src/gromacs/modularsimulator/modularsimulator.cpp

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
   3  *
   4  * Copyright (c) 2019,2020, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
   6  * and including many others, as listed in the AUTHORS file in the
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   8  *
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  35 /*! \internal \file
  36  * \brief Defines the modular simulator
  37  *
  38  * \author Pascal Merz <pascal.merz@me.com>
  39  * \ingroup module_modularsimulator
  40  */
  41
  42 #include "gmxpre.h"
  43
  44 #include "modularsimulator.h"
  45
  46 #include "gromacs/commandline/filenm.h"
  47 #include "gromacs/domdec/domdec.h"
  48 #include "gromacs/ewald/pme.h"
  49 #include "gromacs/ewald/pme_load_balancing.h"
  50 #include "gromacs/gmxlib/network.h"
  51 #include "gromacs/gmxlib/nrnb.h"
  52 #include "gromacs/math/vec.h"
  53 #include "gromacs/mdlib/checkpointhandler.h"
  54 #include "gromacs/mdlib/constr.h"
  55 #include "gromacs/mdlib/energyoutput.h"
  56 #include "gromacs/mdlib/mdatoms.h"
  57 #include "gromacs/mdlib/resethandler.h"
  58 #include "gromacs/mdlib/stat.h"
  59 #include "gromacs/mdlib/update.h"
  60 #include "gromacs/mdrun/replicaexchange.h"
  61 #include "gromacs/mdrun/shellfc.h"
  62 #include "gromacs/mdrunutility/handlerestart.h"
  63 #include "gromacs/mdrunutility/printtime.h"
  64 #include "gromacs/mdtypes/commrec.h"
  65 #include "gromacs/mdtypes/fcdata.h"
  66 #include "gromacs/mdtypes/inputrec.h"
  67 #include "gromacs/mdtypes/mdrunoptions.h"
  68 #include "gromacs/mdtypes/observableshistory.h"
  69 #include "gromacs/mdtypes/state.h"
  70 #include "gromacs/nbnxm/nbnxm.h"
  71 #include "gromacs/timing/walltime_accounting.h"
  72 #include "gromacs/topology/topology.h"
  73 #include "gromacs/utility/cstringutil.h"
  74 #include "gromacs/utility/fatalerror.h"
  75
  76 #include "compositesimulatorelement.h"
  77 #include "computeglobalselement.h"
  78 #include "constraintelement.h"
  79 #include "energyelement.h"
  80 #include "forceelement.h"
  81 #include "freeenergyperturbationelement.h"
  82 #include "parrinellorahmanbarostat.h"
  83 #include "propagator.h"
  84 #include "shellfcelement.h"
  85 #include "signallers.h"
  86 #include "statepropagatordata.h"
  87 #include "trajectoryelement.h"
  88 #include "vrescalethermostat.h"
  89
  90 namespace gmx
  91 {
  92 void ModularSimulator::run()
  93 {
  94     GMX_LOG(mdlog.info).asParagraph().appendText("Using the modular simulator.");
  95     constructElementsAndSignallers();
  96     simulatorSetup();
  97     for (auto& signaller : signallerCallList_)
  98     {
  99         signaller->signallerSetup();
 100     }
 101     if (domDecHelper_)
 102     {
 103         domDecHelper_->setup();
 104     }
 105
 106     for (auto& element : elementsOwnershipList_)
 107     {
 108         element->elementSetup();
 109     }
 110     if (pmeLoadBalanceHelper_)
 111     {
 112         // State must have been initialized so pmeLoadBalanceHelper_ gets a valid box
 113         pmeLoadBalanceHelper_->setup();
 114     }
 115
 116     while (step_ <= signalHelper_->lastStep_)
 117     {
 118         populateTaskQueue();
 119
 120         while (!taskQueue_.empty())
 121         {
 122             auto task = std::move(taskQueue_.front());
 123             taskQueue_.pop();
 124             // run function
 125             (*task)();
 126         }
 127     }
 128
 129     for (auto& element : elementsOwnershipList_)
 130     {
 131         element->elementTeardown();
 132     }
 133     if (pmeLoadBalanceHelper_)
 134     {
 135         pmeLoadBalanceHelper_->teardown();
 136     }
 137     simulatorTeardown();
 138 }
 139
 140 void ModularSimulator::simulatorSetup()
 141 {
 142     if (!mdrunOptions.writeConfout)
 143     {
 144         // This is on by default, and the main known use case for
 145         // turning it off is for convenience in benchmarking, which is
 146         // something that should not show up in the general user
 147         // interface.
 148         GMX_LOG(mdlog.info)
 149                 .asParagraph()
 150                 .appendText(
 151                         "The -noconfout functionality is deprecated, and "
 152                         "may be removed in a future version.");
 153     }
 154
 155     if (MASTER(cr))
 156     {
 157         char        sbuf[STEPSTRSIZE], sbuf2[STEPSTRSIZE];
 158         std::string timeString;
 159         fprintf(stderr, "starting mdrun '%s'\n", *(top_global->name));
 160         if (inputrec->nsteps >= 0)
 161         {
 162             timeString = formatString("%8.1f", static_cast<double>(inputrec->init_step + inputrec->nsteps)
 163                                                        * inputrec->delta_t);
 164         }
 165         else
 166         {
 167             timeString = "infinite";
 168         }
 169         if (inputrec->init_step > 0)
 170         {
 171             fprintf(stderr, "%s steps, %s ps (continuing from step %s, %8.1f ps).\n",
 172                     gmx_step_str(inputrec->init_step + inputrec->nsteps, sbuf), timeString.c_str(),
 173                     gmx_step_str(inputrec->init_step, sbuf2), inputrec->init_step * inputrec->delta_t);
 174         }
 175         else
 176         {
 177             fprintf(stderr, "%s steps, %s ps.\n", gmx_step_str(inputrec->nsteps, sbuf),
 178                     timeString.c_str());
 179         }
 180         fprintf(fplog, "\n");
 181     }
 182
 183     walltime_accounting_start_time(walltime_accounting);
 184     wallcycle_start(wcycle, ewcRUN);
 185     print_start(fplog, cr, walltime_accounting, "mdrun");
 186
 187     step_ = inputrec->init_step;
 188 }
 189
 190 void ModularSimulator::preStep(Step step, Time gmx_unused time, bool isNeighborSearchingStep)
 191 {
 192     if (stopHandler_->stoppingAfterCurrentStep(isNeighborSearchingStep) && step != signalHelper_->lastStep_)
 193     {
 194         /*
 195          * Stop handler wants to stop after the current step, which was
 196          * not known when building the current task queue. This happens
 197          * e.g. when a stop is signalled by OS. We therefore want to purge
 198          * the task queue now, and re-schedule this step as last step.
