Struct GCounter 

pub struct GCounter { /* private fields */ }

A grow-only counter: one tally per replica, join = pointwise max.

Model: Crdt.GCounter ι = ι → ℕ with the Pi join-semilattice. Applying a delta is joining it in, so delivery order and redelivery are irrelevant — SafeMesh.delta_dissemination_sec — and a replica that received bumps B holds, per coordinate, the max over that coordinate’s bumps — SafeMesh.deltaGCounter_correct.

Implementations

impl GCounter

pub const MAX_REPLICAS: usize = 4_096

Maximum constructor domain: 4,096 replicas, matching the default wire version-vector author limit. Storage is at most 32 KiB per G-counter (64 KiB per PN-counter), below the WASM and Python numeric limits.

pub fn new(n: usize) -> Self

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

Panics

Panics above Self::MAX_REPLICAS or on allocator refusal. Use Self::try_new to receive a named error instead.

pub fn try_new(n: usize) -> Result<Self, CoordinateError>

Fresh counter with a domain bounded by Self::MAX_REPLICAS.

The 4,096-replica maximum matches the default wire author limit and bounds storage to 32 KiB. Larger counts return ReplicaLimitExceeded before allocation. Admitted counts use the allocator’s zeroed path, like vec![0; n], without an explicit page-touching initialization loop. As on main, admitted allocations use vec![0; n]; an out-of-memory allocator can abort. The cap bounds this request to 32 KiB.

pub fn len(&self) -> usize

Number of replica coordinates.

pub fn is_empty(&self) -> bool

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

Apply the delta SafeMesh.deltaBump replica tally — a single coordinate on the wire. Joining the delta is max at that coordinate (Pi.single joined into the state); applying the same bump again is a no-op (idempotence, SafeMesh.delta_dissemination_sec).

Out-of-range replica is ignored (a malformed delta must not corrupt state; the Lean model has no such case — Fin n makes it unrepresentable). Use Self::try_apply_bump to receive an error for an invalid index.

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

Apply a single-coordinate delta, returning an error for an invalid index.

Checks the coordinate before mutation. On error, the entire counter is unchanged; on success, behaves exactly like Self::apply_bump, including accepting an equal or lower tally as a no-op.

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

Checked full-state merge: pointwise max, erroring on a replica-count mismatch instead of silently truncating to the shorter vector (WS1). This is the boundary-safe entry point for state received from an untrusted peer.

pub fn merge(&mut self, other: &GCounter) -> Result<(), MergeError>

Full-state merge: pointwise max — Crdt.gcounter_merge_apply. A delta replica and a full-state replica fed the same bumps agree: SafeMesh.deltaGCounter_matches_full.

Returns MergeError::ReplicaCountMismatch without changing state if the replica counts differ, just like GCounter::try_merge.

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

Per-coordinate state (the ι → ℕ vector).

pub fn value(&self) -> u128

The counter’s read: sum of per-replica tallies — Crdt.gcounterValue, a natural number with no upper bound in the model.

The read is exact for every state this counter can hold: at most isize::MAX coordinates, each at most u64::MAX, sum to strictly less than 2^127, so the u128 total never wraps and is never clamped. A total that no longer fits a narrower integer is still returned whole; a caller that needs u64 narrows it with u64::try_from and handles the failure itself.

Trait Implementations

impl Clone for GCounter

fn clone(&self) -> GCounter

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 GCounter

type Delta = GCounterDelta

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

Validate a decoded record before admission or replay into this carrier.

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)

impl Debug for GCounter

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

Formats the value using the given formatter. Read more

impl Mergeable for GCounter

fn merge(&mut self, other: &Self) -> Result<(), MergeError>

Join compatible states, returning an error if their replica domains differ.

impl PartialEq for GCounter

fn eq(&self, other: &GCounter) -> 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 Eq for GCounter

impl StructuralPartialEq for GCounter