From 993ea62108ed2c21bd14e0f1f7e792e0154435b9 Mon Sep 17 00:00:00 2001
From: Yunze Xu <xyzinfernity@163.com>
Date: Fri, 14 May 2021 19:44:27 +0800
Subject: [PATCH] Fix NPE when ACK grouping tracker checks duplicated message
 id (#10586)

---
 .../java/org/apache/pulsar/client/impl/MessageIdImpl.java   | 3 +++
 .../impl/PersistentAcknowledgmentsGroupingTracker.java      | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/MessageIdImpl.java b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/MessageIdImpl.java
index 855ee64bacdc3..2d571852919bc 100644
--- a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/MessageIdImpl.java
+++ b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/MessageIdImpl.java
@@ -200,6 +200,9 @@ public byte[] toByteArray() {
 
     @Override
     public int compareTo(MessageId o) {
+        if (o == null) {
+            throw new UnsupportedOperationException("MessageId is null");
+        }
         if (o instanceof MessageIdImpl) {
             MessageIdImpl other = (MessageIdImpl) o;
             int batchIndex = (o instanceof BatchMessageIdImpl) ? ((BatchMessageIdImpl) o).getBatchIndex() : NO_BATCH;
diff --git a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/PersistentAcknowledgmentsGroupingTracker.java b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/PersistentAcknowledgmentsGroupingTracker.java
index 9eee2bf7b41da..09d6bd51b9f10 100644
--- a/pulsar-client/src/main/java/org/apache/pulsar/client/impl/PersistentAcknowledgmentsGroupingTracker.java
+++ b/pulsar-client/src/main/java/org/apache/pulsar/client/impl/PersistentAcknowledgmentsGroupingTracker.java
@@ -36,6 +36,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import io.netty.util.Recycler;
+import lombok.NonNull;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.tuple.Triple;
 import org.apache.pulsar.client.api.MessageId;
@@ -113,7 +114,10 @@ public PersistentAcknowledgmentsGroupingTracker(ConsumerImpl<?> consumer, Consum
      * resent after a disconnection and for which the user has already sent an acknowledgement.
      */
     @Override
-    public boolean isDuplicate(MessageId messageId) {
+    public boolean isDuplicate(@NonNull MessageId messageId) {
+        if (lastCumulativeAck.messageId == null) {
+            return false;
+        }
         if (messageId.compareTo(lastCumulativeAck.messageId) <= 0) {
             // Already included in a cumulative ack
             return true;