NCHelperHOMME.cpp

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#include "NCHelperHOMME.hpp"
#include "moab/ReadUtilIface.hpp"
#include "moab/FileOptions.hpp"
#include "moab/SpectralMeshTool.hpp"

#include <cmath>

namespace moab
{

NCHelperHOMME::NCHelperHOMME( ReadNC* readNC, int fileId, const FileOptions& opts, EntityHandle fileSet )
    : UcdNCHelper( readNC, fileId, opts, fileSet ), _spectralOrder( -1 ), connectId( -1 ), isConnFile( false )
{
    // Calculate spectral order
    std::map< std::string, ReadNC::AttData >::iterator attIt = readNC->globalAtts.find( "np" );
    if( attIt != readNC->globalAtts.end() )
    {
        int success = NCFUNC( get_att_int )( readNC->fileId, attIt->second.attVarId, attIt->second.attName.c_str(),
                                             &_spectralOrder );
        if( 0 == success ) _spectralOrder--;  // Spectral order is one less than np
    }
    else
    {
        // As can_read_file() returns true and there is no global attribute "np", it should be a
        // connectivity file
        isConnFile     = true;
        _spectralOrder = 3;  // Assume np is 4
    }
}

bool NCHelperHOMME::can_read_file( ReadNC* readNC, int fileId )
{
    // If global attribute "np" exists then it should be the HOMME grid
    if( readNC->globalAtts.find( "np" ) != readNC->globalAtts.end() )
    {
        // Make sure it is CAM grid
        std::map< std::string, ReadNC::AttData >::iterator attIt = readNC->globalAtts.find( "source" );
        if( attIt == readNC->globalAtts.end() ) return false;
        unsigned int sz = attIt->second.attLen;
        std::string att_data;
        att_data.resize( sz + 1 );
        att_data[sz] = '\000';
        int success =
            NCFUNC( get_att_text )( fileId, attIt->second.attVarId, attIt->second.attName.c_str(), &att_data[0] );
        if( success ) return false;
        if( att_data.find( "CAM" ) == std::string::npos ) return false;

        return true;
    }
    else
    {
        // If dimension names "ncol" AND "ncorners" AND "ncells" exist, then it should be the HOMME
        // connectivity file In this case, the mesh can still be created
        std::vector< std::string >& dimNames = readNC->dimNames;
        if( ( std::find( dimNames.begin(), dimNames.end(), std::string( "ncol" ) ) != dimNames.end() ) &&
            ( std::find( dimNames.begin(), dimNames.end(), std::string( "ncorners" ) ) != dimNames.end() ) &&
            ( std::find( dimNames.begin(), dimNames.end(), std::string( "ncells" ) ) != dimNames.end() ) )
            return true;
    }

    return false;
}

ErrorCode NCHelperHOMME::init_mesh_vals()
{
    std::vector< std::string >& dimNames              = _readNC->dimNames;
    std::vector< int >& dimLens                       = _readNC->dimLens;
    std::map< std::string, ReadNC::VarData >& varInfo = _readNC->varInfo;

    ErrorCode rval;
    unsigned int idx;
    std::vector< std::string >::iterator vit;

    // Look for time dimension
    if( isConnFile )
    {
        // Connectivity file might not have time dimension
    }
    else
    {
        if( ( vit = std::find( dimNames.begin(), dimNames.end(), "time" ) ) != dimNames.end() )
            idx = vit - dimNames.begin();
        else if( ( vit = std::find( dimNames.begin(), dimNames.end(), "t" ) ) != dimNames.end() )
            idx = vit - dimNames.begin();
        else
        {
            MB_SET_ERR( MB_FAILURE, "Couldn't find 'time' or 't' dimension" );
        }
        tDim       = idx;
        nTimeSteps = dimLens[idx];
    }

    // Get number of vertices (labeled as number of columns)
    if( ( vit = std::find( dimNames.begin(), dimNames.end(), "ncol" ) ) != dimNames.end() )
        idx = vit - dimNames.begin();
    else
    {
        MB_SET_ERR( MB_FAILURE, "Couldn't find 'ncol' dimension" );
    }
    vDim      = idx;
    nVertices = dimLens[idx];

    // Set number of cells
    nCells = nVertices - 2;

    // Get number of levels
    if( isConnFile )
    {
        // Connectivity file might not have level dimension
    }
    else
    {
        if( ( vit = std::find( dimNames.begin(), dimNames.end(), "lev" ) ) != dimNames.end() )
            idx = vit - dimNames.begin();
        else if( ( vit = std::find( dimNames.begin(), dimNames.end(), "ilev" ) ) != dimNames.end() )
            idx = vit - dimNames.begin();
        else
        {
            MB_SET_ERR( MB_FAILURE, "Couldn't find 'lev' or 'ilev' dimension" );
        }
        levDim  = idx;
        nLevels = dimLens[idx];
    }

