Refactor: Fold DisconnectedNeighborCoupling into GhostPointNeighbors

ChengHauYang · ChengHauYang · commit d100e50ca035 · 2025-11-03T18:55:18.000-06:00
Refactored the ghosting workflow following @roystgnr’s review. Removed the separate DisconnectedNeighborCoupling class and integrated its logic directly into GhostPointNeighbors for a cleaner and more consistent approach. This avoids duplicate functor additions in `UnstructuredMesh::find_neighbors`. - Deleted `DisconnectedNeighborCoupling.[C,h]` and updated Makefiles - Moved all related logic into `GhostPointNeighbors::operator()` - Added move assignment and equality checks for `_disconnected_boundary_pairs` in `MeshBase`. This was a great catch from Roy and is needed for mesh cloning/comparisons to work correctly. - Added `libmesh_deprecated()` warning to `UnstructuredMesh::stitching_helper` for disconnected meshes - Replaced a `libmesh_error_msg` in `MeshRefinement` with `libmesh_not_implemented_msg` - Updated unit tests: added `LOG_UNIT_TEST` for `disconnected_neighbor_test`
diff --git a/Makefile.in b/Makefile.in
diff --git a/build-aux/ltmain.sh b/build-aux/ltmain.sh
@@ -7648,11 +7648,6 @@ func_mode_link ()
 	arg=$func_stripname_result
 	;;
 
-      -Wl,--as-needed)
-	deplibs="$deplibs $arg"
-	continue
-	;;
-
       -Wl,*)
 	func_stripname '-Wl,' '' "$arg"
 	args=$func_stripname_result
@@ -7995,7 +7990,6 @@ func_mode_link ()
 
     case $linkmode in
     lib)
-	as_needed_flag=
 	passes="conv dlpreopen link"
 	for file in $dlfiles $dlprefiles; do
 	  case $file in
@@ -8007,7 +8001,6 @@ func_mode_link ()
 	done
 	;;
     prog)
-	as_needed_flag=
 	compile_deplibs=
 	finalize_deplibs=
 	alldeplibs=false
@@ -8077,15 +8070,6 @@ func_mode_link ()
 	lib=
 	found=false
 	case $deplib in
-	-Wl,--as-needed)
-	  if test prog,link = "$linkmode,$pass" ||
-	     test lib,link = "$linkmode,$pass"; then
-	    as_needed_flag="$deplib "
-	  else
-	    deplibs="$deplib $deplibs"
-	  fi
-	  continue
-	  ;;
 	-mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe \
         |-threads|-fopenmp|-fopenmp=*|-openmp|-mp|-xopenmp|-omp|-qsmp=*)
 	  if test prog,link = "$linkmode,$pass"; then
@@ -10411,13 +10395,6 @@ func_mode_link ()
 	  test "X$libobjs" = "X " && libobjs=
 	fi
 
-	# A bit hacky. I had wanted to add \$as_needed_flag to archive_cmds instead, but that
-	# comes from libtool.m4 which is part of the project being built. This should put it
-	# in the right place though.
-	if test lib,link = "$linkmode,$pass" && test -n "$as_needed_flag"; then
-	  libobjs=$as_needed_flag$libobjs
-	fi
-
 	save_ifs=$IFS; IFS='~'
 	for cmd in $cmds; do
 	  IFS=$sp$nl
@@ -10650,8 +10627,8 @@ func_mode_link ()
       compile_deplibs=$new_libs
 
 
-      func_append compile_command " $as_needed_flag $compile_deplibs"
-      func_append finalize_command " $as_needed_flag $finalize_deplibs"
+      func_append compile_command " $compile_deplibs"
+      func_append finalize_command " $finalize_deplibs"
 
       if test -n "$rpath$xrpath"; then
 	# If the user specified any rpath flags, then add them.
diff --git a/include/Makefile.in b/include/Makefile.in
@@ -780,7 +780,6 @@ include_HEADERS = \
         geom/surface.h \
         ghosting/default_coupling.h \
         ghosting/ghost_point_neighbors.h \
-        ghosting/disconnected_neighbor_coupling.h \
         ghosting/ghosting_functor.h \
         ghosting/non_manifold_coupling.h \
         ghosting/overlap_coupling.h \
@@ -1119,7 +1118,7 @@ include_HEADERS = \
         utils/utility.h \
         utils/vectormap.h \
         utils/win_gettimeofday.h \
-        utils/xdr_cxx.h
+        utils/xdr_cxx.h 
 
