/**
  * Constructs a new stream for reading a file from HDFS.
  *
  * @param uri the Alluxio file URI
  * @param conf Hadoop configuration
  * @param bufferSize the buffer size
  * @param stats filesystem statistics
  * @throws IOException if the underlying file does not exist or its stream cannot be created
  */
 public HdfsFileInputStream(
     AlluxioURI uri,
     org.apache.hadoop.conf.Configuration conf,
     int bufferSize,
     org.apache.hadoop.fs.FileSystem.Statistics stats)
     throws IOException {
   LOG.debug("HdfsFileInputStream({}, {}, {}, {}, {})", uri, conf, bufferSize, stats);
   long bufferBytes = Configuration.getBytes(Constants.USER_FILE_BUFFER_BYTES);
   mBuffer = new byte[Ints.checkedCast(bufferBytes) * 4];
   mCurrentPosition = 0;
   FileSystem fs = FileSystem.Factory.get();
   mHadoopConf = conf;
   mHadoopBufferSize = bufferSize;
   mStatistics = stats;
   try {
     mFileInfo = fs.getStatus(uri);
     mHdfsPath = new Path(mFileInfo.getUfsPath());
     mAlluxioFileInputStream = fs.openFile(uri, OpenFileOptions.defaults());
   } catch (FileDoesNotExistException e) {
     throw new FileNotFoundException(
         ExceptionMessage.HDFS_FILE_NOT_FOUND.getMessage(mHdfsPath, uri));
   } catch (AlluxioException e) {
     throw new IOException(e);
   }
 }
Exemple #2
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  /**
   * Entry point for the {@link MultiMount} program.
   *
   * @param args command-line arguments
   */
  public static void main(String[] args) {
    if (args.length != 1) {
      System.err.println("Usage: ./bin/alluxio runClass alluxio.examples.MultiMount <HDFS_URL>");
      System.exit(-1);
    }

    AlluxioURI mntPath = new AlluxioURI("/mnt");
    AlluxioURI s3Mount = new AlluxioURI("/mnt/s3");
    AlluxioURI inputPath = new AlluxioURI("/mnt/s3/hello.txt");
    AlluxioURI s3Path = new AlluxioURI("s3n://alluxio-demo/");
    AlluxioURI hdfsMount = new AlluxioURI("/mnt/hdfs");
    AlluxioURI outputPath = new AlluxioURI("/mnt/hdfs/hello.txt");
    AlluxioURI hdfsPath = new AlluxioURI(args[0]);
    FileSystem fileSystem = FileSystem.Factory.get();

    try {
      // Make sure mount directory exists.
      if (!fileSystem.exists(mntPath)) {
        System.out.print("creating " + mntPath + " ... ");
        fileSystem.createDirectory(mntPath);
        System.out.println("done");
      }

      // Make sure the S3 mount point does not exist.
      if (fileSystem.exists(s3Mount)) {
        System.out.print("unmounting " + s3Mount + " ... ");
        fileSystem.unmount(s3Mount);
        System.out.println("done");
      }

      // Make sure the HDFS mount point does not exist.
      if (fileSystem.exists(hdfsMount)) {
        System.out.print("unmounting " + hdfsMount + " ... ");
        fileSystem.unmount(hdfsMount);
        System.out.println("done");
      }

      // Mount S3.
      System.out.print("mounting " + s3Path + " to " + s3Mount + " ... ");
      fileSystem.mount(s3Mount, s3Path);
      System.out.println("done");

      // Mount HDFS.
      System.out.print("mounting " + hdfsPath + " to " + hdfsMount + " ... ");
      fileSystem.mount(hdfsMount, hdfsPath);
      System.out.println("done");

      // Make sure output file does not exist.
      if (fileSystem.exists(outputPath)) {
        System.out.print("deleting " + outputPath + " ... ");
        fileSystem.delete(outputPath);
        System.out.println("done");
      }

      // Open the input stream.
      System.out.print("opening " + inputPath + " ... ");
      FileInStream is = fileSystem.openFile(inputPath);
      System.out.println("done");

      // Open the output stream, setting the write type to make sure result is persisted.
      System.out.print("opening " + outputPath + " ... ");
      CreateFileOptions options =
          CreateFileOptions.defaults().setWriteType(WriteType.CACHE_THROUGH);
      FileOutStream os = fileSystem.createFile(outputPath, options);
      System.out.println("done");

      // Copy the data
      System.out.print("transferring data from " + inputPath + " to " + outputPath + " ... ");
      IOUtils.copy(is, os);
      System.out.println("done");

      // Close the input stream.
      System.out.print("closing " + inputPath + " ... ");
      is.close();
      System.out.println("done");

      // Close the output stream.
      System.out.print("closing " + outputPath + " ... ");
      os.close();
      System.out.println("done");
    } catch (Exception e) {
      System.out.println("fail");
      e.printStackTrace();
    } finally {
      // Make sure the S3 mount point is removed.
      try {
        if (fileSystem.exists(s3Mount)) {
          System.out.print("unmounting " + s3Mount + " ... ");
          fileSystem.unmount(s3Mount);
          System.out.println("done");
        }
      } catch (Exception e) {
        System.out.println("fail");
        e.printStackTrace();
      }

      // Make sure the HDFS mount point is removed.
      try {
        if (fileSystem.exists(hdfsMount)) {
          System.out.print("unmounting " + hdfsMount + " ... ");
          fileSystem.unmount(hdfsMount);
          System.out.println("done");
        }
      } catch (Exception e) {
        System.out.println("fail");
        e.printStackTrace();
      }
    }
  }