Struct InactivityScoreTracker 

pub struct InactivityScoreTracker { /* private fields */ }

Per-validator inactivity-score store.

Implements DSL-088 (+ DSL-089/090 in later commits). Traces to SPEC §9.2.

Storage

Vec<u64> indexed by validator_index. Size fixed at construction; caller resizes at validator-set growth via future resize DSL.

Default

InactivityScoreTracker::new(n) zero-initialises all slots.

Implementations

impl InactivityScoreTracker

pub fn new(validator_count: usize) -> Self

New tracker sized for validator_count validators with all scores at 0.

pub fn score(&self, validator_index: u32) -> Option<u64>

Read score at validator_index. None when out of range.

pub fn validator_count(&self) -> usize

Number of validator slots tracked.

pub fn set_score(&mut self, validator_index: u32, score: u64) -> bool

Mutable score access for tests + DSL-089/090 rollout.

pub fn update_for_epoch( &mut self, participation: &ParticipationTracker, in_finality_stall: bool, )

Apply per-epoch score deltas based on the just-finished epoch’s participation (read from participation.previous_flags).

Implements DSL-088. DSL-089 (miss + stall → +4) and DSL-090 (global -16 out of stall) extend the body in later commits.

DSL-088 rule (hit decrement)

For every validator whose previous-epoch flags had TIMELY_TARGET set, decrement the score by 1 saturating at 0. Applies in BOTH regimes (stall + no-stall) — timely target participation is the canonical signal for reducing inactivity score, and the _in_finality_stall argument is reserved (stored, not read) so future DSLs can pick it up without changing the caller signature.

Iteration

Iterates 0..min(validator_count, participation.validator_count()). A validator that is tracked here but missing from the participation tracker receives no delta (defensive: grow happens at the tracker boundary, not here).

pub fn epoch_penalties( &self, effective_balances: &dyn EffectiveBalanceView, in_finality_stall: bool, ) -> Vec<(u32, u64)>

Compute per-validator inactivity-leak debits for the current epoch.

Implements DSL-091. DSL-092 lands the in-stall penalty formula; for now the in-stall branch returns an empty vec, same as the out-of-stall branch.

Out-of-stall (DSL-091)

!in_finality_stall → empty Vec<(u32, u64)>. Inactivity penalties NEVER charge validators outside a stall — DSL-090 global recovery handles score decay and that is the only no-stall effect.

In-stall (DSL-092 — stub today)

Returns empty until DSL-092 lands the formula penalty_mojos = eff_bal * score / INACTIVITY_PENALTY_QUOTIENT. Callers that iterate the return see zero entries either way; once DSL-092 ships, they’ll receive one (validator_index, penalty_mojos) pair per validator whose score contributes.

pub fn rewind_on_reorg(&mut self, depth: u64) -> u64

Grow or shrink the score vector to validator_count slots.

Implements DSL-093. Traces to SPEC §9.2, §10.

Semantics

• Growing: new trailing slots initialise to 0. Matches the activation semantics — freshly-activated validators start with a clean inactivity record.
• Shrinking: trailing entries are dropped. Rarely used (exits don’t reuse indices); provided for symmetry with ParticipationTracker::rotate_epoch.
• Same size: no-op.

Existing scores in the preserved range are unchanged. Rewind the tracker on fork-choice reorg.

Implements the inactivity leg of DSL-130 rewind_all_on_reorg. Zeroes every score — the same conservative-choice rationale as ParticipationTracker::rewind_on_reorg: no historical snapshots to restore, so fresh accumulation on the new canonical tip is safest (no ghost inactivity penalties).

Returns the number of epochs dropped — computed by the caller, not the tracker (the tracker does not carry an epoch counter). Accepts the value as depth so the DSL-130 ReorgReport can carry it uniformly with the participation-side report.

pub fn resize_for(&mut self, validator_count: usize)

Trait Implementations

impl Clone for InactivityScoreTracker

fn clone(&self) -> InactivityScoreTracker

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for InactivityScoreTracker

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.