Struct LWW 

pub struct LWW<T> {
    pub value: T,
    pub ts: u64,
    pub replica: u64,
}

A Last-Writer-Wins register lattice.

The state is a triple (value, ts, replica) where ts is a logical timestamp (e.g. Lamport clock, HLC, or monotone counter) and replica is a unique identifier for the writer. Ordering uses (ts, replica) lexicographically, yielding a total order on register versions; join returns the greater version and is commutative, associative, and idempotent.

This makes LWW<T> a simple register-style lattice that can be used as the payload in higher-level CRDTs or accumulators where “latest value” semantics are needed.

Properties

• Commutative: a.join(b) == b.join(a)
• Associative: a.join(b).join(c) == a.join(b.join(c))
• Idempotent: a.join(a) == a

Use Cases

• Distributed caches (last-write-wins per key)
• Configuration management (latest config wins)
• Watermark tracking where ranks can report decreasing values (failure recovery, reprocessing)

Example

use algebra::JoinSemilattice;
use algebra::LWW;

// Two writers (replicas 1 and 2) with different timestamps
let v1 = LWW::new(100, 1, 1);
let v2 = LWW::new(50, 2, 2);

// Higher timestamp wins, even if value is smaller
assert_eq!(v1.join(&v2), LWW::new(50, 2, 2));

Fields

value: T

The current value of the register.

ts: u64

The logical timestamp associated with this value.

replica: u64

The replica ID of the writer (for deterministic tie-breaking).

Implementations

impl<T> LWW<T>

pub fn new(value: T, ts: u64, replica: u64) -> Self

Create a new LWW register with the given value, timestamp, and replica ID.

pub fn get(&self) -> &T

Get the current value.

pub fn timestamp(&self) -> u64

Get the timestamp.

pub fn replica(&self) -> u64

Get the replica ID.

Trait Implementations

impl<T: Clone + PartialEq + Default> BoundedJoinSemilattice for LWW<T>

fn bottom() -> Self

The bottom element of the lattice (⊥).

fn join_all_from_bottom<I>(it: I) -> Self

where I: IntoIterator<Item = Self>,

Join a finite iterator of values, starting from ⊥.

impl<T: Clone> Clone for LWW<T>

fn clone(&self) -> LWW<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for LWW<T>

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

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for LWW<T>

where T: Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T: Hash> Hash for LWW<T>

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<T: Clone + PartialEq> JoinSemilattice for LWW<T>

fn join(&self, other: &Self) -> Self

The join (least upper bound).

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

In-place variant.

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

where Self: PartialEq,

Derived partial order: x ≤ y iff x ⊔ y = y.

fn join_all<I>(it: I) -> Option<Self>

where I: IntoIterator<Item = Self>,

Join a finite iterator of values. Returns None for empty iterators.

impl<T: PartialEq> PartialEq for LWW<T>

fn eq(&self, other: &LWW<T>) -> 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<T> Serialize for LWW<T>

where T: Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T: Copy> Copy for LWW<T>

impl<T: Eq> Eq for LWW<T>

impl<T> StructuralPartialEq for LWW<T>