 199          */
 200         // clear task queue
 201         std::queue<SimulatorRunFunctionPtr>().swap(taskQueue_);
 202         // rewind step
 203         step_ = step;
 204         return;
 205     }
 206
 207     resetHandler_->setSignal(walltime_accounting);
 208     // This is a hack to avoid having to rewrite StopHandler to be a NeighborSearchSignaller
 209     // and accept the step as input. Eventually, we want to do that, but currently this would
 210     // require introducing NeighborSearchSignaller in the legacy do_md or a lot of code
 211     // duplication.
 212     stophandlerIsNSStep_    = isNeighborSearchingStep;
 213     stophandlerCurrentStep_ = step;
 214     stopHandler_->setSignal();
 215
 216     wallcycle_start(wcycle, ewcSTEP);
 217 }
 218
 219 void ModularSimulator::postStep(Step step, Time gmx_unused time)
 220 {
 221     // Output stuff
 222     if (MASTER(cr))
 223     {
 224         if (do_per_step(step, inputrec->nstlog))
 225         {
 226             if (fflush(fplog) != 0)
 227             {
 228                 gmx_fatal(FARGS, "Cannot flush logfile - maybe you are out of disk space?");
 229             }
 230         }
 231     }
 232     const bool do_verbose = mdrunOptions.verbose
 233                             && (step % mdrunOptions.verboseStepPrintInterval == 0
 234                                 || step == inputrec->init_step || step == signalHelper_->lastStep_);
 235     // Print the remaining wall clock time for the run
 236     if (MASTER(cr) && (do_verbose || gmx_got_usr_signal())
 237         && !(pmeLoadBalanceHelper_ && pmeLoadBalanceHelper_->pmePrinting()))
 238     {
 239         print_time(stderr, walltime_accounting, step, inputrec, cr);
 240     }
 241
 242     double cycles = wallcycle_stop(wcycle, ewcSTEP);
 243     if (DOMAINDECOMP(cr) && wcycle)
 244     {
 245         dd_cycles_add(cr->dd, static_cast<float>(cycles), ddCyclStep);
 246     }
 247
 248     resetHandler_->resetCounters(
 249             step, step - inputrec->init_step, mdlog, fplog, cr, fr->nbv.get(), nrnb, fr->pmedata,
 250             pmeLoadBalanceHelper_ ? pmeLoadBalanceHelper_->loadBalancingObject() : nullptr, wcycle,
 251             walltime_accounting);
 252 }
 253
 254 void ModularSimulator::simulatorTeardown()
 255 {
 256
 257     // Stop measuring walltime
 258     walltime_accounting_end_time(walltime_accounting);
 259
 260     if (!thisRankHasDuty(cr, DUTY_PME))
 261     {
 262         /* Tell the PME only node to finish */
 263         gmx_pme_send_finish(cr);
 264     }
 265
 266     walltime_accounting_set_nsteps_done(walltime_accounting, step_ - inputrec->init_step);
 267 }
 268
 269 void ModularSimulator::populateTaskQueue()
 270 {
 271     auto registerRunFunction = std::make_unique<RegisterRunFunction>(
 272             [this](SimulatorRunFunctionPtr ptr) { taskQueue_.push(std::move(ptr)); });
 273
 274     Time startTime = inputrec->init_t;
 275     Time timeStep  = inputrec->delta_t;
 276     Time time      = startTime + step_ * timeStep;
 277
 278     // Run an initial call to the signallers
 279     for (auto& signaller : signallerCallList_)
 280     {
 281         signaller->signal(step_, time);
 282     }
 283
 284     if (checkpointHelper_)
 285     {
 286         checkpointHelper_->run(step_, time);
 287     }
 288
 289     if (pmeLoadBalanceHelper_)
 290     {
 291         pmeLoadBalanceHelper_->run(step_, time);
 292     }
 293     if (domDecHelper_)
 294     {
 295         domDecHelper_->run(step_, time);
 296     }
 297
 298     do
 299     {
 300         // local variables for lambda capturing
 301         const int  step     = step_;
 302         const bool isNSStep = step == signalHelper_->nextNSStep_;
 303
 304         // register pre-step
 305         (*registerRunFunction)(std::make_unique<SimulatorRunFunction>(
 306                 [this, step, time, isNSStep]() { preStep(step, time, isNSStep); }));
 307         // register elements for step
 308         for (auto& element : elementCallList_)
 309         {
 310             element->scheduleTask(step_, time, registerRunFunction);
 311         }
 312         // register post-step
 313         (*registerRunFunction)(
 314                 std::make_unique<SimulatorRunFunction>([this, step, time]() { postStep(step, time); }));
 315
 316         // prepare next step
 317         step_++;
 318         time = startTime + step_ * timeStep;
 319         for (auto& signaller : signallerCallList_)
 320         {
 321             signaller->signal(step_, time);
 322         }
 323     } while (step_ != signalHelper_->nextNSStep_ && step_ <= signalHelper_->lastStep_);
 324 }
 325
 326 void ModularSimulator::constructElementsAndSignallers()
 327 {
 328     /* When restarting from a checkpoint, it can be appropriate to
 329      * initialize ekind from quantities in the checkpoint. Otherwise,
 330      * compute_globals must initialize ekind before the simulation
 331      * starts/restarts. However, only the master rank knows what was
 332      * found in the checkpoint file, so we have to communicate in
 333      * order to coordinate the restart.
 334      *
 335      * TODO (modular) This should become obsolete when checkpoint reading
 336      *      happens within the modular simulator framework: The energy
 337      *      element should read its data from the checkpoint file pointer,
 338      *      and signal to the compute globals element if it needs anything
 339      *      reduced.
 340      *
 341      * TODO (legacy) Consider removing this communication if/when checkpoint
 342      *      reading directly follows .tpr reading, because all ranks can
 343      *      agree on hasReadEkinState at that time.
