Check that all particles and cells have a time-step assigned at the end of the initialisation step.

src/cell.c

@@ -1293,3 +1293,26 @@ void cell_drift(struct cell *c, const struct engine *e) {
   /* Update the time of the last drift */
   c->ti_old = ti_current;
 }
+
+/**
+ * @brief Recursively checks that all particles in a cell have a time-step
+ */
+void cell_check_timesteps(struct cell *c) {
+#ifdef SWIFT_DEBUG_CHECKS
+
+  if(c->nodeID != engine_rank) return;
+
+  if(c->ti_end_min == 0) error("Cell without assigned time-step");
+  
+  if(c->split) {
+    for(int k=0; k<8; ++k)
+      if(c->progeny[k] != NULL) cell_check_timesteps(c->progeny[k]);
+  } else {
+
+    for(int i=0; i<c->count; ++i)
+      if(c->parts[i].time_bin == 0) 
+	error("Particle without assigned time-bin");
+
+  }
+#endif
+}

src/cell.h

@@ -330,5 +330,6 @@ int cell_is_drift_needed(struct cell *c, const struct engine *e);
 int cell_unskip_tasks(struct cell *c, struct scheduler *s);
 void cell_set_super(struct cell *c, struct cell *super);
 void cell_drift(struct cell *c, const struct engine *e);
+void cell_check_timesteps(struct cell *c);
 
 #endif /* SWIFT_CELL_H */

src/engine.c

@@ -2648,6 +2648,10 @@ void engine_init_particles(struct engine *e, int flag_entropy_ICs) {
 
   clocks_gettime(&time2);
 
+#ifdef SWIFT_DEBUG_CHECKS
+  space_check_timesteps(e->s);
+#endif 
+
   /* Ready to go */
   e->step = -1;
   e->forcerebuild = 1;

src/space.c

@@ -2392,6 +2392,19 @@ void space_check_drift_point(struct space *s, integertime_t ti_current) {
   space_map_cells_pre(s, 1, cell_check_drift_point, &ti_current);
 }
 
+/**
+ * @brief Checks that all particles and local cells have a non-zero time-step.
+ */ 
+void space_check_timesteps(struct space *s) {
+#ifdef SWIFT_DEBUG_CHECKS
+
+  for (int i=0; i<s->nr_cells; ++i) {
+    cell_check_timesteps(&s->cells_top[i]);
+  }
+
+#endif
+}
+
 /**
  * @brief Frees up the memory allocated for this #space
  */

src/space.h

@@ -201,6 +201,8 @@ void space_init_gparts(struct space *s);
 void space_init_sparts(struct space *s);
 void space_link_cleanup(struct space *s);
 void space_check_drift_point(struct space *s, integertime_t ti_current);
+void space_check_timesteps(struct space *s);
 void space_clean(struct space *s);
 
+
 #endif /* SWIFT_SPACE_H */