Source code for apache_beam.io.hadoopfilesystem

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""":class:`~apache_beam.io.filesystem.FileSystem` implementation for accessing
Hadoop Distributed File System files."""

from __future__ import absolute_import

import io
import logging
import posixpath
import re

import hdfs

from apache_beam.io import filesystemio
from apache_beam.io.filesystem import BeamIOError
from apache_beam.io.filesystem import CompressedFile
from apache_beam.io.filesystem import CompressionTypes
from apache_beam.io.filesystem import FileMetadata
from apache_beam.io.filesystem import FileSystem
from apache_beam.options.pipeline_options import HadoopFileSystemOptions
from apache_beam.options.pipeline_options import PipelineOptions

__all__ = ['HadoopFileSystem']

_HDFS_PREFIX = 'hdfs:/'
_URL_RE = re.compile(r'^' + _HDFS_PREFIX + r'(/.*)')
_COPY_BUFFER_SIZE = 2 ** 16
_DEFAULT_BUFFER_SIZE = 20 * 1024 * 1024

# WebHDFS FileChecksum property constants.
_FILE_CHECKSUM_ALGORITHM = 'algorithm'
_FILE_CHECKSUM_BYTES = 'bytes'
_FILE_CHECKSUM_LENGTH = 'length'
# WebHDFS FileStatus property constants.
_FILE_STATUS_LENGTH = 'length'
_FILE_STATUS_PATH_SUFFIX = 'pathSuffix'
_FILE_STATUS_TYPE = 'type'
_FILE_STATUS_TYPE_DIRECTORY = 'DIRECTORY'
_FILE_STATUS_TYPE_FILE = 'FILE'


class HdfsDownloader(filesystemio.Downloader):

  def __init__(self, hdfs_client, path):
    self._hdfs_client = hdfs_client
    self._path = path
    self._size = self._hdfs_client.status(path)[_FILE_STATUS_LENGTH]

  @property
  def size(self):
    return self._size

  def get_range(self, start, end):
    with self._hdfs_client.read(
        self._path, offset=start, length=end - start + 1) as reader:
      return reader.read()


class HdfsUploader(filesystemio.Uploader):

  def __init__(self, hdfs_client, path):
    self._hdfs_client = hdfs_client
    if self._hdfs_client.status(path, strict=False) is not None:
      raise BeamIOError('Path already exists: %s' % path)

    self._handle_context = self._hdfs_client.write(path)
    self._handle = self._handle_context.__enter__()

  def put(self, data):
    self._handle.write(data)

  def finish(self):
    self._handle.__exit__(None, None, None)
    self._handle = None
    self._handle_context = None