 344      */
 345     bool hasReadEkinState = MASTER(cr) ? state_global->ekinstate.hasReadEkinState : false;
 346     if (PAR(cr))
 347     {
 348         gmx_bcast(sizeof(hasReadEkinState), &hasReadEkinState, cr);
 349     }
 350     if (hasReadEkinState)
 351     {
 352         restore_ekinstate_from_state(cr, ekind, &state_global->ekinstate);
 353     }
 354
 355     /*
 356      * Build data structures
 357      */
 358     topologyHolder_ =
 359             std::make_unique<TopologyHolder>(*top_global, cr, inputrec, fr, mdAtoms, constr, vsite);
 360
 361     std::unique_ptr<FreeEnergyPerturbationElement> freeEnergyPerturbationElement    = nullptr;
 362     FreeEnergyPerturbationElement*                 freeEnergyPerturbationElementPtr = nullptr;
 363     if (inputrec->efep != efepNO)
 364     {
 365         freeEnergyPerturbationElement =
 366                 std::make_unique<FreeEnergyPerturbationElement>(fplog, inputrec, mdAtoms);
 367         freeEnergyPerturbationElementPtr = freeEnergyPerturbationElement.get();
 368     }
 369
 370     auto statePropagatorData = std::make_unique<StatePropagatorData>(
 371             top_global->natoms, fplog, cr, state_global, inputrec->nstxout, inputrec->nstvout,
 372             inputrec->nstfout, inputrec->nstxout_compressed, fr->nbv->useGpu(),
 373             freeEnergyPerturbationElementPtr, topologyHolder_.get(), fr->bMolPBC,
 374             mdrunOptions.writeConfout, opt2fn("-c", nfile, fnm), inputrec, mdAtoms->mdatoms());
 375     auto statePropagatorDataPtr = compat::make_not_null(statePropagatorData.get());
 376
 377     auto energyElement = std::make_unique<EnergyElement>(
 378             statePropagatorDataPtr, freeEnergyPerturbationElementPtr, top_global, inputrec, mdAtoms,
 379             enerd, ekind, constr, fplog, fcd, mdModulesNotifier, MASTER(cr), observablesHistory,
 380             startingBehavior);
 381     auto energyElementPtr = compat::make_not_null(energyElement.get());
 382
 383     /*
 384      * Build stop handler
 385      */
 386     const bool simulationsShareState = false;
 387     stopHandler_                     = stopHandlerBuilder->getStopHandlerMD(
 388             compat::not_null<SimulationSignal*>(&signals_[eglsSTOPCOND]), simulationsShareState,
 389             MASTER(cr), inputrec->nstlist, mdrunOptions.reproducible, nstglobalcomm_,
 390             mdrunOptions.maximumHoursToRun, inputrec->nstlist == 0, fplog, stophandlerCurrentStep_,
 391             stophandlerIsNSStep_, walltime_accounting);
 392
 393     /*
 394      * Create simulator builders
 395      */
 396     SignallerBuilder<NeighborSearchSignaller> neighborSearchSignallerBuilder;
 397     SignallerBuilder<LastStepSignaller>       lastStepSignallerBuilder;
 398     SignallerBuilder<LoggingSignaller>        loggingSignallerBuilder;
 399     SignallerBuilder<EnergySignaller>         energySignallerBuilder;
 400     TrajectoryElementBuilder                  trajectoryElementBuilder;
 401
 402     /*
 403      * Register data structures to signallers
 404      */
 405     trajectoryElementBuilder.registerWriterClient(statePropagatorDataPtr);
 406     trajectoryElementBuilder.registerSignallerClient(statePropagatorDataPtr);
 407     lastStepSignallerBuilder.registerSignallerClient(statePropagatorDataPtr);
 408
 409     trajectoryElementBuilder.registerWriterClient(energyElementPtr);
 410     trajectoryElementBuilder.registerSignallerClient(energyElementPtr);
 411     energySignallerBuilder.registerSignallerClient(energyElementPtr);
 412
 413     // Register the simulator itself to the neighbor search / last step signaller
 414     neighborSearchSignallerBuilder.registerSignallerClient(compat::make_not_null(signalHelper_.get()));
 415     lastStepSignallerBuilder.registerSignallerClient(compat::make_not_null(signalHelper_.get()));
 416
 417     /*
 418      * Build integrator - this takes care of force calculation, propagation,
 419      * constraining, and of the place the statePropagatorData and the energy element
 420      * have a full timestep state.
 421      */
 422     // TODO: Make a CheckpointHelperBuilder
 423     std::vector<ICheckpointHelperClient*> checkpointClients = { statePropagatorDataPtr, energyElementPtr,
 424                                                                 freeEnergyPerturbationElementPtr };
 425     CheckBondedInteractionsCallbackPtr checkBondedInteractionsCallback = nullptr;
 426     auto                               integrator =
 427             buildIntegrator(&neighborSearchSignallerBuilder, &energySignallerBuilder,
 428                             &loggingSignallerBuilder, &trajectoryElementBuilder, &checkpointClients,
 429                             &checkBondedInteractionsCallback, statePropagatorDataPtr,
 430                             energyElementPtr, freeEnergyPerturbationElementPtr, hasReadEkinState);
 431
 432     /*
 433      * Build infrastructure elements
 434      */
 435
 436     if (PmeLoadBalanceHelper::doPmeLoadBalancing(mdrunOptions, inputrec, fr))
 437     {
 438         pmeLoadBalanceHelper_ = std::make_unique<PmeLoadBalanceHelper>(
 439                 mdrunOptions.verbose, statePropagatorDataPtr, fplog, cr, mdlog, inputrec, wcycle, fr);
 440         neighborSearchSignallerBuilder.registerSignallerClient(
 441                 compat::make_not_null(pmeLoadBalanceHelper_.get()));
 442     }
 443
 444     if (DOMAINDECOMP(cr))
 445     {
 446         GMX_ASSERT(checkBondedInteractionsCallback,
 447                    "Domain decomposition needs a callback for check the number of bonded "
 448                    "interactions.");
 449         domDecHelper_ = std::make_unique<DomDecHelper>(
 450                 mdrunOptions.verbose, mdrunOptions.verboseStepPrintInterval, statePropagatorDataPtr,
 451                 topologyHolder_.get(), std::move(checkBondedInteractionsCallback), nstglobalcomm_, fplog,
 452                 cr, mdlog, constr, inputrec, mdAtoms, nrnb, wcycle, fr, vsite, imdSession, pull_work);
 453         neighborSearchSignallerBuilder.registerSignallerClient(compat::make_not_null(domDecHelper_.get()));
 454     }
 455
 456     const bool simulationsShareResetCounters = false;
 457     resetHandler_                            = std::make_unique<ResetHandler>(
 458             compat::make_not_null<SimulationSignal*>(&signals_[eglsRESETCOUNTERS]),
 459             simulationsShareResetCounters, inputrec->nsteps, MASTER(cr),
 460             mdrunOptions.timingOptions.resetHalfway, mdrunOptions.maximumHoursToRun, mdlog, wcycle,
 461             walltime_accounting);
 462
 463     /*
 464      * Build signaller list
 465      *
 466      * Note that as signallers depend on each others, the order of calling the signallers
 467      * matters. It is the responsibility of this builder to ensure that the order is
 468      * maintained.
