Struct DualFrontier 

pub struct DualFrontier { /* private fields */ }

One published durable frontier: an application and an administration position.

None in either component means that space has never advanced. The canonical encoding tags presence explicitly so an unchanged frontier is never confused with a zero sequence.

Comparison is the componentwise (product) order and is deliberately partial: a pair whose application component rises while its administration component falls is incomparable, not “greater”. Every caller that needs “does this advance?” must use DualFrontier::advances_from, which answers false for an incomparable pair. This is the same fail-closed discipline crate::ProjectionFrontier::satisfies applies across incarnations: an unproven relation is never treated as satisfied.

Implementations

impl DualFrontier

pub const INITIAL: Self

The frontier of a database on which nothing has ever been published.

pub const fn new( application: Option<CommitSequence>, administration: Option<AdministrationSequence>, ) -> Self

Builds a frontier pair from its two independently optional components.

pub const fn application(self) -> Option<CommitSequence>

Returns the published application commit-sequence component.

pub const fn administration(self) -> Option<AdministrationSequence>

Returns the published administration-sequence component.

pub const fn is_initial(self) -> bool

Returns true when nothing has ever been published.

pub fn advances_from(self, predecessor: Self) -> bool

Returns true when self is a strict successor of predecessor.

Both components must be greater than or equal to the predecessor’s and at least one must be strictly greater. An incomparable pair — one component up, the other down — answers false.

pub const fn to_canonical_bytes(self) -> [u8; 18]

Returns the canonical DUAL_FRONTIER_BYTES-byte encoding.

Layout: [app presence][app u64 BE][admin presence][admin u64 BE]. An absent component encodes its presence tag plus eight zero bytes, so “unchanged” is explicit rather than inferred.

pub fn from_canonical_bytes(bytes: [u8; 18]) -> Result<Self, DualFrontierError>

Decodes a canonical encoding, failing closed on any noncanonical shape.

Trait Implementations

impl Clone for DualFrontier

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for DualFrontier

impl Debug for DualFrontier

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

Formats the value using the given formatter.

impl Display for DualFrontier

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

Formats the value using the given formatter.

impl Eq for DualFrontier

impl Hash for DualFrontier

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for DualFrontier

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for DualFrontier

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for DualFrontier