>::name () << " to MPI_Datatype.");
  }

  err = MPI_Allreduce (sendBuf2, recvBuf2, count, rawMpiType, MPI_SUM, rawMpiComm);
  TEUCHOS_TEST_FOR_EXCEPTION
    (err != MPI_SUCCESS, std::logic_error, "MPI_Allreduce failed!");
  if (root == comm.getRank ()) {
    for (int i = 0; i < count; ++i) {
      TEST_EQUALITY( recvBuf2[i], recvBuf[i] );
    }
  }

  int lclSuccess = success ? 1 : 0;
  int gblSuccess = lclSuccess;
  err = MPI_Allreduce (&lclSuccess, &gblSuccess, 1, MPI_INT, MPI_MIN, rawMpiComm);
  TEUCHOS_TEST_FOR_EXCEPTION
    (err != MPI_SUCCESS, std::logic_error, "MPI_Allreduce failed!");
  success = gblSuccess == 1 ? true : false;

#else // HAVE_TEUCHOS_MPI
  TEUCHOS_TEST_FOR_EXCEPTION
    (comm.getSize () != 1, std::logic_error, "Not building with MPI, but "
     "communicator has size = " << comm.getSize () << " != 1.  We don't know "
     "how to test this case.");
  for (int i = 0; i < count; ++i) {
    TEST_EQUALITY( sendBuf[i], recvBuf[i] );
    TEST_EQUALITY( recvBuf[i], ONE );
  }
#endif // HAVE_TEUCHOS_MPI

  return success;
}


TEUCHOS_UNIT_TEST_TEMPLATE_1_DECL( Comm, ReduceSum, PacketType )
{
  using Teuchos::Comm;
  using Teuchos::RCP;
  using Teuchos::reduce;
  typedef PacketType packet_type;

  RCP<const Comm<int> > comm = Teuchos::DefaultComm<int>::getComm ();
  const int numProcs = comm->getSize ();

  // Make sure that it works for all possible root processes in the
  // communicator, not just Process 0.
  for (int root = 0; root < numProcs; ++root) {
    const bool curSuccess = testReduceSum<packet_type> (success, out, root, *comm);
    TEST_EQUALITY_CONST( curSuccess, true );
    success = success && curSuccess;
  }
}

//
// mfh 14 Jul 2015: We only need to test int for now.  See Bug 6375.
//
TEUCHOS_UNIT_TEST_TEMPLATE_1_INSTANT( Comm, ReduceSum, int )