Source code for fsspec.mapping

import array
from collections.abc import MutableMapping

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( "/" ) # we join on '/' in _key_to_str if missing_exceptions is None: missing_exceptions = ( FileNotFoundError, IsADirectoryError, NotADirectoryError, ) self.missing_exceptions = missing_exceptions if create: if not self.fs.exists(root): self.fs.mkdir(root) if check: if not self.fs.exists(root): raise ValueError( "Path %s does not exist. Create " " with the ``create=True`` keyword" % root ) self.fs.touch(root + "/a") self.fs.rm(root + "/a")
[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 isinstance(key, (tuple, list)): key = str(tuple(key)) else: key = str(key) return self.fs._strip_protocol("/".join([self.root, key]) if self.root else 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): 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 = bytearray(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)