void Partitioner::single_partition_range (MeshBase::element_iterator it,
MeshBase::element_iterator end)
{
LOG_SCOPE("single_partition_range()", "Partitioner");
for ( ; it != end; ++it)
{
Elem * elem = *it;
elem->processor_id() = 0;
// Assign all this element's nodes to processor 0 as well.
for (unsigned int n=0; n<elem->n_nodes(); ++n)
elem->node_ptr(n)->processor_id() = 0;
}
}
void Partitioner::set_node_processor_ids(MeshBase & mesh)
{
LOG_SCOPE("set_node_processor_ids()","Partitioner");
// This function must be run on all processors at once
libmesh_parallel_only(mesh.comm());
// If we have any unpartitioned elements at this
// stage there is a problem
libmesh_assert (MeshTools::n_elem(mesh.unpartitioned_elements_begin(),
mesh.unpartitioned_elements_end()) == 0);
// const dof_id_type orig_n_local_nodes = mesh.n_local_nodes();
// libMesh::err << "[" << mesh.processor_id() << "]: orig_n_local_nodes="
// << orig_n_local_nodes << std::endl;
// Build up request sets. Each node is currently owned by a processor because
// it is connected to an element owned by that processor. However, during the
// repartitioning phase that element may have been assigned a new processor id, but
// it is still resident on the original processor. We need to know where to look
// for new ids before assigning new ids, otherwise we may be asking the wrong processors
// for the wrong information.
//
// The only remaining issue is what to do with unpartitioned nodes. Since they are required
// to live on all processors we can simply rely on ourselves to number them properly.
std::vector<std::vector<dof_id_type> >
requested_node_ids(mesh.n_processors());
// Loop over all the nodes, count the ones on each processor. We can skip ourself
std::vector<dof_id_type> ghost_nodes_from_proc(mesh.n_processors(), 0);
MeshBase::node_iterator node_it = mesh.nodes_begin();
const MeshBase::node_iterator node_end = mesh.nodes_end();
for (; node_it != node_end; ++node_it)
{
Node * node = *node_it;
libmesh_assert(node);
const processor_id_type current_pid = node->processor_id();
if (current_pid != mesh.processor_id() &&
current_pid != DofObject::invalid_processor_id)
{
libmesh_assert_less (current_pid, ghost_nodes_from_proc.size());
ghost_nodes_from_proc[current_pid]++;
}
}
// We know how many objects live on each processor, so reserve()
// space for each.
for (processor_id_type pid=0; pid != mesh.n_processors(); ++pid)
requested_node_ids[pid].reserve(ghost_nodes_from_proc[pid]);
// We need to get the new pid for each node from the processor
// which *currently* owns the node. We can safely skip ourself
for (node_it = mesh.nodes_begin(); node_it != node_end; ++node_it)
{
Node * node = *node_it;
libmesh_assert(node);
const processor_id_type current_pid = node->processor_id();
if (current_pid != mesh.processor_id() &&
current_pid != DofObject::invalid_processor_id)
{
libmesh_assert_less (current_pid, requested_node_ids.size());
libmesh_assert_less (requested_node_ids[current_pid].size(),
ghost_nodes_from_proc[current_pid]);
requested_node_ids[current_pid].push_back(node->id());
}
// Unset any previously-set node processor ids
node->invalidate_processor_id();
}
// Loop over all the active elements
MeshBase::element_iterator elem_it = mesh.active_elements_begin();
const MeshBase::element_iterator elem_end = mesh.active_elements_end();
for ( ; elem_it != elem_end; ++elem_it)
{
Elem * elem = *elem_it;
libmesh_assert(elem);
libmesh_assert_not_equal_to (elem->processor_id(), DofObject::invalid_processor_id);
// For each node, set the processor ID to the min of
// its current value and this Element's processor id.
//
// TODO: we would probably get better parallel partitioning if
// we did something like "min for even numbered nodes, max for
// odd numbered". We'd need to be careful about how that would
// affect solution ordering for I/O, though.
for (unsigned int n=0; n<elem->n_nodes(); ++n)
elem->node_ptr(n)->processor_id() = std::min(elem->node_ptr(n)->processor_id(),
elem->processor_id());
}
// And loop over the subactive elements, but don't reassign
// nodes that are already active on another processor.
