org.apache.hadoop.fs.FileChecksum#equals ( )源码实例Demo

/**
 * Check if the two files are equal by looking at the file length,
 * and at the checksum (if user has specified the verifyChecksum flag).
 */
private boolean sameFile(final FileStatus inputStat, final FileStatus outputStat) {
  // Not matching length
  if (inputStat.getLen() != outputStat.getLen()) return false;

  // Mark files as equals, since user asked for no checksum verification
  if (!verifyChecksum) return true;

  // If checksums are not available, files are not the same.
  FileChecksum inChecksum = getFileChecksum(inputFs, inputStat.getPath());
  if (inChecksum == null) return false;

  FileChecksum outChecksum = getFileChecksum(outputFs, outputStat.getPath());
  if (outChecksum == null) return false;

  return inChecksum.equals(outChecksum);
}
 

private FileAction checkUpdate(FileSystem sourceFS, FileStatus source,
    Path target) throws IOException {
  final FileStatus targetFileStatus;
  try {
    targetFileStatus = targetFS.getFileStatus(target);
  } catch (FileNotFoundException e) {
    return FileAction.OVERWRITE;
  }
  if (targetFileStatus != null && !overWrite) {
    if (canSkip(sourceFS, source, targetFileStatus)) {
      return FileAction.SKIP;
    } else if (append) {
      long targetLen = targetFileStatus.getLen();
      if (targetLen < source.getLen()) {
        FileChecksum sourceChecksum = sourceFS.getFileChecksum(
            source.getPath(), targetLen);
        if (sourceChecksum != null
            && sourceChecksum.equals(targetFS.getFileChecksum(target))) {
          // We require that the checksum is not null. Thus currently only
          // DistributedFileSystem is supported
          return FileAction.APPEND;
        }
      }
    }
  }
  return FileAction.OVERWRITE;
}
 

private FileAction checkUpdate(FileSystem sourceFS, FileStatus source,
    Path target) throws IOException {
  final FileStatus targetFileStatus;
  try {
    targetFileStatus = targetFS.getFileStatus(target);
  } catch (FileNotFoundException e) {
    return FileAction.OVERWRITE;
  }
  if (targetFileStatus != null && !overWrite) {
    if (canSkip(sourceFS, source, targetFileStatus)) {
      return FileAction.SKIP;
    } else if (append) {
      long targetLen = targetFileStatus.getLen();
      if (targetLen < source.getLen()) {
        FileChecksum sourceChecksum = sourceFS.getFileChecksum(
            source.getPath(), targetLen);
        if (sourceChecksum != null
            && sourceChecksum.equals(targetFS.getFileChecksum(target))) {
          // We require that the checksum is not null. Thus currently only
          // DistributedFileSystem is supported
          return FileAction.APPEND;
        }
      }
    }
  }
  return FileAction.OVERWRITE;
}
 

/**
 * Utility to compare checksums for the paths specified.
 *
 * If checksums's can't be retrieved, it doesn't fail the test
 * Only time the comparison would fail is when checksums are
 * available and they don't match
 *
 * @param sourceFS FileSystem for the source path.
 * @param source The source path.
 * @param sourceChecksum The checksum of the source file. If it is null we
 * still need to retrieve it through sourceFS.
 * @param targetFS FileSystem for the target path.
 * @param target The target path.
 * @return If either checksum couldn't be retrieved, the function returns
 * false. If checksums are retrieved, the function returns true if they match,
 * and false otherwise.
 * @throws IOException if there's an exception while retrieving checksums.
 */
public static boolean checksumsAreEqual(FileSystem sourceFS, Path source,
    FileChecksum sourceChecksum, FileSystem targetFS, Path target)
    throws IOException {
  FileChecksum targetChecksum = null;
  try {
    sourceChecksum = sourceChecksum != null ? sourceChecksum : sourceFS
        .getFileChecksum(source);
    targetChecksum = targetFS.getFileChecksum(target);
  } catch (IOException e) {
    LOG.error("Unable to retrieve checksum for " + source + " or " + target, e);
  }
  return (sourceChecksum == null || targetChecksum == null ||
          sourceChecksum.equals(targetChecksum));
}
 

/**
 * Utility to compare checksums for the paths specified.
 *
 * If checksums's can't be retrieved, it doesn't fail the test
 * Only time the comparison would fail is when checksums are
 * available and they don't match
 *
 * @param sourceFS FileSystem for the source path.
 * @param source The source path.
 * @param sourceChecksum The checksum of the source file. If it is null we
 * still need to retrieve it through sourceFS.
 * @param targetFS FileSystem for the target path.
 * @param target The target path.
 * @return If either checksum couldn't be retrieved, the function returns
 * false. If checksums are retrieved, the function returns true if they match,
 * and false otherwise.
 * @throws IOException if there's an exception while retrieving checksums.
 */
public static boolean checksumsAreEqual(FileSystem sourceFS, Path source,
    FileChecksum sourceChecksum, FileSystem targetFS, Path target)
    throws IOException {
  FileChecksum targetChecksum = null;
  try {
    sourceChecksum = sourceChecksum != null ? sourceChecksum : sourceFS
        .getFileChecksum(source);
    targetChecksum = targetFS.getFileChecksum(target);
  } catch (IOException e) {
    LOG.error("Unable to retrieve checksum for " + source + " or " + target, e);
  }
  return (sourceChecksum == null || targetChecksum == null ||
          sourceChecksum.equals(targetChecksum));
}