Add `fmpi_mpi_world_rank()`

include/internal/fmpi_mpi.h

@@ -160,6 +160,13 @@ _Bool fmpi_mpi_check_error(
  * }
  */
 void fmpi_mpi_ctx_print(const struct fmpi_mpi_ctx * ctx);
+/*------------------------------------------------------------------------------
+    fmpi_mpi_world_rank()
+------------------------------------------------------------------------------*/
+/**
+ * TODO
+ */
+int fmpi_mpi_world_rank(const struct fmpi_mpi_ctx * ctx);
 /*==============================================================================
     GUARD
 ==============================================================================*/

src/fmpi_mpi.c

@@ -139,3 +139,16 @@ void fmpi_mpi_ctx_print(const struct fmpi_mpi_ctx * const ctx)
     printf("MPI futhark error class: %d\n", ctx->futhark_err_class);
     printf("MPI futhark error code: %d\n", ctx->futhark_err_code);
 }
+/*------------------------------------------------------------------------------
+    fmpi_mpi_world_rank()
+------------------------------------------------------------------------------*/
+int fmpi_mpi_world_rank(const struct fmpi_mpi_ctx * const ctx)
+{
+    assert(ctx != NULL);
+    int rank = -1;
+    int err_id = MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+    if(fmpi_mpi_check_error(ctx, err_id, "MPI_Comm_rank") == true) {
+        return -1;
+    }
+    return rank;
+}