Hadoop源码学习_DatanodeID

 DatanodeInfo extends DatanodeID implements Node,那么DatanodeID是干什么的呢？它封装了node name、storage ID、infoserverPort、ipcPort。

package org.apache.hadoop.hdfs.protocol;import java.io.DataInput;import java.io.DataOutput;import java.io.IOException;import org.apache.hadoop.io.UTF8;import org.apache.hadoop.io.WritableComparable;/** * DatanodeID is composed of the data node  * name (hostname:portNumber) and the data storage ID,  * which it currently represents. *  */public class DatanodeID implements WritableComparable<DatanodeID> {  public static final DatanodeID[] EMPTY_ARRAY = {};   public String name;      /// hostname:portNumber  public String storageID; /// unique per cluster storageID  protected int infoPort;     /// the port where the infoserver is running  public int ipcPort;     /// the port where the ipc server is running  /** Equivalent to DatanodeID(""). */  public DatanodeID() {this("");}  /** Equivalent to DatanodeID(nodeName, "", -1, -1). */  public DatanodeID(String nodeName) {this(nodeName, "", -1, -1);}  /**   * DatanodeID copy constructor   *    * @param from   */  public DatanodeID(DatanodeID from) {    this(from.getName(),        from.getStorageID(),        from.getInfoPort(),        from.getIpcPort());  }    /**   * Create DatanodeID   * @param nodeName (hostname:portNumber)    * @param storageID data storage ID   * @param infoPort info server port    * @param ipcPort ipc server port   */  public DatanodeID(String nodeName, String storageID,      int infoPort, int ipcPort) {    this.name = nodeName;    this.storageID = storageID;    this.infoPort = infoPort;    this.ipcPort = ipcPort;  }    /**   * @return hostname:portNumber.   */  public String getName() {    return name;  }    /**   * @return data storage ID.   */  public String getStorageID() {    return this.storageID;  }  /**   * @return infoPort (the port at which the HTTP server bound to)   */  public int getInfoPort() {    return infoPort;  }  /**   * @return ipcPort (the port at which the IPC server bound to)   */  public int getIpcPort() {    return ipcPort;  }  /**   * sets the data storage ID.   */  public void setStorageID(String storageID) {    this.storageID = storageID;  }  /**   * @return hostname and no :portNumber.   */  public String getHost() {    int colon = name.indexOf(":");    if (colon < 0) {      return name;    } else {      return name.substring(0, colon);    }  }    public int getPort() {    int colon = name.indexOf(":");    if (colon < 0) {      return 50010; // default port.    }    return Integer.parseInt(name.substring(colon+1));  }  public boolean equals(Object to) {    if (this == to) {      return true;    }    if (!(to instanceof DatanodeID)) {      return false;    }    return (name.equals(((DatanodeID)to).getName()) &&            storageID.equals(((DatanodeID)to).getStorageID()));  }    public int hashCode() {    return name.hashCode()^ storageID.hashCode();  }    public String toString() {    return name;  }    /**   * Update fields when a new registration request comes in.   * Note that this does not update storageID.   */  public void updateRegInfo(DatanodeID nodeReg) {    name = nodeReg.getName();    infoPort = nodeReg.getInfoPort();    ipcPort = nodeReg.getIpcPort();    // update any more fields added in future.  }      /** Comparable.   * Basis of compare is the String name (host:portNumber) only.   * @param that   * @return as specified by Comparable.   */  public int compareTo(DatanodeID that) {    return name.compareTo(that.getName());  }  /////////////////////////////////////////////////  // Writable  /////////////////////////////////////////////////  /** {@inheritDoc} */  public void write(DataOutput out) throws IOException {    UTF8.writeString(out, name);    UTF8.writeString(out, storageID);    out.writeShort(infoPort);  }  /** {@inheritDoc} */  public void readFields(DataInput in) throws IOException {    name = UTF8.readString(in);    storageID = UTF8.readString(in);    // the infoPort read could be negative, if the port is a large number (more    // than 15 bits in storage size (but less than 16 bits).    // So chop off the first two bytes (and hence the signed bits) before     // setting the field.    this.infoPort = in.readShort() & 0x0000ffff;  }}