 
 # definition of include_HEADERS - get from auto-maintained list
diff --git a/include/ghosting/disconnected_neighbor_coupling.h b/include/ghosting/disconnected_neighbor_coupling.h
diff --git a/include/include_HEADERS b/include/include_HEADERS
@@ -176,7 +176,6 @@ include_HEADERS =  \
         geom/surface.h \
         ghosting/default_coupling.h \
         ghosting/ghost_point_neighbors.h \
-        ghosting/disconnected_neighbor_coupling.h \
         ghosting/ghosting_functor.h \
         ghosting/non_manifold_coupling.h \
         ghosting/overlap_coupling.h \
@@ -515,4 +514,4 @@ include_HEADERS =  \
         utils/utility.h \
         utils/vectormap.h \
         utils/win_gettimeofday.h \
-        utils/xdr_cxx.h
+        utils/xdr_cxx.h 
diff --git a/include/libmesh/Makefile.am b/include/libmesh/Makefile.am
@@ -166,7 +166,6 @@ BUILT_SOURCES = \
         surface.h \
         default_coupling.h \
         ghost_point_neighbors.h \
-        disconnected_neighbor_coupling.h \
         ghosting_functor.h \
         non_manifold_coupling.h \
         overlap_coupling.h \
@@ -1098,9 +1097,6 @@ default_coupling.h: $(top_srcdir)/include/ghosting/default_coupling.h
 ghost_point_neighbors.h: $(top_srcdir)/include/ghosting/ghost_point_neighbors.h
 	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
 
-disconnected_neighbor_coupling.h: $(top_srcdir)/include/ghosting/disconnected_neighbor_coupling.h
-	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
-
 ghosting_functor.h: $(top_srcdir)/include/ghosting/ghosting_functor.h
 	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
 
diff --git a/include/libmesh/Makefile.in b/include/libmesh/Makefile.in
@@ -575,8 +575,7 @@ BUILT_SOURCES = dirichlet_boundaries.h dof_map.h dof_map_base.h \
 	face_tri3_subdivision.h face_tri6.h face_tri7.h node.h \
 	node_elem.h node_range.h plane.h point.h reference_elem.h \
 	remote_elem.h sphere.h stored_range.h surface.h \
-	default_coupling.h ghost_point_neighbors.h \
-	disconnected_neighbor_coupling.h ghosting_functor.h \
+	default_coupling.h ghost_point_neighbors.h ghosting_functor.h \
 	non_manifold_coupling.h overlap_coupling.h \
 	point_neighbor_coupling.h sibling_coupling.h abaqus_io.h \
 	boundary_info.h boundary_mesh.h checkpoint_io.h \
@@ -1432,9 +1431,6 @@ default_coupling.h: $(top_srcdir)/include/ghosting/default_coupling.h
 ghost_point_neighbors.h: $(top_srcdir)/include/ghosting/ghost_point_neighbors.h
 	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
 
-disconnected_neighbor_coupling.h: $(top_srcdir)/include/ghosting/disconnected_neighbor_coupling.h
-	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
-
 ghosting_functor.h: $(top_srcdir)/include/ghosting/ghosting_functor.h
 	$(AM_V_GEN)rm -f $@ && $(LN_S) -f $< $@
 
diff --git a/include/mesh/mesh_base.h b/include/mesh/mesh_base.h
@@ -1846,7 +1846,7 @@ class MeshBase : public ParallelObject
 
 protected:
 
- #ifdef LIBMESH_ENABLE_PERIODIC
+#ifdef LIBMESH_ENABLE_PERIODIC
   /// @brief The disconnected boundary id pairs.
   std::unique_ptr<PeriodicBoundaries> _disconnected_boundary_pairs;
 #endif
diff --git a/src/ghosting/disconnected_neighbor_coupling.C b/src/ghosting/disconnected_neighbor_coupling.C
diff --git a/src/ghosting/ghost_point_neighbors.C b/src/ghosting/ghost_point_neighbors.C
@@ -46,8 +46,11 @@ void GhostPointNeighbors::operator()
   bool check_periodic_bcs =
     (_periodic_bcs && !_periodic_bcs->empty());
 
+  auto * db = _mesh->get_disconnected_boundaries();
+  bool check_disconnected_bcs = (db && !db->empty());
+
   std::unique_ptr<PointLocatorBase> point_locator;
-  if (check_periodic_bcs)
+  if (check_periodic_bcs || check_disconnected_bcs)
       point_locator = _mesh->sub_point_locator();
 
