--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2019 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+#ifndef dealii_mapping_q_cache_h
+#define dealii_mapping_q_cache_h
+
+
+#include <deal.II/base/config.h>
+
+#include <deal.II/fe/mapping_q_generic.h>
+
+#include <deal.II/grid/tria.h>
+
+
+DEAL_II_NAMESPACE_OPEN
+
+
+
+/*!@addtogroup mapping */
+/*@{*/
+
+
+/**
+ * This class implements a caching strategy for objects of the MappingQ family
+ * in terms of the MappingQGeneric::compute_mapping_support_points() function,
+ * which is used in all operations of MappingQGeneric. The information of the
+ * mapping is pre-computed by the MappingQCache::initialize() function.
+ *
+ * @author Martin Kronbichler, 2019
+ */
+template <int dim, int spacedim = dim>
+class MappingQCache : public MappingQGeneric<dim, spacedim>
+{
+public:
+ /**
+ * Constructor. @p polynomial_degree denotes the polynomial degree of the
+ * polynomials that are used to map cells from the reference to the real
+ * cell.
+ */
+ explicit MappingQCache(const unsigned int polynomial_degree);
+
+ /**
+ * Copy constructor.
+ */
+ explicit MappingQCache(const MappingQCache<dim, spacedim> &mapping);
+
+ /**
+ * Destructor.
+ */
+ ~MappingQCache();
+
+ /**
+ * clone() functionality. For documentation, see Mapping::clone().
+ */
+ virtual std::unique_ptr<Mapping<dim, spacedim>>
+ clone() const override;
+
+ /**
+ * Returns @p false because the preservation of vertex locations depends on
+ * the mapping handed to the reinit() function.
+ */
+ virtual bool
+ preserves_vertex_locations() const override;
+
+ /**
+ * Initialize the data cache by computing the mapping support points for all
+ * cells (on all levels) of the given triangulation. Note that the cache is
+ * invalidated upon the signal Triangulation::Signals::any_change of the
+ * underlying triangulation.
+ */
+ void
+ initialize(const Triangulation<dim, spacedim> & triangulation,
+ const MappingQGeneric<dim, spacedim> &mapping);
+
+ /**
+ * Return the memory consumption (in bytes) of the cache.
+ */
+ std::size_t
+ memory_consumption() const;
+
+protected:
+ /**
+ * This is the main function overriden from the base class MappingQGeneric.
+ */
+ virtual std::vector<Point<spacedim>>
+ compute_mapping_support_points(
+ const typename Triangulation<dim, spacedim>::cell_iterator &cell)
+ const override;
+
+private:
+ /**
+ * The point cache filled upon calling initialize(). It is made a shared
+ * pointer to allow several instances (created via clone()) to share this
+ * cache.
+ */
+ std::shared_ptr<std::vector<std::vector<std::vector<Point<spacedim>>>>>
+ support_point_cache;
+
+ /**
+ * The connection to Triangulation::signals::any that must be reset once
+ * this class goes out of scope.
+ */
+ boost::signals2::connection clear_signal;
+};
+
+DEAL_II_NAMESPACE_CLOSE
+
+#endif
--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2019 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+#include <deal.II/base/memory_consumption.h>
+#include <deal.II/base/work_stream.h>
+
+#include <deal.II/fe/mapping_q_cache.h>
+
+#include <functional>
+
+DEAL_II_NAMESPACE_OPEN
+
+template <int dim, int spacedim>
+MappingQCache<dim, spacedim>::MappingQCache(
+ const unsigned int polynomial_degree)
+ : MappingQGeneric<dim, spacedim>(polynomial_degree)
+{}
+
+
+
+template <int dim, int spacedim>
+MappingQCache<dim, spacedim>::MappingQCache(
+ const MappingQCache<dim, spacedim> &mapping)
+ : MappingQGeneric<dim, spacedim>(mapping)
+ , support_point_cache(mapping.support_point_cache)
+{}
+
+
+
+template <int dim, int spacedim>
+MappingQCache<dim, spacedim>::~MappingQCache()
+{
+ if (clear_signal.connected())
+ clear_signal.disconnect();
+}
+
+
+
+template <int dim, int spacedim>
+std::unique_ptr<Mapping<dim, spacedim>>
+MappingQCache<dim, spacedim>::clone() const
+{
+ return std_cxx14::make_unique<MappingQCache<dim, spacedim>>(*this);
+}
+
+
+
+template <int dim, int spacedim>
+bool
+MappingQCache<dim, spacedim>::preserves_vertex_locations() const
+{
+ return false;
+}
+
+
+
+template <int dim, int spacedim>
+void
+MappingQCache<dim, spacedim>::initialize(
+ const Triangulation<dim, spacedim> & triangulation,
+ const MappingQGeneric<dim, spacedim> &mapping)
+{
+ AssertDimension(this->get_degree(), mapping.get_degree());
+
+ clear_signal = triangulation.signals.any_change.connect(
+ [&]() -> void { this->support_point_cache.reset(); });
+
+ support_point_cache =
+ std::make_shared<std::vector<std::vector<std::vector<Point<spacedim>>>>>(
+ triangulation.n_levels());
+ for (unsigned int l = 0; l < triangulation.n_levels(); ++l)
+ (*support_point_cache)[l].resize(triangulation.n_raw_cells(l));
+
+ WorkStream::run(
+ triangulation.begin(),
+ triangulation.end(),
+ [&](const typename Triangulation<dim, spacedim>::cell_iterator &cell,
+ void *,
+ void *) {
+ (*support_point_cache)[cell->level()][cell->index()] =
+ mapping.compute_mapping_support_points(cell);
+ },
+ /* copier */ std::function<void(void *)>(),
+ /* scratch_data */ nullptr,
+ /* copy_data */ nullptr,
+ 2 * MultithreadInfo::n_threads(),
+ /* chunk_size = */ 1);
+}
+
+
+
+template <int dim, int spacedim>
+std::size_t
+MappingQCache<dim, spacedim>::memory_consumption() const
+{
+ if (support_point_cache.get() != nullptr)
+ return sizeof(*this) +
+ MemoryConsumption::memory_consumption(*support_point_cache);
+ else
+ return sizeof(*this);
+}
+
+
+
+template <int dim, int spacedim>
+std::vector<Point<spacedim>>
+MappingQCache<dim, spacedim>::compute_mapping_support_points(
+ const typename Triangulation<dim, spacedim>::cell_iterator &cell) const
+{
+ Assert(support_point_cache.get() != nullptr, ExcNotInitialized());
+
+ AssertIndexRange(cell->level(), support_point_cache->size());
+ AssertIndexRange(cell->index(), (*support_point_cache)[cell->level()].size());
+ return (*support_point_cache)[cell->level()][cell->index()];
+}
+
+
+
+//--------------------------- Explicit instantiations -----------------------
+#include "mapping_q_cache.inst"
+
+
+DEAL_II_NAMESPACE_CLOSE
--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2019 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+
+for (deal_II_dimension : DIMENSIONS; deal_II_space_dimension : SPACE_DIMENSIONS)
+ {
+#if deal_II_dimension <= deal_II_space_dimension
+ template class MappingQCache<deal_II_dimension, deal_II_space_dimension>;
+#endif
+ }