    // Store lon values in xVertVals
    std::map< std::string, ReadNC::VarData >::iterator vmit;
    if( ( vmit = varInfo.find( "lon" ) ) != varInfo.end() && ( *vmit ).second.varDims.size() == 1 )
    {
        rval = read_coordinate( "lon", 0, nVertices - 1, xVertVals );MB_CHK_SET_ERR( rval, "Trouble reading 'lon' variable" );
    }
    else
    {
        MB_SET_ERR( MB_FAILURE, "Couldn't find 'lon' variable" );
    }

    // Store lat values in yVertVals
    if( ( vmit = varInfo.find( "lat" ) ) != varInfo.end() && ( *vmit ).second.varDims.size() == 1 )
    {
        rval = read_coordinate( "lat", 0, nVertices - 1, yVertVals );MB_CHK_SET_ERR( rval, "Trouble reading 'lat' variable" );
    }
    else
    {
        MB_SET_ERR( MB_FAILURE, "Couldn't find 'lat' variable" );
    }

    // Store lev values in levVals
    if( isConnFile )
    {
        // Connectivity file might not have level variable
    }
    else
    {
        if( ( vmit = varInfo.find( "lev" ) ) != varInfo.end() && ( *vmit ).second.varDims.size() == 1 )
        {
            rval = read_coordinate( "lev", 0, nLevels - 1, levVals );MB_CHK_SET_ERR( rval, "Trouble reading 'lev' variable" );

            // Decide whether down is positive
            char posval[10] = { 0 };
            int success     = NCFUNC( get_att_text )( _fileId, ( *vmit ).second.varId, "positive", posval );
            if( 0 == success && !strcmp( posval, "down" ) )
            {
                for( std::vector< double >::iterator dvit = levVals.begin(); dvit != levVals.end(); ++dvit )
                    ( *dvit ) *= -1.0;
            }
        }
        else
        {
            MB_SET_ERR( MB_FAILURE, "Couldn't find 'lev' variable" );
        }
    }

    // Store time coordinate values in tVals
    if( isConnFile )
    {
        // Connectivity file might not have time variable
    }
    else
    {
        if( ( vmit = varInfo.find( "time" ) ) != varInfo.end() && ( *vmit ).second.varDims.size() == 1 )
        {
            rval = read_coordinate( "time", 0, nTimeSteps - 1, tVals );MB_CHK_SET_ERR( rval, "Trouble reading 'time' variable" );
        }
        else if( ( vmit = varInfo.find( "t" ) ) != varInfo.end() && ( *vmit ).second.varDims.size() == 1 )
        {
            rval = read_coordinate( "t", 0, nTimeSteps - 1, tVals );MB_CHK_SET_ERR( rval, "Trouble reading 't' variable" );
        }
        else
        {
            // If expected time variable does not exist, set dummy values to tVals
            for( int t = 0; t < nTimeSteps; t++ )
                tVals.push_back( (double)t );
        }
    }

    // For each variable, determine the entity location type and number of levels
    std::map< std::string, ReadNC::VarData >::iterator mit;
    for( mit = varInfo.begin(); mit != varInfo.end(); ++mit )
    {
        ReadNC::VarData& vd = ( *mit ).second;

        // Default entLoc is ENTLOCSET
        if( std::find( vd.varDims.begin(), vd.varDims.end(), tDim ) != vd.varDims.end() )
        {
            if( std::find( vd.varDims.begin(), vd.varDims.end(), vDim ) != vd.varDims.end() )
                vd.entLoc = ReadNC::ENTLOCVERT;
        }

        // Default numLev is 0
        if( std::find( vd.varDims.begin(), vd.varDims.end(), levDim ) != vd.varDims.end() ) vd.numLev = nLevels;
    }

    // Hack: create dummy variables for dimensions (like ncol) with no corresponding coordinate
    // variables
    rval = create_dummy_variables();MB_CHK_SET_ERR( rval, "Failed to create dummy variables" );

    return MB_SUCCESS;
}

// When noMesh option is used on this read, the old ReadNC class instance for last read can get out
// of scope (and deleted). The old instance initialized localGidVerts properly when the mesh was
// created, but it is now lost. The new instance (will not create the mesh with noMesh option) has
// to restore it based on the existing mesh from last read
ErrorCode NCHelperHOMME::check_existing_mesh()
{
    Interface*& mbImpl = _readNC->mbImpl;
    Tag& mGlobalIdTag  = _readNC->mGlobalIdTag;
    bool& noMesh       = _readNC->noMesh;

    if( noMesh && localGidVerts.empty() )
    {
        // We need to populate localGidVerts range with the gids of vertices from current file set
        // localGidVerts is important in reading the variable data into the nodes
        // Also, for our purposes, localGidVerts is truly the GLOBAL_ID tag data, not other
        // file_id tags that could get passed around in other scenarios for parallel reading

        // Get all vertices from current file set (it is the input set in no_mesh scenario)
        Range local_verts;
        ErrorCode rval = mbImpl->get_entities_by_dimension( _fileSet, 0, local_verts );MB_CHK_SET_ERR( rval, "Trouble getting local vertices in current file set" );

        if( !local_verts.empty() )
        {
            std::vector< int > gids( local_verts.size() );

