org.apache.pekko.cluster.ddata.Flag.scala Maven / Gradle / Ivy

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Apache Pekko is a toolkit for building highly concurrent, distributed, and resilient message-driven applications for Java and Scala.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * license agreements; and to You under the Apache License, version 2.0:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * This file is part of the Apache Pekko project, which was derived from Akka.
 */

/*
 * Copyright (C) 2009-2022 Lightbend Inc. 
 */

package org.apache.pekko.cluster.ddata

object Flag {

  /**
   * `Flag` that is initialized to `false`.
   */
  val empty: Flag = new Flag(false)

  /**
   * `Flag` that is initialized to `false`.
   */
  val Disabled: Flag = empty

  /**
   * `Flag` that is initialized to `true`.
   */
  val Enabled: Flag = new Flag(true)

  def apply(): Flag = Disabled

  /**
   * Java API: `Flag` that is initialized to `false`.
   */
  def create(): Flag = Disabled

  // unapply from case class
}

/**
 * Implements a boolean flag CRDT that is initialized to `false` and
 * can be switched to `true`. `true` wins over `false` in merge.
 *
 * This class is immutable, i.e. "modifying" methods return a new instance.
 */
@SerialVersionUID(1L)
final case class Flag(enabled: Boolean) extends ReplicatedData with ReplicatedDataSerialization {

  type T = Flag

  def switchOn: Flag =
    if (enabled) this
    else Flag.Enabled

  override def merge(that: Flag): Flag =
    if (that.enabled) that
    else this
}

object FlagKey {
  def create(id: String): Key[Flag] = FlagKey(id)
}

@SerialVersionUID(1L)
final case class FlagKey(_id: String) extends Key[Flag](_id) with ReplicatedDataSerialization