relay mesh blueprint save / load improvements (#613)

* refactor  relay::blueprint mesh write and read methods

* mesh bp index gen, fix bug with support for new matset flavors

* wrap more mesh bp examples into the blueprint.mesh.examples python module

* bugfix for hdf5 compat check vs conduit empty nodes

* tests for write_mesh opts, cleanup

* lots of moving parts, refactor to simplify testing logic, break out new tests, etc

* use write, read vs save load, to be consistent with other uses related to file creation and or append

* mover barrier into write_mesh -- to avoid fs races out of the box

CHANGELOG.md

@@ -24,7 +24,7 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 - Added the conduit.relay.mpi Python module to support Relay MPI in Python.
 - Added support to write and read Conduit lists to HDF5 files. Since HDF5 Groups do not support unnamed indexed children, each list child is written using a string name that represents its index and a special attribute is written to the HDF5 group to mark the list case. On read, the special attribute is used to detect and read this style of group back into a Conduit list.
 - Added preliminary support to read Sidre Datastore-style HDF5 using Relay IOHandle,  those grouped with a root file.
-- Added `conduit::relay::io::blueprint::load_mesh` functions, were pulled in from Ascent's Blueprint import logic.
+- Added `conduit::relay::io::blueprint::read_mesh` functions, were pulled in from Ascent's Blueprint import logic.
 
 #### Blueprint
 - Added support for sparse one-to-many relationships with the new `blueprint::o2mrelation` protocol. See the `blueprint::o2mrelation::examples::uniform` example for details.
@@ -38,6 +38,7 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 - Added `blueprint::mesh::number_of_domains` property method for trees that conform to the mesh blueprint.
 - Added MPI mesh blueprint methods, `blueprint::mpi::mesh::verify` and  `blueprint::mpi::mesh::number_of_domains` (available in the `conduit_blueprint_mpi` library)
 - Added `blueprint::mpi::mesh::examples::braid_uniform_multi_domain` and `blueprint::mpi::mesh::examples::spiral_round_robin` distributed-memory mesh examples to the `conduit_blueprint_mpi` library.
+- Added `state/path` to the Mesh Blueprint index, needed for consumers to know the proper path to read extended state info (such as `domain_id`)
 
 
 ### Fixed
@@ -49,6 +50,7 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 
 #### Relay
 - Use H5F_ACC_RDONLY in relay::io::is_hdf5_file to avoid errors when checking files that already have open HDF5 handles.
+- Fixed compatibility check for empty Nodes against HDF5 files with existing paths
 
 ### Changed
 
@@ -64,8 +66,8 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 
 #### Relay
 - Provide more context when a Conduit Node cannot be written to a HDF5 file because it is incompatible with the existing HDF5 tree. Error messages now provide the full path and details about the incompatibility.
-- `conduit::relay::io_blueprint::save` functions are deprecated in favor of `conduit::relay::io::blueprint::save_mesh`
-- `conduit::relay::io::blueprint::save_mesh` functions were pulled in from Ascent's Blueprint export logic.
+- `conduit::relay::io_blueprint::save` functions are deprecated in favor of `conduit::relay::io::blueprint::write_mesh`
+- `conduit::relay::io::blueprint::write_mesh` functions were pulled in from Ascent's Blueprint export logic.
 - `conduit_relay_io_mpi` lib now depends on `conduit_relay_io`. Due to this change, a single build supports either ADIOS serial (no-mpi) or ADIOS with MPI support, but not both. If conduit is configured with MPI support, ADIOS MPI is used.
 
 

src/libs/blueprint/conduit_blueprint_mesh.cpp

@@ -2445,17 +2445,25 @@ mesh::generate_index(const Node &mesh,
     index_out.reset();
 
     index_out["state/number_of_domains"] = number_of_domains;
-
-    // check if the input mesh has state/cycle state/time
-    // if so, add those to the index
-    if(mesh.has_path("state/cycle"))
-    {
-        index_out["state/cycle"].set(mesh["state/cycle"]);
-    }
 
-    if(mesh.has_path("state/time"))
+
+    if(mesh.has_child("state"))
     {
-        index_out["state/time"].set(mesh["state/time"]);
+        // check if the input mesh has state/cycle state/time
+        // if so, add those to the index
+        if(mesh.has_path("state/cycle"))
+        {
+            index_out["state/cycle"].set(mesh["state/cycle"]);
+        }
+
+        if(mesh.has_path("state/time"))
+        {
+            index_out["state/time"].set(mesh["state/time"]);
+        }
+        // state may contain other important stuff, like 
+        // the domain_id, so we need a way to read it
+        // from the index
+        index_out["state/path"] = join_path(ref_path, "state");
     }
 
     NodeConstIterator itr = mesh["coordsets"].children();
@@ -2569,11 +2577,40 @@ mesh::generate_index(const Node &mesh,
             Node &idx_matset = index_out["matsets"][matset_name];
 
             idx_matset["topology"] = matset["topology"].as_string();
-            NodeConstIterator mats_itr = matset["volume_fractions"].children();
-            while(mats_itr.has_next())
+
+            // support different flavors of valid matset protos
+            if(matset.has_child("material_map"))
+            {
+                NodeConstIterator mats_itr = matset["material_map"].children();
+                while(mats_itr.has_next())
+                {
+                    mats_itr.next();
+                    idx_matset["materials"][mats_itr.name()];
+                }
+            }
+            else if(matset.has_child("materials"))
+            {
+                NodeConstIterator mats_itr = matset["materials"].children();
+                while(mats_itr.has_next())
+                {
+                    mats_itr.next();
+                    idx_matset["materials"][mats_itr.name()];
+                }
+            }
+            else if(matset.has_child("volume_fractions"))
+            {
+                NodeConstIterator mats_itr = matset["volume_fractions"].children();
+                while(mats_itr.has_next())
+                {
+                    mats_itr.next();
+                    idx_matset["materials"][mats_itr.name()];
+                }
+            }
+            else // surprise!
             {
-                mats_itr.next();
-                idx_matset["materials"][mats_itr.name()];
+                CONDUIT_ERROR("blueprint::mesh::generate_index: "
+                              "Invalid matset flavor."
+                              "Input node does not conform to mesh blueprint.");
             }
 
             std::string ms_ref_path = join_path(ref_path, "matsets");

src/libs/blueprint/conduit_blueprint_mesh_examples_venn.cpp

@@ -703,7 +703,6 @@ void venn(const std::string &matset_type,
     res["meta/importance/c"] = c_importance;
 
     // Shape in materials; compute fields with matset values.
-    std::cout << "[Shaping in materials]" << std::endl;
 
     if (matset_type == "full")
     {