[pulsar] branch master updated: Fix NPE in checkSubscriptionTypesEnable (#12961)

[penghui]

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


The following commit(s) were added to refs/heads/master by this push:
     new 877bf3a  Fix NPE in checkSubscriptionTypesEnable (#12961)
877bf3a is described below

commit 877bf3a34e72336c05706ffd48826e4347606196
Author: Zike Yang <a...@armail.top>
AuthorDate: Fri Nov 26 11:23:12 2021 +0800

    Fix NPE in checkSubscriptionTypesEnable (#12961)
    
    ### Motivation
    
    The NPE may appear in `PersistentTopic.checkSubscriptionTypesEnable`.   The 
`topicPolicies.getSubscriptionTypesEnabled()` may be null.
    
    The problem occurred when upgrading from pulsar version 2.7 to 2.8. We 
added `SubscriptionTypesEnable` in 2.8: 
https://github.com/apache/pulsar/pull/9401. When we initialize a topic's 
topicPolicy in pulasr 2.7, and then get the topic's topicPolicy in version 2.8, 
the `SubscriptionTypesEnable` will be null. This leads to the problem.
    
    Here are steps to reproduce:
    * Start broker 2.7
    * Create a topic and init the topic policy
    * Upgrade broker to 2.8
    * We will get the `SubscriptionTypesEnable` with the value of null
    ```sh
    ➜  pulsar-281 bin/pulsar-admin topics get-subscription-types-enabled  
my-topic
    null
    ```
    * When we consume from that topic, the issue occurs
    ```
    Caused by: java.lang.NullPointerException
        at 
org.apache.pulsar.broker.service.persistent.PersistentTopic.checkSubscriptionTypesEnable(PersistentTopic.java:3206)
 ~[io.streamnative-pulsar-broker-2.8.1.21.jar:2.8.1.21]
        at 
org.apache.pulsar.broker.service.persistent.PersistentTopic.subscribe(PersistentTopic.java:688)
 ~[io.streamnative-pulsar-broker-2.8.1.21.jar:2.8.1.21]
        at 
org.apache.pulsar.broker.service.ServerCnx.lambda$null$13(ServerCnx.java:1029) 
~[io.streamnative-pulsar-broker-2.8.1.21.jar:2.8.1.21]
        at 
java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1106)
 ~[?:?]
        ... 31 more
    ```
    
    ### Modifications
    
    * Use `CollectionUtils.isEmpty` to determine if the list is empty to fix 
the problem of throwing NPE.
---
 .../org/apache/pulsar/broker/service/persistent/PersistentTopic.java   | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git 
a/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java
 
b/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java
index 5c94e61..415a988 100644
--- 
a/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java
+++ 
b/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java
@@ -73,6 +73,7 @@ import org.apache.bookkeeper.mledger.impl.ManagedCursorImpl;
 import org.apache.bookkeeper.mledger.impl.ManagedLedgerImpl;
 import org.apache.bookkeeper.mledger.impl.PositionImpl;
 import org.apache.bookkeeper.net.BookieId;
+import org.apache.commons.collections.CollectionUtils;
 import org.apache.commons.collections4.MapUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.pulsar.broker.PulsarServerException;
@@ -3232,7 +3233,7 @@ public class PersistentTopic extends AbstractTopic
                 if (topicPolicies == null) {
                     return checkNsAndBrokerSubscriptionTypesEnable(topicName, 
subType);
                 } else {
-                    if (topicPolicies.getSubscriptionTypesEnabled().isEmpty()) 
{
+                    if 
(CollectionUtils.isEmpty(topicPolicies.getSubscriptionTypesEnabled())) {
                         return 
checkNsAndBrokerSubscriptionTypesEnable(topicName, subType);
                     }
                     return 
topicPolicies.getSubscriptionTypesEnabled().contains(subType);