            // !IMPORTANT : this has to be the GLOBAL_ID tag
            rval = mbImpl->tag_get_data( mGlobalIdTag, local_verts, &gids[0] );MB_CHK_SET_ERR( rval, "Trouble getting local gid values of vertices" );

            // Restore localGidVerts
            std::copy( gids.rbegin(), gids.rend(), range_inserter( localGidVerts ) );
            nLocalVertices = localGidVerts.size();
        }
    }

    return MB_SUCCESS;
}

ErrorCode NCHelperHOMME::create_mesh( Range& faces )
{
    Interface*& mbImpl         = _readNC->mbImpl;
    std::string& fileName      = _readNC->fileName;
    Tag& mGlobalIdTag          = _readNC->mGlobalIdTag;
    const Tag*& mpFileIdTag    = _readNC->mpFileIdTag;
    DebugOutput& dbgOut        = _readNC->dbgOut;
    bool& spectralMesh         = _readNC->spectralMesh;
    int& gatherSetRank         = _readNC->gatherSetRank;
    int& trivialPartitionShift = _readNC->trivialPartitionShift;

    int rank  = 0;
    int procs = 1;
#ifdef MOAB_HAVE_MPI
    bool& isParallel = _readNC->isParallel;
    if( isParallel )
    {
        ParallelComm*& myPcomm = _readNC->myPcomm;
        rank                   = myPcomm->proc_config().proc_rank();
        procs                  = myPcomm->proc_config().proc_size();
    }
#endif

    ErrorCode rval;
    int success = 0;

    // Need to get/read connectivity data before creating elements
    std::string conn_fname;

    if( isConnFile )
    {
        // Connectivity file has already been read
        connectId = _readNC->fileId;
    }
    else
    {
        // Try to open the connectivity file through CONN option, if used
        rval = _opts.get_str_option( "CONN", conn_fname );
        if( MB_SUCCESS != rval )
        {
            // Default convention for reading HOMME is a file HommeMapping.nc in same dir as data
            // file
            conn_fname = std::string( fileName );
            size_t idx = conn_fname.find_last_of( "/" );
            if( idx != std::string::npos )
                conn_fname = conn_fname.substr( 0, idx ).append( "/HommeMapping.nc" );
            else
                conn_fname = "HommeMapping.nc";
        }
#ifdef MOAB_HAVE_PNETCDF
#ifdef MOAB_HAVE_MPI
        if( isParallel )
        {
            ParallelComm*& myPcomm = _readNC->myPcomm;
            success =
                NCFUNC( open )( myPcomm->proc_config().proc_comm(), conn_fname.c_str(), 0, MPI_INFO_NULL, &connectId );
        }
        else
            success = NCFUNC( open )( MPI_COMM_SELF, conn_fname.c_str(), 0, MPI_INFO_NULL, &connectId );
#endif
#else
        success = NCFUNC( open )( conn_fname.c_str(), 0, &connectId );
#endif
        if( success ) MB_SET_ERR( MB_FAILURE, "Failed on open" );
    }

    std::vector< std::string > conn_names;
    std::vector< int > conn_vals;
    rval = _readNC->get_dimensions( connectId, conn_names, conn_vals );MB_CHK_SET_ERR( rval, "Failed to get dimensions for connectivity" );

    // Read connectivity into temporary variable
    int num_fine_quads   = 0;
    int num_coarse_quads = 0;
    int start_idx        = 0;
    std::vector< std::string >::iterator vit;
    int idx = 0;
    if( ( vit = std::find( conn_names.begin(), conn_names.end(), "ncells" ) ) != conn_names.end() )
        idx = vit - conn_names.begin();
    else if( ( vit = std::find( conn_names.begin(), conn_names.end(), "ncenters" ) ) != conn_names.end() )
        idx = vit - conn_names.begin();
    else
    {
        MB_SET_ERR( MB_FAILURE, "Failed to get number of quads" );
    }
    int num_quads = conn_vals[idx];
    if( !isConnFile && num_quads != nCells )
    {
        dbgOut.tprintf( 1,
                        "Warning: number of quads from %s and cells from %s are inconsistent; "
                        "num_quads = %d, nCells = %d.\n",
                        conn_fname.c_str(), fileName.c_str(), num_quads, nCells );
    }

