Struct PnCounter 

pub struct PnCounter { /* private fields */ }

An increment/decrement counter: a pair of G-Counters (increments P, decrements N), join = componentwise.

Model: Crdt.PNCounter ι = (ι → ℕ) × (ι → ℕ) with the Prod lattice. Deltas bump one side, one coordinate (SafeMesh.deltaBumpP / deltaBumpN); each side accumulates exactly as a delta G-Counter (SafeMesh.deltaPNCounter_correct_P / _N), and equal state gives an equal read (SafeMesh.deltaPNCounter_value_matches).

Implementations

impl PnCounter

pub fn new(n: usize) -> Self

Fresh counter for n replicas — the lattice bottom (⊥, ⊥).

pub fn apply_inc(&mut self, replica: usize, tally: u64)

Apply SafeMesh.deltaBumpP replica tally — increment side, one coordinate on the wire, ⊥ on the other side. Out-of-range indices are ignored; use Self::try_apply_inc for an error.

pub fn try_apply_inc( &mut self, replica: usize, tally: u64, ) -> Result<(), CoordinateError>

Apply an increment-side delta with a checked replica coordinate.

Returns CoordinateError::ReplicaOutOfRange before any mutation if the index is invalid. Both sides remain unchanged on error. Valid input has the same effect as Self::apply_inc.

pub fn apply_dec(&mut self, replica: usize, tally: u64)

Apply SafeMesh.deltaBumpN replica tally — decrement side. Out-of-range indices are ignored; use Self::try_apply_dec for an error.

pub fn try_apply_dec( &mut self, replica: usize, tally: u64, ) -> Result<(), CoordinateError>

Apply a decrement-side delta with a checked replica coordinate.

Returns CoordinateError::ReplicaOutOfRange before any mutation if the index is invalid. Both sides remain unchanged on error. Valid input has the same effect as Self::apply_dec.

pub fn try_merge(&mut self, other: &PnCounter) -> Result<(), MergeError>

Checked full-state merge: componentwise checked G-Counter merge, erroring on a replica-count mismatch on either side instead of silently truncating (WS1). Both sides are length-checked before any mutation, so the operation is all-or-nothing: on error self is left unchanged.

pub fn merge(&mut self, other: &PnCounter)

Full-state merge: componentwise G-Counter merge — Crdt.pncounter_merge_apply.

Infallible variant for the proven equal-length invariant; panics on a replica-count mismatch. Use PnCounter::try_merge for untrusted input.

pub fn p_state(&self) -> &[u64]

Increment-side state.

pub fn n_state(&self) -> &[u64]

Decrement-side state.

pub fn value(&self) -> i64

The counter’s read: (sum of increments) − (sum of decrements) — Crdt.pncounterValue (ℤ in the model, i64 here).

Trait Implementations

impl Clone for PnCounter

fn clone(&self) -> PnCounter

Returns a duplicate of the value. Read more

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

Performs copy-assignment from source. Read more

impl Crdt for PnCounter

type Delta = PnCounterDelta

fn replica_count(&self) -> Option<usize>

Fixed replica domain, or None for CRDTs without a fixed arity.

fn apply_delta(&mut self, delta: Self::Delta)

fn validate_record( &self, _id: RecordId, _delta: &Self::Delta, ) -> Result<(), WireError>

Validate decoded records before admission or replay into this carrier.

impl Debug for PnCounter

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

Formats the value using the given formatter. Read more

impl Eq for PnCounter

impl Mergeable for PnCounter

fn merge(&mut self, other: &Self)

impl PartialEq for PnCounter

fn eq(&self, other: &PnCounter) -> 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 StructuralPartialEq for PnCounter