MeshBase::element_iterator sub_it = mesh.subactive_elements_begin();
const MeshBase::element_iterator sub_end = mesh.subactive_elements_end();
for ( ; sub_it != sub_end; ++sub_it)
{
Elem * elem = *sub_it;
libmesh_assert(elem);
libmesh_assert_not_equal_to (elem->processor_id(), DofObject::invalid_processor_id);
for (unsigned int n=0; n<elem->n_nodes(); ++n)
if (elem->node_ptr(n)->processor_id() == DofObject::invalid_processor_id)
elem->node_ptr(n)->processor_id() = elem->processor_id();
}
// Same for the inactive elements -- we will have already gotten most of these
// nodes, *except* for the case of a parent with a subset of children which are
// ghost elements. In that case some of the parent nodes will not have been
// properly handled yet
MeshBase::element_iterator not_it = mesh.not_active_elements_begin();
const MeshBase::element_iterator not_end = mesh.not_active_elements_end();
for ( ; not_it != not_end; ++not_it)
{
Elem * elem = *not_it;
libmesh_assert(elem);
libmesh_assert_not_equal_to (elem->processor_id(), DofObject::invalid_processor_id);
for (unsigned int n=0; n<elem->n_nodes(); ++n)
if (elem->node_ptr(n)->processor_id() == DofObject::invalid_processor_id)
elem->node_ptr(n)->processor_id() = elem->processor_id();
}
// We can't assert that all nodes are connected to elements, because
// a DistributedMesh with NodeConstraints might have pulled in some
// remote nodes solely for evaluating those constraints.
// MeshTools::libmesh_assert_connected_nodes(mesh);
// For such nodes, we'll do a sanity check later when making sure
// that we successfully reset their processor ids to something
// valid.
// Next set node ids from other processors, excluding self
for (processor_id_type p=1; p != mesh.n_processors(); ++p)
{
// Trade my requests with processor procup and procdown
processor_id_type procup = cast_int<processor_id_type>
((mesh.processor_id() + p) % mesh.n_processors());
processor_id_type procdown = cast_int<processor_id_type>
((mesh.n_processors() + mesh.processor_id() - p) %
mesh.n_processors());
std::vector<dof_id_type> request_to_fill;
mesh.comm().send_receive(procup, requested_node_ids[procup],
procdown, request_to_fill);
// Fill those requests in-place
for (std::size_t i=0; i != request_to_fill.size(); ++i)
{
Node & node = mesh.node_ref(request_to_fill[i]);
const processor_id_type new_pid = node.processor_id();
// We may have an invalid processor_id() on nodes that have been
// "detatched" from coarsened-away elements but that have not yet
// themselves been removed.
// libmesh_assert_not_equal_to (new_pid, DofObject::invalid_processor_id);
// libmesh_assert_less (new_pid, mesh.n_partitions()); // this is the correct test --
request_to_fill[i] = new_pid; // the number of partitions may
} // not equal the number of processors
// Trade back the results
std::vector<dof_id_type> filled_request;
mesh.comm().send_receive(procdown, request_to_fill,
procup, filled_request);
libmesh_assert_equal_to (filled_request.size(), requested_node_ids[procup].size());
// And copy the id changes we've now been informed of
for (std::size_t i=0; i != filled_request.size(); ++i)
{
Node & node = mesh.node_ref(requested_node_ids[procup][i]);
// this is the correct test -- the number of partitions may
// not equal the number of processors
// But: we may have an invalid processor_id() on nodes that
// have been "detatched" from coarsened-away elements but
// that have not yet themselves been removed.
// libmesh_assert_less (filled_request[i], mesh.n_partitions());
node.processor_id(cast_int<processor_id_type>(filled_request[i]));
}
}
#ifdef DEBUG
MeshTools::libmesh_assert_valid_procids<Node>(mesh);
#endif
}
void MeshTools::Subdivision::add_boundary_ghosts(MeshBase & mesh)
{
static const Real tol = 1e-5;
// add the mirrored ghost elements (without using iterators, because the mesh is modified in the course)
std::vector<Tri3Subdivision *> ghost_elems;
std::vector<Node *> ghost_nodes;
const unsigned int n_elem = mesh.n_elem();
for (unsigned int eid = 0; eid < n_elem; ++eid)
{
Elem * elem = mesh.elem_ptr(eid);
libmesh_assert_equal_to(elem->type(), TRI3SUBDIVISION);
// If the triangle happens to be in a corner (two boundary
// edges), we perform a counter-clockwise loop by mirroring the
// previous triangle until we come back to the original
// triangle. This prevents degenerated triangles in the mesh
// corners and guarantees that the node in the middle of the
// loop is of valence=6.
