ENH: reading and data in file tests for MPI IO

io-prototyping/heatTransfer/write/IOmpiLevel0.cpp

@@ -54,22 +54,20 @@ void IOmpiLevel0::read( const int step,
                         std::vector<double>& buffer,
                         const Settings& s,
                         MPI_Comm comm ) {
-  // We avoid extending the IO interface by a file pointer reset functionality
-  // by restoring the file pointer when reading the first time step.
-  // Definitly violates SRP.
-  if ( step == 0 )
-  {
-    // Set initial rank-related offset
-    MPI_Offset offset = _rank * _buffercount * sizeof( double );
-    MPI_File_seek( _filehandle, offset, MPI_SEEK_SET );
-  }
+  _outputfilename = MakeFilename( s.outputfile, ".mpiio_write", -1, step );
+
+  // Open file and set initial rank-related offset
+  MPI_File_open( comm,
+                 _outputfilename.c_str(),
+                 MPI_MODE_RDONLY,
+                 MPI_INFO_NULL,
+                 &_filehandle );
+  MPI_Offset offset = _rank * _buffercount * sizeof( double );
+  MPI_File_seek( _filehandle, offset, MPI_SEEK_SET );
   
   MPI_File_read( _filehandle, buffer.data(), _buffercount, MPI_DOUBLE, MPI_STATUS_IGNORE);
   
-  // Set file pointer to next time step. Assumes sequentiell reads!
-  // Prevents MPI_Offset overflow.
-  MPI_Offset offset = ( _nprocs - 1 ) * _buffercount * sizeof( double );
-  MPI_File_seek( _filehandle, offset, MPI_SEEK_CUR );
+  MPI_File_close( &_filehandle );
 }
 
 void IOmpiLevel0::remove( const int step ) {

io-prototyping/heatTransfer/write/IOmpiLevel3.cpp

@@ -108,7 +108,28 @@ void IOmpiLevel3::read( const int step,
                         std::vector<double>& buffer,
                         const Settings& s,
                         MPI_Comm comm ) {
-  MPI_File_read_all( _filehandle, buffer.data(), _buffercount, MPI_DOUBLE, MPI_STATUS_IGNORE);
+  _outputfilename = MakeFilename( s.outputfile, ".mpiio_write_all", -1, step );
+
+  // Open file and set file view
+  MPI_File filehandle_onestep;
+  MPI_File_open( comm,
+                 _outputfilename.c_str(),
+                 MPI_MODE_RDONLY,
+                 MPI_INFO_NULL,
+                 &filehandle_onestep );
+  MPI_File_set_view( filehandle_onestep,
+                     0,
+                     MPI_DOUBLE,
+                     _fileview._filetype,
+                     "native",
+                     MPI_INFO_NULL);
+  MPI_File_read_all( filehandle_onestep,
+                     buffer.data(),
+                     _buffercount,
+                     MPI_DOUBLE,
+                     MPI_STATUS_IGNORE);
+
+  MPI_File_close( &filehandle_onestep );
 }
 
 void IOmpiLevel3::remove( const int step ) {

io-prototyping/heatTransfer/write/main.cpp

@@ -107,18 +107,24 @@ int main( int argc, char* argv[] ) {
            settings.format.compare( "adios2" ) == 0
            ||
            settings.format.compare( "binary" ) == 0
+           ||
+           settings.format.compare( "level0" ) == 0
+           ||
+           settings.format.compare( "level3" ) == 0
          )
       {
-          IO<IOVariant> istream( settings, MPI_COMM_WORLD);
-          istream.chooseFormat( settings.format );
-          std::vector<double> input_buffer( settings.ndx * settings.ndy, -1.0 );
-          istream.read( t, input_buffer, settings, MPI_COMM_WORLD );
-          bool equal = std::equal( std::begin( input_buffer ),
-                                   std::end( input_buffer ),
-                                   std::begin( ht.data_noghost() ) );
-          if ( !equal ) {
-             std::cout << "WARNING: read data is not equal to written data" << std::endl;
-          }
+        IO<IOVariant> istream( settings, MPI_COMM_WORLD );
+        istream.chooseFormat( settings.format );
+        std::vector<double> input_buffer( settings.ndx * settings.ndy, -1.0 );
+
+        istream.read( t, input_buffer, settings, MPI_COMM_WORLD );
+
+        bool equal = std::equal( std::begin( input_buffer ),
+                                 std::end( input_buffer ),
+                                 std::begin( ht.data_noghost() ) );
+        if ( !equal ) {
+          std::cout << "WARNING: read data is not equal to written data" << std::endl;
+        }
       }
 
       io.remove( t );