    // Get the connectivity into tmp_conn2 and permute into tmp_conn
    int cornerVarId;
    success = NCFUNC( inq_varid )( connectId, "element_corners", &cornerVarId );
    if( success ) MB_SET_ERR( MB_FAILURE, "Failed to get variable id of 'element_corners'" );
    NCDF_SIZE tmp_starts[2] = { 0, 0 };
    NCDF_SIZE tmp_counts[2] = { 4, static_cast< NCDF_SIZE >( num_quads ) };
    std::vector< int > tmp_conn( 4 * num_quads ), tmp_conn2( 4 * num_quads );
    success = NCFUNCAG( _vara_int )( connectId, cornerVarId, tmp_starts, tmp_counts, &tmp_conn2[0] );
    if( success ) MB_SET_ERR( MB_FAILURE, "Failed to get temporary connectivity" );
    if( isConnFile )
    {
        // This data/connectivity file will be closed later in ReadNC::load_file()
    }
    else
    {
        success = NCFUNC( close )( connectId );
        if( success ) MB_SET_ERR( MB_FAILURE, "Failed on close" );
    }
    // Permute the connectivity
    for( int i = 0; i < num_quads; i++ )
    {
        tmp_conn[4 * i]     = tmp_conn2[i];
        tmp_conn[4 * i + 1] = tmp_conn2[i + 1 * num_quads];
        tmp_conn[4 * i + 2] = tmp_conn2[i + 2 * num_quads];
        tmp_conn[4 * i + 3] = tmp_conn2[i + 3 * num_quads];
    }

    // Need to know whether we'll be creating gather mesh later, to make sure
    // we allocate enough space in one shot
    bool create_gathers = false;
    if( rank == gatherSetRank ) create_gathers = true;

    // Shift rank to obtain a rotated trivial partition
    int shifted_rank = rank;
    if( procs >= 2 && trivialPartitionShift > 0 ) shifted_rank = ( rank + trivialPartitionShift ) % procs;

    // Compute the number of local quads, accounting for coarse or fine representation
    // spectral_unit is the # fine quads per coarse quad, or spectralOrder^2
    int spectral_unit = ( spectralMesh ? _spectralOrder * _spectralOrder : 1 );
    // num_coarse_quads is the number of quads instantiated in MOAB; if !spectralMesh,
    // num_coarse_quads = num_fine_quads
    num_coarse_quads = int( std::floor( 1.0 * num_quads / ( spectral_unit * procs ) ) );
    // start_idx is the starting index in the HommeMapping connectivity list for this proc, before
    // converting to coarse quad representation
    start_idx = 4 * shifted_rank * num_coarse_quads * spectral_unit;
    // iextra = # coarse quads extra after equal split over procs
    int iextra = num_quads % ( procs * spectral_unit );
    if( shifted_rank < iextra ) num_coarse_quads++;
    start_idx += 4 * spectral_unit * std::min( shifted_rank, iextra );
    // num_fine_quads is the number of quads in the connectivity list in HommeMapping file assigned
    // to this proc
    num_fine_quads = spectral_unit * num_coarse_quads;

    // Now create num_coarse_quads
    EntityHandle* conn_arr;
    EntityHandle start_vertex;
    Range tmp_range;

    // Read connectivity into that space
    EntityHandle* sv_ptr = NULL;
    EntityHandle start_quad;
    SpectralMeshTool smt( mbImpl, _spectralOrder );
    if( !spectralMesh )
    {
        rval = _readNC->readMeshIface->get_element_connect( num_coarse_quads, 4, MBQUAD, 0, start_quad, conn_arr,
                                                            // Might have to create gather mesh later
                                                            ( create_gathers ? num_coarse_quads + num_quads
                                                                             : num_coarse_quads ) );MB_CHK_SET_ERR( rval, "Failed to create local quads" );
        tmp_range.insert( start_quad, start_quad + num_coarse_quads - 1 );
        int* tmp_conn_end = ( &tmp_conn[start_idx + 4 * num_fine_quads - 1] ) + 1;
        std::copy( &tmp_conn[start_idx], tmp_conn_end, conn_arr );
        std::copy( conn_arr, conn_arr + 4 * num_fine_quads, range_inserter( localGidVerts ) );
    }
    else
    {
        rval = smt.create_spectral_elems( &tmp_conn[0], num_fine_quads, 2, tmp_range, start_idx, &localGidVerts );MB_CHK_SET_ERR( rval, "Failed to create spectral elements" );
        int count, v_per_e;
        rval = mbImpl->connect_iterate( tmp_range.begin(), tmp_range.end(), conn_arr, v_per_e, count );MB_CHK_SET_ERR( rval, "Failed to get connectivity of spectral elements" );
        rval = mbImpl->tag_iterate( smt.spectral_vertices_tag( true ), tmp_range.begin(), tmp_range.end(), count,
                                    (void*&)sv_ptr );MB_CHK_SET_ERR( rval, "Failed to get fine connectivity of spectral elements" );
    }

    // Create vertices
    nLocalVertices = localGidVerts.size();
    std::vector< double* > arrays;
    rval = _readNC->readMeshIface->get_node_coords( 3, nLocalVertices, 0, start_vertex, arrays,
                                                    // Might have to create gather mesh later
                                                    ( create_gathers ? nLocalVertices + nVertices : nLocalVertices ) );MB_CHK_SET_ERR( rval, "Failed to create local vertices" );