for (unsigned int i = 0; i < elem->n_sides(); ++i)
{
libmesh_assert_not_equal_to(elem->neighbor(i), elem);
if (elem->neighbor(i) == libmesh_nullptr &&
elem->neighbor(next[i]) == libmesh_nullptr)
{
Elem * nelem = elem;
unsigned int k = i;
for (unsigned int l=0;l<4;l++)
{
// this is the vertex to be mirrored
Point point = nelem->point(k) + nelem->point(next[k]) - nelem->point(prev[k]);
// Check if the proposed vertex doesn't coincide
// with one of the existing vertices. This is
// necessary because for some triangulations, it can
// happen that two mirrored ghost vertices coincide,
// which would then lead to a zero size ghost
// element below.
Node * node = libmesh_nullptr;
for (unsigned int j = 0; j < ghost_nodes.size(); ++j)
{
if ((*ghost_nodes[j] - point).norm() < tol * (elem->point(k) - point).norm())
{
node = ghost_nodes[j];
break;
}
}
// add the new vertex only if no other is nearby
if (node == libmesh_nullptr)
{
node = mesh.add_point(point);
ghost_nodes.push_back(node);
}
Tri3Subdivision * newelem = new Tri3Subdivision();
// add the first new ghost element to the list just as in the non-corner case
if (l == 0)
ghost_elems.push_back(newelem);
newelem->set_node(0) = nelem->node_ptr(next[k]);
newelem->set_node(1) = nelem->node_ptr(k);
newelem->set_node(2) = node;
newelem->set_neighbor(0, nelem);
newelem->set_ghost(true);
if (l>0)
newelem->set_neighbor(2, libmesh_nullptr);
nelem->set_neighbor(k, newelem);
mesh.add_elem(newelem);
mesh.get_boundary_info().add_node(nelem->node_ptr(k), 1);
mesh.get_boundary_info().add_node(nelem->node_ptr(next[k]), 1);
mesh.get_boundary_info().add_node(nelem->node_ptr(prev[k]), 1);
mesh.get_boundary_info().add_node(node, 1);
nelem = newelem;
k = 2 ;
}
Tri3Subdivision * newelem = new Tri3Subdivision();
newelem->set_node(0) = elem->node_ptr(next[i]);
newelem->set_node(1) = nelem->node_ptr(2);
newelem->set_node(2) = elem->node_ptr(prev[i]);
newelem->set_neighbor(0, nelem);
nelem->set_neighbor(2, newelem);
newelem->set_ghost(true);
newelem->set_neighbor(2, elem);
elem->set_neighbor(next[i],newelem);
mesh.add_elem(newelem);
break;
}
}
for (unsigned int i = 0; i < elem->n_sides(); ++i)
{
libmesh_assert_not_equal_to(elem->neighbor(i), elem);
if (elem->neighbor(i) == libmesh_nullptr)
{
// this is the vertex to be mirrored
Point point = elem->point(i) + elem->point(next[i]) - elem->point(prev[i]);
// Check if the proposed vertex doesn't coincide with
// one of the existing vertices. This is necessary
// because for some triangulations, it can happen that
// two mirrored ghost vertices coincide, which would
// then lead to a zero size ghost element below.
