This inheritance list is sorted roughly, but not completely, alphabetically:

[detail level 12]

CRdKafka::BrokerMetadata	Metadata: Broker information
CRdKafka::Conf	Configuration interface
CRdKafka::ConsumeCb	Consume callback class
CRdKafka::DeliveryReportCb	Delivery Report callback class
CRdKafka::Event	Event object class as passed to the EventCb callback
CRdKafka::EventCb	Event callback class
▼CRdKafka::Handle	Base handle, super class for specific clients
CRdKafka::Consumer	Simple Consumer (legacy)
CRdKafka::KafkaConsumer	High-level KafkaConsumer (for brokers 0.9 and later)
CRdKafka::Producer	Producer
CRdKafka::Message	Message object
CRdKafka::MessageTimestamp	Message timestamp object
CRdKafka::Metadata	Metadata container
CRdKafka::OffsetCommitCb	Offset Commit callback class
CRdKafka::OpenCb	Portability: OpenCb callback class
CRdKafka::PartitionerCb	Partitioner callback class
CRdKafka::PartitionerKeyPointerCb	Variant partitioner with key pointer
CRdKafka::PartitionMetadata	Metadata: Partition information
CRdKafka::Queue	Queue interface
Crd_kafka_err_desc	Error code value, name and description. Typically for use with language bindings to automatically expose the full set of librdkafka error codes
Crd_kafka_group_info	Group information
Crd_kafka_group_list	List of groups
Crd_kafka_group_member_info	Group member information
Crd_kafka_message_t	A Kafka message as returned by the `rd_kafka_consume*`() family of functions as well as provided to the Producer `dr_msg_cb()`
Crd_kafka_metadata_broker_t	Broker information
Crd_kafka_metadata_partition_t	Partition information
Crd_kafka_metadata_t	Metadata container
Crd_kafka_metadata_topic_t	Topic information
Crd_kafka_topic_partition_list_t	A growable list of Topic+Partitions
Crd_kafka_topic_partition_t	Topic+Partition place holder
CRdKafka::RebalanceCb	KafkaConsunmer: Rebalance callback class
CRdKafka::SocketCb	Portability: SocketCb callback class
CRdKafka::Topic	Topic handle
CRdKafka::TopicMetadata	Metadata: Topic information
CRdKafka::TopicPartition	Topic+Partition