   std::set<const Elem *> periodic_elems_examined;
@@ -176,6 +179,30 @@ void GhostPointNeighbors::operator()
                 }
             }
         }
+
+      if (check_disconnected_bcs)
+        {
+          // Also ghost their disconnected neighbors
+          for (auto s : elem->side_index_range())
+          {
+            for (const auto & [id, boundary_ptr] : *db)
+            {
+              if (!_mesh->get_boundary_info().has_boundary_id(elem, s, id))
+                continue;
+
+              unsigned int neigh_side = invalid_uint;
+              const Elem * neigh =
+                  db->neighbor(id, *point_locator, elem, s, &neigh_side);
+
+              if (!neigh || neigh == remote_elem)
+                continue;
+
+              if (neigh->processor_id() != p)
+                coupled_elements.emplace(neigh, nullcm);
+            }
+          }
+        }
+
 #endif // LIBMESH_ENABLE_PERIODIC
     }
 }
diff --git a/src/libmesh_SOURCES b/src/libmesh_SOURCES
@@ -193,7 +193,6 @@ libmesh_SOURCES =  \
         src/geom/surface.C \
         src/ghosting/default_coupling.C \
         src/ghosting/ghost_point_neighbors.C \
-        src/ghosting/disconnected_neighbor_coupling.C \
         src/ghosting/non_manifold_coupling.C \
         src/ghosting/overlap_coupling.C \
         src/ghosting/point_neighbor_coupling.C \
@@ -476,4 +475,4 @@ libmesh_SOURCES =  \
         src/utils/tree.C \
         src/utils/tree_node.C \
         src/utils/utility.C \
-        src/utils/xdr_cxx.C
+        src/utils/xdr_cxx.C 
diff --git a/src/mesh/mesh_base.C b/src/mesh/mesh_base.C
@@ -202,6 +202,10 @@ MeshBase& MeshBase::operator= (MeshBase && other_mesh)
   _node_integer_default_values = std::move(other_mesh._node_integer_default_values);
   _point_locator_close_to_point_tol = other_mesh.get_point_locator_close_to_point_tol();
 
+#ifdef LIBMESH_ENABLE_PERIODIC
+  _disconnected_boundary_pairs = std::move(other_mesh._disconnected_boundary_pairs);
+#endif
+
   // This relies on our subclasses *not* invalidating pointers when we
   // do their portion of the move assignment later!
   boundary_info = std::move(other_mesh.boundary_info);
@@ -308,6 +312,12 @@ bool MeshBase::locally_equals (const MeshBase & other_mesh) const
     return false;
   if (*boundary_info != *other_mesh.boundary_info)
     return false;
+  // First check whether the "existence" of the two pointers differs (one present, one absent)
+  if ((bool)_disconnected_boundary_pairs != (bool)other_mesh._disconnected_boundary_pairs)
+    return false;
+  // If both exist, compare the contents
+  if (_disconnected_boundary_pairs && (*_disconnected_boundary_pairs != *other_mesh._disconnected_boundary_pairs))
+    return false;
 
   const constraint_rows_type & other_rows =
     other_mesh.get_constraint_rows();
diff --git a/src/mesh/mesh_refinement.C b/src/mesh/mesh_refinement.C
@@ -696,11 +696,8 @@ bool MeshRefinement::refine_elements ()
   // present.
   if (_mesh.get_disconnected_boundaries())
     {
-      libmesh_error_msg(
-        "Mesh contains disconnected boundary interfaces; refinement is disabled.\n"
-        "MeshRefinement::refine_elements() cannot proceed because disconnected\n"
-        "boundaries may produce invalid neighbor relations. Please remove or\n"
-        "repair disconnected boundary interfaces before attempting refinement.");
+      libmesh_not_implemented_msg(
+        "Mesh refinement is not yet implemented for meshes with disconnected boundary interfaces.\n");
     }
 
   if (_face_level_mismatch_limit)
diff --git a/src/mesh/unstructured_mesh.C b/src/mesh/unstructured_mesh.C
@@ -50,9 +50,6 @@
 // for disconnected neighbors
 #include "libmesh/periodic_boundaries.h"
 #include "libmesh/periodic_boundary.h"
-
-#include <libmesh/disconnected_neighbor_coupling.h>
-
 namespace {
 
 using namespace libMesh;
@@ -1035,9 +1032,6 @@ void UnstructuredMesh::find_neighbors (const bool reset_remote_elements,
                 }
             }
         }
-
-      // Ghost the disconnected elements
-      this->add_ghosting_functor(std::make_unique<DisconnectedNeighborCoupling>(*this));
     }
 #endif // LIBMESH_ENABLE_PERIODIC
 
@@ -1848,6 +1842,14 @@ UnstructuredMesh::stitching_helper (const MeshBase * other_mesh,
   MeshTools::libmesh_assert_valid_neighbors(*this);
 #endif
 
+  auto * this_db = this->get_disconnected_boundaries();
+  auto * other_db = (other_mesh ? other_mesh->get_disconnected_boundaries() : nullptr);
+
+  const bool have_disc_bdys = ((this_db && !this_db->empty()) ||
+                              (other_db && !other_db->empty()));
+  if (have_disc_bdys)
+    libmesh_not_implemented_msg("stitching meshes with disconnected boundaries is not supported yet.");
+
   // We can't even afford any unset neighbor links here.
   if (!this->is_prepared())
     this->find_neighbors();
diff --git a/tests/systems/disconnected_neighbor_test.C b/tests/systems/disconnected_neighbor_test.C
