RocketMQ原理解析-producer 5.消息在broker落地之普通消息
http://blog.****.net/quhongwei_zhanqiu/article/details/39142503
Broker根据producer请求的RequestCode.SEND_MESSAGE选择对应的处理器SendMessageProcessor
根据请求消息内容构建消息内部结构MessageExtBrokerInner
调DefaultMessageStore加消息写入commitlog