zookeeper processor

Chain of Responsibility
为了实现各种服务器的代码结构的高度统一，不同角色的server对应不同的processor chain

interface RequestProcessor {
    void processRequest(Request request) throws RequestProcessorException;
}

LeaderZooKeeperServer.java

FollowerZooKeeperServer.java

ZooKeeperServer.java

func processPacket() {
    submitRequest()
}

func submitRequest(req) {
    firstProcessor.processRequest(req)
}