Struct ConsistencyTracker 

pub struct ConsistencyTracker { /* private fields */ }

Tracks the replica’s applied state and blocks a read until the configured ConsistencyPolicy is satisfied.

Port of com.sleepycat.je.rep.impl.node.Replica.ConsistencyTracker (awaitVLSN / lagAwait / await). In JE the tracker holds ordered CountDownLatches that the replay thread trips as VLSNs are applied; a reader parks on the latch with the policy timeout and gets a ReplicaConsistencyException if it expires.

Here the predicate is the REP-7 last_applied_vlsn handle (ReplicaReplay::last_applied_vlsn_handle) — the SAME Arc<AtomicU64> the replay driver advances after each committed apply. We do NOT add a parallel tracker; we read the existing hook. master_vlsn is the master’s latest known commit VLSN (the feeder stream / heartbeat high-water), used by the time policy — JE’s masterTxnEndVLSN.

Implementations

impl ConsistencyTracker

pub fn new(last_applied_vlsn: Arc<AtomicU64>) -> Self

Build a tracker over the REP-7 last_applied_vlsn handle.

pub fn last_applied_vlsn(&self) -> u64

The replica’s last-applied VLSN (the wait predicate).

pub fn set_master_vlsn(&self, vlsn: u64)

Record the master’s latest known commit VLSN (feeder / heartbeat).

Port of ConsistencyTracker.trackHeartbeat updating masterTxnEndVLSN. Monotone.

pub fn master_vlsn(&self) -> u64

The master’s latest known commit VLSN.

pub fn notify_applied(&self)

Wake any reader parked in Self::await_consistency.

Called when the replica applies a new entry (the replay thread can invoke this after advancing last_applied_vlsn). Equivalent to the latch trip in ConsistencyTracker.trackVLSN. Optional: a waiter also re-checks every Self::RECHECK_TICK, so a missed notify only delays (never hangs) the read.

pub fn await_consistency(&self, policy: &ConsistencyPolicy) -> Result<()>

Block until the replica’s applied state satisfies policy, or the policy timeout expires.

Port of ReplicaConsistencyPolicy.ensureConsistency → ConsistencyTracker.awaitVLSN / lagAwait:

• ConsistencyPolicy::NoConsistency: returns immediately (JE NoConsistencyRequiredPolicy.ensureConsistency is a no-op).
• ConsistencyPolicy::CommitPointConsistency: waits until last_applied_vlsn >= token.vlsn (JE awaitVLSN comparing against lastReplayedTxnVLSN).
• ConsistencyPolicy::TimeConsistency: waits until the estimated lag behind the master is within max_lag (JE lagAwait).

On timeout returns a clean RepError — RepError::ConsistencyTimeout for the commit-point policy and RepError::ReplicaLagExceeded for the time policy — the equivalent of JE’s ReplicaConsistencyException. NEVER hangs.

Trait Implementations

impl Clone for ConsistencyTracker

fn clone(&self) -> ConsistencyTracker

Returns a duplicate of the value.

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

Performs copy-assignment from source.