Merge pull request #1590 from LLNL/task/rhornung67/mv-sidre_array-example

Task/rhornung67/mv sidre array example

Author: rhornung67

src/axom/sidre/examples/CMakeLists.txt

@@ -17,7 +17,7 @@ set(example_sources
 
 if(AXOM_ENABLE_MPI)
     set (example_parallel_sources
-         sidre_array.cpp
+         sidre_mcarray.cpp
          sidre_createdatastore.cpp
          sidre_external_array.cpp
          sidre_generateindex.cpp)

src/axom/sidre/examples/sidre_array.cpp src/axom/sidre/examples/sidre_mcarray.cppsrc/axom/sidre/examples/sidre_array.cpp renamed to src/axom/sidre/examples/sidre_mcarray.cpp

@@ -21,6 +21,9 @@ namespace sidre = axom::sidre;
 
 int main(int argc, char** argv)
 {
+  //
+  // Basic MPI setup with global communicator
+  // 
   MPI_Init(&argc, &argv);
   MPI_Comm problem_comm = MPI_COMM_WORLD;
 
@@ -31,15 +34,18 @@ int main(int argc, char** argv)
 
   axom::slic::SimpleLogger logger;
 
-  // STEP 0: create the data store
+  // STEP 0: create a data store instance, with one child group of root
   sidre::DataStore* dataStore1 = new sidre::DataStore();
   sidre::Group* root1 = dataStore1->getRoot();
 
-  // STEP 1: create an array with some data
+  // STEP 1: Create a sidre::MCArray with data held in a Sidre View.
+  //         A sidre::MCArray is similar to axom::Array, except that
+  //         the array data can be accessed using a Sidre View.
   constexpr axom::IndexType NUM_NODES = 10;
   constexpr axom::IndexType DIMENSION = 4;
   sidre::MCArray<int> nodes_1(root1->createView("nodes_1/data"), NUM_NODES, DIMENSION);
 
+  // STEP 1a: Initialize array data values
   int value = 0;
   for(axom::IndexType i = 0; i < NUM_NODES; ++i)
   {
@@ -51,35 +57,43 @@ int main(int argc, char** argv)
   }    // END for all nodes
 
   // DEBUG
+  // STEP 1b: Print contents of data store showing that array data is in View
   SLIC_INFO("Here is the array data in DataStore_1:\n");
   root1->print();
   std::cout << std::endl;
   // END DEBUG
 
-  // STEP 2: save the array data in to a file
+  // STEP 2: Write out the data store contents to a file.
   sidre::IOManager sidre_io(problem_comm);
 #if defined(AXOM_USE_HDF5)
   sidre_io.write(root1, nranks, "sidre_array_mesh", "sidre_hdf5");
 #else
   sidre_io.write(root1, nranks, "sidre_array_mesh", "sidre_conduit_json");
 #endif
 
-  // STEP 3: read the data from the file into a new DataStore
+  // STEP 3: Create a new data store object and read the data from the 
+  //         file into it.
   sidre::DataStore* dataStore2 = new sidre::DataStore();
   sidre::Group* root2 = dataStore2->getRoot();
   sidre_io.read(root2, "sidre_array_mesh.root");
 
   // DEBUG
+  // STEP 3a: Print contents of data store showing that array data was
+  //          read into a View
   SLIC_INFO("Here is the array data in DataStore_2:\n");
   root2->print();
   std::cout << std::endl;
   // END DEBUG
 
+  // STEP 3b: Create a new sidre::MCArray with data held in a View in the
+  //          new data store. Verify that the shape and size of the data is
+  //          what it is expected to be.
   sidre::MCArray<int> nodes_2(root2->getView("nodes_1/data"));
   SLIC_ASSERT(nodes_2.shape()[0] == NUM_NODES);
   SLIC_ASSERT(nodes_2.shape()[1] == DIMENSION);
 
-  // STEP 4: ensure the data is correct
+  // STEP 4: Check the values are correct when accessed through the 
+  //         sidre::MCArray
   int expected_value = 0;
   for(axom::IndexType i = 0; i < NUM_NODES; ++i)
   {
@@ -90,7 +104,7 @@ int main(int argc, char** argv)
     }  // END for all components
   }    // END for all nodes
 
-  // STEP 5: delete the datastores
+  // STEP 5: Delete both data stores (and associated data).
   delete dataStore2;
   dataStore2 = nullptr;