    // Set vertex coordinates
    Range::iterator rit;
    double* xptr = arrays[0];
    double* yptr = arrays[1];
    double* zptr = arrays[2];
    int i;
    for( i = 0, rit = localGidVerts.begin(); i < nLocalVertices; i++, ++rit )
    {
        assert( *rit < xVertVals.size() + 1 );
        xptr[i] = xVertVals[( *rit ) - 1];  // lon
        yptr[i] = yVertVals[( *rit ) - 1];  // lat
    }

    // Convert lon/lat/rad to x/y/z
    const double pideg = acos( -1.0 ) / 180.0;
    double rad         = ( isConnFile ) ? 8000.0 : 8000.0 + levVals[0];
    for( i = 0; i < nLocalVertices; i++ )
    {
        double cosphi = cos( pideg * yptr[i] );
        double zmult  = sin( pideg * yptr[i] );
        double xmult  = cosphi * cos( xptr[i] * pideg );
        double ymult  = cosphi * sin( xptr[i] * pideg );
        xptr[i]       = rad * xmult;
        yptr[i]       = rad * ymult;
        zptr[i]       = rad * zmult;
    }

    // Get ptr to gid memory for vertices
    Range vert_range( start_vertex, start_vertex + nLocalVertices - 1 );
    void* data;
    int count;
    rval = mbImpl->tag_iterate( mGlobalIdTag, vert_range.begin(), vert_range.end(), count, data );MB_CHK_SET_ERR( rval, "Failed to iterate global id tag on local vertices" );
    assert( count == nLocalVertices );
    int* gid_data = (int*)data;
    std::copy( localGidVerts.begin(), localGidVerts.end(), gid_data );

    // Duplicate global id data, which will be used to resolve sharing
    if( mpFileIdTag )
    {
        rval = mbImpl->tag_iterate( *mpFileIdTag, vert_range.begin(), vert_range.end(), count, data );MB_CHK_SET_ERR( rval, "Failed to iterate file id tag on local vertices" );
        assert( count == nLocalVertices );
        int bytes_per_tag = 4;
        rval              = mbImpl->tag_get_bytes( *mpFileIdTag, bytes_per_tag );MB_CHK_SET_ERR( rval, "Can't get number of bytes for file id tag" );
        if( 4 == bytes_per_tag )
        {
            gid_data = (int*)data;
            std::copy( localGidVerts.begin(), localGidVerts.end(), gid_data );
        }
        else if( 8 == bytes_per_tag )
        {  // Should be a handle tag on 64 bit machine?
            long* handle_tag_data = (long*)data;
            std::copy( localGidVerts.begin(), localGidVerts.end(), handle_tag_data );
        }
    }

    // Create map from file ids to vertex handles, used later to set connectivity
    std::map< EntityHandle, EntityHandle > vert_handles;
    for( rit = localGidVerts.begin(), i = 0; rit != localGidVerts.end(); ++rit, i++ )
        vert_handles[*rit] = start_vertex + i;

    // Compute proper handles in connectivity using offset
    for( int q = 0; q < 4 * num_coarse_quads; q++ )
    {
        conn_arr[q] = vert_handles[conn_arr[q]];
        assert( conn_arr[q] );
    }
    if( spectralMesh )
    {
        int verts_per_quad = ( _spectralOrder + 1 ) * ( _spectralOrder + 1 );
        for( int q = 0; q < verts_per_quad * num_coarse_quads; q++ )
        {
            sv_ptr[q] = vert_handles[sv_ptr[q]];
            assert( sv_ptr[q] );
        }
    }

    // Add new vertices and quads to current file set
    faces.merge( tmp_range );
    tmp_range.insert( start_vertex, start_vertex + nLocalVertices - 1 );
    rval = mbImpl->add_entities( _fileSet, tmp_range );MB_CHK_SET_ERR( rval, "Failed to add new vertices and quads to current file set" );

    // Mark the set with the spectral order
    Tag sporder;
    rval = mbImpl->tag_get_handle( "SPECTRAL_ORDER", 1, MB_TYPE_INTEGER, sporder, MB_TAG_SPARSE | MB_TAG_CREAT );MB_CHK_SET_ERR( rval, "Trouble creating SPECTRAL_ORDER tag" );
    rval = mbImpl->tag_set_data( sporder, &_fileSet, 1, &_spectralOrder );MB_CHK_SET_ERR( rval, "Trouble setting data to SPECTRAL_ORDER tag" );

    if( create_gathers )
    {
        EntityHandle gather_set;
        rval = _readNC->readMeshIface->create_gather_set( gather_set );MB_CHK_SET_ERR( rval, "Failed to create gather set" );

        // Create vertices
        arrays.clear();
        // Don't need to specify allocation number here, because we know enough verts were created
        // before
        rval = _readNC->readMeshIface->get_node_coords( 3, nVertices, 0, start_vertex, arrays );MB_CHK_SET_ERR( rval, "Failed to create gather set vertices" );

        xptr = arrays[0];
        yptr = arrays[1];
        zptr = arrays[2];
        for( i = 0; i < nVertices; i++ )
        {
            double cosphi = cos( pideg * yVertVals[i] );
            double zmult  = sin( pideg * yVertVals[i] );
            double xmult  = cosphi * cos( xVertVals[i] * pideg );
            double ymult  = cosphi * sin( xVertVals[i] * pideg );
            xptr[i]       = rad * xmult;
            yptr[i]       = rad * ymult;
            zptr[i]       = rad * zmult;
        }

