Zookeeper源码解读

Posted 2020-11-10 勿忘初心，进无止境.

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1.1. 客户端源码

1.1.1. 总体流程

启动客户端 zkCli.sh文件里面的配置

实际运行

  public static void main(String args[])

        throws KeeperException, IOException, InterruptedException

    {

        ZooKeeperMain main = new ZooKeeperMain(args);  

        main.run();

    }

Main方法流程：

new ZooKeeperMain 对象
调用run（）方法

在ZookeeperMain的构造方法里面，重点是

 public ZooKeeperMain(String args[]) throws IOException, InterruptedException {

        cl.parseOptions(args);

        System.out.println("Connecting to " + cl.getOption("server"));

　　　　　//连接上ZK

        connectToZK(cl.getOption("server"));

    }

　　protected void connectToZK(String newHost) throws InterruptedException, IOException {

        if (zk != null && zk.getState().isAlive()) {

            zk.close();

        }

        host = newHost;

        boolean readOnly = cl.getOption("readonly") != null;

        zk = new ZooKeeper(host,

                 Integer.parseInt(cl.getOption("timeout")),

                 new MyWatcher(), readOnly);

    }

最终在connectToZK方法里面也就是使用原生的Zk客户端进行连接的。

　　 public ZooKeeper(String connectString, int sessionTimeout, Watcher watcher,

            boolean canBeReadOnly)

        throws IOException

    {

        LOG.info("Initiating client connection, connectString=" + connectString

                + " sessionTimeout=" + sessionTimeout + " watcher=" + watcher);

 

        watchManager.defaultWatcher = watcher;

 

        ConnectStringParser connectStringParser = new ConnectStringParser(

                connectString);

        HostProvider hostProvider = new StaticHostProvider(

                connectStringParser.getServerAddresses());

        cnxn = new ClientCnxn(connectStringParser.getChrootPath(),

                hostProvider, sessionTimeout, this, watchManager,

//获得和服务端连接的对象

                getClientCnxnSocket(), canBeReadOnly);

         //调用start()

        cnxn.start();

    }