def open(self):
"""
Open the object.
This implementation opens the data file representing the object, reads
the associated metadata in the extended attributes, additionally
combining metadata from fast-POST `.meta` files.
.. note::
An implementation is allowed to raise any of the following
exceptions, but is only required to raise `DiskFileNotExist` when
the object representation does not exist.
:raises DiskFileNotExist: if the object does not exist
:raises DiskFileExpired: if the object has expired
:returns: itself for use as a context manager
"""
# Writes are always performed to a temporary file
try:
fd = do_open(self._data_file, os.O_RDONLY | O_CLOEXEC)
except GlusterFileSystemOSError as err:
if err.errno in (errno.ENOENT, errno.ENOTDIR):
# If the file does exist, or some part of the path does not
# exist, raise the expected DiskFileNotExist
raise DiskFileNotExist
raise
else:
stats = do_fstat(fd)
if not stats:
return
self._is_dir = stat.S_ISDIR(stats.st_mode)
obj_size = stats.st_size
self._metadata = read_metadata(fd)
if not validate_object(self._metadata):
create_object_metadata(fd)
self._metadata = read_metadata(fd)
assert self._metadata is not None
self._filter_metadata()
if self._is_dir:
do_close(fd)
obj_size = 0
self._fd = -1
else:
if self._is_object_expired(self._metadata):
raise DiskFileExpired(metadata=self._metadata)
self._fd = fd
self._obj_size = obj_size
return self
def read_metadata(self):
"""
Return the metadata for an object without requiring the caller to open
the object first.
This method is invoked by Swift code in POST, PUT, HEAD and DELETE path
metadata = disk_file.read_metadata()
The operations performed here is very similar to those made in open().
This is to avoid opening and closing of file (two syscalls over
network). IOW, this optimization addresses the case where the fd
returned by open() isn't going to be used i.e the file is not read (GET
or metadata recalculation)
:returns: metadata dictionary for an object
:raises DiskFileError: this implementation will raise the same
errors as the `open()` method.
"""
try:
self._metadata = read_metadata(self._data_file)
except (OSError, IOError) as err:
if err.errno in (errno.ENOENT, errno.ESTALE):
self._disk_file_does_not_exist = True
raise DiskFileNotExist
raise err
if self._metadata and self._is_object_expired(self._metadata):
raise DiskFileExpired(metadata=self._metadata)
try:
self._stat = do_stat(self._data_file)
except (OSError, IOError) as err:
if err.errno in (errno.ENOENT, errno.ESTALE):
self._disk_file_does_not_exist = True
raise DiskFileNotExist
raise err
if not validate_object(self._metadata, self._stat):
# Metadata is stale/invalid. So open the object for reading
# to update Etag and other metadata.
with self.open():
return self._metadata
else:
# Metadata is valid. Don't have to open the file.
self._filter_metadata()
return self._metadata
def open(self):
"""
Open the object.
This implementation opens the data file representing the object, reads
the associated metadata in the extended attributes, additionally
combining metadata from fast-POST `.meta` files.
.. note::
An implementation is allowed to raise any of the following
exceptions, but is only required to raise `DiskFileNotExist` when
the object representation does not exist.
:raises DiskFileNotExist: if the object does not exist
:raises DiskFileExpired: if the object has expired
:returns: itself for use as a context manager
"""
# Writes are always performed to a temporary file
try:
self._fd = do_open(self._data_file, os.O_RDONLY | O_CLOEXEC)
except SwiftOnFileSystemOSError as err:
if err.errno in (errno.ENOENT, errno.ENOTDIR):
# If the file does exist, or some part of the path does not
# exist, raise the expected DiskFileNotExist
raise DiskFileNotExist
raise
try:
self._stat = do_fstat(self._fd)
self._is_dir = stat.S_ISDIR(self._stat.st_mode)
obj_size = self._stat.st_size
self._metadata = read_metadata(self._fd)
if not validate_object(self._metadata, self._stat):
create_object_metadata(self._fd)
self._metadata = read_metadata(self._fd)
assert self._metadata is not None
self._filter_metadata()
if self._is_dir:
do_close(self._fd)
obj_size = 0
self._fd = -1
else:
if self._is_object_expired(self._metadata):
raise DiskFileExpired(metadata=self._metadata)
self._obj_size = obj_size
except (OSError, IOError, DiskFileExpired) as err:
# Something went wrong. Context manager will not call
# __exit__. So we close the fd manually here.
self._close_fd()
if hasattr(err, 'errno') and err.errno == errno.ENOENT:
# Handle races: ENOENT can be raised by read_metadata()
# call in GlusterFS if file gets deleted by another
# client after do_open() succeeds
logging.warn("open(%s) succeeded but one of the subsequent "
"syscalls failed with ENOENT. Raising "
"DiskFileNotExist." % (self._data_file))
raise DiskFileNotExist
else:
# Re-raise the original exception after fd has been closed
raise
return self