Function is_validator

pub(crate) fn is_validator(
    replica: &VerifyingKey,
    validator_set_state: &ValidatorSetState,
) -> bool

Determine whether the replica is an “active” validator, given the current validator_set_state.

An active validator can:

• Propose/Nudge and phase vote in the HotStuff protocol,
• Contribute timeout votes and advance view messages.

is_validator logic

Whether or not replica is an active validator given the current validator_set_state depends on two factors:

1. Whether replica is part of the Committed Validator Set (CVS), the Previous Validator Set (PVS), both validator sets, or neither.
2. Whether validator_set_state.update_decided() or not.

The below table specifies exactly the return value of is_validator in every possible combination of the two factors:

	Validator Set Update Decided	Validator Set Update Not Decided
Part of CVS (and maybe also PVS)	true	true
Part of PVS only	false	true
Part of neither neither CVS or PVS	false	false