src/gromacs/domdec/localatomset.h

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  35 /*! \file
  36  * \libinternal \brief
  37  * Declares gmx::LocalAtomSet.
  38  *
  39  * \author Christian Blau <cblau@gwdg.de>
  40  * \inlibraryapi
  41  * \ingroup module_domdec
  42  */
  43 #ifndef GMX_DOMDEC_LOCALATOMSET_H
  44 #define GMX_DOMDEC_LOCALATOMSET_H
  45
  46 #include <cstddef>
  47
  48 namespace gmx
  49 {
  50 template<typename>
  51 class ArrayRef;
  52 namespace internal
  53 {
  54 class LocalAtomSetData;
  55 } // namespace internal
  56 /*! \libinternal \brief
  57  * A local atom set collects local, global and collective indices of
  58  * the home atoms on a rank. The indices of the home atoms are automatically
  59  * updated during domain decomposition, thus gmx::LocalAtomSet::localIndex
  60  * enables iteration over local atoms properties like coordinates or forces.
  61  * TODO: add a LocalAtomSet iterator.
  62  *
  63  * To generate a LocalAtomSet call gmx::LocalAtomSetManger::add and keep the
  64  * handle to the LocalAtomSet returned from this call.
  65  *
  66  * \inlibraryapi
  67  * \ingroup module_domdec
  68  */
  69 class LocalAtomSet
  70 {
  71 public:
  72     friend class LocalAtomSetManager;
  73     /*! \brief Maps indices on rank [0..numAtomsLocal_) to global atom indicices.
  74      *
  75      * \returns the collective index.
  76      */
  77     ArrayRef<const int> collectiveIndex() const;
  78     /*! \brief Global indices of the atoms in this set.
  79      *
  80      * \note For best performance, store and use a local copy of the arrayref.
  81      *
  82      * \returns the global index.
  83      */
  84     ArrayRef<const int> globalIndex() const;
  85     /*! \brief Local indices of the atoms.
  86      *
  87      * For example, the i-th local atom coordinate of this set is
  88      * x[atomSet.localIndex()[i]].
  89      *
  90      * When using in a loop other than a range-based for loop,
  91      * performance may improve if the ArrayRef is stored in
  92      * a local variable before the loop is entered.
  93      * Updated within domain-decomposition.
  94      *
  95      * \note For best performance, store and use a local copy of the ArrayRef.
  96      *
  97      * \returns the local index.
  98      */
  99     ArrayRef<const int> localIndex() const;
 100     /*! \brief The number of atoms from this group index on this rank.
 101      *
 102      * \note For best performance, store and use a local copy of the ArrayRef.
 103      */
 104     std::size_t numAtomsLocal() const;
 105     /*! \brief The number of all atoms from this group index on all ranks together.
 106      *
 107      * \note For best performance, store and use a local copy.
 108      */
 109     std::size_t numAtomsGlobal() const;
 110
 111 private:
 112     /*! \brief Constructs a new atom set by setting a reference to its
 113      * internal data.
 114      * \param[in] data The data for the atom set is stored
 115      * in LocalAtomSetData, which is manged by \ref gmx::LocalAtomSetManager.
 116      */
 117     explicit LocalAtomSet(const internal::LocalAtomSetData& data);
 118
 119     const internal::LocalAtomSetData* data_;
 120 };
 121
 122 } // namespace gmx
 123
 124 #endif