Storm-原始碼分析-Thrift的使用

寒凝雪發表於2017-05-02
ORM原始碼

1 IDL

首先是storm.thrift, 作為IDL裡面定義了用到的資料結構和service 
然後backtype.storm.generated, 存放從IDL通過Thrift自動轉化成的Java程式碼

比如對於nimbus service 
在IDL的定義為,

service Nimbus {
  void submitTopology(1: string name, 2: string uploadedJarLocation, 3: string jsonConf, 4: StormTopology topology) throws (1: AlreadyAliveException e, 2: InvalidTopologyException ite);
  void submitTopologyWithOpts(1: string name, 2: string uploadedJarLocation, 3: string jsonConf, 4: StormTopology topology, 5: SubmitOptions options) throws (1: AlreadyAliveException e, 2: InvalidTopologyException ite);
  void killTopology(1: string name) throws (1: NotAliveException e);
  void killTopologyWithOpts(1: string name, 2: KillOptions options) throws (1: NotAliveException e);
  void activate(1: string name) throws (1: NotAliveException e);
  void deactivate(1: string name) throws (1: NotAliveException e);
  void rebalance(1: string name, 2: RebalanceOptions options) throws (1: NotAliveException e, 2: InvalidTopologyException ite);

  // need to add functions for asking about status of storms, what nodes they`re running on, looking at task logs
  string beginFileUpload();
  void uploadChunk(1: string location, 2: binary chunk);
  void finishFileUpload(1: string location);
  
  string beginFileDownload(1: string file);
  //can stop downloading chunks when receive 0-length byte array back
  binary downloadChunk(1: string id);

  // returns json
  string getNimbusConf();
  // stats functions
  ClusterSummary getClusterInfo();
  TopologyInfo getTopologyInfo(1: string id) throws (1: NotAliveException e);
  //returns json
  string getTopologyConf(1: string id) throws (1: NotAliveException e);
  StormTopology getTopology(1: string id) throws (1: NotAliveException e);
  StormTopology getUserTopology(1: string id) throws (1: NotAliveException e);
}

而對應在Nimbus.java的Java程式碼如下,

public class Nimbus {

  public interface Iface {

    public void submitTopology(String name, String uploadedJarLocation, String jsonConf, StormTopology topology) throws AlreadyAliveException, InvalidTopologyException, org.apache.thrift7.TException;

    public void submitTopologyWithOpts(String name, String uploadedJarLocation, String jsonConf, StormTopology topology, SubmitOptions options) throws AlreadyAliveException, InvalidTopologyException, org.apache.thrift7.TException;

    public void killTopology(String name) throws NotAliveException, org.apache.thrift7.TException;

    public void killTopologyWithOpts(String name, KillOptions options) throws NotAliveException, org.apache.thrift7.TException;

    public void activate(String name) throws NotAliveException, org.apache.thrift7.TException;

    public void deactivate(String name) throws NotAliveException, org.apache.thrift7.TException;

    public void rebalance(String name, RebalanceOptions options) throws NotAliveException, InvalidTopologyException, org.apache.thrift7.TException;

    public String beginFileUpload() throws org.apache.thrift7.TException;

    public void uploadChunk(String location, ByteBuffer chunk) throws org.apache.thrift7.TException;

    public void finishFileUpload(String location) throws org.apache.thrift7.TException;

    public String beginFileDownload(String file) throws org.apache.thrift7.TException;

    public ByteBuffer downloadChunk(String id) throws org.apache.thrift7.TException;

    public String getNimbusConf() throws org.apache.thrift7.TException;

    public ClusterSummary getClusterInfo() throws org.apache.thrift7.TException;

    public TopologyInfo getTopologyInfo(String id) throws NotAliveException, org.apache.thrift7.TException;

    public String getTopologyConf(String id) throws NotAliveException, org.apache.thrift7.TException;

    public StormTopology getTopology(String id) throws NotAliveException, org.apache.thrift7.TException;

    public StormTopology getUserTopology(String id) throws NotAliveException, org.apache.thrift7.TException;

  }

 

2 Client

1. 首先Get Client,

NimbusClient client = NimbusClient.getConfiguredClient(conf);

看看backtype.storm.utils下面的client.getConfiguredClient的邏輯, 
只是從配置中取出nimbus的host:port, 並new NimbusClient

    public static NimbusClient getConfiguredClient(Map conf) {
        try {
            String nimbusHost = (String) conf.get(Config.NIMBUS_HOST);
            int nimbusPort = Utils.getInt(conf.get(Config.NIMBUS_THRIFT_PORT));
            return new NimbusClient(conf, nimbusHost, nimbusPort);
        } catch (TTransportException ex) {
            throw new RuntimeException(ex);
        }
    }

