Package akka.persistence.query.journal.leveldb.javadsl

Class LeveldbReadJournal

    • Constructor Detail

      • LeveldbReadJournal

        public LeveldbReadJournal​(LeveldbReadJournal scaladslReadJournal)

    • Method Detail

      • Identifier

        public static final java.lang.String Identifier()

      • currentPersistenceIds

        public Source<java.lang.String,​NotUsed> currentPersistenceIds()
        Same type of query as persistenceIds() but the stream is completed immediately when it reaches the end of the "result set". Persistent actors that are created after the query is completed are not included in the stream.
        Specified by:
        currentPersistenceIds in interface CurrentPersistenceIdsQuery
        Returns:
        (undocumented)

      • eventsByPersistenceId

        public Source<EventEnvelope,​NotUsed> eventsByPersistenceId​(java.lang.String persistenceId,
                                                                 long fromSequenceNr,
                                                                 long toSequenceNr)
        eventsByPersistenceId is used for retrieving events for a specific PersistentActor identified by persistenceId.

        You can retrieve a subset of all events by specifying fromSequenceNr and toSequenceNr or use 0L and Long.MaxValue respectively to retrieve all events. Note that the corresponding sequence number of each event is provided in the EventEnvelope, which makes it possible to resume the stream at a later point from a given sequence number.

        The returned event stream is ordered by sequence number, i.e. the same order as the PersistentActor persisted the events. The same prefix of stream elements (in same order) are returned for multiple executions of the query, except for when events have been deleted.

        The stream is not completed when it reaches the end of the currently stored events, but it continues to push new events when new events are persisted. Corresponding query that is completed when it reaches the end of the currently stored events is provided by currentEventsByPersistenceId(java.lang.String, long, long).

        The LevelDB write journal is notifying the query side as soon as events are persisted, but for efficiency reasons the query side retrieves the events in batches that sometimes can be delayed up to the configured refresh-interval.

        The stream is completed with failure if there is a failure in executing the query in the backend journal.

        Specified by:
        eventsByPersistenceId in interface EventsByPersistenceIdQuery
        Parameters:
        persistenceId - (undocumented)
        fromSequenceNr - (undocumented)
        toSequenceNr - (undocumented)
        Returns:
        (undocumented)

      • eventsByTag

        public Source<EventEnvelope,​NotUsed> eventsByTag​(java.lang.String tag,
                                                       Offset offset)
        eventsByTag is used for retrieving events that were marked with a given tag, e.g. all events of an Aggregate Root type.

        To tag events you create an EventAdapter that wraps the events in a Tagged with the given tags.

        You can retrieve a subset of all events by specifying offset, or use 0L to retrieve all events with a given tag. The offset corresponds to an ordered sequence number for the specific tag. Note that the corresponding offset of each event is provided in the EventEnvelope, which makes it possible to resume the stream at a later point from a given offset.

        In addition to the offset the EventEnvelope also provides persistenceId and sequenceNr for each event. The sequenceNr is the sequence number for the persistent actor with the persistenceId that persisted the event. The persistenceId + sequenceNr is an unique identifier for the event.

        The offset is exclusive, i.e. the event with the exact same sequence number will not be included in the returned stream. This means that you can use the offset that is returned in EventEnvelope as the offset parameter in a subsequent query.

        The returned event stream is ordered by the offset (tag sequence number), which corresponds to the same order as the write journal stored the events. The same stream elements (in same order) are returned for multiple executions of the query. Deleted events are not deleted from the tagged event stream.

        The stream is not completed when it reaches the end of the currently stored events, but it continues to push new events when new events are persisted. Corresponding query that is completed when it reaches the end of the currently stored events is provided by currentEventsByTag(java.lang.String, akka.persistence.query.Offset).

        The LevelDB write journal is notifying the query side as soon as tagged events are persisted, but for efficiency reasons the query side retrieves the events in batches that sometimes can be delayed up to the configured refresh-interval.

        The stream is completed with failure if there is a failure in executing the query in the backend journal.

        Specified by:
        eventsByTag in interface EventsByTagQuery
        Parameters:
        tag - (undocumented)
        offset - (undocumented)
        Returns:
        (undocumented)