Java Text.compareTo方法代碼示例

import org.apache.hadoop.io.Text; //導入方法依賴的package包/類
public int compare(Text a, Text b) {
  return -a.compareTo(b);
}
 

import org.apache.hadoop.io.Text; //導入方法依賴的package包/類
public int compare(int i, int j) {
  Text left = records.get(i);
  Text right = records.get(j);
  return left.compareTo(right);
}
 

import org.apache.hadoop.io.Text; //導入方法依賴的package包/類
/**
 * Delete the dst files/dirs which do not exist in src
 * 
 * @return total count of files and directories deleted from destination
 * @throws IOException
 */
static private long deleteNonexisting(
    FileSystem dstfs, FileStatus dstroot, Path dstsorted,
    FileSystem jobfs, Path jobdir, JobConf jobconf, Configuration conf
    ) throws IOException {
  if (dstroot.isFile()) {
    throw new IOException("dst must be a directory when option "
        + Options.DELETE.cmd + " is set, but dst (= " + dstroot.getPath()
        + ") is not a directory.");
  }

  //write dst lsr results
  final Path dstlsr = new Path(jobdir, "_distcp_dst_lsr");
  try (final SequenceFile.Writer writer = SequenceFile.createWriter(jobconf,
      Writer.file(dstlsr), Writer.keyClass(Text.class),
      Writer.valueClass(NullWritable.class), Writer.compression(
      SequenceFile.CompressionType.NONE))) {
    //do lsr to get all file statuses in dstroot
    final Stack<FileStatus> lsrstack = new Stack<FileStatus>();
    for(lsrstack.push(dstroot); !lsrstack.isEmpty(); ) {
      final FileStatus status = lsrstack.pop();
      if (status.isDirectory()) {
        for(FileStatus child : dstfs.listStatus(status.getPath())) {
          String relative = makeRelative(dstroot.getPath(), child.getPath());
          writer.append(new Text(relative), NullWritable.get());
          lsrstack.push(child);
        }
      }
    }
  }

  //sort lsr results
  final Path sortedlsr = new Path(jobdir, "_distcp_dst_lsr_sorted");
  SequenceFile.Sorter sorter = new SequenceFile.Sorter(jobfs,
      new Text.Comparator(), Text.class, NullWritable.class, jobconf);
  sorter.sort(dstlsr, sortedlsr);

  //compare lsr list and dst list  
  long deletedPathsCount = 0;
  try (SequenceFile.Reader lsrin =
           new SequenceFile.Reader(jobconf, Reader.file(sortedlsr));
       SequenceFile.Reader  dstin =
           new SequenceFile.Reader(jobconf, Reader.file(dstsorted))) {
    //compare sorted lsr list and sorted dst list
    final Text lsrpath = new Text();
    final Text dstpath = new Text();
    final Text dstfrom = new Text();
    final Trash trash = new Trash(dstfs, conf);
    Path lastpath = null;

    boolean hasnext = dstin.next(dstpath, dstfrom);
    while (lsrin.next(lsrpath, NullWritable.get())) {
      int dst_cmp_lsr = dstpath.compareTo(lsrpath);
      while (hasnext && dst_cmp_lsr < 0) {
        hasnext = dstin.next(dstpath, dstfrom);
        dst_cmp_lsr = dstpath.compareTo(lsrpath);
      }
      
      if (dst_cmp_lsr == 0) {
        //lsrpath exists in dst, skip it
        hasnext = dstin.next(dstpath, dstfrom);
      } else {
        //lsrpath does not exist, delete it
        final Path rmpath = new Path(dstroot.getPath(), lsrpath.toString());
        ++deletedPathsCount;
        if ((lastpath == null || !isAncestorPath(lastpath, rmpath))) {
          if (!(trash.moveToTrash(rmpath) || dstfs.delete(rmpath, true))) {
            throw new IOException("Failed to delete " + rmpath);
          }
          lastpath = rmpath;
        }
      }
    }
  }
  return deletedPathsCount;
}
 

import org.apache.hadoop.io.Text; //導入方法依賴的package包/類
private void deleteMissing(Configuration conf) throws IOException {
  LOG.info("-delete option is enabled. About to remove entries from " +
      "target that are missing in source");

  // Sort the source-file listing alphabetically.
  Path sourceListing = new Path(conf.get(DistCpConstants.CONF_LABEL_LISTING_FILE_PATH));
  FileSystem clusterFS = sourceListing.getFileSystem(conf);
  Path sortedSourceListing = DistCpUtils.sortListing(clusterFS, conf, sourceListing);

  // Similarly, create the listing of target-files. Sort alphabetically.
  Path targetListing = new Path(sourceListing.getParent(), "targetListing.seq");
  CopyListing target = new GlobbedCopyListing(new Configuration(conf), null);

  List<Path> targets = new ArrayList<Path>(1);
  Path targetFinalPath = new Path(conf.get(DistCpConstants.CONF_LABEL_TARGET_FINAL_PATH));
  targets.add(targetFinalPath);
  DistCpOptions options = new DistCpOptions(targets, new Path("/NONE"));
  //
  // Set up options to be the same from the CopyListing.buildListing's perspective,
  // so to collect similar listings as when doing the copy
  //
  options.setOverwrite(overwrite);
  options.setSyncFolder(syncFolder);
  options.setTargetPathExists(targetPathExists);
  
  target.buildListing(targetListing, options);
  Path sortedTargetListing = DistCpUtils.sortListing(clusterFS, conf, targetListing);
  long totalLen = clusterFS.getFileStatus(sortedTargetListing).getLen();

  SequenceFile.Reader sourceReader = new SequenceFile.Reader(conf,
                               SequenceFile.Reader.file(sortedSourceListing));
  SequenceFile.Reader targetReader = new SequenceFile.Reader(conf,
                               SequenceFile.Reader.file(sortedTargetListing));

  // Walk both source and target file listings.
  // Delete all from target that doesn't also exist on source.
  long deletedEntries = 0;
  try {
    CopyListingFileStatus srcFileStatus = new CopyListingFileStatus();
    Text srcRelPath = new Text();
    CopyListingFileStatus trgtFileStatus = new CopyListingFileStatus();
    Text trgtRelPath = new Text();

    FileSystem targetFS = targetFinalPath.getFileSystem(conf);
    boolean srcAvailable = sourceReader.next(srcRelPath, srcFileStatus);
    while (targetReader.next(trgtRelPath, trgtFileStatus)) {
      // Skip sources that don't exist on target.
      while (srcAvailable && trgtRelPath.compareTo(srcRelPath) > 0) {
        srcAvailable = sourceReader.next(srcRelPath, srcFileStatus);
      }

      if (srcAvailable && trgtRelPath.equals(srcRelPath)) continue;

      // Target doesn't exist at source. Delete.
      boolean result = (!targetFS.exists(trgtFileStatus.getPath()) ||
          targetFS.delete(trgtFileStatus.getPath(), true));
      if (result) {
        LOG.info("Deleted " + trgtFileStatus.getPath() + " - Missing at source");
        deletedEntries++;
      } else {
        throw new IOException("Unable to delete " + trgtFileStatus.getPath());
      }
      taskAttemptContext.progress();
      taskAttemptContext.setStatus("Deleting missing files from target. [" +
          targetReader.getPosition() * 100 / totalLen + "%]");
    }
  } finally {
    IOUtils.closeStream(sourceReader);
    IOUtils.closeStream(targetReader);
  }
  LOG.info("Deleted " + deletedEntries + " from target: " + targets.get(0));
}