Merge pull request #23583 from akka/wip-multi-dc-merge-master-patriknw

merge wip-multi-dc-dev back to master

akka-docs/src/test/java/jdocs/cluster/ClusterDocTest.java

@@ -5,6 +5,7 @@ package jdocs.cluster;
 
 import akka.testkit.javadsl.TestKit;
 import com.typesafe.config.ConfigFactory;
+import java.util.Set;
 import jdocs.AbstractJavaTest;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
@@ -12,6 +13,7 @@ import org.junit.Test;
 
 import akka.actor.ActorSystem;
 import akka.cluster.Cluster;
+import akka.cluster.Member;
 
 
 public class ClusterDocTest extends AbstractJavaTest {
@@ -38,5 +40,20 @@ public class ClusterDocTest extends AbstractJavaTest {
     //#leave
 
   }
+  
+  // compile only 
+  @SuppressWarnings("unused")
+  public void demonstrateDataCenter() {
+    //#dcAccess
+    final Cluster cluster = Cluster.get(system);
+    // this node's data center
+    String dc = cluster.selfDataCenter();
+    // all known data centers
+    Set<String> allDc = cluster.state().getAllDataCenters();
+    // a specific member's data center
+    Member aMember = cluster.state().getMembers().iterator().next();
+    String aDc = aMember.dataCenter();
+    //#dcAccess
+  }
 
 }

akka-docs/src/test/java/jdocs/sharding/ClusterShardingTest.java

@@ -6,6 +6,7 @@ package jdocs.sharding;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 
+import java.util.Optional;
 import scala.concurrent.duration.Duration;
 
 import akka.actor.AbstractActor;
@@ -101,6 +102,15 @@ public class ClusterShardingTest {
     ClusterSharding.get(system).start("SupervisedCounter",
         Props.create(CounterSupervisor.class), settings, messageExtractor);
     //#counter-supervisor-start
+
+    //#proxy-dc
+    ActorRef counterProxyDcB =
+      ClusterSharding.get(system).startProxy(
+        "Counter",
+        Optional.empty(),
+        Optional.of("B"), // data center name
+        messageExtractor);
+    //#proxy-dc
   }
 
   public void demonstrateUsage2() {