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SST::RealTimeAction

RealTimeActions are actions that SST executes in response to an OS signal such as SIGINT or SIGUSR1. See the signal handling guide for more information about using these actions.

RealTimeActions are SST elements and can be registered with SST as part of an element library.

The following example creates an element examples.helloExample which when triggered via a signal, prints the rank, thread, and simulated time.

helloExample.h
#include <sst/core/realtimeAction.h>
#include <sst/core/rankInfo.h>

class ExampleRealTimeAction : public SST::RealTimeAction
{
    public:

    // ELI macro to register action with SST-Core
    SST_ELI_REGISTER_REALTIMEACTION(
        ExampleRealTimeAction,                  // Class
        "examples",                             // Library name
        "helloExample",                         // Element name
        SST_ELI_ELEMENT_VERSION(0, 1, 0),       // Version
        "Prints hello in response to a signal") // Description

    ExampleRealTimeAction(); // Constructor
    ~ExampleRealTimeAction(); // Destructor

    virtual void execute() override; // Action to take
}
helloExample.cc
#include <sst/core/sst_config.h>

#include "helloExample.h"

#include <sst/core/realtimeAction.h> 
#include <sst/core/unitAlgebra.h>
#include <sst/core/rankInfo.h>

ExampleRealTimeAction::ExampleRealTimeAction() { }

~ExampleRealTimeAction::ExampleRealTimeAction() { }

void ExampleRealTimeAction::execute()
{
    Output sim_output = getSimulationOutput();
    RankInfo rank     = getRank();

    sim_output.output("Hello from rank %u, thread %u at simulated time %s.\n", 
        rank.rank, rank.thread, getElapsedSimTime().toStringBestSI().c_str());
}

Parallel execution​

Actions are executed only when SST's global state is synchronized so unlike most element objects, actions may perform synchronization and invoke MPI calls. Each thread and/or rank instantiates its own action object. When a signal causes an action to execute, each rank and thread calls execute() on its local instance of the action.

#include <sst/core/realtimeAction.h>