Module dk.cloudcreate.essentials.components.eventsourced.aggregates

Package dk.cloudcreate.essentials.components.eventsourced.aggregates.snapshot

Interface AggregateSnapshotDeletionStrategy

All Known Implementing Classes:

AggregateSnapshotDeletionStrategy.DeleteAllHistoricSnapshots, AggregateSnapshotDeletionStrategy.KeepHistoricSnapshots

public interface AggregateSnapshotDeletionStrategy

Strategy for which historic aggregate snapshots (i.e. old aggregate snapshots) should be deleted when a new aggregate snapshot is persisted

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	AggregateSnapshotDeletionStrategy.DeleteAllHistoricSnapshots	Strategy that deletes any historic aggregate snapshots when a new snapshot is persisted
static class	AggregateSnapshotDeletionStrategy.KeepHistoricSnapshots	Strategy that keeps all or a specific number of historic aggregate snapshots

Method Summary

Modifier and Type	Method	Description
static AggregateSnapshotDeletionStrategy	deleteAllHistoricSnapshots()	Strategy that deletes any historic aggregate snapshots when a new aggregate snapshot is persisted
static AggregateSnapshotDeletionStrategy	keepALimitedNumberOfHistoricSnapshots(long numberOfHistoricSnapshotsToKeep)	Strategy that keeps a specific number historic aggregate snapshots
static AggregateSnapshotDeletionStrategy	keepAllHistoricSnapshots()	Strategy that keeps all historic aggregate snapshots
boolean	requiresExistingSnapshotDetailsToDetermineWhichAggregateSnapshotsToDelete()	Guard method that determines if Aggregate Snapshot statistics are required in order to determine which Snapshots to delete
<ID,AGGREGATE_IMPL_TYPE> Stream<AggregateSnapshot<ID,AGGREGATE_IMPL_TYPE>>	resolveSnapshotsToDelete(List<AggregateSnapshot<ID,AGGREGATE_IMPL_TYPE>> existingSnapshots)	Out of all the existing snapshots (loaded without the snapshot payload), return the AggregateSnapshot's that should be deleted This method is called just prior to adding a new AggregateSnapshot, so if the purpose it to keep 3 snapshots, and we already have 3 snapshots, then this method should return a Stream containing the oldest snapshot, which will then be deleted

Method Detail

keepALimitedNumberOfHistoricSnapshots

static AggregateSnapshotDeletionStrategy keepALimitedNumberOfHistoricSnapshots(long numberOfHistoricSnapshotsToKeep)

Strategy that keeps a specific number historic aggregate snapshots

Parameters:

numberOfHistoricSnapshotsToKeep - the number of historic aggregate snapshots to keep

Returns:

Strategy that keeps all historic aggregate snapshot events

keepAllHistoricSnapshots

static AggregateSnapshotDeletionStrategy keepAllHistoricSnapshots()

Strategy that keeps all historic aggregate snapshots

Returns:

Strategy that keeps all historic aggregate snapshots

deleteAllHistoricSnapshots

static AggregateSnapshotDeletionStrategy deleteAllHistoricSnapshots()

Strategy that deletes any historic aggregate snapshots when a new aggregate snapshot is persisted

Returns:

Strategy that deletes any historic aggregate snapshots when a new aggregate snapshot is persisted

requiresExistingSnapshotDetailsToDetermineWhichAggregateSnapshotsToDelete

boolean requiresExistingSnapshotDetailsToDetermineWhichAggregateSnapshotsToDelete()

Guard method that determines if Aggregate Snapshot statistics are required in order to determine which Snapshots to delete

Returns:

true if AggregateSnapshotRepository.aggregateUpdated(Object, AggregateEventStream) should fetch existing AggregateSnapshot's (without the payload) as input to resolveSnapshotsToDelete(List) or false if all existing snapshots can be deleted (solves AggregateSnapshotDeletionStrategy.DeleteAllHistoricSnapshots without incurring additional DB queries)

resolveSnapshotsToDelete

<ID,AGGREGATE_IMPL_TYPE> Stream<AggregateSnapshot<ID,AGGREGATE_IMPL_TYPE>> resolveSnapshotsToDelete(List<AggregateSnapshot<ID,AGGREGATE_IMPL_TYPE>> existingSnapshots)

Out of all the existing snapshots (loaded without the snapshot payload), return the AggregateSnapshot's that should be deleted
This method is called just prior to adding a new AggregateSnapshot, so if the purpose it to keep 3 snapshots, and we already have 3 snapshots, then this method should return a Stream containing the oldest snapshot, which will then be deleted

Type Parameters:

ID - the id type for the aggregate

AGGREGATE_IMPL_TYPE - the aggregate type implementation type

Parameters:

existingSnapshots - all the existing snapshots pertaining to a given aggregate instance

Returns:

all the AggregateSnapshot's that should be deleted