Add support in cpp client for 1 partitioned topic (#5016)

### Motivation

IN PR #4883, we support 1 partitioned topic producer/consumer in java client. this is for Cpp client support.

### Modifications
- change cpp client 
- add unit test

### Verifying this change
New added Ut Passed

pulsar-client-cpp/lib/ClientImpl.cc

@@ -164,7 +164,7 @@ void ClientImpl::handleCreateProducer(const Result result, const LookupDataResul
                                       CreateProducerCallback callback) {
     if (!result) {
         ProducerImplBasePtr producer;
-        if (partitionMetadata->getPartitions() > 1) {
+        if (partitionMetadata->getPartitions() > 0) {
             producer = std::make_shared<PartitionedProducerImpl>(shared_from_this(), topicName,
                                                                  partitionMetadata->getPartitions(), conf);
         } else {
@@ -221,7 +221,7 @@ void ClientImpl::handleReaderMetadataLookup(const Result result, const LookupDat
         return;
     }
 
-    if (partitionMetadata->getPartitions() > 1) {
+    if (partitionMetadata->getPartitions() > 0) {
         LOG_ERROR("Topic reader cannot be created on a partitioned topic: " << topicName->toString());
         callback(ResultOperationNotSupported, Reader());
         return;
@@ -360,7 +360,7 @@ void ClientImpl::handleSubscribe(const Result result, const LookupDataResultPtr
             conf.setConsumerName(generateRandomName());
         }
         ConsumerImplBasePtr consumer;
-        if (partitionMetadata->getPartitions() > 1) {
+        if (partitionMetadata->getPartitions() > 0) {
             if (conf.getReceiverQueueSize() == 0) {
                 LOG_ERROR("Can't use partitioned topic if the queue size is 0.");
                 callback(ResultInvalidConfiguration, Consumer());
@@ -435,7 +435,7 @@ void ClientImpl::handleGetPartitions(const Result result, const LookupDataResult
 
     StringList partitions;
 
-    if (partitionMetadata->getPartitions() > 1) {
+    if (partitionMetadata->getPartitions() > 0) {
         for (unsigned int i = 0; i < partitionMetadata->getPartitions(); i++) {
             partitions.push_back(topicName->getTopicPartitionName(i));
         }

pulsar-client-cpp/lib/MultiTopicsConsumerImpl.cc

@@ -162,21 +162,23 @@ void MultiTopicsConsumerImpl::subscribeTopicPartitions(const Result result,
     config.setMessageListener(std::bind(&MultiTopicsConsumerImpl::messageReceived, shared_from_this(),
                                         std::placeholders::_1, std::placeholders::_2));
 
-    int numPartitions = partitionMetadata->getPartitions() >= 1 ? partitionMetadata->getPartitions() : 1;
+    int numPartitions = partitionMetadata->getPartitions();
+    int partitions = numPartitions == 0 ? 1 : numPartitions;
+
     // Apply total limit of receiver queue size across partitions
     config.setReceiverQueueSize(
         std::min(conf_.getReceiverQueueSize(),
-                 (int)(conf_.getMaxTotalReceiverQueueSizeAcrossPartitions() / numPartitions)));
+                 (int)(conf_.getMaxTotalReceiverQueueSizeAcrossPartitions() / partitions)));
 
     Lock lock(mutex_);
-    topicsPartitions_.insert(std::make_pair(topicName->toString(), numPartitions));
+    topicsPartitions_.insert(std::make_pair(topicName->toString(), partitions));
     lock.unlock();
-    numberTopicPartitions_->fetch_add(numPartitions);
+    numberTopicPartitions_->fetch_add(partitions);
 
-    std::shared_ptr<std::atomic<int>> partitionsNeedCreate =
-        std::make_shared<std::atomic<int>>(numPartitions);
+    std::shared_ptr<std::atomic<int>> partitionsNeedCreate = std::make_shared<std::atomic<int>>(partitions);
 
-    if (numPartitions == 1) {
+    // non-partitioned topic
+    if (numPartitions == 0) {
         // We don't have to add partition-n suffix
         consumer = std::make_shared<ConsumerImpl>(client_, topicName->toString(), subscriptionName_, config,
                                                   internalListenerExecutor, NonPartitioned);

pulsar-client-cpp/tests/BasicEndToEndTest.cc

@@ -2978,3 +2978,72 @@ TEST(BasicEndToEndTest, testRegexTopicsWithMessageListener) {
         timeWaited += 500;
     }
 }
+
+TEST(BasicEndToEndTest, testPartitionedTopicWithOnePartition) {
+    ClientConfiguration config;
+    Client client(lookupUrl);
+    std::string topicName = "testPartitionedTopicWithOnePartition";
+    std::string subsName = topicName + "-sub-";
+
+    // call admin api to make 1 partition
+    std::string url = adminUrl + "admin/v2/persistent/public/default/" + topicName + "/partitions";
+    int putRes = makePutRequest(url, "1");
+    LOG_INFO("res = " << putRes);
+    ASSERT_FALSE(putRes != 204 && putRes != 409);
+
+    Consumer consumer1;
+    ConsumerConfiguration conf;
+    Result result = client.subscribe(topicName, subsName + "1", consumer1);
+    ASSERT_EQ(ResultOk, result);
+
+    Consumer consumer2;
+    result = client.subscribe(topicName + "-partition-0", subsName + "2", consumer2);
+    ASSERT_EQ(ResultOk, result);
+
+    LOG_INFO("created 2 consumer");
+
+    Producer producer1;
+    ProducerConfiguration producerConf;
+    producerConf.setBatchingEnabled(false);
+    result = client.createProducer(topicName, producerConf, producer1);
+    ASSERT_EQ(ResultOk, result);
+
+    Producer producer2;
+    result = client.createProducer(topicName + "-partition-0", producerConf, producer2);
+    ASSERT_EQ(ResultOk, result);
+
+    LOG_INFO("created 2 producer");
+
+    // create messages
+    int numMessages = 10;
+    for (int i = 0; i < numMessages; i++) {
+        Message msg = MessageBuilder().setContent("test-producer1-" + topicName + std::to_string(i)).build();
+        producer1.send(msg);
+        msg = MessageBuilder().setContent("test-producer2-" + topicName + std::to_string(i)).build();
+        producer2.send(msg);
+    }
+
+    // produced 10 messages by each producer.
+    // expected receive 20 messages by each consumer.
+    for (int i = 0; i < numMessages * 2; i++) {
+        LOG_INFO("begin to receive message " << i);
+
+        Message msg;
+        Result res = consumer1.receive(msg, 100);
+        ASSERT_EQ(ResultOk, res);
+        consumer1.acknowledge(msg);
+
+        res = consumer2.receive(msg, 100);
+        ASSERT_EQ(ResultOk, res);
+        consumer2.acknowledge(msg);
+    }
+
+    // No more messages expected
+    Message msg;
+    Result res = consumer1.receive(msg, 100);
+    ASSERT_EQ(ResultTimeout, res);
+
+    res = consumer2.receive(msg, 100);
+    ASSERT_EQ(ResultTimeout, res);
+    client.shutdown();
+}
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