lww-register

(no submodules)

Purpose

Provides LWWRegister<T>, a Last-Write-Wins Register CRDT. The register holds a single value; when two replicas have different values, the one with the higher timestamp wins during merge. Ties are broken by node ID lexicographic order, ensuring deterministic convergence.

Features

set(value, timestamp?) — sets the value with optional explicit timestamp (defaults to Date.now())
get() — returns the current value or undefined
merge(state) — higher timestamp wins; tie-broken by nodeId lexicographic order
toJSON() / fromJSON() — serialization round-trip
clone() — deep copy

Usage: Basic Example

import { LWWRegister } from "@suaveplan/crdt";

const reg = new LWWRegister<string>("node-1");
reg.set("hello");
console.log(reg.get()); // "hello"

Usage: Advanced Example

import { LWWRegister } from "@suaveplan/crdt";

const a = new LWWRegister<number>("n1");
a.set(42, 1000);

const b = new LWWRegister<number>("n2");
b.set(99, 2000);

a.merge(b.state());
console.log(a.get()); // 99 (higher timestamp)

API Reference

`LWWRegister<T>`

constructor(nodeId, id?) — nodeId is required for tie-breaking
set(value, timestamp?) — sets value with timestamp
get(): T | undefined — current value
merge(state: LWWRegisterState<T>): void

Implementation Notes

Wall-clock timestamps from Date.now() can cause issues if clocks are not synchronized. For distributed deployments, use a monotonic or hybrid logical clock and pass the timestamp explicitly via set(value, timestamp).

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