jstorm源码之TransactionalState

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一、作用
  主要是通过结合zookeeper，在zookeeper指定的目录下创建不同的自己 代表不同的transaction state，并赋予不同的内容；通过zookeeper完成对partitions的transaction的管理
二、源码分析
package storm.trident.topology.state;


import backtype.storm.Config;
import backtype.storm.utils.Utils;
import backtype.storm.utils.ZookeeperAuthInfo;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.api.ProtectACLCreateModePathAndBytesable;
import org.apache.curator.framework.api.PathAndBytesable;

import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.json.simple.JSONValue;
// 事务状态
// 通过zookeeper来进行完成操作

public class TransactionalState {
    // zookeeper 的监护器
    CuratorFramework _curator;
    // zookeeper 访问控制列表
    List _zkAcls = null;
   // 构建用户的transaction的状态
    public static TransactionalState newUserState(Map conf, String id) {
        return new TransactionalState(conf, id, "user");
    }
   // 构建协调器的transaction的状态
    public static TransactionalState newCoordinatorState(Map conf, String id) {
        return new TransactionalState(conf, id, "coordinator");       
    }
    //  在zookeeper上构建对应的transaction的state的目录
    protected TransactionalState(Map conf, String id, String subroot) {
        try {
            conf = new HashMap(conf);
            //  zookeeper的root目录
            String transactionalRoot = (String)conf.get(Config.TRANSACTIONAL_ZOOKEEPER_ROOT);
           //   zookeeper的transaction的state的根目录
            String rootDir = transactionalRoot + "/" + id + "/" + subroot;
            // 根据配置信息中的transactional servers 和 zookeeper servers获取servers 优先使用transactional的servers 否则使用zookeeper servers
            List servers = (List) getWithBackup(conf, Config.TRANSACTIONAL_ZOOKEEPER_SERVERS, Config.STORM_ZOOKEEPER_SERVERS);
            //  根据配置信息中的transactional ports和zookeeper port设置对应的ports
            Object port = getWithBackup(conf, Config.TRANSACTIONAL_ZOOKEEPER_PORT, Config.STORM_ZOOKEEPER_PORT);
            // 设定zookeeper权限控制
            ZookeeperAuthInfo auth = new ZookeeperAuthInfo(conf);
            //  根据config、servers、port、auth完成zookeeper监护器初始化 并启动
            CuratorFramework initter = Utils.newCuratorStarted(conf, servers, port, auth);
            //  获取zookeeper可用列表
            _zkAcls = Utils.getWorkerACL(conf);
            try {
                 // 在zookeeper上创建对应的transaction 根目录node
                TransactionalState.createNode(initter, transactionalRoot, null, null, null);
            } catch (KeeperException.NodeExistsException e) {
            }
            try {
                //  创建对应的transaction state的node的子根目录
                TransactionalState.createNode(initter, rootDir, null, _zkAcls, null);
            } catch (KeeperException.NodeExistsException e) {
            }
            //  关闭初始化监护器
            initter.close();
            //  开启全局监护器
            _curator = Utils.newCuratorStarted(conf, servers, port, rootDir, auth);
        } catch (Exception e) {
           throw new RuntimeException(e);
        }
    }

    protected static String forPath(PathAndBytesable builder,
            String path, byte[] data) throws Exception {
        return (data == null)
            ? builder.forPath(path)
            : builder.forPath(path, data);
    }

    protected static void createNode(CuratorFramework curator, String path,
            byte[] data, List acls, CreateMode mode) throws Exception {
        ProtectACLCreateModePathAndBytesable builder =
            curator.create().creatingParentsIfNeeded();

        if (acls == null) {
            if (mode == null ) {
                TransactionalState.forPath(builder, path, data);
            } else {
                TransactionalState.forPath(builder.withMode(mode), path, data);
            }
            return;
        }

        TransactionalState.forPath(builder.withACL(acls), path, data);
    }

    // 指定path设置data
    public void setData(String path, Object obj) {
        path = "/" + path;
        byte[] ser;
        try {
            ser = JSONValue.toJSONString(obj).getBytes("UTF-8");
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
        try {
            if(_curator.checkExists().forPath(path)!=null) {
                _curator.setData().forPath(path, ser);
            } else {
                TransactionalState.createNode(_curator, path, ser, _zkAcls,
                        CreateMode.PERSISTENT);
            }
        } catch(Exception e) {
            throw new RuntimeException(e);
        }       
    }
   // 删除指定path
    public void delete(String path) {
        path = "/" + path;
        try {
            _curator.delete().forPath(path);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
    // 罗列出指定path下所有的子节点
    public List list(String path) {
        path = "/" + path;
        try {
            if(_curator.checkExists().forPath(path)==null) {
                return new ArrayList();
            } else {
                return _curator.getChildren().forPath(path);
            }
        } catch(Exception e) {
            throw new RuntimeException(e);
        }  
    }
   
    public void mkdir(String path) {
        setData(path, 7);
    }
     // 获取指定路径的data
    public Object getData(String path) {
        path = "/" + path;
        try {
            if(_curator.checkExists().forPath(path)!=null) {
                return JSONValue.parse(new String(_curator.getData().forPath(path), "UTF-8"));
            } else {
                return null;
            }
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
    }
    // 关闭监护器
    public void close() {
        _curator.close();
    }
    // 根据指定内容返回对应的结果
    private Object getWithBackup(Map amap, Object primary, Object backup) {
        Object ret = amap.get(primary);
        if(ret==null) return amap.get(backup);
        return ret;
    }
}