An persistent actor has to define its initial receive behavior by implementing the createReceive method, also known as the command handler. Typically validates commands against current state (and/or by communication with other actors). On successful validation, one or more events are derived from a command and these events are then persisted by calling persist.

Recovery handler that receives persisted events during recovery. If a state snapshot has been captured and saved, this handler will receive a SnapshotOffer message followed by events that are younger than the offered snapshot.

This handler must not have side-effects other than changing persistent actor state i.e. it should not perform actions that may fail, such as interacting with external services, for example.

If there is a problem with recovering the state of the actor from the journal, the error will be logged and the actor will be stopped.

Id of the persistent entity for which messages should be replayed.

INTERNAL API.

INTERNAL API.

INTERNAL API.

INTERNAL API.

INTERNAL API.

Defer the handler execution until all pending handlers have been executed. It is guaranteed that no new commands will be received by a persistent actor between a call to defer and the execution of its handler. Allows to define logic within the actor, which will respect the invocation-order-guarantee in respect to persistAsync or persist calls. That is, if persistAsync or persist was invoked before defer, the corresponding handlers will be invoked in the same order as they were registered in.

This call will NOT result in event being persisted, use persist or persistAsync instead if the given event should possible to replay.

If there are no pending persist handler calls, the handler will be called immediately.

If persistence of an earlier event fails, the persistent actor will stop, and the handler will not be run.

Defer the handler execution until all pending handlers have been executed. Allows to define logic within the actor, which will respect the invocation-order-guarantee in respect to persistAsync calls. That is, if persistAsync was invoked before defer, the corresponding handlers will be invoked in the same order as they were registered in.

This call will NOT result in event being persisted, please use persist or persistAsync, if the given event should possible to replay.

If there are no pending persist handler calls, the handler will be called immediately.

If persistence of an earlier event fails, the persistent actor will stop, and the handler will not be run.

Permanently deletes all persistent messages with sequence numbers less than or equal toSequenceNr.

If the delete is successful a DeleteMessagesSuccess will be sent to the actor. If the delete fails a DeleteMessagesFailure will be sent to the actor.

The given toSequenceNr must be less than or equal to Eventsourced#lastSequenceNr, otherwise DeleteMessagesFailure is sent to the actor without performing the delete. All persistent messages may be deleted without specifying the actual sequence number by using Long.MaxValue as the toSequenceNr.

Deletes the snapshot identified by sequenceNr.

The PersistentActor will be notified about the status of the deletion via an DeleteSnapshotSuccess or DeleteSnapshotFailure message.

Deletes all snapshots matching criteria.

The PersistentActor will be notified about the status of the deletion via an DeleteSnapshotsSuccess or DeleteSnapshotsFailure message.

The returned StashOverflowStrategy object determines how to handle the message failed to stash when the internal Stash capacity exceeded.

Configuration id of the journal plugin servicing this persistent actor. When empty, looks in pekko.persistence.journal.plugin to find configuration entry path. When configured, uses journalPluginId as absolute path to the journal configuration entry. Configuration entry must contain few required fields, such as class. See src/main/resources/reference.conf.

Highest received sequence number so far or 0L if this actor hasn't replayed or stored any persistent events yet.

Instructs the snapshot store to load the specified snapshot and send it via an SnapshotOffer to the running PersistentActor.

Called when persist fails. By default it logs the error. Subclass may override to customize logging and for example send negative acknowledgment to sender.

The actor is always stopped after this method has been invoked.

Note that the event may or may not have been saved, depending on the type of failure.

Called when the journal rejected persist of an event. The event was not stored. By default this method logs the problem as an error, and the actor continues. The callback handler that was passed to the persist method will not be invoked.

Called whenever a message replay fails. By default it logs the error.

Subclass may override to customize logging.

The actor is always stopped after this method has been invoked.

Java API: asynchronously persists event. On successful persistence, handler is called with the persisted event. It is guaranteed that no new commands will be received by a persistent actor between a call to persist and the execution of its handler. This also holds for multiple persist calls per received command. Internally, this is achieved by stashing new commands and unstashing them when the event has been persisted and handled. The stash used for that is an internal stash which doesn't interfere with the inherited user stash.

An event handler may close over persistent actor state and modify it. The getSender() of a persisted event is the sender of the corresponding command. This means that one can reply to a command sender within an event handler.

Within an event handler, applications usually update persistent actor state using persisted event data, notify listeners and reply to command senders.

If persistence of an event fails, #onPersistFailure will be invoked and the actor will unconditionally be stopped. The reason that it cannot resume when persist fails is that it is unknown if the event was actually persisted or not, and therefore it is in an inconsistent state. Restarting on persistent failures will most likely fail anyway, since the journal is probably unavailable. It is better to stop the actor and after a back-off timeout start it again.

Java API: asynchronously persists events in specified order. This is equivalent to calling persist[A](event: A, handler: Procedure[A]) multiple times with the same handler, except that events are persisted atomically with this method.

Java API: asynchronously persists events in specified order. This is equivalent to calling persistAsync[A](event: A)(handler: A => Unit) multiple times with the same handler, except that events are persisted atomically with this method.

Java API: asynchronously persists event. On successful persistence, handler is called with the persisted event.

Unlike persist the persistent actor will continue to receive incoming commands between the call to persistAsync and executing it's handler. This asynchronous, non-stashing, version of of persist should be used when you favor throughput over the strict ordering guarantees that persist guarantees.

If persistence of an event fails, #onPersistFailure will be invoked and the actor will unconditionally be stopped. The reason that it cannot resume when persist fails is that it is unknown if the event was actually persisted or not, and therefore it is in an inconsistent state. Restarting on persistent failures will most likely fail anyway, since the journal is probably unavailable. It is better to stop the actor and after a back-off timeout start it again.

Command handler. Typically validates commands against current state (and/or by communication with other actors). On successful validation, one or more events are derived from a command and these events are then persisted by calling persist.

Recovery handler that receives persisted events during recovery. If a state snapshot has been captured and saved, this handler will receive a SnapshotOffer message followed by events that are younger than the offered snapshot.

This handler must not have side-effects other than changing persistent actor state i.e. it should not perform actions that may fail, such as interacting with external services, for example.

If there is a problem with recovering the state of the actor from the journal, the error will be logged and the actor will be stopped.

Called when the persistent actor is started for the first time. The returned Recovery object defines how the Actor will recover its persistent state before handling the first incoming message.

To skip recovery completely return Recovery.none.

Returns true if this persistent actor has successfully finished recovery.

Returns true if this persistent actor is currently recovering.

Saves a snapshot of this snapshotter's state.

The PersistentActor will be notified about the success or failure of this via an SaveSnapshotSuccess or SaveSnapshotFailure message.

Configuration id of the snapshot plugin servicing this persistent actor. When empty, looks in pekko.persistence.snapshot-store.plugin to find configuration entry path. When configured, uses snapshotPluginId as absolute path to the snapshot store configuration entry. Configuration entry must contain few required fields, such as class. See src/main/resources/reference.conf.

Returns lastSequenceNr.

Returns persistenceId.