Akka/Scala example source code file (Snapshot.scala)

This example Akka source code file (Snapshot.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

akka, any, latest, long, none, persistence, selectedsnapshot, serialversionuid, snapshotmetadata, snapshotselectioncriteria, string, use

The Snapshot.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 * Copyright (C) 2012-2013 Eligotech BV.
 */

package akka.persistence

/**
 * Snapshot metadata.
 *
 * @param persistenceId id of persistent actor from which the snapshot was taken.
 * @param sequenceNr sequence number at which the snapshot was taken.
 * @param timestamp time at which the snapshot was saved.
 */
@SerialVersionUID(1L) //#snapshot-metadata
final case class SnapshotMetadata(@deprecatedName('processorId) persistenceId: String, sequenceNr: Long, timestamp: Long = 0L) {
  @deprecated("Use persistenceId instead.", since = "2.3.4")
  def processorId: String = persistenceId
}
//#snapshot-metadata

/**
 * Sent to a [[PersistentActor]] after successful saving of a snapshot.
 *
 * @param metadata snapshot metadata.
 */
@SerialVersionUID(1L)
final case class SaveSnapshotSuccess(metadata: SnapshotMetadata)

/**
 * Sent to a [[PersistentActor]] after failed saving of a snapshot.
 *
 * @param metadata snapshot metadata.
 * @param cause failure cause.
 */
@SerialVersionUID(1L)
final case class SaveSnapshotFailure(metadata: SnapshotMetadata, cause: Throwable)

/**
 * Offers a [[PersistentActor]] a previously saved `snapshot` during recovery. This offer is received
 * before any further replayed messages.
 */
@SerialVersionUID(1L)
final case class SnapshotOffer(metadata: SnapshotMetadata, snapshot: Any)

/**
 * Selection criteria for loading and deleting snapshots.
 *
 * @param maxSequenceNr upper bound for a selected snapshot's sequence number. Default is no upper bound.
 * @param maxTimestamp upper bound for a selected snapshot's timestamp. Default is no upper bound.
 *
 * @see [[Recover]]
 */
@SerialVersionUID(1L)
final case class SnapshotSelectionCriteria(maxSequenceNr: Long = Long.MaxValue, maxTimestamp: Long = Long.MaxValue) {
  /**
   * INTERNAL API.
   */
  private[persistence] def limit(toSequenceNr: Long): SnapshotSelectionCriteria =
    if (toSequenceNr < maxSequenceNr) copy(maxSequenceNr = toSequenceNr) else this

  /**
   * INTERNAL API.
   */
  private[persistence] def matches(metadata: SnapshotMetadata): Boolean =
    metadata.sequenceNr <= maxSequenceNr && metadata.timestamp <= maxTimestamp
}

object SnapshotSelectionCriteria {
  /**
   * The latest saved snapshot.
   */
  val Latest = SnapshotSelectionCriteria()

  /**
   * No saved snapshot matches.
   */
  val None = SnapshotSelectionCriteria(0L, 0L)

  /**
   * Java API.
   */
  def create(maxSequenceNr: Long, maxTimestamp: Long) =
    SnapshotSelectionCriteria(maxSequenceNr, maxTimestamp)

  /**
   * Java API.
   */
  def latest() = Latest

  /**
   * Java API.
   */
  def none() = None
}

/**
 * Plugin API: a selected snapshot matching [[SnapshotSelectionCriteria]].
 *
 * @param metadata snapshot metadata.
 * @param snapshot snapshot.
 */
final case class SelectedSnapshot(metadata: SnapshotMetadata, snapshot: Any)

object SelectedSnapshot {
  /**
   * Java API, Plugin API.
   */
  def create(metadata: SnapshotMetadata, snapshot: Any): SelectedSnapshot =
    SelectedSnapshot(metadata, snapshot)
}

/**
 * INTERNAL API.
 *
 * Defines messages exchanged between persistent actors and a snapshot store.
 */
private[persistence] object SnapshotProtocol {
  /**
   * Instructs a snapshot store to load a snapshot.
   *
   * @param persistenceId persistent actor id.
   * @param criteria criteria for selecting a snapshot from which recovery should start.
   * @param toSequenceNr upper sequence number bound (inclusive) for recovery.
   */
  final case class LoadSnapshot(@deprecatedName('processorId) persistenceId: String, criteria: SnapshotSelectionCriteria, toSequenceNr: Long) {
    @deprecated("Use persistenceId instead.", since = "2.3.4")
    def processorId: String = persistenceId
  }

  /**
   * Response message to a [[LoadSnapshot]] message.
   *
   * @param snapshot loaded snapshot, if any.
   */
  final case class LoadSnapshotResult(snapshot: Option[SelectedSnapshot], toSequenceNr: Long)

  /**
   * Instructs snapshot store to save a snapshot.
   *
   * @param metadata snapshot metadata.
   * @param snapshot snapshot.
   */
  final case class SaveSnapshot(metadata: SnapshotMetadata, snapshot: Any)

  /**
   * Instructs snapshot store to delete a snapshot.
   *
   * @param metadata snapshot metadata.
   */
  final case class DeleteSnapshot(metadata: SnapshotMetadata)

  /**
   * Instructs snapshot store to delete all snapshots that match `criteria`.
   *
   * @param persistenceId persistent actor id.
   * @param criteria criteria for selecting snapshots to be deleted.
   */
  final case class DeleteSnapshots(@deprecatedName('processorId) persistenceId: String, criteria: SnapshotSelectionCriteria) {
    @deprecated("Use persistenceId instead.", since = "2.3.4")
    def processorId: String = persistenceId
  }
}