src/gromacs/modularsimulator/computeglobalselement.h

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  35 /*! \libinternal
  36  * \brief Declares the global reduction element for the modular simulator
  37  *
  38  * \author Pascal Merz <pascal.merz@me.com>
  39  * \ingroup module_modularsimulator
  40  */
  41
  42 #ifndef GMX_MODULARSIMULATOR_COMPUTEGLOBALSELEMENT_H
  43 #define GMX_MODULARSIMULATOR_COMPUTEGLOBALSELEMENT_H
  44
  45 #include "gromacs/mdlib/simulationsignal.h"
  46 #include "gromacs/mdlib/vcm.h"
  47
  48 #include "energyelement.h"
  49 #include "modularsimulatorinterfaces.h"
  50 #include "statepropagatordata.h"
  51 #include "topologyholder.h"
  52
  53 struct gmx_global_stat;
  54 struct gmx_wallcycle;
  55 struct t_nrnb;
  56
  57 namespace gmx
  58 {
  59 class MDAtoms;
  60 class MDLogger;
  61
  62 //! \addtogroup module_modularsimulator
  63 //! \{
  64
  65 //! The different global reduction schemes we know about
  66 enum class ComputeGlobalsAlgorithm
  67 {
  68     LeapFrog,
  69     VelocityVerletAtFullTimeStep,
  70     VelocityVerletAfterCoordinateUpdate
  71 };
  72
  73 //! The function type allowing to request a check of the number of bonded interactions
  74 typedef std::function<void()> CheckBondedInteractionsCallback;
  75 //! Pointer to the function type allowing to request a check of the number of bonded interactions
  76 typedef std::unique_ptr<CheckBondedInteractionsCallback> CheckBondedInteractionsCallbackPtr;
  77
  78 /*! \libinternal
  79  * \brief Encapsulate the calls to `compute_globals`
  80  *
  81  * This element aims at offering an interface to the legacy
  82  * implementation which is compatible with the new simulator approach.
  83  *
  84  * The element comes in 3 (templated) flavors: the leap-frog case, the first
  85  * call during a velocity-verlet integrator, and the second call during a
  86  * velocity-verlet integrator. In velocity verlet, the state at the beginning
  87  * of the step corresponds to
  88  *     positions at time t
  89  *     velocities at time t - dt/2
  90  * The first velocity propagation (+dt/2) therefore actually corresponds to the
  91  * previous step, bringing the state to the full timestep at time t. Most global
  92  * reductions are made at this point. The second call is needed to correct the
  93  * constraint virial after the second propagation of velocities (+dt/2) and of
  94  * the positions (+dt).
  95  *
  96  * @tparam algorithm  The global reduction scheme
  97  */
  98 template <ComputeGlobalsAlgorithm algorithm>
  99 class ComputeGlobalsElement final :
 100     public                  ISimulatorElement,
 101     public                  IEnergySignallerClient,
 102     public                  ITrajectorySignallerClient,
 103     public                  ITopologyHolderClient
 104 {
 105     public:
 106         //! Constructor
 107         ComputeGlobalsElement(
 108             StatePropagatorData *statePropagatorData,
 109             EnergyElement       *energyElement,
 110             int                  nstglobalcomm,
 111             FILE                *fplog,
 112             const MDLogger      &mdlog,
 113             t_commrec           *cr,
 114             t_inputrec          *inputrec,
 115             const MDAtoms       *mdAtoms,
 116             t_nrnb              *nrnb,
 117             gmx_wallcycle       *wcycle,
 118             t_forcerec          *fr,
 119             const gmx_mtop_t    *global_top,
 120             Constraints         *constr);
 121
 122         //! Destructor
 123         ~ComputeGlobalsElement() override;
 124
 125         /*! \brief Element setup - first call to compute_globals
 126          *
 127          */
 128         void elementSetup() override;
 129
 130         /*! \brief Register run function for step / time
 131          *
 132          * This registers the call to compute_globals when needed.
