[fix][client]Producer stuck or geo-replication stuck due to wrong value of message.numMessagesInBatch

pulsar-broker/src/test/java/org/apache/pulsar/client/api/SimpleProducerConsumerTest.java

@@ -100,6 +100,8 @@
 import org.apache.pulsar.client.admin.PulsarAdminException;
 import org.apache.pulsar.client.api.schema.GenericRecord;
 import org.apache.pulsar.client.impl.BatchMessageIdImpl;
+import org.apache.pulsar.client.impl.ClientBuilderImpl;
+import org.apache.pulsar.client.impl.ClientCnx;
 import org.apache.pulsar.client.impl.ConsumerBase;
 import org.apache.pulsar.client.impl.ConsumerImpl;
 import org.apache.pulsar.client.impl.MessageIdImpl;
@@ -111,10 +113,12 @@
 import org.apache.pulsar.client.impl.TopicMessageImpl;
 import org.apache.pulsar.client.impl.TypedMessageBuilderImpl;
 import org.apache.pulsar.client.impl.crypto.MessageCryptoBc;
+import org.apache.pulsar.client.impl.metrics.InstrumentProvider;
 import org.apache.pulsar.client.impl.schema.writer.AvroWriter;
 import org.apache.pulsar.common.allocator.PulsarByteBufAllocator;
 import org.apache.pulsar.common.api.EncryptionContext;
 import org.apache.pulsar.common.api.EncryptionContext.EncryptionKey;
+import org.apache.pulsar.common.api.proto.CommandProducerSuccess;
 import org.apache.pulsar.common.api.proto.MessageMetadata;
 import org.apache.pulsar.common.api.proto.SingleMessageMetadata;
 import org.apache.pulsar.common.compression.CompressionCodec;
@@ -5433,4 +5437,66 @@ public void testBacklogAfterCreatedSubscription(boolean trimLegderBeforeGetStats
         // cleanup
         admin.topics().delete(topic, false);
     }
+
+    /**
+     * The internal producer of replicator will resend messages after reconnected. This test guarantees that the
+     * internal producer will continuously resent messages even though the client side encounters the following bugs.
+     * - The client side issue causes `message.metadata.numMessagesInBatch` being `0`, such as
+     *   https://github.com/streamnative/pulsar-rs/issues/376.
+     * - Before the fix, the resend mechanism relies on `message.metadata.numMessagesInBatch`, after the fix, the
+     *   producer only care about whether there are pending messages.
+     * see also https://github.com/apache/pulsar/pull/25106.
+     */
+    @Test
+    public void testResendMessagesWhichNumMessagesInBatchIsZero() throws Exception {
+        final String topic = BrokerTestUtil.newUniqueName("persistent://my-property/my-ns/tp");
+        final String subscriptionName = "s1";
+        admin.topics().createNonPartitionedTopic(topic);
+        admin.topics().createSubscription(topic, subscriptionName, MessageId.earliest);
+
+        // Create a producer which can be paused to publish.
+        AtomicBoolean stuckProducerReconnection = new AtomicBoolean(false);
+        ClientBuilderImpl clientBuilder = (ClientBuilderImpl) PulsarClient.builder().serviceUrl(lookupUrl.toString());
+        PulsarClient client = InjectedClientCnxClientBuilder.create(clientBuilder, (conf, eventLoopGroup) ->
+            new ClientCnx(InstrumentProvider.NOOP, conf, eventLoopGroup) {
+                protected void handleProducerSuccess(CommandProducerSuccess success) {
+                    if (stuckProducerReconnection.get()) {
+                        synchronized (stuckProducerReconnection) {
+                            super.handleProducerSuccess(success);
+                        }
+                    } else {
+                        super.handleProducerSuccess(success);
+                    }
+                }
+            });
+        ProducerImpl<byte[]> producer1 = (ProducerImpl<byte[]>) client.newProducer().topic(topic)
+                .sendTimeout(0, TimeUnit.SECONDS)
+                .enableBatching(false).create();
+
+        // Trigger a resending by unloading topics.
+        AtomicReference<CompletableFuture<MessageId>> latestPublishing = new AtomicReference<>();
+        synchronized (stuckProducerReconnection) {
+            stuckProducerReconnection.set(true);
+            admin.topics().unload(topic);
+            for (int i = 0; i < 10; i++) {
+                ByteBuf payload = PulsarByteBufAllocator.DEFAULT.heapBuffer(1);
+                MessageMetadata messageMetadata = new MessageMetadata();
+                messageMetadata.setUncompressedSize(1);
+                MessageImpl<byte[]> message1 = MessageImpl.create(topic, null, messageMetadata, payload,
+                        Optional.empty(), null, Schema.BYTES, 0, true, 0);
+                // Mock bugs, which publish messages with 0 numMessagesInBatch.
+                message1.getMessageBuilder().setNumMessagesInBatch(0);
+                latestPublishing.set(producer1.sendAsync(message1));
+            }
+            stuckProducerReconnection.set(false);
+        }
+
+        // Verify: no messages being stuck.
+        latestPublishing.get().get(10, TimeUnit.SECONDS);
+
+        // cleanup.
+        producer1.close();
+        client.close();
+        admin.topics().delete(topic, false);
+    }
 }

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

@@ -56,7 +56,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.Queue;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
@@ -1781,7 +1780,7 @@ protected OpSendMsg newObject(Handle<OpSendMsg> handle) {
      */
     protected static class OpSendMsgQueue implements Iterable<OpSendMsg> {
         @VisibleForTesting
-        final Queue<OpSendMsg> delegate = new ArrayDeque<>();
+        final ArrayDeque<OpSendMsg> delegate = new ArrayDeque<>();
         private int forEachDepth = 0;
         private List<OpSendMsg> postponedOpSendMgs;
         private final AtomicInteger messagesCount = new AtomicInteger(0);
@@ -1836,6 +1835,10 @@ public int messagesCount() {
             return messagesCount.get();
         }
 
+        public int size() {
+            return delegate.size();
+        }
+
         @Override
         public Iterator<OpSendMsg> iterator() {
             Iterator<OpSendMsg> delegateIterator = delegate.iterator();
@@ -2148,7 +2151,7 @@ private void resendMessages(ClientCnx cnx, long expectedEpoch) {
                 }
 
                 int messagesToResend = pendingMessages.messagesCount();
-                if (messagesToResend == 0) {
+                if (pendingMessages.size() == 0) {
                     if (log.isDebugEnabled()) {
                         log.debug("[{}] [{}] No pending messages to resend {}", topic, producerName, messagesToResend);
                     }