package org.apache.hadoop.dfs;import java.io.*;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.*;/** * This class creates a single-process DFS cluster for junit testing. * One thread is created for each server. * The data directories for DFS are undering the testing directory. * @author Owen O'Malley */public class MiniDFSCluster {  private Configuration conf;  private Thread nameNodeThread;  private Thread dataNodeThread;  private NameNodeRunner nameNode;  private DataNodeRunner dataNode;  /**   * An inner class that runs a name node.   */  class NameNodeRunner implements Runnable {    private NameNode node;        /**     * Create the name node and run it.     */    public void run() {      try {        node = new NameNode(conf);      } catch (Throwable e) {        node = null;        System.err.println("Name node crashed:");        e.printStackTrace();      }    }        /**     * Shutdown the name node and wait for it to finish.     */    public void shutdown() {      if (node != null) {        node.stop();        node.join();      }    }  }    /**   * An inner class to run the data node.   */  class DataNodeRunner implements Runnable {    private DataNode node;        /**     * Create and run the data node.     */    public void run() {      try {        File dataDir = new File(conf.get("dfs.data.dir"));        dataDir.mkdirs();        node = new DataNode(conf, dataDir.getPath());        node.run();      } catch (Throwable e) {        node = null;        System.err.println("Data node crashed:");        e.printStackTrace();      }    }    /**         * Shut down the server and wait for it to finish.     */    public void shutdown() {      if (node != null) {        node.shutdown();      }    }  }    /**   * Create the config and start up the servers.   */  public MiniDFSCluster(int namenodePort, Configuration conf) throws IOException {    this.conf = conf;    conf.set("fs.default.name",              "localhost:"+ Integer.toString(namenodePort));    File base_dir = new File(System.getProperty("test.build.data"),                             "dfs/");    conf.set("dfs.name.dir", new File(base_dir, "name").getPath());    conf.set("dfs.data.dir", new File(base_dir, "data").getPath());    conf.setInt("dfs.replication", 1);    // this timeout seems to control the minimum time for the test, so    // set it down at 5 seconds.    conf.setInt("ipc.client.timeout", 5000);    NameNode.format(conf);    nameNode = new NameNodeRunner();    nameNodeThread = new Thread(nameNode);    nameNodeThread.start();    dataNode = new DataNodeRunner();    dataNodeThread = new Thread(dataNode);    dataNodeThread.start();    try {                                     // let daemons get started      Thread.sleep(1000);    } catch(InterruptedException e) {    }  }    /**   * Shut down the servers.   */  public void shutdown() {    nameNode.shutdown();    dataNode.shutdown();  }    /**   * Get a client handle to the DFS cluster.   */  public FileSystem getFileSystem() throws IOException {    return FileSystem.get(conf);  }}