Skip writing data if no output is provided

changelog-entries/225.md

@@ -0,0 +1 @@
+- Added support for solver `B` to skip writing data when `precice-aste-run` is run without `--output` flag.

docs/README.md

@@ -148,7 +148,14 @@ precice-aste-run -p A --mesh fine_mesh --data "dummyData"
 precice-aste-run -p B --mesh coarse_mesh --data "mappedData" --output mappedMesh
 ```
 
-While the example above executes the mapping in serial, `precice-aste-run` can be executed in parallel (using MPI). However, this requires a partitioned mesh (one per parallel rank). In order to decompose a single mesh appropriately, the tools `precice-aste-partition` and `precice-aste-join` can be used.
+Exporting output mesh on participant B is optional and can be disabled by omitting the `--output` and `--data` flags from the command line. This is useful for repeatedly running the appication to collect multiple runtime measurements as it speeds up the process and avoids wear of the storage.
+
+```bash
+precice-aste-run -p A --mesh fine_mesh --data "dummyData"
+precice-aste-run -p B --mesh coarse_mesh # no output mesh
+```
+
+While the examples above execute the mapping in serial, `precice-aste-run` can be executed in parallel (using MPI). However, this requires a partitioned mesh (one per parallel rank). In order to decompose a single mesh appropriately, the tools `precice-aste-partition` and `precice-aste-join` can be used.
 
 {% tip %}
 If you want to reproduce a specific setup of your solvers, you can use the [export functionality](https://precice.org/configuration-export.html#enabling-exporters) of preCICE and use the generated meshes directly in `precice-aste-run`. If you run your solver in parallel, preCICE exports the decomposed meshes directly, so that no further partitioning is required.

src/modes.cpp

@@ -274,21 +274,25 @@ void aste::runMapperMode(const aste::ExecutionContext &context, const OptionMap
 
   // Write out results in same format as data was read
   if (asteConfiguration.participantName == "B") {
-    auto meshname = asteConfiguration.asteInterfaces.front().meshes.front();
-    auto filename = fs::path(options["output"].as<std::string>());
-    if (context.rank == 0 && fs::exists(filename)) {
-      if (context.isParallel() && !filename.parent_path().empty()) {
-        auto dir = filename.parent_path();
-        fs::remove_all(dir);
-        fs::create_directory(dir);
-      } else if (!context.isParallel()) {
-        fs::remove(filename);
+    if (options["output"].empty()) {
+      ASTE_INFO << "Not writing results as no output was provided";
+    } else {
+      auto meshname = asteConfiguration.asteInterfaces.front().meshes.front();
+      auto filename = fs::path(options["output"].as<std::string>());
+      if (context.rank == 0 && fs::exists(filename)) {
+        if (context.isParallel() && !filename.parent_path().empty()) {
+          auto dir = filename.parent_path();
+          fs::remove_all(dir);
+          fs::create_directory(dir);
+        } else if (!context.isParallel()) {
+          fs::remove(filename);
+        }
       }
+      MPI_Barrier(MPI_COMM_WORLD);
+      //
+      ASTE_INFO << "Writing results to " << options["output"].as<std::string>();
+      meshname.save(asteConfiguration.asteInterfaces.front().mesh, options["output"].as<std::string>());
     }
-    MPI_Barrier(MPI_COMM_WORLD);
-    //
-    ASTE_INFO << "Writing results to " << options["output"].as<std::string>();
-    meshname.save(asteConfiguration.asteInterfaces.front().mesh, options["output"].as<std::string>());
   }
   preciceInterface.finalize();
   return;