 133          *
 134          * @param step                 The step number
 135          * @param time                 The time
 136          * @param registerRunFunction  Function allowing to register a run function
 137          */
 138         void scheduleTask(
 139             Step step, Time time,
 140             const RegisterRunFunctionPtr &registerRunFunction) override;
 141
 142         //! Get callback to request checking of bonded interactions
 143         CheckBondedInteractionsCallbackPtr getCheckNumberOfBondedInteractionsCallback();
 144
 145         //! No element teardown needed
 146         void elementTeardown() override {}
 147
 148     private:
 149         //! ITopologyClient implementation
 150         void setTopology(const gmx_localtop_t *top) override;
 151         //! IEnergySignallerClient implementation
 152         SignallerCallbackPtr registerEnergyCallback(EnergySignallerEvent event) override;
 153         //! ITrajectorySignallerClient implementation
 154         SignallerCallbackPtr registerTrajectorySignallerCallback(TrajectoryEvent event) override;
 155         //! The compute_globals call
 156         void compute(
 157             Step step, unsigned int flags,
 158             SimulationSignaller *signaller, bool useLastBox,
 159             bool isInit = false);
 160
 161         //! Next step at which energy needs to be reduced
 162         Step energyReductionStep_;
 163         //! Next step at which virial needs to be reduced
 164         Step virialReductionStep_;
 165
 166         //! Whether center of mass motion stopping is enabled
 167         const bool                           doStopCM_;
 168         //! Number of steps after which center of mass motion is removed
 169         int                                  nstcomm_;
 170         //! Compute globals communication period
 171         int                                  nstglobalcomm_;
 172         //! The initial step (only used for VV)
 173         const Step                           initStep_;
 174         //! A dummy signaller (used for setup and VV)
 175         std::unique_ptr<SimulationSignaller> nullSignaller_;
 176
 177         /*! \brief Check that DD doesn't miss bonded interactions
 178          *
 179          * Domain decomposition could incorrectly miss a bonded
 180          * interaction, but checking for that requires a global
 181          * communication stage, which does not otherwise happen in DD
 182          * code. So we do that alongside the first global energy reduction
 183          * after a new DD is made. These variables handle whether the
 184          * check happens, and the result it returns.
 185          */
 186         //! @{
 187         int  totalNumberOfBondedInteractions_;
 188         bool shouldCheckNumberOfBondedInteractions_;
 189         //! @}
 190
 191         /*! \brief Signal to ComputeGlobalsElement that it should check for DD errors
 192          *
 193          * Note that this should really be the responsibility of the DD element.
 194          * MDLogger, global and local topology are only needed due to the call to
 195          * checkNumberOfBondedInteractions(...).
 196          *
 197          * The DD element should have a single variable which gets reduced, and then
 198          * be responsible for the checking after a global reduction has happened.
 199          * This would, however, require a new approach for the compute_globals calls,
 200          * which is not yet implemented. So for now, we're leaving this here.
 201          */
 202         void needToCheckNumberOfBondedInteractions();
 203
 204         //! Whether we need to sum ekinh_old at a later run
 205         bool needToSumEkinhOld_;
 206
 207         //! Global reduction struct
 208         gmx_global_stat *gstat_;
 209
 210         //! Pointer to the microstate
 211         StatePropagatorData  *statePropagatorData_;
 212         //! Pointer to the energy element (needed for the tensors and mu_tot)
 213         EnergyElement        *energyElement_;
 214         //! Pointer to the local topology (only needed for checkNumberOfBondedInteractions)
 215         const gmx_localtop_t *localTopology_;
 216
 217         //! Center of mass motion removal
 218         t_vcm             vcm_;
 219         //! Signals
 220         SimulationSignals signals_;
 221
 222         // Access to ISimulator data
 223         //! Handles logging.
 224         FILE             *fplog_;
 225         //! Handles logging.
 226         const MDLogger   &mdlog_;
 227         //! Handles communication.
 228         t_commrec        *cr_;
 229         //! Contains user input mdp options.
 230         t_inputrec       *inputrec_;
 231         //! Full system topology - only needed for checkNumberOfBondedInteractions.
 232         const gmx_mtop_t *top_global_;
 233         //! Atom parameters for this domain.
 234         const MDAtoms    *mdAtoms_;
 235         //! Handles constraints.
 236         Constraints      *constr_;
 237         //! Manages flop accounting.
 238         t_nrnb           *nrnb_;
 239         //! Manages wall cycle accounting.
 240         gmx_wallcycle    *wcycle_;
 241         //! Parameters for force calculations.
 242         t_forcerec       *fr_;
 243 };
 244
 245 //! \}
 246 }      // namespace gmx
 247
 248 #endif // GMX_MODULARSIMULATOR_COMPUTEGLOBALSELEMENT_H