com.hazelcast.journal

Interface EventJournalReader<E>

Type Parameters:

E - journal event type

All Known Implementing Classes:

CacheProxy, MapProxyImpl, NearCachedMapProxyImpl

public interface EventJournalReader<E>

This interface provides methods to subscribe and read from an event journal.

Method Summary

Modifier and Type	Method and Description
<T> ICompletableFuture<ReadResultSet<T>>	readFromEventJournal(long startSequence, int minSize, int maxSize, int partitionId, Predicate<? super E> predicate, Projection<? super E,T> projection) Reads from the event journal.
ICompletableFuture<EventJournalInitialSubscriberState>	subscribeToEventJournal(int partitionId) Subscribe to the event journal for this reader and a specific partition ID.

Method Detail

subscribeToEventJournal

ICompletableFuture<EventJournalInitialSubscriberState> subscribeToEventJournal(int partitionId)

Subscribe to the event journal for this reader and a specific partition ID. The method will return the newest and oldest event journal sequence.

Parameters:

partitionId - the partition ID of the entries to which we are subscribing

Returns:

future with the initial subscriber state containing the newest and oldest event journal sequence

Throws:

UnsupportedOperationException - if the cluster version is lower than 3.9 or there is no event journal configured for this data structure

Since:

3.9

readFromEventJournal

<T> ICompletableFuture<ReadResultSet<T>> readFromEventJournal(long startSequence,
                                                              int minSize,
                                                              int maxSize,
                                                              int partitionId,
                                                              Predicate<? super E> predicate,
                                                              Projection<? super E,T> projection)

Reads from the event journal. The returned future may throw UnsupportedOperationException if the cluster version is lower than 3.9 or there is no event journal configured for this data structure.

NOTE: Configuring evictions may cause unexpected results when reading from the event journal and there are cluster changes (a backup replica is promoted into a partition owner). See MapEventJournal or CacheEventJournal for more details.

Type Parameters:

T - the return type of the projection. It is equal to the journal event type if the projection is null or it is the identity projection

Parameters:

startSequence - the sequence of the first item to read

maxSize - the maximum number of items to read

partitionId - the partition ID of the entries in the journal

predicate - the predicate which the events must pass to be included in the response. May be null in which case all events pass the predicate

projection - the projection which is applied to the events before returning. May be null in which case the event is returned without being projected

Returns:

the future with the filtered and projected journal items

Since:

3.9