Interface IAsyncRecovery

TBD

Namespace: Akka.Persistence.Journal
Assembly: Akka.Persistence.dll
Syntax
public interface IAsyncRecovery

Methods

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ReadHighestSequenceNrAsync(string, long, CancellationToken)

Asynchronously reads the highest stored sequence number for provided persistenceId. The persistent actor will use the highest sequence number after recovery as the starting point when persisting new events. This sequence number is also used as toSequenceNr in subsequent calls to ReplayMessagesAsync(IActorContext, string, long, long, long, Action<IPersistentRepresentation>) unless the user has specified a lower toSequenceNr. Journal must maintain the highest sequence number and never decrease it.

This call is protected with a circuit-breaker.

Please also not that requests for the highest sequence number may be made concurrently to writes executing for the same persistenceId, in particular it is possible that a restarting actor tries to recover before its outstanding writes have completed.

Declaration
Task<long> ReadHighestSequenceNrAsync(string persistenceId, long fromSequenceNr, CancellationToken cancellationToken)
Parameters
Type Name Description
string persistenceId

Persistent actor identifier
long fromSequenceNr

Hint where to start searching for the highest sequence number. When a persistent actor is recovering this fromSequenceNr will the sequence number of the used snapshot, or 0L if no snapshot is used.
CancellationToken cancellationToken

CancellationToken used to signal cancelled recovery operation
Returns
Type Description
Task<long>

TBD
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ReplayMessagesAsync(IActorContext, string, long, long, long, Action<IPersistentRepresentation>)

Asynchronously replays persistent messages. Implementations replay a message by calling recoveryCallback. The returned task must be completed when all messages (matching the sequence number bounds) have been replayed. The task must be completed with a failure if any of the persistent messages could not be replayed.

The toSequenceNr is the lowest of what was returned by ReadHighestSequenceNrAsync(string, long, CancellationToken) and what the user specified as recovery Recovery parameter. This does imply that this call is always preceded by reading the highest sequence number for the given persistenceId.

This call is NOT protected with a circuit-breaker because it may take a long time to replay all events. The plugin implementation itself must protect against an unresponsive backend store and make sure that the returned Task is completed with success or failure within reasonable time. It is not allowed to ignore completing the Task.

Declaration
Task ReplayMessagesAsync(IActorContext context, string persistenceId, long fromSequenceNr, long toSequenceNr, long max, Action<IPersistentRepresentation> recoveryCallback)
Parameters
Type Name Description
IActorContext context

The contextual information about the actor processing replayed messages.
string persistenceId

Persistent actor identifier
long fromSequenceNr

Inclusive sequence number where replay should start
long toSequenceNr

Inclusive sequence number where replay should end
long max

Maximum number of messages to be replayed
Action<IPersistentRepresentation> recoveryCallback

Called to replay a message, may be called from any thread.
Returns
Type Description
Task

TBD

Extension Methods