def __init__(self, storage_writer, path):
"""Initializes a storage merge reader.
Args:
storage_writer (StorageWriter): storage writer.
path (str): path to the input file.
Raises:
IOError: if the input file cannot be opened.
"""
# On Windows the file can sometimes be in use and we have to wait.
gzip_file = None
for attempt in range(1, self._MAXIMUM_NUMBER_OF_LOCKED_FILE_ATTEMPTS):
try:
gzip_file = gzip.open(path, 'rb')
break
except IOError:
if attempt == (self._MAXIMUM_NUMBER_OF_LOCKED_FILE_ATTEMPTS -
1):
raise
time.sleep(self._LOCKED_FILE_SLEEP_TIME)
if platform_specific.PlatformIsWindows():
file_handle = gzip_file.fileno()
platform_specific.DisableWindowsFileHandleInheritance(file_handle)
super(GZIPStorageMergeReader, self).__init__(storage_writer)
self._data_buffer = None
self._gzip_file = gzip_file
self._path = path
def Open(self, path=None, read_only=True, **unused_kwargs):
"""Opens the storage.
Args:
path (Optional[str]): path of the storage file.
read_only (Optional[bool]): True if the file should be opened in
read-only mode.
Raises:
IOError: if the storage file is already opened.
ValueError: if path is missing.
"""
if self._is_open:
raise IOError(u'Storage file already opened.')
if not path:
raise ValueError(u'Missing path.')
if read_only:
access_mode = 'rb'
else:
access_mode = 'wb'
self._gzip_file = gzip.open(path, access_mode, self._COMPRESSION_LEVEL)
if platform_specific.PlatformIsWindows():
file_handle = self._gzip_file.fileno()
platform_specific.DisableWindowsFileHandleInheritance(file_handle)
if read_only:
self._OpenRead()
self._is_open = True
self._read_only = read_only