import array
import posixpath
import warnings
from collections.abc import MutableMapping
from functools import cached_property
from .core import url_to_fs
[docs]class FSMap(MutableMapping):
"""Wrap a FileSystem instance as a mutable wrapping.
The keys of the mapping become files under the given root, and the
values (which must be bytes) the contents of those files.
Parameters
----------
root: string
prefix for all the files
fs: FileSystem instance
check: bool (=True)
performs a touch at the location, to check for write access.
Examples
--------
>>> fs = FileSystem(**parameters) # doctest: +SKIP
>>> d = FSMap('my-data/path/', fs) # doctest: +SKIP
or, more likely
>>> d = fs.get_mapper('my-data/path/')
>>> d['loc1'] = b'Hello World' # doctest: +SKIP
>>> list(d.keys()) # doctest: +SKIP
['loc1']
>>> d['loc1'] # doctest: +SKIP
b'Hello World'
"""
def __init__(self, root, fs, check=False, create=False, missing_exceptions=None):
self.fs = fs
self.root = fs._strip_protocol(root).rstrip("/")
self._root_key_to_str = fs._strip_protocol(posixpath.join(root, "x"))[:-1]
if missing_exceptions is None:
missing_exceptions = (
FileNotFoundError,
IsADirectoryError,
NotADirectoryError,
)
self.missing_exceptions = missing_exceptions
self.check = check
self.create = create
if create:
if not self.fs.exists(root):
self.fs.mkdir(root)
if check:
if not self.fs.exists(root):
raise ValueError(
f"Path {root} does not exist. Create "
f" with the ``create=True`` keyword"
)
self.fs.touch(root + "/a")
self.fs.rm(root + "/a")
@cached_property
def dirfs(self):
"""dirfs instance that can be used with the same keys as the mapper"""
from .implementations.dirfs import DirFileSystem
return DirFileSystem(path=self._root_key_to_str, fs=self.fs)
[docs] def clear(self):
"""Remove all keys below root - empties out mapping"""
try:
self.fs.rm(self.root, True)
self.fs.mkdir(self.root)
except: # noqa: E722
pass
[docs] def getitems(self, keys, on_error="raise"):
"""Fetch multiple items from the store
If the backend is async-able, this might proceed concurrently
Parameters
----------
keys: list(str)
They keys to be fetched
on_error : "raise", "omit", "return"
If raise, an underlying exception will be raised (converted to KeyError
if the type is in self.missing_exceptions); if omit, keys with exception
will simply not be included in the output; if "return", all keys are
included in the output, but the value will be bytes or an exception
instance.
Returns
-------
dict(key, bytes|exception)
"""
keys2 = [self._key_to_str(k) for k in keys]
oe = on_error if on_error == "raise" else "return"
try:
out = self.fs.cat(keys2, on_error=oe)
if isinstance(out, bytes):
out = {keys2[0]: out}
except self.missing_exceptions as e:
raise KeyError from e
out = {
k: (KeyError() if isinstance(v, self.missing_exceptions) else v)
for k, v in out.items()
}
return {
key: out[k2]
for key, k2 in zip(keys, keys2)
if on_error == "return" or not isinstance(out[k2], BaseException)
}
[docs] def setitems(self, values_dict):
"""Set the values of multiple items in the store
Parameters
----------
values_dict: dict(str, bytes)
"""
values = {self._key_to_str(k): maybe_convert(v) for k, v in values_dict.items()}
self.fs.pipe(values)
[docs] def delitems(self, keys):
"""Remove multiple keys from the store"""
self.fs.rm([self._key_to_str(k) for k in keys])
def _key_to_str(self, key):
"""Generate full path for the key"""
if not isinstance(key, str):
# raise TypeError("key must be of type `str`, got `{type(key).__name__}`"
warnings.warn(
"from fsspec 2023.5 onward FSMap non-str keys will raise TypeError",
DeprecationWarning,
)
if isinstance(key, list):
key = tuple(key)
key = str(key)
return f"{self._root_key_to_str}{key}"
def _str_to_key(self, s):
"""Strip path of to leave key name"""
return s[len(self.root) :].lstrip("/")
def __getitem__(self, key, default=None):
"""Retrieve data"""
k = self._key_to_str(key)
try:
result = self.fs.cat(k)
except self.missing_exceptions:
if default is not None:
return default
raise KeyError(key)
return result
[docs] def pop(self, key, default=None):
"""Pop data"""
result = self.__getitem__(key, default)
try:
del self[key]
except KeyError:
pass
return result
def __setitem__(self, key, value):
"""Store value in key"""
key = self._key_to_str(key)
self.fs.mkdirs(self.fs._parent(key), exist_ok=True)
self.fs.pipe_file(key, maybe_convert(value))
def __iter__(self):
return (self._str_to_key(x) for x in self.fs.find(self.root))
def __len__(self):
return len(self.fs.find(self.root))
def __delitem__(self, key):
"""Remove key"""
try:
self.fs.rm(self._key_to_str(key))
except: # noqa: E722
raise KeyError
def __contains__(self, key):
"""Does key exist in mapping?"""
path = self._key_to_str(key)
return self.fs.exists(path) and self.fs.isfile(path)
def __reduce__(self):
return FSMap, (self.root, self.fs, False, False, self.missing_exceptions)
def maybe_convert(value):
if isinstance(value, array.array) or hasattr(value, "__array__"):
# bytes-like things
if hasattr(value, "dtype") and value.dtype.kind in "Mm":
# The buffer interface doesn't support datetime64/timdelta64 numpy
# arrays
value = value.view("int64")
value = bytes(memoryview(value))
return value
[docs]def get_mapper(
url="",
check=False,
create=False,
missing_exceptions=None,
alternate_root=None,
**kwargs,
):
"""Create key-value interface for given URL and options
The URL will be of the form "protocol://location" and point to the root
of the mapper required. All keys will be file-names below this location,
and their values the contents of each key.
Also accepts compound URLs like zip::s3://bucket/file.zip , see ``fsspec.open``.
Parameters
----------
url: str
Root URL of mapping
check: bool
Whether to attempt to read from the location before instantiation, to
check that the mapping does exist
create: bool
Whether to make the directory corresponding to the root before
instantiating
missing_exceptions: None or tuple
If given, these exception types will be regarded as missing keys and
return KeyError when trying to read data. By default, you get
(FileNotFoundError, IsADirectoryError, NotADirectoryError)
alternate_root: None or str
In cases of complex URLs, the parser may fail to pick the correct part
for the mapper root, so this arg can override
Returns
-------
``FSMap`` instance, the dict-like key-value store.
"""
# Removing protocol here - could defer to each open() on the backend
fs, urlpath = url_to_fs(url, **kwargs)
root = alternate_root if alternate_root is not None else urlpath
return FSMap(root, fs, check, create, missing_exceptions=missing_exceptions)