【zookeeper核心源码解析】第一课：zk启动类核心流程序列图

系列文章目录

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1. zk 启动核心流程序列图

QueermpeerMain核心代码start()方法：

    @Override
    public synchronized void start() {
        loadDataBase();
        cnxnFactory.start();        //绑定2181
        startLeaderElection();
        super.start();
    }

序列图如下：

2、启动流程说明

1. 进程入口类： QuermpeerMain，从mian方法开始找
2. 主要初始化QuorumPeer，该类三个核心方法, start() ，该类是核心类，该类是一个线程类，run方法中是核心后台线程
3. 启动连接
4. 初始化选举算法FastLeaderElection, 这时还没开始选举

3. 核心类解释

3.1 QuorumPeer类注释

 * This class manages the quorum protocol. There are three states this server
 * can be in:
 * <ol>
 * <li>Leader election - each server will elect a leader (proposing itself as a
 * leader initially).</li>
 * <li>Follower - the server will synchronize with the leader and replicate any
 * transactions.</li>
 * <li>Leader - the server will process requests and forward them to followers.
 * A majority of followers must log the request before it can be accepted.
 * </ol>
 *
 * This class will setup a datagram socket that will always respond with its
 * view of the current leader. The response will take the form of:
 *
核心方法功能有三个，分别是：1.leader选举 2.Follower  功能 3.Leader 功能

3.2 ServerCnxnFactory

Server网络连接工厂：服务端管理连接核心类
负责请求的连接与管理