Teuchos_GlobalMPISession.cpp

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//                    Teuchos: Common Tools Package
//                 Copyright (2004) Sandia Corporation
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#include "Teuchos_GlobalMPISession.hpp"
#include "Teuchos_Assert.hpp"

namespace Teuchos {

bool GlobalMPISession::haveMPIState_ = false;
bool GlobalMPISession::mpiIsFinalized_ = false;
int GlobalMPISession::rank_ = 0 ;
int GlobalMPISession::nProc_ = 1 ;

GlobalMPISession::GlobalMPISession( int* argc, char*** argv, std::ostream *out )
{
  std::ostringstream oss;

  // Above is used to create all output before sending to *out to avoid
  // jumbled parallel output between processors

#ifdef HAVE_MPI
  // initialize MPI
  int mpiHasBeenStarted = 0, mpierr = 0;
  MPI_Initialized(&mpiHasBeenStarted);
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpiHasBeenStarted, std::runtime_error
    ,"Error, you can only call this constructor once!"
    ,out
    );

  mpierr = ::MPI_Init (argc, (char ***) argv);
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpierr != 0, std::runtime_error
    ,"Error code=" << mpierr << " detected in GlobalMPISession::GlobalMPISession(argc,argv)"
    ,out
    );

  initialize(out); // Get NProc_ and rank_
  
  int nameLen;
  char procName[MPI_MAX_PROCESSOR_NAME];
  mpierr = ::MPI_Get_processor_name(procName,&nameLen);
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpierr != 0, std::runtime_error
    ,"Error code=" << mpierr << " detected in MPI_Get_processor_name()"
    ,out
    );

  oss << "Teuchos::GlobalMPISession::GlobalMPISession(): started processor with name "
      << procName << " and rank " << rank_ << "!" << std::endl;

#else
  oss << "Teuchos::GlobalMPISession::GlobalMPISession(): started serial run" << std::endl;
#endif
#ifndef TEUCHOS_SUPPRESS_PROC_STARTUP_BANNER
  // See if we should suppress the startup banner
  bool printStartupBanner = true;
  const std::string suppress_option("--teuchos-suppress-startup-banner");
  for( int opt_i = 0; opt_i < *argc; ++opt_i ) { 
    if( suppress_option == (*argv)[opt_i] ) {
      // We are suppressing the output!
      printStartupBanner = false;
      // Remove this option!
      // Note that (*argv)[*argc]==0 but convention so we copy it too!
      for( int i = opt_i; i < *argc; ++i )
        (*argv)[i] = (*argv)[i+1];
      --*argc;
    }
  }
  if( out && printStartupBanner )
    *out << oss.str() << std::flush;
#endif
}

GlobalMPISession::~GlobalMPISession()
{
  haveMPIState_ = false;
  mpiIsFinalized_ = true;
#ifdef HAVE_MPI
  int mpierr = ::MPI_Finalize();
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpierr != 0, std::runtime_error
    ,"Error code=" << mpierr << " detected in MPI_Finalize()"
    ,&std::cerr
    );
#endif
}

bool GlobalMPISession::mpiIsInitialized() {
  if(!haveMPIState_)
    initialize(&std::cerr);
  return haveMPIState_;
}

bool GlobalMPISession::mpiIsFinalized()
{
  return mpiIsFinalized_;
}
  
int GlobalMPISession::getRank()
{
  if(!haveMPIState_)
    initialize(&std::cerr);
  return rank_;
}

int GlobalMPISession::getNProc() {
  if(!haveMPIState_)
    initialize(&std::cerr);
  return nProc_;
}

// private

void GlobalMPISession::initialize( std::ostream *out )
{
#ifdef HAVE_MPI

  if(mpiIsFinalized_) {
    // MPI has aleady been finalized so we have a serial machine again!
    rank_ = 0;
    nProc_ = 1;
    return;
  }

  if(haveMPIState_)
    return; // We already have what we need!

  // We don't have the state of MPI so the constructor for this class must not
  // have been called.  However, if MPI has been called in another way we
  // can still get the state of MPI_COMM_WORLD here.

  int mpiHasBeenStarted = 0, mpierr = 0;
  MPI_Initialized(&mpiHasBeenStarted);
  
  if(!mpiHasBeenStarted)
    return;  // We have to give up and just leave NProc_ and rank_ at the default values.
  
  // Get the state of MPI
  
  mpierr = ::MPI_Comm_rank( MPI_COMM_WORLD, &rank_ );
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpierr != 0, std::runtime_error
    ,"Error code=" << mpierr << " detected in MPI_Comm_rank()"
    ,out
    );
  
  mpierr = ::MPI_Comm_size( MPI_COMM_WORLD, &nProc_ );
  TEUCHOS_TEST_FOR_EXCEPTION_PRINT(
    mpierr != 0, std::runtime_error
    ,"Error code=" << mpierr << " detected in MPI_Comm_size()"
    ,out
    );

  haveMPIState_ = true;
  mpiIsFinalized_ = false;

#endif // HAVE_MPI
  
}

} // namespace Teuchos