From 70b62a247c36e4780092a1b317a537d88a465c36 Mon Sep 17 00:00:00 2001
From: Yannick Welsch <yannick@welsch.lu>
Date: Mon, 13 Nov 2017 15:18:59 +0100
Subject: [PATCH] Stop responding to ping requests before master abdication
 (#27329)

When the current master node is shutting down, it sends a leave request to the other nodes so that they can eagerly start a fresh master election. Unfortunately, it was still possible for the master node that was shutting down to respond to ping requests, possibly influencing the election decision as it still appeared as an active master in the ping responses. This commit ensures that UnicastZenPing does not respond to ping requests once it's been closed. ZenDiscovery.doStop() continues to ensure that the pinging component is first closed before it triggers a master election.

Closes #27328
---
 .../elasticsearch/discovery/zen/UnicastZenPing.java    |  6 +++++-
 .../discovery/zen/UnicastZenPingTests.java             | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/org/elasticsearch/discovery/zen/UnicastZenPing.java b/core/src/main/java/org/elasticsearch/discovery/zen/UnicastZenPing.java
index d0a9a212bdd14..06269706e0d5f 100644
--- a/core/src/main/java/org/elasticsearch/discovery/zen/UnicastZenPing.java
+++ b/core/src/main/java/org/elasticsearch/discovery/zen/UnicastZenPing.java
@@ -575,7 +575,8 @@ public void handleResponse(UnicastPingResponse response) {
 
             @Override
             public void handleException(TransportException exp) {
-                if (exp instanceof ConnectTransportException || exp.getCause() instanceof ConnectTransportException) {
+                if (exp instanceof ConnectTransportException || exp.getCause() instanceof ConnectTransportException ||
+                    exp.getCause() instanceof AlreadyClosedException) {
                     // ok, not connected...
                     logger.trace((Supplier<?>) () -> new ParameterizedMessage("failed to connect to {}", node), exp);
                 } else if (closed == false) {
@@ -608,6 +609,9 @@ class UnicastPingRequestHandler implements TransportRequestHandler<UnicastPingRe
 
         @Override
         public void messageReceived(UnicastPingRequest request, TransportChannel channel) throws Exception {
+            if (closed) {
+                throw new AlreadyClosedException("node is shutting down");
+            }
             if (request.pingResponse.clusterName().equals(clusterName)) {
                 channel.sendResponse(handlePingRequest(request));
             } else {
diff --git a/core/src/test/java/org/elasticsearch/discovery/zen/UnicastZenPingTests.java b/core/src/test/java/org/elasticsearch/discovery/zen/UnicastZenPingTests.java
index 3c7a49a176635..853294de186d1 100644
--- a/core/src/test/java/org/elasticsearch/discovery/zen/UnicastZenPingTests.java
+++ b/core/src/test/java/org/elasticsearch/discovery/zen/UnicastZenPingTests.java
@@ -258,6 +258,16 @@ protected Version getVersion() {
         assertPingCount(handleD, handleA, 0);
         assertPingCount(handleD, handleB, 0);
         assertPingCount(handleD, handleC, 3);
+
+        zenPingC.close();
+        handleD.counters.clear();
+        logger.info("ping from UZP_D after closing UZP_C");
+        pingResponses = zenPingD.pingAndWait().toList();
+        // check that node does not respond to pings anymore after the ping service has been closed
+        assertThat(pingResponses.size(), equalTo(0));
+        assertPingCount(handleD, handleA, 0);
+        assertPingCount(handleD, handleB, 0);
+        assertPingCount(handleD, handleC, 3);
     }
 
     public void testUnknownHostNotCached() throws ExecutionException, InterruptedException {