 469      */
 470     auto energySignaller = energySignallerBuilder.build(
 471             inputrec->nstcalcenergy, inputrec->fepvals->nstdhdl, inputrec->nstpcouple);
 472     trajectoryElementBuilder.registerSignallerClient(compat::make_not_null(energySignaller.get()));
 473     loggingSignallerBuilder.registerSignallerClient(compat::make_not_null(energySignaller.get()));
 474     auto trajectoryElement = trajectoryElementBuilder.build(
 475             fplog, nfile, fnm, mdrunOptions, cr, outputProvider, mdModulesNotifier, inputrec,
 476             top_global, oenv, wcycle, startingBehavior);
 477     loggingSignallerBuilder.registerSignallerClient(compat::make_not_null(trajectoryElement.get()));
 478
 479     // Add checkpoint helper here since we need a pointer to the trajectory element and
 480     // need to register it with the lastStepSignallerBuilder
 481     auto checkpointHandler = std::make_unique<CheckpointHandler>(
 482             compat::make_not_null<SimulationSignal*>(&signals_[eglsCHKPT]), simulationsShareState,
 483             inputrec->nstlist == 0, MASTER(cr), mdrunOptions.writeConfout,
 484             mdrunOptions.checkpointOptions.period);
 485     checkpointHelper_ = std::make_unique<CheckpointHelper>(
 486             std::move(checkpointClients), std::move(checkpointHandler), inputrec->init_step,
 487             trajectoryElement.get(), top_global->natoms, fplog, cr, observablesHistory,
 488             walltime_accounting, state_global, mdrunOptions.writeConfout);
 489     lastStepSignallerBuilder.registerSignallerClient(compat::make_not_null(checkpointHelper_.get()));
 490
 491     lastStepSignallerBuilder.registerSignallerClient(compat::make_not_null(trajectoryElement.get()));
 492     auto loggingSignaller =
 493             loggingSignallerBuilder.build(inputrec->nstlog, inputrec->init_step, inputrec->init_t);
 494     lastStepSignallerBuilder.registerSignallerClient(compat::make_not_null(loggingSignaller.get()));
 495     auto lastStepSignaller =
 496             lastStepSignallerBuilder.build(inputrec->nsteps, inputrec->init_step, stopHandler_.get());
 497     neighborSearchSignallerBuilder.registerSignallerClient(compat::make_not_null(lastStepSignaller.get()));
 498     auto neighborSearchSignaller = neighborSearchSignallerBuilder.build(
 499             inputrec->nstlist, inputrec->init_step, inputrec->init_t);
 500
 501     addToCallListAndMove(std::move(neighborSearchSignaller), signallerCallList_, signallersOwnershipList_);
 502     addToCallListAndMove(std::move(lastStepSignaller), signallerCallList_, signallersOwnershipList_);
 503     addToCallListAndMove(std::move(loggingSignaller), signallerCallList_, signallersOwnershipList_);
 504     addToCallList(trajectoryElement, signallerCallList_);
 505     addToCallListAndMove(std::move(energySignaller), signallerCallList_, signallersOwnershipList_);
 506
 507     /*
 508      * Build the element list
 509      *
 510      * This is the actual sequence of (non-infrastructure) elements to be run.
 511      * For NVE, the trajectory element is used outside of the integrator
 512      * (composite) element, as well as the checkpoint helper. The checkpoint
 513      * helper should be on top of the loop, and is only part of the simulator
 514      * call list to be able to react to the last step being signalled.
