MOAB: Mesh Oriented datABase  (version 5.2.1)
HelloParMOAB.cpp
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00001 /** @example HelloParMOAB.cpp \n
00002  * \brief Read mesh into MOAB and resolve/exchange/report shared and ghosted entities \n
00003  * <b>To run</b>: mpiexec -np 4 HelloParMOAB [filename]\n
00004  *
00005  *  It shows how to load the mesh independently, on multiple
00006  *  communicators (with second argument, the number of comms)
00007  *
00008  *  mpiexec -np 8 HelloParMOAB [filename] [nbComms]
00009  */
00010 
00011 #include "moab/Core.hpp"
00012 #ifdef MOAB_HAVE_MPI
00013 #include "moab/ParallelComm.hpp"
00014 #endif
00015 #include "MBParallelConventions.h"
00016 #include <iostream>
00017 
00018 using namespace moab;
00019 using namespace std;
00020 
00021 string test_file_name = string( MESH_DIR ) + string( "/64bricks_512hex_256part.h5m" );
00022 
00023 int main( int argc, char** argv )
00024 {
00025 #ifdef MOAB_HAVE_MPI
00026     MPI_Init( &argc, &argv );
00027 
00028     string options;
00029 
00030     // Need option handling here for input filename
00031     if( argc > 1 )
00032     {
00033         // User has input a mesh file
00034         test_file_name = argv[1];
00035     }
00036 
00037     int nbComms = 1;
00038     if( argc > 2 ) nbComms = atoi( argv[2] );
00039 
00040     options = "PARALLEL=READ_PART;PARTITION=PARALLEL_PARTITION;PARALLEL_RESOLVE_SHARED_ENTS";
00041 
00042     // Get MOAB instance
00043     Interface* mb = new( std::nothrow ) Core;
00044     if( NULL == mb ) return 1;
00045 
00046     MPI_Comm comm;
00047     int global_rank, global_size;
00048     MPI_Comm_rank( MPI_COMM_WORLD, &global_rank );
00049     MPI_Comm_rank( MPI_COMM_WORLD, &global_size );
00050 
00051     int color = global_rank % nbComms;  // For each angle group a different color
00052     if( nbComms > 1 )
00053     {
00054         // Split the communicator, into ngroups = nbComms
00055         MPI_Comm_split( MPI_COMM_WORLD, color, global_rank, &comm );
00056     }
00057     else
00058         comm = MPI_COMM_WORLD;
00059 
00060     // Get the ParallelComm instance
00061     ParallelComm* pcomm = new ParallelComm( mb, comm );
00062     int nprocs          = pcomm->proc_config().proc_size();
00063     int rank            = pcomm->proc_config().proc_rank();
00064 #ifndef NDEBUG
00065     MPI_Comm rcomm = pcomm->proc_config().proc_comm();
00066     assert( rcomm == comm );
00067 #endif
00068     if( 0 == global_rank )
00069         cout << " global rank:" << global_rank << " color:" << color << " rank:" << rank << " of " << nprocs
00070              << " processors\n";
00071 
00072     if( 1 == global_rank )
00073         cout << " global rank:" << global_rank << " color:" << color << " rank:" << rank << " of " << nprocs
00074              << " processors\n";
00075 
00076     MPI_Barrier( MPI_COMM_WORLD );
00077 
00078     if( 0 == global_rank )
00079         cout << "Reading file " << test_file_name << "\n with options: " << options << "\n on " << nprocs
00080              << " processors on " << nbComms << " communicator(s)\n";
00081 
00082     // Read the file with the specified options
00083     ErrorCode rval = mb->load_file( test_file_name.c_str(), 0, options.c_str() );MB_CHK_ERR( rval );
00084 
00085     Range shared_ents;
00086     // Get entities shared with all other processors
00087     rval = pcomm->get_shared_entities( -1, shared_ents );MB_CHK_ERR( rval );
00088 
00089     // Filter shared entities with not not_owned, which means owned
00090     Range owned_entities;
00091     rval = pcomm->filter_pstatus( shared_ents, PSTATUS_NOT_OWNED, PSTATUS_NOT, -1, &owned_entities );MB_CHK_ERR( rval );
00092 
00093     unsigned int nums[4] = { 0 };  // to store the owned entities per dimension
00094     for( int i = 0; i < 4; i++ )
00095         nums[i] = (int)owned_entities.num_of_dimension( i );
00096     vector< int > rbuf( nprocs * 4, 0 );
00097     MPI_Gather( nums, 4, MPI_INT, &rbuf[0], 4, MPI_INT, 0, comm );
00098     // Print the stats gathered:
00099     if( 0 == global_rank )
00100     {
00101         for( int i = 0; i < nprocs; i++ )
00102             cout << " Shared, owned entities on proc " << i << ": " << rbuf[4 * i] << " verts, " << rbuf[4 * i + 1]
00103                  << " edges, " << rbuf[4 * i + 2] << " faces, " << rbuf[4 * i + 3] << " elements" << endl;
00104     }
00105 
00106     // Now exchange 1 layer of ghost elements, using vertices as bridge
00107     // (we could have done this as part of reading process, using the PARALLEL_GHOSTS read option)
00108     rval = pcomm->exchange_ghost_cells( 3,  // int ghost_dim
00109                                         0,  // int bridge_dim
00110                                         1,  // int num_layers
00111                                         0,  // int addl_ents
00112                                         true );MB_CHK_ERR( rval );  // bool store_remote_handles
00113 
00114     // Repeat the reports, after ghost exchange
00115     shared_ents.clear();
00116     owned_entities.clear();
00117     rval = pcomm->get_shared_entities( -1, shared_ents );MB_CHK_ERR( rval );
00118     rval = pcomm->filter_pstatus( shared_ents, PSTATUS_NOT_OWNED, PSTATUS_NOT, -1, &owned_entities );MB_CHK_ERR( rval );
00119 
00120     // Find out how many shared entities of each dimension are owned on this processor
00121     for( int i = 0; i < 4; i++ )
00122         nums[i] = (int)owned_entities.num_of_dimension( i );
00123 
00124     // Gather the statistics on processor 0
00125     MPI_Gather( nums, 4, MPI_INT, &rbuf[0], 4, MPI_INT, 0, comm );
00126     if( 0 == global_rank )
00127     {
00128         cout << " \n\n After exchanging one ghost layer: \n";
00129         for( int i = 0; i < nprocs; i++ )
00130         {
00131             cout << " Shared, owned entities on proc " << i << ": " << rbuf[4 * i] << " verts, " << rbuf[4 * i + 1]
00132                  << " edges, " << rbuf[4 * i + 2] << " faces, " << rbuf[4 * i + 3] << " elements" << endl;
00133         }
00134     }
00135 
00136     delete mb;
00137 
00138     MPI_Finalize();
00139 #else
00140     std::cout << " compile with MPI and hdf5 for this example to work\n";
00141 
00142 #endif
00143     return 0;
00144 }
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