[fix][client] Fix consumer can't consume resent chunked messages (#21070

)

### Motivation

Current, when the producer resend the chunked message like this:
- M1: UUID: 0, ChunkID: 0
- M2: UUID: 0, ChunkID: 0 // Resend the first chunk
- M3: UUID: 0, ChunkID: 1

When the consumer received the M2, it will find that it's already tracking the UUID:0 chunked messages, and will then discard the message M1 and M2. This will lead to unable to consume the whole chunked message even though it's already persisted in the Pulsar topic.

Here is the code logic:
https://github.com/apache/pulsar/blob/44a055b8a55078bcf93f4904991598541aa6c1ee/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConsumerImpl.java#L1436-L1482

The bug can be easily reproduced using the testcase `testResendChunkMessages` introduced by this PR.

### Modifications

- When receiving the new duplicated first chunk of a chunked message, the consumer discard the current chunked message context and create a new context to track the following messages. For the case mentioned in Motivation, the M1 will be released and the consumer will assemble M2 and M3 as the chunked message.

(cherry picked from commit eb2e3a2)

pulsar-broker/src/test/java/org/apache/pulsar/client/impl/MessageChunkingTest.java

@@ -356,6 +356,47 @@ public void testMaxPendingChunkMessages() throws Exception {
         assertNull(consumer.receive(5, TimeUnit.SECONDS));
     }
 
+    @Test
+    public void testResendChunkMessages() throws Exception {
+        log.info("-- Starting {} test --", methodName);
+        final String topicName = "persistent://my-property/my-ns/testResendChunkMessages";
+
+        @Cleanup
+        Consumer<String> consumer = pulsarClient.newConsumer(Schema.STRING)
+                .topic(topicName)
+                .subscriptionName("my-subscriber-name")
+                .maxPendingChunkedMessage(10)
+                .autoAckOldestChunkedMessageOnQueueFull(true)
+                .subscribe();
+        @Cleanup
+        Producer<String> producer = pulsarClient.newProducer(Schema.STRING)
+                .topic(topicName)
+                .chunkMaxMessageSize(100)
+                .enableChunking(true)
+                .enableBatching(false)
+                .create();
+
+        sendSingleChunk(producer, "0", 0, 2);
+
+        sendSingleChunk(producer, "0", 0, 2); // Resending the first chunk
+        sendSingleChunk(producer, "1", 0, 3); // This is for testing the interwoven chunked message
+        sendSingleChunk(producer, "1", 1, 3);
+        sendSingleChunk(producer, "1", 0, 3); // Resending the UUID-1 chunked message
+
+        sendSingleChunk(producer, "0", 1, 2);
+
+        Message<String> receivedMsg = consumer.receive(5, TimeUnit.SECONDS);
+        assertEquals(receivedMsg.getValue(), "chunk-0-0|chunk-0-1|");
+        consumer.acknowledge(receivedMsg);
+
+        sendSingleChunk(producer, "1", 1, 3);
+        sendSingleChunk(producer, "1", 2, 3);
+
+        receivedMsg = consumer.receive(5, TimeUnit.SECONDS);
+        assertEquals(receivedMsg.getValue(), "chunk-1-0|chunk-1-1|chunk-1-2|");
+        consumer.acknowledge(receivedMsg);
+    }
+
     /**
      * Validate that chunking is not supported with batching and non-persistent topic
      *

pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConsumerImpl.java

@@ -1433,7 +1433,17 @@ private ByteBuf processMessageChunk(ByteBuf compressedPayload, MessageMetadata m
 
         ChunkedMessageCtx chunkedMsgCtx = chunkedMessagesMap.get(msgMetadata.getUuid());
 
-        if (msgMetadata.getChunkId() == 0 && chunkedMsgCtx == null) {
+        if (msgMetadata.getChunkId() == 0) {
+            if (chunkedMsgCtx != null) {
+                // The first chunk of a new chunked-message received before receiving other chunks of previous
+                // chunked-message
+                // so, remove previous chunked-message from map and release buffer
+                if (chunkedMsgCtx.chunkedMsgBuffer != null) {
+                    ReferenceCountUtil.safeRelease(chunkedMsgCtx.chunkedMsgBuffer);
+                }
+                chunkedMsgCtx.recycle();
+                chunkedMessagesMap.remove(msgMetadata.getUuid());
+            }
             pendingChunkedMessageCount++;
             if (maxPendingChunkedMessage > 0 && pendingChunkedMessageCount > maxPendingChunkedMessage) {
                 removeOldestPendingChunkedMessage();