Remove samples (#22288)

Add code, that was used for documentation to the appropriate projects
or akka-docs.

akka-docs/rst/scala/code/docs/ddata/ShoppingCart.scala

@@ -0,0 +1,111 @@
+package scala.docs.ddata
+
+import scala.concurrent.duration._
+import akka.actor.Actor
+import akka.actor.ActorRef
+import akka.actor.Props
+import akka.cluster.Cluster
+import akka.cluster.ddata.DistributedData
+import akka.cluster.ddata.LWWMap
+import akka.cluster.ddata.LWWMapKey
+
+object ShoppingCart {
+  import akka.cluster.ddata.Replicator._
+
+  def props(userId: String): Props = Props(new ShoppingCart(userId))
+
+  case object GetCart
+  final case class AddItem(item: LineItem)
+  final case class RemoveItem(productId: String)
+
+  final case class Cart(items: Set[LineItem])
+  final case class LineItem(productId: String, title: String, quantity: Int)
+
+  //#read-write-majority
+  private val timeout = 3.seconds
+  private val readMajority = ReadMajority(timeout)
+  private val writeMajority = WriteMajority(timeout)
+  //#read-write-majority
+
+}
+
+class ShoppingCart(userId: String) extends Actor {
+  import ShoppingCart._
+  import akka.cluster.ddata.Replicator._
+
+  val replicator = DistributedData(context.system).replicator
+  implicit val cluster = Cluster(context.system)
+
+  val DataKey = LWWMapKey[String, LineItem]("cart-" + userId)
+
+  def receive = receiveGetCart
+    .orElse[Any, Unit](receiveAddItem)
+    .orElse[Any, Unit](receiveRemoveItem)
+    .orElse[Any, Unit](receiveOther)
+
+  //#get-cart
+  def receiveGetCart: Receive = {
+    case GetCart =>
+      replicator ! Get(DataKey, readMajority, Some(sender()))
+
+    case g @ GetSuccess(DataKey, Some(replyTo: ActorRef)) =>
+      val data = g.get(DataKey)
+      val cart = Cart(data.entries.values.toSet)
+      replyTo ! cart
+
+    case NotFound(DataKey, Some(replyTo: ActorRef)) =>
+      replyTo ! Cart(Set.empty)
+
+    case GetFailure(DataKey, Some(replyTo: ActorRef)) =>
+      // ReadMajority failure, try again with local read
+      replicator ! Get(DataKey, ReadLocal, Some(replyTo))
+  }
+  //#get-cart
+
+  //#add-item
+  def receiveAddItem: Receive = {
+    case cmd @ AddItem(item) =>
+      val update = Update(DataKey, LWWMap.empty[String, LineItem], writeMajority, Some(cmd)) {
+        cart => updateCart(cart, item)
+      }
+      replicator ! update
+  }
+  //#add-item
+
+  def updateCart(data: LWWMap[String, LineItem], item: LineItem): LWWMap[String, LineItem] =
+    data.get(item.productId) match {
+      case Some(LineItem(_, _, existingQuantity)) =>
+        data + (item.productId -> item.copy(quantity = existingQuantity + item.quantity))
+      case None => data + (item.productId -> item)
+    }
+
+  //#remove-item
+  def receiveRemoveItem: Receive = {
+    case cmd @ RemoveItem(productId) =>
+      // Try to fetch latest from a majority of nodes first, since ORMap
+      // remove must have seen the item to be able to remove it.
+      replicator ! Get(DataKey, readMajority, Some(cmd))
+
+    case GetSuccess(DataKey, Some(RemoveItem(productId))) =>
+      replicator ! Update(DataKey, LWWMap(), writeMajority, None) {
+        _ - productId
+      }
+
+    case GetFailure(DataKey, Some(RemoveItem(productId))) =>
+      // ReadMajority failed, fall back to best effort local value
+      replicator ! Update(DataKey, LWWMap(), writeMajority, None) {
+        _ - productId
+      }
+
+    case NotFound(DataKey, Some(RemoveItem(productId))) =>
+    // nothing to remove
+  }
+  //#remove-item
+
+  def receiveOther: Receive = {
+    case _: UpdateSuccess[_] | _: UpdateTimeout[_] =>
+    // UpdateTimeout, will eventually be replicated
+    case e: UpdateFailure[_]                       => throw new IllegalStateException("Unexpected failure: " + e)
+  }
+
+}