        // Get ptr to gid memory for vertices
        Range gather_set_verts_range( start_vertex, start_vertex + nVertices - 1 );
        rval = mbImpl->tag_iterate( mGlobalIdTag, gather_set_verts_range.begin(), gather_set_verts_range.end(), count,
                                    data );MB_CHK_SET_ERR( rval, "Failed to iterate global id tag on gather set vertices" );
        assert( count == nVertices );
        gid_data = (int*)data;
        for( int j = 1; j <= nVertices; j++ )
            gid_data[j - 1] = j;
        // Set the file id tag too, it should be bigger something not interfering with global id
        if( mpFileIdTag )
        {
            rval = mbImpl->tag_iterate( *mpFileIdTag, gather_set_verts_range.begin(), gather_set_verts_range.end(),
                                        count, data );MB_CHK_SET_ERR( rval, "Failed to iterate file id tag on gather set vertices" );
            assert( count == nVertices );
            int bytes_per_tag = 4;
            rval              = mbImpl->tag_get_bytes( *mpFileIdTag, bytes_per_tag );MB_CHK_SET_ERR( rval, "Can't get number of bytes for file id tag" );
            if( 4 == bytes_per_tag )
            {
                gid_data = (int*)data;
                for( int j = 1; j <= nVertices; j++ )
                    gid_data[j - 1] = nVertices + j;  // Bigger than global id tag
            }
            else if( 8 == bytes_per_tag )
            {  // Should be a handle tag on 64 bit machine?
                long* handle_tag_data = (long*)data;
                for( int j = 1; j <= nVertices; j++ )
                    handle_tag_data[j - 1] = nVertices + j;  // Bigger than global id tag
            }
        }

        rval = mbImpl->add_entities( gather_set, gather_set_verts_range );MB_CHK_SET_ERR( rval, "Failed to add vertices to the gather set" );

        // Create quads
        Range gather_set_quads_range;
        // Don't need to specify allocation number here, because we know enough quads were created
        // before
        rval = _readNC->readMeshIface->get_element_connect( num_quads, 4, MBQUAD, 0, start_quad, conn_arr );MB_CHK_SET_ERR( rval, "Failed to create gather set quads" );
        gather_set_quads_range.insert( start_quad, start_quad + num_quads - 1 );
        int* tmp_conn_end = ( &tmp_conn[4 * num_quads - 1] ) + 1;
        std::copy( &tmp_conn[0], tmp_conn_end, conn_arr );
        for( i = 0; i != 4 * num_quads; i++ )
            conn_arr[i] += start_vertex - 1;  // Connectivity array is shifted by where the gather verts start
        rval = mbImpl->add_entities( gather_set, gather_set_quads_range );MB_CHK_SET_ERR( rval, "Failed to add quads to the gather set" );
    }

    return MB_SUCCESS;
}

ErrorCode NCHelperHOMME::read_ucd_variables_to_nonset_allocate( std::vector< ReadNC::VarData >& vdatas,
                                                                std::vector< int >& tstep_nums )
{
    Interface*& mbImpl          = _readNC->mbImpl;
    std::vector< int >& dimLens = _readNC->dimLens;
    DebugOutput& dbgOut         = _readNC->dbgOut;

    Range* range = NULL;

    // Get vertices
    Range verts;
    ErrorCode rval = mbImpl->get_entities_by_dimension( _fileSet, 0, verts );MB_CHK_SET_ERR( rval, "Trouble getting vertices in current file set" );
    assert( "Should only have a single vertex subrange, since they were read in one shot" && verts.psize() == 1 );

    for( unsigned int i = 0; i < vdatas.size(); i++ )
    {
        // Support non-set variables with 3 dimensions like (time, lev, ncol)
        assert( 3 == vdatas[i].varDims.size() );

        // For a non-set variable, time should be the first dimension
        assert( tDim == vdatas[i].varDims[0] );

        // Set up readStarts and readCounts
        vdatas[i].readStarts.resize( 3 );
        vdatas[i].readCounts.resize( 3 );

        // First: time
        vdatas[i].readStarts[0] = 0;  // This value is timestep dependent, will be set later
        vdatas[i].readCounts[0] = 1;

        // Next: lev
        vdatas[i].readStarts[1] = 0;
        vdatas[i].readCounts[1] = vdatas[i].numLev;

        // Finally: ncol
        switch( vdatas[i].entLoc )
        {
            case ReadNC::ENTLOCVERT:
                // Vertices
                // Start from the first localGidVerts
                // Actually, this will be reset later on in a loop
                vdatas[i].readStarts[2] = localGidVerts[0] - 1;
                vdatas[i].readCounts[2] = nLocalVertices;
                range                   = &verts;
                break;
            default:
                MB_SET_ERR( MB_FAILURE, "Unexpected entity location type for variable " << vdatas[i].varName );
        }

