Class SnapshotScheduler

java.lang.Object

com.loomcache.server.persistence.SnapshotScheduler

public class SnapshotScheduler
extends Object

Schedules and manages state machine snapshots for Raft log compaction.

Automatically triggers snapshots after a configured number of committed entries, using virtual threads to avoid blocking the Raft processing thread.

Maintains bounded storage by retaining only the latest N snapshots.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	SnapshotScheduler.SnapshotSchedulerStats	Statistics about snapshot scheduler activity.

Constructor Summary

Constructors

Constructor	Description
SnapshotScheduler(StateMachineSnapshotManager snapshotManager)	Create a snapshot scheduler with default configuration.
SnapshotScheduler(StateMachineSnapshotManager snapshotManager, long snapshotIntervalEntries, int maxSnapshotsToRetain)	Create a snapshot scheduler with custom configuration and default delta count (3).
SnapshotScheduler(StateMachineSnapshotManager snapshotManager, long snapshotIntervalEntries, int maxSnapshotsToRetain, int maxDeltasBetweenFullSnapshots)	Create a snapshot scheduler with custom configuration.

Method Summary

Modifier and Type	Method	Description
long	getLastSnapshotIndex()	Get the index of the last snapshot taken.
SnapshotScheduler.SnapshotSchedulerStats	getStats()	Get current scheduler statistics.
void	maybeSnapshot(long currentCommittedIndex, long currentTerm, Map<String, ? extends Snapshotable> dataStructures)	Check if a snapshot should be triggered based on the committed index.
void	setLastSnapshotIndex(long index)	Set the last snapshot index (useful for recovery).

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SnapshotScheduler

public SnapshotScheduler(StateMachineSnapshotManager snapshotManager,
 long snapshotIntervalEntries,
 int maxSnapshotsToRetain,
 int maxDeltasBetweenFullSnapshots)

Create a snapshot scheduler with custom configuration.

Parameters:

snapshotManager - the underlying snapshot manager

snapshotIntervalEntries - trigger snapshot after this many committed entries (default: 10000)

maxSnapshotsToRetain - keep at most this many snapshots (default: 3)

maxDeltasBetweenFullSnapshots - max delta snapshots before forcing a full snapshot (default: 3)

SnapshotScheduler

public SnapshotScheduler(StateMachineSnapshotManager snapshotManager,
 long snapshotIntervalEntries,
 int maxSnapshotsToRetain)

Create a snapshot scheduler with custom configuration and default delta count (3).

Parameters:

snapshotManager - the underlying snapshot manager

snapshotIntervalEntries - trigger snapshot after this many committed entries

maxSnapshotsToRetain - keep at most this many snapshots

SnapshotScheduler

public SnapshotScheduler(StateMachineSnapshotManager snapshotManager)

Create a snapshot scheduler with default configuration. Default: snapshot every 10,000 committed entries, retain 3 snapshots, max 3 deltas.

Parameters:

snapshotManager - the underlying snapshot manager

Method Details

maybeSnapshot

public void maybeSnapshot(long currentCommittedIndex,
 long currentTerm,
 Map<String, ? extends Snapshotable> dataStructures)

Check if a snapshot should be triggered based on the committed index. If needed, trigger snapshot asynchronously using a virtual thread.

Parameters:

currentCommittedIndex - the current Raft committed log index

currentTerm - the current Raft term

dataStructures - the data structures to snapshot

getStats

public SnapshotScheduler.SnapshotSchedulerStats getStats()

Get current scheduler statistics.

Returns:

SnapshotSchedulerStats with current metrics

getLastSnapshotIndex

public long getLastSnapshotIndex()

Get the index of the last snapshot taken.

Returns:

the last snapshot index, or -1 if no snapshots taken yet

setLastSnapshotIndex

public void setLastSnapshotIndex(long index)

Set the last snapshot index (useful for recovery).

Parameters:

index - the index to set