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40 * \brief This file declares functions for inter-rank signalling by mdrun
42 * This handles details of responding to termination conditions,
43 * coordinating checkpoints, and coordinating multi-simulations.
45 * \todo Move this to mdrunutility module alongside gathering
46 * multi-simulation communication infrastructure there.
48 * \author Berk Hess <hess@kth.se>
49 * \author Mark Abraham <mark.j.abraham@gmail.com>
51 * \ingroup module_mdlib
53 #ifndef GMX_MDLIB_SIMULATIONSIGNAL_H
54 #define GMX_MDLIB_SIMULATIONSIGNAL_H
58 #include "gromacs/utility/real.h"
60 struct gmx_multisim_t;
63 //! Kinds of simulation conditions to signal about.
79 * \brief POD-style object used by mdrun ranks to set and
80 * receive signals within and between simulations.
82 * Keep in mind that the values of signals are transmitted to other
83 * ranks through an MPI_Reduce after casting them to a real (so the
84 * signals can be sent together with other data). This means that the
85 * only meaningful values are positive, negative or zero.
87 * isLocal permits (for example) replica-exchange to require that any
88 * checkpointing is synchronized across all simulations, by setting
89 * isLocal to false, so that the trigger for action is set only when
90 * inter-simulation signalling happens. Replica-exchange can
91 * coordinate this at run time when a SimulationSignaller is made. */
92 class SimulationSignal
96 SimulationSignal(bool isSignalLocal = true) : sig(0), set(0), isLocal(isSignalLocal) {}
97 //! The signal set by this rank in do_md().
99 //! The communicated signal that triggers action, which will be equal for all ranks, once communication has occured.
101 //! Is the signal in one simulation independent of other simulations?
105 //! Convenience typedef for the group of signals used.
106 typedef std::array<SimulationSignal, eglsNR> SimulationSignals;
109 * \brief Object used by mdrun ranks to signal to each other at this step.
111 * This object has responsibility to read signal values from \c gs,
112 * coordinate communication within and perhaps between simulations,
113 * and set result signal values in \c gs as appropriate.
115 * It is intended to have a very short lifetime, so should remain easy
116 * to construct and destruct on the stack just when the global
117 * communication occurs. */
118 class SimulationSignaller
122 SimulationSignaller(SimulationSignals* signals,
124 const gmx_multisim_t* ms,
127 /*! \brief Return a reference to an array of signal values to communicate.
129 * \return If intra-sim signalling will take place, fill and
130 * return a reference to the array of reals in which signals
131 * will be communicated with the signal values to be
132 * sent. Otherwise return a EmptyArrayRef. */
133 gmx::ArrayRef<real> getCommunicationBuffer();
134 /*! \brief Handle inter-simulation signal communication.
136 * If an inter-simulation signal should be handled, communicate between
137 * simulation-master ranks, then propagate from the masters to the
138 * rest of the ranks for each simulation. It is the responsibility of
139 * the calling code to ensure that any necessary intra-simulation
140 * signalling has already occurred, e.g. in global_stat(). */
141 void signalInterSim();
142 /*! \brief Propagate signals when appropriate.
144 * Always propagate an mdrun signal value when doing
145 * inter-simulation signalling; otherwise, propagate it only
146 * if should be propagated within this simulation,
147 * ie. locally. See documentation of SimulationSignal for
150 //! Convenience wrapper that calls signalInterSim() then setSignals().
151 void finalizeSignals();
154 //! Source and sink for mdrun signals
155 SimulationSignals* signals_;
156 //! Communication object.
157 const t_commrec* cr_;
158 //! Multi-sim handler.
159 const gmx_multisim_t* ms_;
160 //! Do inter-sim communication at this step.
162 //! Do intra-sim communication at this step.
164 //! Buffer for MPI communication.
165 std::array<real, eglsNR> mpiBuffer_;