        // Get variable size
        vdatas[i].sz = 1;
        for( std::size_t idx = 0; idx != 3; idx++ )
            vdatas[i].sz *= vdatas[i].readCounts[idx];

        for( unsigned int t = 0; t < tstep_nums.size(); t++ )
        {
            dbgOut.tprintf( 2, "Reading variable %s, time step %d\n", vdatas[i].varName.c_str(), tstep_nums[t] );

            if( tstep_nums[t] >= dimLens[tDim] )
            {
                MB_SET_ERR( MB_INDEX_OUT_OF_RANGE, "Wrong value for timestep number " << tstep_nums[t] );
            }

            // Get the tag to read into
            if( !vdatas[i].varTags[t] )
            {
                rval = get_tag_to_nonset( vdatas[i], tstep_nums[t], vdatas[i].varTags[t], vdatas[i].numLev );MB_CHK_SET_ERR( rval, "Trouble getting tag for variable " << vdatas[i].varName );
            }

            // Get ptr to tag space
            void* data;
            int count;
            rval = mbImpl->tag_iterate( vdatas[i].varTags[t], range->begin(), range->end(), count, data );MB_CHK_SET_ERR( rval, "Failed to iterate tag for variable " << vdatas[i].varName );
            assert( (unsigned)count == range->size() );
            vdatas[i].varDatas[t] = data;
        }
    }

    return rval;
}

#ifdef MOAB_HAVE_PNETCDF
ErrorCode NCHelperHOMME::read_ucd_variables_to_nonset_async( std::vector< ReadNC::VarData >& vdatas,
                                                             std::vector< int >& tstep_nums )
{
    DebugOutput& dbgOut = _readNC->dbgOut;

    ErrorCode rval = read_ucd_variables_to_nonset_allocate( vdatas, tstep_nums );MB_CHK_SET_ERR( rval, "Trouble allocating space to read non-set variables" );

    // Finally, read into that space
    int success;

    for( unsigned int i = 0; i < vdatas.size(); i++ )
    {
        std::size_t sz = vdatas[i].sz;

        // A typical supported variable: float T(time, lev, ncol)
        // For tag values, need transpose (lev, ncol) to (ncol, lev)
        size_t ni = vdatas[i].readCounts[2];  // ncol
        size_t nj = 1;                        // Here we should just set nj to 1
        size_t nk = vdatas[i].readCounts[1];  // lev

        for( unsigned int t = 0; t < tstep_nums.size(); t++ )
        {
            // We will synchronize all these reads with the other processors,
            // so the wait will be inside this double loop; is it too much?
            size_t nb_reads = localGidVerts.psize();
            std::vector< int > requests( nb_reads ), statuss( nb_reads );
            size_t idxReq = 0;

            // Tag data for this timestep
            void* data = vdatas[i].varDatas[t];

            // Set readStart for each timestep along time dimension
            vdatas[i].readStarts[0] = tstep_nums[t];

            switch( vdatas[i].varDataType )
            {
                case NC_FLOAT:
                case NC_DOUBLE: {
                    // Read float as double
                    std::vector< double > tmpdoubledata( sz );

                    // In the case of ucd mesh, and on multiple proc,
                    // we need to read as many times as subranges we have in the
                    // localGidVerts range;
                    // basically, we have to give a different point
                    // for data to start, for every subrange :(
                    size_t indexInDoubleArray = 0;
                    size_t ic                 = 0;
                    for( Range::pair_iterator pair_iter = localGidVerts.pair_begin();
                         pair_iter != localGidVerts.pair_end(); ++pair_iter, ic++ )
                    {
                        EntityHandle starth     = pair_iter->first;
                        EntityHandle endh       = pair_iter->second;  // Inclusive
                        vdatas[i].readStarts[2] = (NCDF_SIZE)( starth - 1 );
                        vdatas[i].readCounts[2] = (NCDF_SIZE)( endh - starth + 1 );

                        // Do a partial read, in each subrange
                        // Wait outside this loop
                        success =
                            NCFUNCREQG( _vara_double )( _fileId, vdatas[i].varId, &( vdatas[i].readStarts[0] ),
                                                        &( vdatas[i].readCounts[0] ),
                                                        &( tmpdoubledata[indexInDoubleArray] ), &requests[idxReq++] );
                        if( success )
                            MB_SET_ERR( MB_FAILURE,
                                        "Failed to read double data in a loop for variable " << vdatas[i].varName );
                        // We need to increment the index in double array for the
                        // next subrange
                        indexInDoubleArray += ( endh - starth + 1 ) * 1 * vdatas[i].numLev;
                    }
                    assert( ic == localGidVerts.psize() );

                    success = ncmpi_wait_all( _fileId, requests.size(), &requests[0], &statuss[0] );
                    if( success ) MB_SET_ERR( MB_FAILURE, "Failed on wait_all" );

                    if( vdatas[i].numLev > 1 )
                        // Transpose (lev, ncol) to (ncol, lev)
                        kji_to_jik_stride( ni, nj, nk, data, &tmpdoubledata[0], localGidVerts );
                    else
                    {
                        for( std::size_t idx = 0; idx != tmpdoubledata.size(); idx++ )
                            ( (double*)data )[idx] = tmpdoubledata[idx];
                    }

                    break;
                }
                default:
                    MB_SET_ERR( MB_FAILURE, "Unexpected data type for variable " << vdatas[i].varName );
            }
        }
    }

