Add flags for setting event parameters

[soumyadipghosh]

I am planning to choose a threshold of the form alpha * beta ^ k for event-based communication where k is the iteration number. To try out different values of alpha and beta, it would be helpful to get them in runtime through flags.

[pratikvn]

We use gflags to provide options to the executable at run-time.

I would suggest adding these as member variable to comm_struct object within the Settings struct. You could add another struct inside that struct called event_based and in that struct you could add alpha and beta as double type variables.

In the bench_ras.cpp file, use the Gflags syntax to create a double flags (event_based_alpha and event_based_beta) similar to the tolerance flags. Then you populate the settings.comm_settings.event_based.alpha by setting it to FLAGS_event_based_alpha and so on in the solve function of the BenchRas class as done for the tolerance and other flags.

And in your function, you use it in the same way, settings.comm_settings.event_based.alpha will contain the value of alpha set by the user. The user sets it by passing --event_based_alpha=0.1 to the executable bench_ras