Merge branch 'dev' into dev

src/global/global.cpp

@@ -57,6 +57,26 @@ int Sgn(Real x)
   }
 }
 
+// global mpi-related variables (they are declared here because they are initialized even when
+// the MPI_CHOLLA variable is not defined)
+
+int procID; /*process rank*/
+int nproc;  /*number of processes in global comm*/
+int root;   /*rank of root process*/
+
+/* Used when MPI_CHOLLA is not defined to initialize a subset of the global mpi-related variables
+ * that still meaningful in non-mpi simulations.
+ */
+void Init_Global_Parallel_Vars_No_MPI()
+{
+#ifdef MPI_CHOLLA
+  CHOLLA_ERROR("This function should not be executed when compiled with MPI");
+#endif
+  procID = 0;
+  nproc  = 1;
+  root   = 0;
+}
+
 /*! \fn char Trim(char *s)
  *  \brief Gets rid of trailing and leading whitespace. */
 char *Trim(char *s)

src/global/global.h

@@ -155,6 +155,20 @@ extern double Get_Time(void);
  *  \brief Mathematical sign function. Returns sign of x. */
 extern int Sgn(Real x);
 
+/* Global variables for mpi (but they are also initialized to sensible defaults when not using mpi)
+ *
+ * It may make sense to move these back into mpi_routines (but reorganizing the ifdef statements
+ * would take some work). It may make sense to also put these into their own namespace.
+ */
+extern int procID; /*process rank*/
+extern int nproc;  /*number of processes executing simulation*/
+extern int root;   /*rank of root process*/
+
+/* Used when MPI_CHOLLA is not defined to initialize a subset of the global mpi-related variables
+ * that still meaningful in non-mpi simulations.
+ */
+void Init_Global_Parallel_Vars_No_MPI();
+
 struct Parameters {
   int nx;
   int ny;

src/main.cpp

@@ -47,9 +47,12 @@ int main(int argc, char *argv[])
   // start the total time
   start_total = Get_Time();
 
-/* Initialize MPI communication */
 #ifdef MPI_CHOLLA
+  /* Initialize MPI communication */
   InitializeChollaMPI(&argc, &argv);
+#else
+  // Initialize subset of global parallelism variables usually managed by MPI
+  Init_Global_Parallel_Vars_No_MPI();
 #endif /*MPI_CHOLLA*/
 
   Real dti = 0;  // inverse time step, 1.0 / dt

src/mpi/mpi_routines.cpp

@@ -13,9 +13,7 @@
   #include "../utils/error_handling.h"
 
 /*Global MPI Variables*/
-int procID; /*process rank*/
-int nproc;  /*number of processes in global comm*/
-int root;   /*rank of root process*/
+// note: some relevant global variables are declared in global.h
 
 int procID_node; /*process rank on node*/
 int nproc_node;  /*number of MPI processes on node*/

src/mpi/mpi_routines.h

@@ -15,9 +15,9 @@
     #endif /*FFTW*/
 
 /*Global MPI Variables*/
-extern int procID;      /*process rank*/
-extern int nproc;       /*number of processes in global comm*/
-extern int root;        /*rank of root process*/
+// NOTE: some variable heavily used by mpi are declared in global.h so that they are defined even
+//       when compiled without mpi
+
 extern int procID_node; /*process rank on node*/
 extern int nproc_node;  /*number of MPI processes on node*/