    // Debug output, if requested
    if( 1 == dbgOut.get_verbosity() )
    {
        dbgOut.printf( 1, "Read variables: %s", vdatas.begin()->varName.c_str() );
        for( unsigned int i = 1; i < vdatas.size(); i++ )
            dbgOut.printf( 1, ", %s ", vdatas[i].varName.c_str() );
        dbgOut.tprintf( 1, "\n" );
    }

    return rval;
}
#else
ErrorCode NCHelperHOMME::read_ucd_variables_to_nonset( std::vector< ReadNC::VarData >& vdatas,
                                                       std::vector< int >& tstep_nums )
{
    DebugOutput& dbgOut = _readNC->dbgOut;

    ErrorCode rval = read_ucd_variables_to_nonset_allocate( vdatas, tstep_nums );MB_CHK_SET_ERR( rval, "Trouble allocating space to read non-set variables" );

    // Finally, read into that space
    int success;
    for( unsigned int i = 0; i < vdatas.size(); i++ )
    {
        std::size_t sz = vdatas[i].sz;

        // A typical supported variable: float T(time, lev, ncol)
        // For tag values, need transpose (lev, ncol) to (ncol, lev)
        size_t ni = vdatas[i].readCounts[2];  // ncol
        size_t nj = 1;                        // Here we should just set nj to 1
        size_t nk = vdatas[i].readCounts[1];  // lev

        for( unsigned int t = 0; t < tstep_nums.size(); t++ )
        {
            // Tag data for this timestep
            void* data = vdatas[i].varDatas[t];

            // Set readStart for each timestep along time dimension
            vdatas[i].readStarts[0] = tstep_nums[t];

            switch( vdatas[i].varDataType )
            {
                case NC_FLOAT:
                case NC_DOUBLE: {
                    // Read float as double
                    std::vector< double > tmpdoubledata( sz );

                    // In the case of ucd mesh, and on multiple proc,
                    // we need to read as many times as subranges we have in the
                    // localGidVerts range;
                    // basically, we have to give a different point
                    // for data to start, for every subrange :(
                    size_t indexInDoubleArray = 0;
                    size_t ic = 0;
                    for( Range::pair_iterator pair_iter = localGidVerts.pair_begin();
                         pair_iter != localGidVerts.pair_end(); ++pair_iter, ic++ )
                    {
                        EntityHandle starth = pair_iter->first;
                        EntityHandle endh = pair_iter->second;  // Inclusive
                        vdatas[i].readStarts[2] = (NCDF_SIZE)( starth - 1 );
                        vdatas[i].readCounts[2] = (NCDF_SIZE)( endh - starth + 1 );

                        success = NCFUNCAG( _vara_double )( _fileId, vdatas[i].varId, &( vdatas[i].readStarts[0] ),
                                                            &( vdatas[i].readCounts[0] ),
                                                            &( tmpdoubledata[indexInDoubleArray] ) );
                        if( success )
                            MB_SET_ERR( MB_FAILURE,
                                        "Failed to read double data in a loop for variable " << vdatas[i].varName );
                        // We need to increment the index in double array for the
                        // next subrange
                        indexInDoubleArray += ( endh - starth + 1 ) * 1 * vdatas[i].numLev;
                    }
                    assert( ic == localGidVerts.psize() );

                    if( vdatas[i].numLev > 1 )
                        // Transpose (lev, ncol) to (ncol, lev)
                        kji_to_jik_stride( ni, nj, nk, data, &tmpdoubledata[0], localGidVerts );
                    else
                    {
                        for( std::size_t idx = 0; idx != tmpdoubledata.size(); idx++ )
                            ( (double*)data )[idx] = tmpdoubledata[idx];
                    }

                    break;
                }
                default:
                    MB_SET_ERR( MB_FAILURE, "Unexpected data type for variable " << vdatas[i].varName );
            }
        }
    }

    // Debug output, if requested
    if( 1 == dbgOut.get_verbosity() )
    {
        dbgOut.printf( 1, "Read variables: %s", vdatas.begin()->varName.c_str() );
        for( unsigned int i = 1; i < vdatas.size(); i++ )
            dbgOut.printf( 1, ", %s ", vdatas[i].varName.c_str() );
        dbgOut.tprintf( 1, "\n" );
    }

    return rval;
}
#endif

}  // namespace moab