Struct HybridLogicalClock 

pub struct HybridLogicalClock { /* private fields */ }

Hybrid Logical Clock for generating causally consistent timestamps.

Thread-safe via atomic operations. Each node should have one HLC instance.

Example

use lnc_core::HybridLogicalClock;

let hlc = HybridLogicalClock::new(1);
let ts1 = hlc.now();
let ts2 = hlc.now();
assert!(ts1 < ts2);

Implementations

impl HybridLogicalClock

pub const MAX_DRIFT_WARNING_MS: u64 = 100

Maximum drift allowed before warning (milliseconds).

pub const MAX_DRIFT_CRITICAL_MS: u64 = 1000

Maximum drift allowed before critical alert (milliseconds).

pub fn new(node_id: u16) -> Self

Create a new HLC instance for a given node.

pub const fn node_id(&self) -> u16

Get the node ID associated with this clock.

pub fn now(&self) -> HlcTimestamp

Generate a new HLC timestamp for a local event.

This method is lock-free and thread-safe via CAS operations.

Algorithm

1. If wall clock > last physical: use wall clock, reset logical to 0
2. Otherwise: keep physical, increment logical
3. CAS to ensure monotonicity under concurrent access

pub fn receive(&self, remote_ts: HlcTimestamp) -> HlcTimestamp

Update HLC upon receiving a message with a remote timestamp.

Returns a new timestamp that is greater than both the local clock and the remote timestamp, ensuring causal ordering.

Algorithm

1. If wall clock > max(local, remote): use wall clock, reset logical
2. If local > remote: use local physical, increment local logical
3. If remote > local: use remote physical, increment remote logical
4. If equal physical: use that physical, increment max logical

pub fn current(&self) -> HlcTimestamp

Get the current HLC timestamp without advancing it.

Useful for reading the last known time without generating a new event.

pub fn drift_ms(&self) -> i64

Calculate the drift between HLC physical time and wall clock.

Returns positive value if HLC is ahead of wall clock.

pub fn health(&self) -> ClockHealth

Check if the clock drift is within acceptable bounds.

Trait Implementations

impl Debug for HybridLogicalClock

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

Formats the value using the given formatter.