 515      */
 516     addToCallList(checkpointHelper_, elementCallList_);
 517     if (freeEnergyPerturbationElement)
 518     {
 519         addToCallListAndMove(std::move(freeEnergyPerturbationElement), elementCallList_,
 520                              elementsOwnershipList_);
 521     }
 522     addToCallListAndMove(std::move(integrator), elementCallList_, elementsOwnershipList_);
 523     addToCallListAndMove(std::move(trajectoryElement), elementCallList_, elementsOwnershipList_);
 524     // for vv, we need to setup statePropagatorData after the compute
 525     // globals so that we reset the right velocities
 526     // TODO: Avoid this by getting rid of the need of resetting velocities in vv
 527     elementsOwnershipList_.emplace_back(std::move(statePropagatorData));
 528     elementsOwnershipList_.emplace_back(std::move(energyElement));
 529 }
 530
 531 std::unique_ptr<ISimulatorElement>
 532 ModularSimulator::buildForces(SignallerBuilder<NeighborSearchSignaller>* neighborSearchSignallerBuilder,
 533                               SignallerBuilder<EnergySignaller>*         energySignallerBuilder,
 534                               StatePropagatorData*                       statePropagatorDataPtr,
 535                               EnergyElement*                             energyElementPtr,
 536                               FreeEnergyPerturbationElement* freeEnergyPerturbationElement)
 537 {
 538     const bool isVerbose    = mdrunOptions.verbose;
 539     const bool isDynamicBox = inputrecDynamicBox(inputrec);
 540     // Check for polarizable models and flexible constraints
 541     if (ShellFCElement::doShellsOrFlexConstraints(&topologyHolder_->globalTopology(),
 542                                                   constr ? constr->numFlexibleConstraints() : 0))
 543     {
 544         auto shellFCElement = std::make_unique<ShellFCElement>(
 545                 statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElement, isVerbose,
 546                 isDynamicBox, fplog, cr, inputrec, mdAtoms, nrnb, fr, fcd, wcycle, runScheduleWork, vsite,
 547                 imdSession, pull_work, constr, &topologyHolder_->globalTopology(), enforcedRotation);
 548         topologyHolder_->registerClient(shellFCElement.get());
 549         neighborSearchSignallerBuilder->registerSignallerClient(
 550                 compat::make_not_null(shellFCElement.get()));
 551         energySignallerBuilder->registerSignallerClient(compat::make_not_null(shellFCElement.get()));
 552
 553         // std::move *should* not be needed with c++-14, but clang-3.6 still requires it
 554         return std::move(shellFCElement);
 555     }
 556     else
 557     {
 558         auto forceElement = std::make_unique<ForceElement>(
 559                 statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElement,
 560                 isDynamicBox, fplog, cr, inputrec, mdAtoms, nrnb, fr, fcd, wcycle, runScheduleWork,
 561                 vsite, imdSession, pull_work, enforcedRotation);
 562         topologyHolder_->registerClient(forceElement.get());
 563         neighborSearchSignallerBuilder->registerSignallerClient(compat::make_not_null(forceElement.get()));
 564         energySignallerBuilder->registerSignallerClient(compat::make_not_null(forceElement.get()));
 565
 566         // std::move *should* not be needed with c++-14, but clang-3.6 still requires it
 567         return std::move(forceElement);
 568     }
 569 }
 570
 571 std::unique_ptr<ISimulatorElement> ModularSimulator::buildIntegrator(
 572         SignallerBuilder<NeighborSearchSignaller>* neighborSearchSignallerBuilder,
 573         SignallerBuilder<EnergySignaller>*         energySignallerBuilder,
 574         SignallerBuilder<LoggingSignaller>*        loggingSignallerBuilder,
 575         TrajectoryElementBuilder*                  trajectoryElementBuilder,
 576         std::vector<ICheckpointHelperClient*>*     checkpointClients,
 577         CheckBondedInteractionsCallbackPtr*        checkBondedInteractionsCallback,
 578         compat::not_null<StatePropagatorData*>     statePropagatorDataPtr,
 579         compat::not_null<EnergyElement*>           energyElementPtr,
 580         FreeEnergyPerturbationElement*             freeEnergyPerturbationElementPtr,
 581         bool                                       hasReadEkinState)
 582 {
 583     auto forceElement =
 584             buildForces(neighborSearchSignallerBuilder, energySignallerBuilder,
 585                         statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr);
 586
 587     // list of elements owned by the simulator composite object
 588     std::vector<std::unique_ptr<ISimulatorElement>> elementsOwnershipList;
 589     // call list of the simulator composite object
 590     std::vector<compat::not_null<ISimulatorElement*>> elementCallList;
 591
 592     std::function<void()> needToCheckNumberOfBondedInteractions;
 593     if (inputrec->eI == eiMD)
 594     {
 595         auto computeGlobalsElement =
 596                 std::make_unique<ComputeGlobalsElement<ComputeGlobalsAlgorithm::LeapFrog>>(
 597                         statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 598                         &signals_, nstglobalcomm_, fplog, mdlog, cr, inputrec, mdAtoms, nrnb,
 599                         wcycle, fr, &topologyHolder_->globalTopology(), constr, hasReadEkinState);
 600         topologyHolder_->registerClient(computeGlobalsElement.get());
 601         energySignallerBuilder->registerSignallerClient(compat::make_not_null(computeGlobalsElement.get()));
 602         trajectoryElementBuilder->registerSignallerClient(
 603                 compat::make_not_null(computeGlobalsElement.get()));
 604
 605         *checkBondedInteractionsCallback =
 606                 computeGlobalsElement->getCheckNumberOfBondedInteractionsCallback();
 607
 608         auto propagator = std::make_unique<Propagator<IntegrationStep::LeapFrog>>(
 609                 inputrec->delta_t, statePropagatorDataPtr, mdAtoms, wcycle);
 610
 611         addToCallListAndMove(std::move(forceElement), elementCallList, elementsOwnershipList);
 612         addToCallList(statePropagatorDataPtr, elementCallList); // we have a full microstate at time t here!
 613         if (inputrec->etc == etcVRESCALE)
 614         {
 615             // TODO: With increased complexity of the propagator, this will need further development,
 616             //       e.g. using propagators templated for velocity propagation policies and a builder
 617             propagator->setNumVelocityScalingVariables(inputrec->opts.ngtc);
 618             auto thermostat = std::make_unique<VRescaleThermostat>(
 619                     inputrec->nsttcouple, -1, false, inputrec->ld_seed, inputrec->opts.ngtc,
 620                     inputrec->delta_t * inputrec->nsttcouple, inputrec->opts.ref_t, inputrec->opts.tau_t,
 621                     inputrec->opts.nrdf, energyElementPtr, propagator->viewOnVelocityScaling(),
 622                     propagator->velocityScalingCallback(), state_global, cr, inputrec->bContinuation);
 623             checkpointClients->emplace_back(thermostat.get());
 624             energyElementPtr->setVRescaleThermostat(thermostat.get());
 625             addToCallListAndMove(std::move(thermostat), elementCallList, elementsOwnershipList);
 626         }
 627
 628         std::unique_ptr<ParrinelloRahmanBarostat> prBarostat = nullptr;
 629         if (inputrec->epc == epcPARRINELLORAHMAN)
 630         {
 631             // Building the PR barostat here since it needs access to the propagator
 632             // and we want to be able to move the propagator object
 633             prBarostat = std::make_unique<ParrinelloRahmanBarostat>(
 634                     inputrec->nstpcouple, -1, inputrec->delta_t * inputrec->nstpcouple,
 635                     inputrec->init_step, propagator->viewOnPRScalingMatrix(),
 636                     propagator->prScalingCallback(), statePropagatorDataPtr, energyElementPtr,
 637                     fplog, inputrec, mdAtoms, state_global, cr, inputrec->bContinuation);
 638             energyElementPtr->setParrinelloRahamnBarostat(prBarostat.get());
 639             checkpointClients->emplace_back(prBarostat.get());
 640         }
 641         addToCallListAndMove(std::move(propagator), elementCallList, elementsOwnershipList);
 642         if (constr)
 643         {
 644             auto constraintElement = std::make_unique<ConstraintsElement<ConstraintVariable::Positions>>(
 645                     constr, statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 646                     MASTER(cr), fplog, inputrec, mdAtoms->mdatoms());
 647             auto constraintElementPtr = compat::make_not_null(constraintElement.get());
 648             energySignallerBuilder->registerSignallerClient(constraintElementPtr);
 649             trajectoryElementBuilder->registerSignallerClient(constraintElementPtr);
 650             loggingSignallerBuilder->registerSignallerClient(constraintElementPtr);
 651
 652             addToCallListAndMove(std::move(constraintElement), elementCallList, elementsOwnershipList);
 653         }
 654
 655         addToCallListAndMove(std::move(computeGlobalsElement), elementCallList, elementsOwnershipList);
 656         addToCallList(energyElementPtr, elementCallList); // we have the energies at time t here!
