From e7bbbdf8eda101220413e7bdd35f83500e6c17cb Mon Sep 17 00:00:00 2001
From: danischroeter <dsc@theone.ch>
Date: Sat, 11 Nov 2017 00:25:33 +0100
Subject: [PATCH] Provide access to known shard types #23912 (#23913)

* Provide access to known shard types #23912

* applied format
---
 .../akka/cluster/sharding/ClusterSharding.scala  | 16 ++++++++++++++++
 akka-docs/src/main/paradox/cluster-sharding.md   |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
index 10f6b69fb4..3d5fc32dba 100644
--- a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
+++ b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
@@ -6,6 +6,7 @@ package akka.cluster.sharding
 import java.net.URLEncoder
 import java.util.Optional
 import java.util.concurrent.ConcurrentHashMap
+
 import scala.concurrent.Await
 import akka.actor.Actor
 import akka.actor.ActorRef
@@ -27,10 +28,15 @@ import akka.pattern.ask
 import akka.dispatch.Dispatchers
 import akka.cluster.ddata.ReplicatorSettings
 import akka.cluster.ddata.Replicator
+
 import scala.util.control.NonFatal
 import akka.actor.Status
 import akka.cluster.ClusterSettings
 import akka.cluster.ClusterSettings.DataCenter
+import akka.stream.{ Inlet, Outlet }
+
+import scala.collection.immutable
+import scala.collection.JavaConverters._
 
 /**
  * This extension provides sharding functionality of actors in a cluster.
@@ -445,6 +451,16 @@ class ClusterSharding(system: ExtendedActorSystem) extends Extension {
 
   }
 
+  /**
+   * Scala API: get all currently defined sharding type names.
+   */
+  def shardTypeNames: immutable.Set[String] = regions.keySet().asScala.toSet
+
+  /**
+   * Java API: get all currently defined sharding type names.
+   */
+  def getShardTypeNames: java.util.Set[String] = regions.keySet()
+
   /**
    * Retrieve the actor reference of the [[ShardRegion]] actor responsible for the named entity type.
    * The entity type must be registered with the [[#start]] or [[#startProxy]] method before it
diff --git a/akka-docs/src/main/paradox/cluster-sharding.md b/akka-docs/src/main/paradox/cluster-sharding.md
index 09ccb5af4c..82c0dc73a5 100644
--- a/akka-docs/src/main/paradox/cluster-sharding.md
+++ b/akka-docs/src/main/paradox/cluster-sharding.md
@@ -464,6 +464,8 @@ the identifiers of the shards running in a Region and what entities are alive fo
 a `ShardRegion.ClusterShardingStats` containing the identifiers of the shards running in each region and a count
 of entities that are alive in each shard.
 
+The type names of all started shards can be aquired via @scala[`ClusterSharding.shardTypeNames`]  @java[`ClusterSharding.getShardTypeNames`].
+
 The purpose of these messages is testing and monitoring, they are not provided to give access to
 directly sending messages to the individual entities.