[grid] Delete existing sessions if the Node is restarted

Author: pujagani

java/src/org/openqa/selenium/grid/data/NodeRestartedEvent.java

@@ -0,0 +1,40 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.openqa.selenium.grid.data;
+
+import org.openqa.selenium.events.Event;
+import org.openqa.selenium.events.EventListener;
+import org.openqa.selenium.events.EventName;
+import org.openqa.selenium.internal.Require;
+
+import java.util.function.Consumer;
+
+public class NodeRestartedEvent extends Event {
+
+  private static final EventName NODE_RESTARTED_EVENT = new EventName("node-restarted");
+
+  public NodeRestartedEvent(NodeStatus nodes) {
+    super(NODE_RESTARTED_EVENT, nodes);
+  }
+
+  public static EventListener<NodeStatus> listener(Consumer<NodeStatus> handler) {
+    Require.nonNull("Handler", handler);
+
+    return new EventListener<>(NODE_RESTARTED_EVENT, NodeStatus.class , handler);
+  }
+}

java/src/org/openqa/selenium/grid/distributor/GridModel.java

@@ -24,6 +24,7 @@
 import org.openqa.selenium.grid.data.NodeDrainStarted;
 import org.openqa.selenium.grid.data.NodeId;
 import org.openqa.selenium.grid.data.NodeRemovedEvent;
+import org.openqa.selenium.grid.data.NodeRestartedEvent;
 import org.openqa.selenium.grid.data.NodeStatus;
 import org.openqa.selenium.grid.data.Session;
 import org.openqa.selenium.grid.data.SessionClosedEvent;
@@ -104,6 +105,16 @@ public void add(NodeStatus node) {
           return;
         }
 
+        // If the URI is the same but NodeId is different then the Node has restarted
+        if(!next.getNodeId().equals(node.getNodeId()) &&
+           next.getExternalUri().equals(node.getExternalUri())) {
+          LOG.info(String.format("Re-adding node with id %s and URI %s.", node.getNodeId(), node.getExternalUri()));
+
+          events.fire(new NodeRestartedEvent(node));
+          iterator.remove();
+          break;
+        }
+
         // If the URI has changed, then assume this is a new node and fall
         // out of the loop: we want to add it as `DOWN` until something
         // changes our mind.

java/src/org/openqa/selenium/grid/sessionmap/local/LocalSessionMap.java

@@ -21,6 +21,7 @@
 import org.openqa.selenium.events.EventBus;
 import org.openqa.selenium.grid.config.Config;
 import org.openqa.selenium.grid.data.NodeRemovedEvent;
+import org.openqa.selenium.grid.data.NodeRestartedEvent;
 import org.openqa.selenium.grid.data.Session;
 import org.openqa.selenium.grid.data.SessionClosedEvent;
 import org.openqa.selenium.grid.log.LoggingOptions;
@@ -77,6 +78,9 @@ public LocalSessionMap(Tracer tracer, EventBus bus) {
       .map(slot -> slot.getSession().getId())
       .forEach(knownSessions::remove)));
 
+    bus.addListener(NodeRestartedEvent.listener(nodeStatus -> knownSessions.values()
+      .removeIf(value -> value.getUri().equals(nodeStatus.getExternalUri()))));
+
   }
 
   public static SessionMap create(Config config) {