 657         if (prBarostat)
 658         {
 659             addToCallListAndMove(std::move(prBarostat), elementCallList, elementsOwnershipList);
 660         }
 661     }
 662     else if (inputrec->eI == eiVV)
 663     {
 664         auto computeGlobalsElementAtFullTimeStep =
 665                 std::make_unique<ComputeGlobalsElement<ComputeGlobalsAlgorithm::VelocityVerletAtFullTimeStep>>(
 666                         statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 667                         &signals_, nstglobalcomm_, fplog, mdlog, cr, inputrec, mdAtoms, nrnb,
 668                         wcycle, fr, &topologyHolder_->globalTopology(), constr, hasReadEkinState);
 669         topologyHolder_->registerClient(computeGlobalsElementAtFullTimeStep.get());
 670         energySignallerBuilder->registerSignallerClient(
 671                 compat::make_not_null(computeGlobalsElementAtFullTimeStep.get()));
 672         trajectoryElementBuilder->registerSignallerClient(
 673                 compat::make_not_null(computeGlobalsElementAtFullTimeStep.get()));
 674
 675         auto computeGlobalsElementAfterCoordinateUpdate =
 676                 std::make_unique<ComputeGlobalsElement<ComputeGlobalsAlgorithm::VelocityVerletAfterCoordinateUpdate>>(
 677                         statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 678                         &signals_, nstglobalcomm_, fplog, mdlog, cr, inputrec, mdAtoms, nrnb,
 679                         wcycle, fr, &topologyHolder_->globalTopology(), constr, hasReadEkinState);
 680         topologyHolder_->registerClient(computeGlobalsElementAfterCoordinateUpdate.get());
 681         energySignallerBuilder->registerSignallerClient(
 682                 compat::make_not_null(computeGlobalsElementAfterCoordinateUpdate.get()));
 683         trajectoryElementBuilder->registerSignallerClient(
 684                 compat::make_not_null(computeGlobalsElementAfterCoordinateUpdate.get()));
 685
 686         *checkBondedInteractionsCallback =
 687                 computeGlobalsElementAfterCoordinateUpdate->getCheckNumberOfBondedInteractionsCallback();
 688
 689         auto propagatorVelocities = std::make_unique<Propagator<IntegrationStep::VelocitiesOnly>>(
 690                 inputrec->delta_t * 0.5, statePropagatorDataPtr, mdAtoms, wcycle);
 691         auto propagatorVelocitiesAndPositions =
 692                 std::make_unique<Propagator<IntegrationStep::VelocityVerletPositionsAndVelocities>>(
 693                         inputrec->delta_t, statePropagatorDataPtr, mdAtoms, wcycle);
 694
 695         addToCallListAndMove(std::move(forceElement), elementCallList, elementsOwnershipList);
 696
 697         std::unique_ptr<ParrinelloRahmanBarostat> prBarostat = nullptr;
 698         if (inputrec->epc == epcPARRINELLORAHMAN)
 699         {
 700             // Building the PR barostat here since it needs access to the propagator
 701             // and we want to be able to move the propagator object
 702             prBarostat = std::make_unique<ParrinelloRahmanBarostat>(
 703                     inputrec->nstpcouple, -1, inputrec->delta_t * inputrec->nstpcouple,
 704                     inputrec->init_step, propagatorVelocities->viewOnPRScalingMatrix(),
 705                     propagatorVelocities->prScalingCallback(), statePropagatorDataPtr, energyElementPtr,
 706                     fplog, inputrec, mdAtoms, state_global, cr, inputrec->bContinuation);
 707             energyElementPtr->setParrinelloRahamnBarostat(prBarostat.get());
 708             checkpointClients->emplace_back(prBarostat.get());
 709         }
 710         addToCallListAndMove(std::move(propagatorVelocities), elementCallList, elementsOwnershipList);
 711         if (constr)
 712         {
 713             auto constraintElement = std::make_unique<ConstraintsElement<ConstraintVariable::Velocities>>(
 714                     constr, statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 715                     MASTER(cr), fplog, inputrec, mdAtoms->mdatoms());
 716             energySignallerBuilder->registerSignallerClient(compat::make_not_null(constraintElement.get()));
 717             trajectoryElementBuilder->registerSignallerClient(
 718                     compat::make_not_null(constraintElement.get()));
 719             loggingSignallerBuilder->registerSignallerClient(
 720                     compat::make_not_null(constraintElement.get()));
 721
 722             addToCallListAndMove(std::move(constraintElement), elementCallList, elementsOwnershipList);
 723         }
 724         addToCallListAndMove(std::move(computeGlobalsElementAtFullTimeStep), elementCallList,
 725                              elementsOwnershipList);
 726         addToCallList(statePropagatorDataPtr, elementCallList); // we have a full microstate at time t here!
