[zookeeper] branch master updated: ZOOKEEPER-4247: NPE while processing message from restarted quorum member

[arshad]

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arshad pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/zookeeper.git


The following commit(s) were added to refs/heads/master by this push:
     new ea75e1f  ZOOKEEPER-4247: NPE while processing message from restarted 
quorum member
ea75e1f is described below

commit ea75e1f63572fc72fb8520ba8c793523047acb49
Author: Mate Szalay-Beko <sy...@apache.org>
AuthorDate: Wed Apr 14 22:22:09 2021 +0530

    ZOOKEEPER-4247: NPE while processing message from restarted quorum member
    
    When a ZooKeeper server realizes that an other quorum peer was shut down 
(e.g. during a rolling upgrade or
    rolling restart), the ServerCnxn.zkServer variable is set to null by 
QuorumPear.close(). This is why in the code
    we usually check the zkServer variable before using it. But this check was 
missing in one place thus causing
    NPE in NettyServerCnx.receiveMessage:
    
    ```
    2021-02-08T12:42:08.229+0000 [myid:] - ERROR
    [nioEventLoopGroup-4-1:NettyServerCnxnFactory$CnxnChannelHandler329]- 
Unexpected exception in receive
     java.lang.NullPointerException: null ~[zookeeper-3.6.2.jar:3.6.2]
     at 
org.apache.zookeeper.server.NettyServerCnxn.receiveMessage(NettyServerCnxn.java:518)
     at 
org.apache.zookeeper.server.NettyServerCnxn.processMessage(NettyServerCnxn.java:368)
     at org.apache.zookeeper.server.NettyServerCnxnFactory
            $CnxnChannelHandler.channelRead(NettyServerCnxnFactory.java:326)
    ...
    ```
    
    In this commit we add the necessary check and (after throwing an 
IOException) we will basically ignore the
    processing of the received message when the remote ZooKeeper server is 
already down.
    
    Author: Mate Szalay-Beko <sy...@apache.org>
    
    Reviewers: Enrico Olivelli <eolive...@apache.org>, Mohammad Arshad 
<ars...@apache.org>
    
    Closes #1681 from symat/ZOOKEEPER-4247 and squashes the following commits:
    
    7b140177d [Mate Szalay-Beko] ZOOKEEPER-4247: address PR comments
    b99ee986b [Mate Szalay-Beko] ZOOKEEPER-4247: address PR comments
    3c8478a40 [Mate Szalay-Beko] ZOOKEEPER-4247: fix NPE happens while 
processing messages during quorum member restart
---
 .../src/main/java/org/apache/zookeeper/server/NettyServerCnxn.java  | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git 
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxn.java
 
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxn.java
index 110807a..269fcd9 100644
--- 
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxn.java
+++ 
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/NettyServerCnxn.java
@@ -520,8 +520,12 @@ public class NettyServerCnxn extends ServerCnxn {
                         if (len < 0 || len > BinaryInputArchive.maxBuffer) {
                             throw new IOException("Len error " + len);
                         }
+                        ZooKeeperServer zks = this.zkServer;
+                        if (zks == null || !zks.isRunning()) {
+                            throw new IOException("ZK down");
+                        }
                         // checkRequestSize will throw IOException if request 
is rejected
-                        zkServer.checkRequestSizeWhenReceivingMessage(len);
+                        zks.checkRequestSizeWhenReceivingMessage(len);
                         bb = ByteBuffer.allocate(len);
                     }
                 }