NimbusClient 繼承自ThriftClient, public class NimbusClient extends ThriftClient 
ThriftClient又做了什麼? 關鍵是怎麼進行資料序列化和怎麼將資料傳輸到remote 
這裡看出Thrift對Transport和Protocol的封裝 
對於Transport, 其實就是對Socket的封裝, 使用TSocket(host, port) 
然後對於protocol, 預設使用TBinaryProtocol, 如果你不指定的話

    public ThriftClient(Map storm_conf, String host, int port, Integer timeout) throws TTransportException {
        try {
            //locate login configuration 
            Configuration login_conf = AuthUtils.GetConfiguration(storm_conf);

            //construct a transport plugin
            ITransportPlugin  transportPlugin = AuthUtils.GetTransportPlugin(storm_conf, login_conf);

            //create a socket with server
            if(host==null) {
                throw new IllegalArgumentException("host is not set");
            }
            if(port<=0) {
                throw new IllegalArgumentException("invalid port: "+port);
            }            
            TSocket socket = new TSocket(host, port);
            if(timeout!=null) {
                socket.setTimeout(timeout);
            }
            final TTransport underlyingTransport = socket;

            //establish client-server transport via plugin
            _transport =  transportPlugin.connect(underlyingTransport, host); 
        } catch (IOException ex) {
            throw new RuntimeException(ex);
        }
        _protocol = null;
        if (_transport != null)
            _protocol = new  TBinaryProtocol(_transport);
    }

 

2. 呼叫任意RPC 
那麼就看看submitTopologyWithOpts

client.getClient().submitTopologyWithOpts(name, submittedJar, serConf, topology, opts);

可以看出上面的Nimbus的interface裡面有這個方法的定義, 而且Thrift不僅僅自動產生java interface, 而且還提供整個RPC client端的實現

    public void submitTopologyWithOpts(String name, String uploadedJarLocation, String jsonConf, StormTopology topology, SubmitOptions options) throws AlreadyAliveException, InvalidTopologyException, org.apache.thrift7.TException
    {
      send_submitTopologyWithOpts(name, uploadedJarLocation, jsonConf, topology, options);
      recv_submitTopologyWithOpts();
    }

分兩步, 
首先send_submitTopologyWithOpts, 呼叫sendBase 
接著, recv_submitTopologyWithOpts, 呼叫receiveBase 

  protected void sendBase(String methodName, TBase args) throws TException {
    oprot_.writeMessageBegin(new TMessage(methodName, TMessageType.CALL, ++seqid_));
    args.write(oprot_);
    oprot_.writeMessageEnd();
    oprot_.getTransport().flush();
  }

  protected void receiveBase(TBase result, String methodName) throws TException {
    TMessage msg = iprot_.readMessageBegin();
    if (msg.type == TMessageType.EXCEPTION) {
      TApplicationException x = TApplicationException.read(iprot_);
      iprot_.readMessageEnd();
      throw x;
    }
    if (msg.seqid != seqid_) {
      throw new TApplicationException(TApplicationException.BAD_SEQUENCE_ID, methodName + " failed: out of sequence response");
    }
    result.read(iprot_);
    iprot_.readMessageEnd();
  }

可以看出Thrift對protocol的封裝, 不需要自己處理序列化, 呼叫protocol的介面搞定 

 

3 Server

Thrift強大的地方是, 實現了整個協議棧而不光只是IDL的轉化, 對於server也給出多種實現 
下面看看在nimbus server端, 是用clojure來寫的 
可見其中使用Thrift封裝的NonblockingServerSocket, THsHaServer, TBinaryProtocol, Proccessor, 非常簡單 
其中processor會使用service-handle來處理recv到的資料, 所以作為使用者只需要在service-handle中實現Nimbus$Iface, 其他和server相關的, Thrift都已經幫你封裝好了, 這裡使用的IDL也在backtype.storm.generated, 因為clojure基於JVM所以IDL只需要轉化成Java即可.

(defn launch-server! [conf nimbus]
  (validate-distributed-mode! conf)
  (let [service-handler (service-handler conf nimbus)
        options (-> (TNonblockingServerSocket. (int (conf NIMBUS-THRIFT-PORT)))
                    (THsHaServer$Args.)
                    (.workerThreads 64)
                    (.protocolFactory (TBinaryProtocol$Factory.))
                    (.processor (Nimbus$Processor. service-handler))
                    )
       server (THsHaServer. options)]
    (.addShutdownHook (Runtime/getRuntime) (Thread. (fn [] (.shutdown service-handler) (.stop server))))
    (log-message "Starting Nimbus server...")
    (.serve server)))


本文章摘自部落格園，原文釋出日期：2013-06-04


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