 727         if (inputrec->etc == etcVRESCALE)
 728         {
 729             // TODO: With increased complexity of the propagator, this will need further development,
 730             //       e.g. using propagators templated for velocity propagation policies and a builder
 731             propagatorVelocitiesAndPositions->setNumVelocityScalingVariables(inputrec->opts.ngtc);
 732             auto thermostat = std::make_unique<VRescaleThermostat>(
 733                     inputrec->nsttcouple, 0, true, inputrec->ld_seed, inputrec->opts.ngtc,
 734                     inputrec->delta_t * inputrec->nsttcouple, inputrec->opts.ref_t,
 735                     inputrec->opts.tau_t, inputrec->opts.nrdf, energyElementPtr,
 736                     propagatorVelocitiesAndPositions->viewOnVelocityScaling(),
 737                     propagatorVelocitiesAndPositions->velocityScalingCallback(), state_global, cr,
 738                     inputrec->bContinuation);
 739             checkpointClients->emplace_back(thermostat.get());
 740             energyElementPtr->setVRescaleThermostat(thermostat.get());
 741             addToCallListAndMove(std::move(thermostat), elementCallList, elementsOwnershipList);
 742         }
 743         addToCallListAndMove(std::move(propagatorVelocitiesAndPositions), elementCallList,
 744                              elementsOwnershipList);
 745         if (constr)
 746         {
 747             auto constraintElement = std::make_unique<ConstraintsElement<ConstraintVariable::Positions>>(
 748                     constr, statePropagatorDataPtr, energyElementPtr, freeEnergyPerturbationElementPtr,
 749                     MASTER(cr), fplog, inputrec, mdAtoms->mdatoms());
 750             energySignallerBuilder->registerSignallerClient(compat::make_not_null(constraintElement.get()));
 751             trajectoryElementBuilder->registerSignallerClient(
 752                     compat::make_not_null(constraintElement.get()));
 753             loggingSignallerBuilder->registerSignallerClient(
 754                     compat::make_not_null(constraintElement.get()));
 755
 756             addToCallListAndMove(std::move(constraintElement), elementCallList, elementsOwnershipList);
 757         }
 758         addToCallListAndMove(std::move(computeGlobalsElementAfterCoordinateUpdate), elementCallList,
 759                              elementsOwnershipList);
 760         addToCallList(energyElementPtr, elementCallList); // we have the energies at time t here!
 761         if (prBarostat)
 762         {
 763             addToCallListAndMove(std::move(prBarostat), elementCallList, elementsOwnershipList);
 764         }
 765     }
 766     else
 767     {
 768         gmx_fatal(FARGS, "Integrator not implemented for the modular simulator.");
 769     }
 770
 771     auto integrator = std::make_unique<CompositeSimulatorElement>(std::move(elementCallList),
 772                                                                   std::move(elementsOwnershipList));
 773     // std::move *should* not be needed with c++-14, but clang-3.6 still requires it
 774     return std::move(integrator);
 775 }
 776
 777 bool ModularSimulator::isInputCompatible(bool                             exitOnFailure,
 778                                          const t_inputrec*                inputrec,
 779                                          bool                             doRerun,
 780                                          const gmx_vsite_t*               vsite,
 781                                          const gmx_multisim_t*            ms,
 782                                          const ReplicaExchangeParameters& replExParams,
 783                                          const t_fcdata*                  fcd,
 784                                          int                              nfile,
 785                                          const t_filenm*                  fnm,
 786                                          ObservablesHistory*              observablesHistory,
 787                                          const gmx_membed_t*              membed)
 788 {
 789     auto conditionalAssert = [exitOnFailure](bool condition, const char* message) {
 790         if (exitOnFailure)
 791         {
 792             GMX_RELEASE_ASSERT(condition, message);
 793         }
 794         return condition;
 795     };
 796
 797     bool isInputCompatible = true;
 798
 799     // GMX_USE_MODULAR_SIMULATOR allows to use modular simulator also for non-standard uses,
 800     // such as the leap-frog integrator
 801     const auto modularSimulatorExplicitlyTurnedOn = (getenv("GMX_USE_MODULAR_SIMULATOR") != nullptr);
 802     // GMX_USE_MODULAR_SIMULATOR allows to use disable modular simulator for all uses,
 803     // including the velocity-verlet integrator used by default
 804     const auto modularSimulatorExplicitlyTurnedOff = (getenv("GMX_DISABLE_MODULAR_SIMULATOR") != nullptr);
 805
 806     GMX_RELEASE_ASSERT(
 807             !(modularSimulatorExplicitlyTurnedOn && modularSimulatorExplicitlyTurnedOff),
 808             "Cannot have both GMX_USE_MODULAR_SIMULATOR=ON and GMX_DISABLE_MODULAR_SIMULATOR=ON. "
 809             "Unset one of the two environment variables to explicitly chose which simulator to "
 810             "use, "
 811             "or unset both to recover default behavior.");
 812
 813     GMX_RELEASE_ASSERT(
 814             !(modularSimulatorExplicitlyTurnedOff && inputrec->eI == eiVV
 815               && inputrec->epc == epcPARRINELLORAHMAN),
 816             "Cannot use a Parrinello-Rahman barostat with md-vv and "
 817             "GMX_DISABLE_MODULAR_SIMULATOR=ON, "
 818             "as the Parrinello-Rahman barostat is not implemented in the legacy simulator. Unset "
 819             "GMX_DISABLE_MODULAR_SIMULATOR or use a different pressure control algorithm.");
 820
 821     isInputCompatible =
 822             isInputCompatible
 823             && conditionalAssert(
 824                        inputrec->eI == eiMD || inputrec->eI == eiVV,
 825                        "Only integrators md and md-vv are supported by the modular simulator.");
 826     isInputCompatible = isInputCompatible
 827                         && conditionalAssert(inputrec->eI != eiMD || modularSimulatorExplicitlyTurnedOn,
 828                                              "Set GMX_USE_MODULAR_SIMULATOR=ON to use the modular "
 829                                              "simulator with integrator md.");
 830     isInputCompatible =
 831             isInputCompatible
 832             && conditionalAssert(!doRerun, "Rerun is not supported by the modular simulator.");
 833     isInputCompatible =
 834             isInputCompatible
 835             && conditionalAssert(
 836                        inputrec->etc == etcNO || inputrec->etc == etcVRESCALE,
 837                        "Only v-rescale thermostat is supported by the modular simulator.");
 838     isInputCompatible =
 839             isInputCompatible
 840             && conditionalAssert(
 841                        inputrec->epc == epcNO || inputrec->epc == epcPARRINELLORAHMAN,
 842                        "Only Parrinello-Rahman barostat is supported by the modular simulator.");
 843     isInputCompatible =
 844             isInputCompatible
