make nrn_multithread_job accept arguments (#260)

* reduce global variable for keeping state
* keep openmp version that can be used in serial/multi-threaded case

Author: Nicolas Cornu

coreneuron/sim/fadvance_core.cpp

@@ -26,6 +26,8 @@ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+#include <functional>
+
 #include "coreneuron/coreneuron.hpp"
 #include "coreneuron/nrnconf.h"
 #include "coreneuron/sim/multicore.hpp"
@@ -43,7 +45,7 @@ THE POSSIBILITY OF SUCH DAMAGE.
 namespace coreneuron {
 
 static void* nrn_fixed_step_thread(NrnThread*);
-static void* nrn_fixed_step_group_thread(NrnThread*);
+static void* nrn_fixed_step_group_thread(NrnThread*, int, int, int&);
 
 void dt2thread(double adt) { /* copied from nrnoc/fadvance.c */
     if (adt != nrn_threads[0]._dt) {
@@ -84,9 +86,6 @@ void nrn_fixed_step_minimal() { /* not so minimal anymore with gap junctions */
 integration interval before joining
 */
 /// --> Coreneuron
-static int step_group_n;
-static int step_group_begin;
-static int step_group_end;
 static progressbar* progress;
 
 void initialize_progress_bar(int nstep) {
@@ -137,13 +136,13 @@ void nrn_fixed_step_group_minimal(int total_sim_steps) {
     static int current_steps = 0;
     dt2thread(dt);
     nrn_thread_table_check();
-    step_group_n = total_sim_steps;
-    step_group_begin = 0;
-    step_group_end = 0;
+    int step_group_n = total_sim_steps;
+    int step_group_begin = 0;
+    int step_group_end = 0;
     initialize_progress_bar(step_group_n);
 
     while (step_group_end < step_group_n) {
-        nrn_multithread_job(nrn_fixed_step_group_thread);
+        nrn_multithread_job(nrn_fixed_step_group_thread, step_group_n, step_group_begin, step_group_end);
 #if NRNMPI
         nrn_spike_exchange(nrn_threads);
 #endif
@@ -162,9 +161,9 @@ void nrn_fixed_step_group_minimal(int total_sim_steps) {
     finalize_progress_bar();
 }
 
-static void* nrn_fixed_step_group_thread(NrnThread* nth) {
+static void* nrn_fixed_step_group_thread(NrnThread* nth, int step_group_max, int step_group_begin, int& step_group_end) {
     nth->_stop_stepping = 0;
-    for (int i = step_group_begin; i < step_group_n; ++i) {
+    for (int i = step_group_begin; i < step_group_max; ++i) {
         nrn_fixed_step_thread(nth);
         if (nth->_stop_stepping) {
             if (nth->id == 0) {
@@ -175,7 +174,7 @@ static void* nrn_fixed_step_group_thread(NrnThread* nth) {
         }
     }
     if (nth->id == 0) {
-        step_group_end = step_group_n;
+        step_group_end = step_group_max;
     }
     return nullptr;
 }

coreneuron/sim/multicore.cpp

@@ -31,7 +31,6 @@ THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "coreneuron/nrnconf.h"
 #include "coreneuron/sim/multicore.hpp"
-#include "coreneuron/mpi/nrnmpi.h"
 #include "coreneuron/utils/memory.h"
 #include "coreneuron/coreneuron.hpp"
 #include "coreneuron/utils/nrnoc_aux.hpp"
@@ -157,22 +156,4 @@ void nrn_thread_table_check() {
                                                      ml->_thread, &nt, tml->index);
     }
 }
-
-void nrn_multithread_job(void* (*job)(NrnThread*)) {
-    int i;
-#if defined(_OPENMP)
-// clang-format off
-    #pragma omp parallel for private(i) shared(nrn_threads, job, nrn_nthread, \
-                                           nrnmpi_myid) schedule(static, 1)
-    for (i = 0; i < nrn_nthread; ++i) {
-        (*job)(nrn_threads + i);
-    }
-// clang-format on
-#else
-    for (i = 1; i < nrn_nthread; ++i) {
-        (*job)(nrn_threads + i);
-    }
-    (*job)(nrn_threads);
-#endif
-}
 }  // namespace coreneuron

coreneuron/sim/multicore.hpp

@@ -31,6 +31,7 @@ THE POSSIBILITY OF SUCH DAMAGE.
 #include "coreneuron/nrnconf.h"
 #include "coreneuron/mechanism/membfunc.hpp"
 #include "coreneuron/utils/memory.h"
+#include "coreneuron/mpi/nrnmpi.h"
 
 namespace coreneuron {
 class NetCon;
@@ -154,7 +155,18 @@ struct NrnThread : public MemoryManaged {
 extern void nrn_threads_create(int n);
 extern int nrn_nthread;
 extern NrnThread* nrn_threads;
-extern void nrn_multithread_job(void* (*)(NrnThread*));
+template<typename F, typename... Args>
+void nrn_multithread_job(F&& job, Args&&... args) {
+    int i;
+// clang-format off
+    #pragma omp parallel for private(i) shared(nrn_threads, job, nrn_nthread, \
+                                           nrnmpi_myid) schedule(static, 1)
+    for (i = 0; i < nrn_nthread; ++i) {
+        job(nrn_threads + i, std::forward<Args>(args)...);
+    }
+// clang-format on
+}
+
 extern void nrn_thread_table_check(void);
 
 extern void nrn_threads_free(void);