Add hostname to nodeinfo(#6156)

java/api/src/main/java/org/ray/api/runtimecontext/NodeInfo.java

@@ -12,14 +12,17 @@ public class NodeInfo {
 
   public final String nodeAddress;
 
+  public final String nodeHostname;
+
   public final boolean isAlive;
 
   public final Map<String, Double> resources;
 
-  public NodeInfo(UniqueId nodeId,  String nodeAddress,
+  public NodeInfo(UniqueId nodeId,  String nodeAddress, String nodeHostname,
                   boolean isAlive, Map<String, Double> resources) {
     this.nodeId = nodeId;
     this.nodeAddress = nodeAddress;
+    this.nodeHostname = nodeHostname;
     this.isAlive = isAlive;
     this.resources = resources;
   }
@@ -28,6 +31,7 @@ public class NodeInfo {
     return "NodeInfo{"
         + "nodeId='" + nodeId + '\''
         + ", nodeAddress='" + nodeAddress + "\'"
+        + ", nodeHostname'" + nodeHostname + "\'"
         + ", isAlive=" + isAlive
         + ", resources=" + resources
         + "}";

java/runtime/src/main/java/org/ray/runtime/gcs/GcsClient.java

@@ -77,12 +77,14 @@ public class GcsClient {
       if (data.getState() == GcsNodeInfo.GcsNodeState.ALIVE) {
         //Code path of node insertion.
         NodeInfo nodeInfo = new NodeInfo(
-            nodeId, data.getNodeManagerAddress(), true, new HashMap<>());
+            nodeId, data.getNodeManagerAddress(),
+            data.getNodeManagerHostname(),
+            true, new HashMap<>());
         nodes.put(nodeId, nodeInfo);
       } else {
         // Code path of node deletion.
         NodeInfo nodeInfo = new NodeInfo(nodeId, nodes.get(nodeId).nodeAddress,
-            false, new HashMap<>());
+            nodes.get(nodeId).nodeHostname, false, new HashMap<>());
         nodes.put(nodeId, nodeInfo);
       }
     }