 845             && conditionalAssert(
 846                        !(inputrecNptTrotter(inputrec) || inputrecNphTrotter(inputrec)
 847                          || inputrecNvtTrotter(inputrec)),
 848                        "Legacy Trotter decomposition is not supported by the modular simulator.");
 849     isInputCompatible = isInputCompatible
 850                         && conditionalAssert(inputrec->efep == efepNO || inputrec->efep == efepYES
 851                                                      || inputrec->efep == efepSLOWGROWTH,
 852                                              "Expanded ensemble free energy calculation is not "
 853                                              "supported by the modular simulator.");
 854     isInputCompatible = isInputCompatible
 855                         && conditionalAssert(!inputrec->bPull,
 856                                              "Pulling is not supported by the modular simulator.");
 857     isInputCompatible =
 858             isInputCompatible
 859             && conditionalAssert(inputrec->opts.ngacc == 1 && inputrec->opts.acc[0][XX] == 0.0
 860                                          && inputrec->opts.acc[0][YY] == 0.0
 861                                          && inputrec->opts.acc[0][ZZ] == 0.0 && inputrec->cos_accel == 0.0,
 862                                  "Acceleration is not supported by the modular simulator.");
 863     isInputCompatible =
 864             isInputCompatible
 865             && conditionalAssert(inputrec->opts.ngfrz == 1 && inputrec->opts.nFreeze[0][XX] == 0
 866                                          && inputrec->opts.nFreeze[0][YY] == 0
 867                                          && inputrec->opts.nFreeze[0][ZZ] == 0,
 868                                  "Freeze groups are not supported by the modular simulator.");
 869     isInputCompatible =
 870             isInputCompatible
 871             && conditionalAssert(
 872                        inputrec->deform[XX][XX] == 0.0 && inputrec->deform[XX][YY] == 0.0
 873                                && inputrec->deform[XX][ZZ] == 0.0 && inputrec->deform[YY][XX] == 0.0
 874                                && inputrec->deform[YY][YY] == 0.0 && inputrec->deform[YY][ZZ] == 0.0
 875                                && inputrec->deform[ZZ][XX] == 0.0 && inputrec->deform[ZZ][YY] == 0.0
 876                                && inputrec->deform[ZZ][ZZ] == 0.0,
 877                        "Deformation is not supported by the modular simulator.");
 878     isInputCompatible =
 879             isInputCompatible
 880             && conditionalAssert(vsite == nullptr,
 881                                  "Virtual sites are not supported by the modular simulator.");
 882     isInputCompatible = isInputCompatible
 883                         && conditionalAssert(!inputrec->bDoAwh,
 884                                              "AWH is not supported by the modular simulator.");
 885     isInputCompatible =
 886             isInputCompatible
 887             && conditionalAssert(ms == nullptr,
 888                                  "Multi-sim are not supported by the modular simulator.");
 889     isInputCompatible =
 890             isInputCompatible
 891             && conditionalAssert(replExParams.exchangeInterval == 0,
 892                                  "Replica exchange is not supported by the modular simulator.");
 893     isInputCompatible =
 894             isInputCompatible
 895             && conditionalAssert(fcd->disres.nsystems <= 1,
 896                                  "Ensemble restraints are not supported by the modular simulator.");
 897     isInputCompatible =
 898             isInputCompatible
 899             && conditionalAssert(!doSimulatedAnnealing(inputrec),
 900                                  "Simulated annealing is not supported by the modular simulator.");
 901     isInputCompatible =
 902             isInputCompatible
 903             && conditionalAssert(!inputrec->bSimTemp,
 904                                  "Simulated tempering is not supported by the modular simulator.");
 905     isInputCompatible = isInputCompatible
 906                         && conditionalAssert(!inputrec->bExpanded,
 907                                              "Expanded ensemble simulations are not supported by "
 908                                              "the modular simulator.");
 909     isInputCompatible =
 910             isInputCompatible
 911             && conditionalAssert(
 912                        !(opt2bSet("-ei", nfile, fnm) || observablesHistory->edsamHistory != nullptr),
 913                        "Essential dynamics is not supported by the modular simulator.");
 914     isInputCompatible = isInputCompatible
 915                         && conditionalAssert(inputrec->eSwapCoords == eswapNO,
 916                                              "Ion / water position swapping is not supported by "
 917                                              "the modular simulator.");
 918     isInputCompatible =
 919             isInputCompatible
 920             && conditionalAssert(!inputrec->bIMD,
 921                                  "Interactive MD is not supported by the modular simulator.");
 922     isInputCompatible =
 923             isInputCompatible
 924             && conditionalAssert(membed == nullptr,
 925                                  "Membrane embedding is not supported by the modular simulator.");
 926     // TODO: Change this to the boolean passed when we merge the user interface change for the GPU update.
 927     isInputCompatible =
 928             isInputCompatible
 929             && conditionalAssert(
 930                        getenv("GMX_FORCE_UPDATE_DEFAULT_GPU") == nullptr,
 931                        "Integration on the GPU is not supported by the modular simulator.");
 932     // Modular simulator is centered around NS updates
 933     // TODO: think how to handle nstlist == 0
 934     isInputCompatible = isInputCompatible
 935                         && conditionalAssert(inputrec->nstlist != 0,
 936                                              "Simulations without neighbor list update are not "
 937                                              "supported by the modular simulator.");
 938     isInputCompatible = isInputCompatible
 939                         && conditionalAssert(!GMX_FAHCORE,
 940                                              "GMX_FAHCORE not supported by the modular simulator.");
 941
 942     return isInputCompatible;
 943 }
 944
 945 void ModularSimulator::checkInputForDisabledFunctionality()
 946 {
 947     isInputCompatible(true, inputrec, doRerun, vsite, ms, replExParams, fcd, nfile, fnm,
 948                       observablesHistory, membed);
 949 }
 950
 951 SignallerCallbackPtr ModularSimulator::SignalHelper::registerLastStepCallback()
 952 {
 953     return std::make_unique<SignallerCallback>(
 954             [this](Step step, Time gmx_unused time) { this->lastStep_ = step; });
 955 }
 956
 957 SignallerCallbackPtr ModularSimulator::SignalHelper::registerNSCallback()
 958 {
 959     return std::make_unique<SignallerCallback>(
 960             [this](Step step, Time gmx_unused time) { this->nextNSStep_ = step; });
 961 }
 962 } // namespace gmx