[docs]class HadoopFileSystem(FileSystem): """``FileSystem`` implementation that supports HDFS. URL arguments to methods expect strings starting with ``hdfs://``. """ def __init__(self, pipeline_options): """Initializes a connection to HDFS. Connection configuration is done by passing pipeline options. See :class:`~apache_beam.options.pipeline_options.HadoopFileSystemOptions`. """ super(HadoopFileSystem, self).__init__(pipeline_options) logging.getLogger('hdfs.client').setLevel(logging.WARN) if pipeline_options is None: raise ValueError('pipeline_options is not set') if isinstance(pipeline_options, PipelineOptions): hdfs_options = pipeline_options.view_as(HadoopFileSystemOptions) hdfs_host = hdfs_options.hdfs_host hdfs_port = hdfs_options.hdfs_port hdfs_user = hdfs_options.hdfs_user else: hdfs_host = pipeline_options.get('hdfs_host') hdfs_port = pipeline_options.get('hdfs_port') hdfs_user = pipeline_options.get('hdfs_user') if hdfs_host is None: raise ValueError('hdfs_host is not set') if hdfs_port is None: raise ValueError('hdfs_port is not set') if hdfs_user is None: raise ValueError('hdfs_user is not set') self._hdfs_client = hdfs.InsecureClient( 'http://%s:%s' % (hdfs_host, str(hdfs_port)), user=hdfs_user)
[docs] @classmethod def scheme(cls): return 'hdfs'
@staticmethod def _parse_url(url): """Verifies that url begins with hdfs:// prefix, strips it and adds a leading /. Raises: ValueError if url doesn't begin with hdfs://. Args: url: A URL in the form hdfs://path/... Returns: For an input of 'hdfs://path/...', will return '/path/...'. """ m = _URL_RE.match(url) if m is None: raise ValueError('Could not parse url: %s' % url) return m.group(1)
[docs] def join(self, base_url, *paths): """Join two or more pathname components. Args: base_url: string path of the first component of the path. Must start with hdfs://. paths: path components to be added Returns: Full url after combining all the passed components. """ basepath = self._parse_url(base_url) return _HDFS_PREFIX + self._join(basepath, *paths)
def _join(self, basepath, *paths): return posixpath.join(basepath, *paths)
[docs] def split(self, url): rel_path = self._parse_url(url) head, tail = posixpath.split(rel_path) return _HDFS_PREFIX + head, tail
[docs] def mkdirs(self, url): path = self._parse_url(url) if self._exists(path): raise BeamIOError('Path already exists: %s' % path) return self._mkdirs(path)
def _mkdirs(self, path): self._hdfs_client.makedirs(path)
[docs] def has_dirs(self): return True
def _list(self, url): try: path = self._parse_url(url) for res in self._hdfs_client.list(path, status=True): yield FileMetadata(_HDFS_PREFIX + self._join(path, res[0]), res[1][_FILE_STATUS_LENGTH]) except Exception as e: # pylint: disable=broad-except raise BeamIOError('List operation failed', {url: e}) @staticmethod def _add_compression(stream, path, mime_type, compression_type): if mime_type != 'application/octet-stream': logging.warning('Mime types are not supported. Got non-default mime_type:' ' %s', mime_type) if compression_type == CompressionTypes.AUTO: compression_type = CompressionTypes.detect_compression_type(path) if compression_type != CompressionTypes.UNCOMPRESSED: return CompressedFile(stream) return stream
[docs] def create(self, url, mime_type='application/octet-stream', compression_type=CompressionTypes.AUTO): """ Returns: A Python File-like object. """ path = self._parse_url(url) return self._create(path, mime_type, compression_type)
def _create(self, path, mime_type='application/octet-stream', compression_type=CompressionTypes.AUTO): stream = io.BufferedWriter( filesystemio.UploaderStream( HdfsUploader(self._hdfs_client, path)), buffer_size=_DEFAULT_BUFFER_SIZE) return self._add_compression(stream, path, mime_type, compression_type)
[docs] def open(self, url, mime_type='application/octet-stream', compression_type=CompressionTypes.AUTO): """ Returns: A Python File-like object. """ path = self._parse_url(url) return self._open(path, mime_type, compression_type)
def _open(self, path, mime_type='application/octet-stream', compression_type=CompressionTypes.AUTO): stream = io.BufferedReader( filesystemio.DownloaderStream( HdfsDownloader(self._hdfs_client, path)), buffer_size=_DEFAULT_BUFFER_SIZE) return self._add_compression(stream, path, mime_type, compression_type)
[docs] def copy(self, source_file_names, destination_file_names): """ It is an error if any file to copy already exists at the destination. Raises ``BeamIOError`` if any error occurred. Args: source_file_names: iterable of URLs. destination_file_names: iterable of URLs. """ if len(source_file_names) != len(destination_file_names): raise BeamIOError( 'source_file_names and destination_file_names should ' 'be equal in length: %d != %d' % ( len(source_file_names), len(destination_file_names))) def _copy_file(source, destination): with self._open(source) as f1: with self._create(destination) as f2: while True: buf = f1.read(_COPY_BUFFER_SIZE) if not buf: break f2.write(buf) def _copy_path(source, destination): """Recursively copy the file tree from the source to the destination.""" if self._hdfs_client.status( source)[_FILE_STATUS_TYPE] != _FILE_STATUS_TYPE_DIRECTORY: _copy_file(source, destination) return for path, dirs, files in self._hdfs_client.walk(source): for dir in dirs: new_dir = self._join(destination, dir) if not self._exists(new_dir): self._mkdirs(new_dir) rel_path = posixpath.relpath(path, source) if rel_path == '.': rel_path = '' for file in files: _copy_file(self._join(path, file), self._join(destination, rel_path, file)) exceptions = {} for source, destination in zip(source_file_names, destination_file_names): try: rel_source = self._parse_url(source) rel_destination = self._parse_url(destination) _copy_path(rel_source, rel_destination) except Exception as e: # pylint: disable=broad-except exceptions[(source, destination)] = e if exceptions: raise BeamIOError('Copy operation failed', exceptions)
[docs] def rename(self, source_file_names, destination_file_names): exceptions = {} for source, destination in zip(source_file_names, destination_file_names): try: rel_source = self._parse_url(source) rel_destination = self._parse_url(destination) try: self._hdfs_client.rename(rel_source, rel_destination) except hdfs.HdfsError as e: raise BeamIOError( 'libhdfs error in renaming %s to %s' % (source, destination), e) except Exception as e: # pylint: disable=broad-except exceptions[(source, destination)] = e if exceptions: raise BeamIOError('Rename operation failed', exceptions)
[docs] def exists(self, url): """Checks existence of url in HDFS. Args: url: String in the form hdfs://... Returns: True if url exists as a file or directory in HDFS. """ path = self._parse_url(url) return self._exists(path)
def _exists(self, path): """Returns True if path exists as a file or directory in HDFS. Args: path: String in the form /... """ return self._hdfs_client.status(path, strict=False) is not None
[docs] def size(self, url): path = self._parse_url(url) status = self._hdfs_client.status(path, strict=False) if status is None: raise BeamIOError('File not found: %s' % url) return status[_FILE_STATUS_LENGTH]
[docs] def checksum(self, url): """Fetches a checksum description for a URL. Returns: String describing the checksum. """ path = self._parse_url(url) file_checksum = self._hdfs_client.checksum(path) return '%s-%d-%s' % ( file_checksum[_FILE_CHECKSUM_ALGORITHM], file_checksum[_FILE_CHECKSUM_LENGTH], file_checksum[_FILE_CHECKSUM_BYTES], )
[docs] def delete(self, urls): exceptions = {} for url in urls: try: path = self._parse_url(url) self._hdfs_client.delete(path, recursive=True) except Exception as e: # pylint: disable=broad-except exceptions[url] = e if exceptions: raise BeamIOError("Delete operation failed", exceptions)