feat: allow forcings engine provider to set MPI communicator [no ci]

include/forcing/ForcingsEngineDataProvider.hpp

@@ -15,11 +15,34 @@ namespace data_access {
 struct ForcingsEngineDataProvider
   : public GenericDataProvider
 {
+    /**
+     * @brief Construct a new Forcings Engine Data Provider instance
+     * 
+     * @param init Path to initialization config
+     * @param time_start start time for module as a unix epoch
+     * @param time_end end time for module as a unix epoch
+     */
     explicit ForcingsEngineDataProvider(const std::string& init, std::size_t time_start, std::size_t time_end);
+
+    /**
+     * @brief Construct a new Forcings Engine Data Provider instance
+     * 
+     * @param init Path to initialization config
+     * @param time_start start time for module as a string timestamp
+     * @param time_end end time for module as a string timestamp
+     * @param fmt format of timestamps
+     */
     explicit ForcingsEngineDataProvider(const std::string& init, const std::string& time_start, const std::string& time_end, const std::string& fmt = "%Y-%m-%d %H:%M:%S");
 
     ~ForcingsEngineDataProvider() override;
 
+    /**
+     * @brief Set the MPI communicator that the Forcings Engine should use.
+     * 
+     * @param handle int representing a communicator handle.
+     */
+    void set_communicator(int handle);
+
     auto get_available_variable_names()
       -> boost::span<const std::string> override;
 

src/forcing/ForcingsEngineDataProvider.cpp

@@ -37,6 +37,12 @@ ForcingsEngineDataProvider::ForcingsEngineDataProvider(const std::string& init,
 
 ForcingsEngineDataProvider::~ForcingsEngineDataProvider() = default;
 
+void ForcingsEngineDataProvider::set_communicator(int handle)
+{
+    int idx = 0;
+    instance_.set_value_at_indices<int>("bmi_mpi_comm_handle", &idx, 1, &handle, "int");
+}
+
 auto ForcingsEngineDataProvider::get_available_variable_names()
   -> boost::span<const std::string>
 {