Node * node = libmesh_nullptr;
for (unsigned int j = 0; j < ghost_nodes.size(); ++j)
{
if ((*ghost_nodes[j] - point).norm() < tol * (elem->point(i) - point).norm())
{
node = ghost_nodes[j];
break;
}
}
// add the new vertex only if no other is nearby
if (node == libmesh_nullptr)
{
node = mesh.add_point(point);
ghost_nodes.push_back(node);
}
Tri3Subdivision * newelem = new Tri3Subdivision();
ghost_elems.push_back(newelem);
newelem->set_node(0) = elem->node_ptr(next[i]);
newelem->set_node(1) = elem->node_ptr(i);
newelem->set_node(2) = node;
newelem->set_neighbor(0, elem);
newelem->set_ghost(true);
elem->set_neighbor(i, newelem);
mesh.add_elem(newelem);
mesh.get_boundary_info().add_node(elem->node_ptr(i), 1);
mesh.get_boundary_info().add_node(elem->node_ptr(next[i]), 1);
mesh.get_boundary_info().add_node(elem->node_ptr(prev[i]), 1);
mesh.get_boundary_info().add_node(node, 1);
}
}
}
// add the missing ghost elements (connecting new ghost nodes)
std::vector<Tri3Subdivision *> missing_ghost_elems;
std::vector<Tri3Subdivision *>::iterator ghost_el = ghost_elems.begin();
const std::vector<Tri3Subdivision *>::iterator end_ghost_el = ghost_elems.end();
for (; ghost_el != end_ghost_el; ++ghost_el)
{
Tri3Subdivision * elem = *ghost_el;
libmesh_assert(elem->is_ghost());
for (unsigned int i = 0; i < elem->n_sides(); ++i)
{
if (elem->neighbor(i) == libmesh_nullptr &&
elem->neighbor(prev[i]) != libmesh_nullptr)
{
// go around counter-clockwise
Tri3Subdivision * nb1 = static_cast<Tri3Subdivision *>(elem->neighbor(prev[i]));
Tri3Subdivision * nb2 = nb1;
unsigned int j = i;
unsigned int n_nb = 0;
while (nb1 != libmesh_nullptr && nb1->id() != elem->id())
{
j = nb1->local_node_number(elem->node_id(i));
nb2 = nb1;
nb1 = static_cast<Tri3Subdivision *>(nb1->neighbor(prev[j]));
libmesh_assert(nb1 == libmesh_nullptr || nb1->id() != nb2->id());
n_nb++;
}
libmesh_assert_not_equal_to(nb2->id(), elem->id());
// Above, we merged coinciding ghost vertices. Therefore, we need
// to exclude the case where there is no ghost element to add between
// these two (identical) ghost nodes.
if (elem->node_ptr(next[i])->id() == nb2->node_ptr(prev[j])->id())
break;
// If the number of already present neighbors is less than 4, we add another extra element
// so that the node in the middle of the loop ends up being of valence=6.
// This case usually happens when the middle node corresponds to a corner of the original mesh,
// and the extra element below prevents degenerated triangles in the mesh corners.
if (n_nb < 4)
{
// this is the vertex to be mirrored
Point point = nb2->point(j) + nb2->point(prev[j]) - nb2->point(next[j]);
// Check if the proposed vertex doesn't coincide with one of the existing vertices.
// This is necessary because for some triangulations, it can happen that two mirrored
// ghost vertices coincide, which would then lead to a zero size ghost element below.
Node * node = libmesh_nullptr;
for (unsigned int k = 0; k < ghost_nodes.size(); ++k)
{
if ((*ghost_nodes[k] - point).norm() < tol * (nb2->point(j) - point).norm())
{
node = ghost_nodes[k];
break;
}
}
// add the new vertex only if no other is nearby
if (node == libmesh_nullptr)
{
node = mesh.add_point(point);
ghost_nodes.push_back(node);
}
Tri3Subdivision * newelem = new Tri3Subdivision();
newelem->set_node(0) = nb2->node_ptr(j);
newelem->set_node(1) = nb2->node_ptr(prev[j]);
newelem->set_node(2) = node;
newelem->set_neighbor(0, nb2);
newelem->set_neighbor(1, libmesh_nullptr);
newelem->set_ghost(true);
nb2->set_neighbor(prev[j], newelem);
mesh.add_elem(newelem);
mesh.get_boundary_info().add_node(nb2->node_ptr(j), 1);
mesh.get_boundary_info().add_node(nb2->node_ptr(prev[j]), 1);
mesh.get_boundary_info().add_node(node, 1);
nb2 = newelem;
j = nb2->local_node_number(elem->node_id(i));
}
Tri3Subdivision * newelem = new Tri3Subdivision();
newelem->set_node(0) = elem->node_ptr(next[i]);
newelem->set_node(1) = elem->node_ptr(i);
newelem->set_node(2) = nb2->node_ptr(prev[j]);
newelem->set_neighbor(0, elem);
newelem->set_neighbor(1, nb2);
newelem->set_neighbor(2, libmesh_nullptr);
newelem->set_ghost(true);
elem->set_neighbor(i, newelem);
nb2->set_neighbor(prev[j], newelem);
missing_ghost_elems.push_back(newelem);
break;
}
} // end side loop
} // end ghost element loop
// add the missing ghost elements to the mesh
std::vector<Tri3Subdivision *>::iterator missing_el = missing_ghost_elems.begin();
const std::vector<Tri3Subdivision *>::iterator end_missing_el = missing_ghost_elems.end();
for (; missing_el != end_missing_el; ++missing_el)
mesh.add_elem(*missing_el);
}