Struct RetirementFrontier 

struct RetirementFrontier {
    highest_retired: Option<SsaIndex>,
    registered: HashSet<SsaIndex>,
    retriable: HashSet<SsaIndex>,
    recovered_tail: Option<RecoveredSsaTail>,
}

Compact retirement state for one Session.

highest_retired alone is not enough: a later member of a batch may retire while an earlier member is still live. The exception sets retain only indices that still own a registration or were released before going live and may be retried. Live registrations are bounded by the Session layer’s generation limit; a failed pre-live request closes a production Session, whose scope releases its retriable entries. The number of completed cycles is represented by one watermark rather than one allocation each.

Fields

highest_retired: Option<SsaIndex>

registered: HashSet<SsaIndex>

retriable: HashSet<SsaIndex>

recovered_tail: Option<RecoveredSsaTail>

The most recently recovered cycle’s bounded liveness tail.

One slot is sufficient and security-critical: the Entry emits cycles in index order, so only the immediate recovered predecessor can legitimately remain in the Exit’s FIFO. A newer recovered cycle replaces it, preventing old shares from buying service indefinitely while keeping retirement memory constant over the Session’s lifetime.

Implementations

impl RetirementFrontier

fn is_retired(&self, index: SsaIndex) -> bool

fn register(&mut self, index: SsaIndex) -> bool

fn abandon(&mut self, index: SsaIndex)

Releases a registration that never went live while leaving its index reusable.

fn retire(&mut self, index: SsaIndex) -> bool

Retires a known registration and raises the compact watermark.

Returning false for an unknown index is load-bearing: allowing an arbitrary retire_ssa call to raise the watermark would condemn legitimate lower indices that are registered later.

fn retire_recovered(&mut self, index: SsaIndex, tail: RecoveredSsaTail) -> bool

Trait Implementations

impl Default for RetirementFrontier

fn default() -> RetirementFrontier

Returns the “default value” for a type.