Struct ProjectionFrontier 

pub struct ProjectionFrontier { /* private fields */ }

Freshness policy and commit token types used by projected queries. An opaque, scoped projection visibility frontier.

V2 binds (database_id, history_incarnation, FrontierPosition). Comparison and ProjectionFrontier::satisfies require equal scopes; a restore that bumps the incarnation can never satisfy a pre-restore causal token.

Implementations

impl ProjectionFrontier

pub fn new( history_incarnation: u64, position: FrontierPosition, ) -> ProjectionFrontier

Builds an engine-local or legacy V1 frontier with no database scope.

pub fn new_scoped( database_id: DatabaseId, history_incarnation: u64, position: FrontierPosition, ) -> ProjectionFrontier

Builds a V2 frontier bound to one database and history incarnation.

pub fn from_bytes( bytes: Vec<u8>, ) -> Result<ProjectionFrontier, FreshnessTokenError>

Parses opaque frontier bytes produced by Self::as_bytes.

pub const fn database_id(&self) -> Option<DatabaseId>

Database scope; absent only on legacy V1 frontiers.

pub fn commit_token(&self) -> Option<CommitToken>

Returns a token for an applied position without losing its scope.

pub const fn history_incarnation(&self) -> u64

History incarnation bound into the frontier.

pub const fn position(&self) -> FrontierPosition

Sequence position of the frontier (may be [FrontierPosition::BeforeFirst]).

pub fn as_bytes(&self) -> &[u8]

Opaque bytes for wire carriage (CP2b protocol) and storage.

pub fn into_bytes(self) -> Vec<u8>

Consumes the frontier and returns its opaque bytes.

pub fn satisfies(&self, required: &CommitToken) -> bool

Whether this frontier covers required under exactly the same scope.

Database, version-scope, or incarnation mismatch always fails closed.

pub fn lag_sequences(&self, head: &ProjectionFrontier) -> Option<u64>

Sequence distance from this frontier to head when both share an database scope and incarnation and are sequenced.

Trait Implementations

impl Clone for ProjectionFrontier

fn clone(&self) -> ProjectionFrontier

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProjectionFrontier

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

Formats the value using the given formatter.

impl Eq for ProjectionFrontier

impl Hash for ProjectionFrontier

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

where H: Hasher,

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 Ord for ProjectionFrontier

fn cmp(&self, other: &ProjectionFrontier) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for ProjectionFrontier

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for ProjectionFrontier

fn partial_cmp(&self, other: &ProjectionFrontier) -> 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 TryFrom<Vec<u8>> for ProjectionFrontier

type Error = FreshnessTokenError

The type returned in the event of a conversion error.

fn try_from( value: Vec<u8>, ) -> Result<ProjectionFrontier, <ProjectionFrontier as TryFrom<Vec<u8>>>::Error>

Performs the conversion.