Hbase Clinet scan流程与关键代码分析

 

一.Hbase Connection

1.Connection是由那个类创建的

 

org.apache.hadoop.hbase.client.ConnectionFactory.createConnection(Configuration, ExecutorService, User)
 //默认以ConnectionImplementation进行初始化
 String className = conf.get(ClusterConnection.HBASE_CLIENT_CONNECTION_IMPL,
      ConnectionImplementation.class.getName());
    Class<?> clazz;
    try {
      clazz = Class.forName(className);
    } catch (ClassNotFoundException e) {
      throw new IOException(e);
    }

2.ConnectionImplementation 初始化流程

 

/**
   * constructor
   * @param conf Configuration object
   */
  ConnectionImplementation(Configuration conf,
                           ExecutorService pool, User user) throws IOException {
    this.conf = conf;
    this.user = user;
    this.batchPool = pool;
    //使用默认的配置
    this.connectionConfig = new ConnectionConfiguration(conf);
    this.closed = false;
    //rpc失败后的重试暂停时间
    this.pause = conf.getLong(HConstants.HBASE_CLIENT_PAUSE,
        HConstants.DEFAULT_HBASE_CLIENT_PAUSE);
    long configuredPauseForCQTBE = conf.getLong(HConstants.HBASE_CLIENT_PAUSE_FOR_CQTBE, pause);
    if (configuredPauseForCQTBE < pause) {
      LOG.warn("The " + HConstants.HBASE_CLIENT_PAUSE_FOR_CQTBE + " setting: "
          + configuredPauseForCQTBE + " is smaller than " + HConstants.HBASE_CLIENT_PAUSE
          + ", will use " + pause + " instead.");
      this.pauseForCQTBE = pause;
    } else {
      this.pauseForCQTBE = configuredPauseForCQTBE;
    }
      //是否开启 meta replica
      this.useMetaReplicas = conf.getBoolean(HConstants.USE_META_REPLICAS,
      HConstants.DEFAULT_USE_META_REPLICAS);
      //meta replica的读取超时时间
    this.metaReplicaCallTimeoutScanInMicroSecond =
        connectionConfig.getMetaReplicaCallTimeoutMicroSecondScan();
    
    // how many times to try, one more than max *retry* time
    this.numTries = retries2Attempts(connectionConfig.getRetriesNumber());
    //单次rpc超时时间，与之对应的有hbase.client.operation.timeout和hbase.client.scanner.timeout.period
    this.rpcTimeout = conf.getInt(
        HConstants.HBASE_RPC_TIMEOUT_KEY,
        HConstants.DEFAULT_HBASE_RPC_TIMEOUT);
    if (conf.getBoolean(NonceGenerator.CLIENT_NONCES_ENABLED_KEY, true)) {
      synchronized (nonceGeneratorCreateLock) {
        if (nonceGenerator == null) {
          nonceGenerator = PerClientRandomNonceGenerator.get();
        }
      }
    } else {
      nonceGenerator = NO_NONCE_GENERATOR;
    }
    //记录region locator
    this.stats = ServerStatisticTracker.create(conf);
    this.interceptor = (new RetryingCallerInterceptorFactory(conf)).build();
    this.rpcControllerFactory = RpcControllerFactory.instantiate(conf);
    this.rpcCallerFactory = RpcRetryingCallerFactory.instantiate(conf, interceptor, this.stats);
    this.backoffPolicy = ClientBackoffPolicyFactory.create(conf);
    this.asyncProcess = new AsyncProcess(this, conf, rpcCallerFactory, rpcControllerFactory);
    if (conf.getBoolean(CLIENT_SIDE_METRICS_ENABLED_KEY, false)) {
      this.metrics = new MetricsConnection(this);
    } else {
      this.metrics = null;
    }
    this.metaCache = new MetaCache(this.metrics);

    boolean shouldListen = conf.getBoolean(HConstants.STATUS_PUBLISHED,
        HConstants.STATUS_PUBLISHED_DEFAULT);
    this.hostnamesCanChange = conf.getBoolean(RESOLVE_HOSTNAME_ON_FAIL_KEY, true);
    Class<? extends ClusterStatusListener.Listener> listenerClass =
        conf.getClass(ClusterStatusListener.STATUS_LISTENER_CLASS,
            ClusterStatusListener.DEFAULT_STATUS_LISTENER_CLASS,
            ClusterStatusListener.Listener.class);

    // Is there an alternate BufferedMutator to use?
    this.alternateBufferedMutatorClassName =
        this.conf.get(BufferedMutator.CLASSNAME_KEY);

    try {
        //获取zk连接，用于查找Hbase保存在zk上的信息
      this.registry = AsyncRegistryFactory.getRegistry(conf);
      retrieveClusterId();
      //创建rpcClient,默认为nettyRpcClient
      this.rpcClient = RpcClientFactory.createClient(this.conf, this.clusterId, this.metrics);

      //