Builder
RecordAccumulator
+append()+drain()
-client
ClientRequest
ProducerBatch
-sender
sender线程
add
ProducerInterceptors
+onSend()+onAcknowledgement()
使用KafkaProducer客户端发送消息（ProducerRecord），需要经历拦截器（Interceptor）、序列化器（Serializer）和分区器（Partitioner）等一系列的作用
ProducerInterceptor
-accumulator
request
drain
main线程
ProduceRequest
send
interfacePartitioner
+partition()
-interceptors
Deque
一条消息（ProducerRecord）在经过拦截器、序列化器、分区器处理之后，被存入到RecordAccumulator中。在RecordAccumulator中维护了一个名为batches的Map，其以分区信息（TopicPartition）为键，双端队列（Deque）为值，这个队列由若干ProducerBatch组成，而一个ProducerBatch又包含若干条消息
-clientId:String-producerConfig:ProducerConfig
+KafkaProducer()+send(ProducerRecord)
interfaceRunnable
+run()
以broker节点为维度，存放发往broker节点的封装后的InFlightRequest消息，根据配置（max.in.flight.requests.per.connection）可能限制每个broker的缓存请求
-inFlightRequests
a:TopicPartitiona IN node1
InFlightRequests
+add()+canSendMore():boolean
sender线程在实例化KafkaProducer时被创建，并以守护线程的方式运行
进一步封装消息
c:TopicPartitiona IN node1
interfaceSerializer
+serialize()+configure()
b:TopicPartitiona IN node2
append
将从RecordAccumulator获取的消息集合封装
-partitioner
-keySerializer
-valueSerializer
InFlightRequest
destination:Stringheader:RequestHeadercallback:RequestCompletionHandler
+InFlightRequest()+completed()+disconnected()
NetworkClient
-selector:Selectable
AbstractRequest
0...n
Sender
+Sender()+run()-runOnce()-sendProducerData()-sendProduceRequests()-sendProduceRequest()
