Copy command line parameters from master

Copy command line parameters from master to slave command line. Also
replace data file name in master argv with data file name of the slave.

opm/simulators/flow/ReservoirCouplingMaster.cpp

@@ -46,6 +46,10 @@ ReservoirCouplingMaster::ReservoirCouplingMaster(
     schedule_{schedule}
 { }
 
+// ------------------
+// Public methods
+// ------------------
+
 // NOTE: This functions is executed for all ranks, but only rank 0 will spawn
 //   the slave processes
 void ReservoirCouplingMaster::spawnSlaveProcesses([[maybe_unused]]int argc, char **argv) {
@@ -61,11 +65,7 @@ void ReservoirCouplingMaster::spawnSlaveProcesses([[maybe_unused]]int argc, char
         std::filesystem::path dir_path(directory_path);
         std::filesystem::path data_file(data_file_name);
         std::filesystem::path full_path = dir_path / data_file;
-        std::vector<char*> slave_argv(3);
-        char enable_slave_arg[] = "--slave=true";
-        slave_argv[0] = enable_slave_arg;
-        slave_argv[1] = const_cast<char*>(full_path.c_str());
-        slave_argv[2] = nullptr;
+        std::vector<char *> slave_argv = getSlaveArgv(argc, argv, full_path);
         auto num_procs = slave.numprocs();
         std::vector<int> errcodes(num_procs);
         // TODO: We need to decide how to handle the output from the slave processes..
@@ -87,7 +87,7 @@ void ReservoirCouplingMaster::spawnSlaveProcesses([[maybe_unused]]int argc, char
                     char error_string[MPI_MAX_ERROR_STRING];
                     int length_of_error_string;
                     MPI_Error_string(errcodes[i], error_string, &length_of_error_string);
-                    std::cerr << "Error spawning process " << i << ": " << error_string << std::endl;
+                    OpmLog::info(fmt::format("Error spawning process {}: {}", i, error_string));
                 }
             }
             OPM_THROW(std::runtime_error, "Failed to spawn slave process");
@@ -97,5 +97,35 @@ void ReservoirCouplingMaster::spawnSlaveProcesses([[maybe_unused]]int argc, char
     }
 }
 
+// ------------------
+// Private methods
+// ------------------
+
+std::vector<char *> ReservoirCouplingMaster::getSlaveArgv(
+    int argc, char **argv, const std::filesystem::path &data_file
+) {
+    // Calculate the size of the slave_argv vector like this:
+    // - We will not use the first argument, as it is the program name
+    // - We will replace the data file name in argv with the data_file path
+    // - We will also add the argument "--slave=true" to the argv
+    // - And we will add a nullptr at the end of the argv
+    // So the size of the slave_argv vector will be argc + 1
+    //
+    // Assume: All parameters will be on the form --parameter=value (as a string without spaces)
+    std::vector<char *> slave_argv(argc + 1);
+    for (int i = 1; i < argc; i++) {
+        // Check if the argument starts with "--", if not it will be a positional argument
+        //   and we will replace it with the data file path
+        if (std::string(argv[i]).substr(0, 2) == "--") {
+            slave_argv[i-1] = argv[i];
+        } else {
+            slave_argv[i-1] = const_cast<char*>(data_file.c_str());
+        }
+    }
+    slave_argv[argc-1] = const_cast<char*>("--slave=true");
+    slave_argv[argc] = nullptr;
+    return slave_argv;
+}
+
 } // namespace Opm
 

opm/simulators/flow/ReservoirCouplingMaster.hpp

@@ -26,6 +26,7 @@
 
 #include <mpi.h>
 
+#include <filesystem>
 #include <vector>
 
 namespace Opm {
@@ -50,6 +51,9 @@ public:
 
 
 private:
+    std::vector<char *> getSlaveArgv(
+        int argc, char **argv, const std::filesystem::path &data_file);
+
     const Parallel::Communication &comm_;
     const Schedule& schedule_;
     // MPI communicators for the slave processes