from __future__ import annotations
import inspect
import logging
import os
import tempfile
import time
import weakref
from shutil import rmtree
from typing import TYPE_CHECKING, Any, Callable, ClassVar
from fsspec import AbstractFileSystem, filesystem
from fsspec.callbacks import DEFAULT_CALLBACK
from fsspec.compression import compr
from fsspec.core import BaseCache, MMapCache
from fsspec.exceptions import BlocksizeMismatchError
from fsspec.implementations.cache_mapper import create_cache_mapper
from fsspec.implementations.cache_metadata import CacheMetadata
from fsspec.spec import AbstractBufferedFile
from fsspec.transaction import Transaction
from fsspec.utils import infer_compression
if TYPE_CHECKING:
from fsspec.implementations.cache_mapper import AbstractCacheMapper
logger = logging.getLogger("fsspec.cached")
class WriteCachedTransaction(Transaction):
def complete(self, commit=True):
rpaths = [f.path for f in self.files]
lpaths = [f.fn for f in self.files]
if commit:
self.fs.put(lpaths, rpaths)
# else remove?
self.fs._intrans = False
[docs]class CachingFileSystem(AbstractFileSystem):
"""Locally caching filesystem, layer over any other FS
This class implements chunk-wise local storage of remote files, for quick
access after the initial download. The files are stored in a given
directory with hashes of URLs for the filenames. If no directory is given,
a temporary one is used, which should be cleaned up by the OS after the
process ends. The files themselves are sparse (as implemented in
:class:`~fsspec.caching.MMapCache`), so only the data which is accessed
takes up space.
Restrictions:
- the block-size must be the same for each access of a given file, unless
all blocks of the file have already been read
- caching can only be applied to file-systems which produce files
derived from fsspec.spec.AbstractBufferedFile ; LocalFileSystem is also
allowed, for testing
"""
protocol: ClassVar[str | tuple[str, ...]] = ("blockcache", "cached")
[docs] def __init__(
self,
target_protocol=None,
cache_storage="TMP",
cache_check=10,
check_files=False,
expiry_time=604800,
target_options=None,
fs=None,
same_names: bool | None = None,
compression=None,
cache_mapper: AbstractCacheMapper | None = None,
**kwargs,
):
"""
Parameters
----------
target_protocol: str (optional)
Target filesystem protocol. Provide either this or ``fs``.
cache_storage: str or list(str)
Location to store files. If "TMP", this is a temporary directory,
and will be cleaned up by the OS when this process ends (or later).
If a list, each location will be tried in the order given, but
only the last will be considered writable.
cache_check: int
Number of seconds between reload of cache metadata
check_files: bool
Whether to explicitly see if the UID of the remote file matches
the stored one before using. Warning: some file systems such as
HTTP cannot reliably give a unique hash of the contents of some
path, so be sure to set this option to False.
expiry_time: int
The time in seconds after which a local copy is considered useless.
Set to falsy to prevent expiry. The default is equivalent to one
week.
target_options: dict or None
Passed to the instantiation of the FS, if fs is None.
fs: filesystem instance
The target filesystem to run against. Provide this or ``protocol``.
same_names: bool (optional)
By default, target URLs are hashed using a ``HashCacheMapper`` so
that files from different backends with the same basename do not
conflict. If this argument is ``true``, a ``BasenameCacheMapper``
is used instead. Other cache mapper options are available by using
the ``cache_mapper`` keyword argument. Only one of this and
``cache_mapper`` should be specified.
compression: str (optional)
To decompress on download. Can be 'infer' (guess from the URL name),
one of the entries in ``fsspec.compression.compr``, or None for no
decompression.
cache_mapper: AbstractCacheMapper (optional)
The object use to map from original filenames to cached filenames.
Only one of this and ``same_names`` should be specified.
"""
super().__init__(**kwargs)
if fs is None and target_protocol is None:
raise ValueError(
"Please provide filesystem instance(fs) or target_protocol"
)
if not (fs is None) ^ (target_protocol is None):
raise ValueError(
"Both filesystems (fs) and target_protocol may not be both given."
)
if cache_storage == "TMP":
tempdir = tempfile.mkdtemp()
storage = [tempdir]
weakref.finalize(self, self._remove_tempdir, tempdir)
else:
if isinstance(cache_storage, str):
storage = [cache_storage]
else:
storage = cache_storage
os.makedirs(storage[-1], exist_ok=True)
self.storage = storage
self.kwargs = target_options or {}
self.cache_check = cache_check
self.check_files = check_files
self.expiry = expiry_time
self.compression = compression
# Size of cache in bytes. If None then the size is unknown and will be
# recalculated the next time cache_size() is called. On writes to the
# cache this is reset to None.
self._cache_size = None
if same_names is not None and cache_mapper is not None:
raise ValueError(
"Cannot specify both same_names and cache_mapper in "
"CachingFileSystem.__init__"
)
if cache_mapper is not None:
self._mapper = cache_mapper
else:
self._mapper = create_cache_mapper(
same_names if same_names is not None else False
)
self.target_protocol = (
target_protocol
if isinstance(target_protocol, str)
else (fs.protocol if isinstance(fs.protocol, str) else fs.protocol[0])
)
self._metadata = CacheMetadata(self.storage)
self.load_cache()
self.fs = fs if fs is not None else filesystem(target_protocol, **self.kwargs)
def _strip_protocol(path):
# acts as a method, since each instance has a difference target
return self.fs._strip_protocol(type(self)._strip_protocol(path))
self._strip_protocol: Callable = _strip_protocol
@staticmethod
def _remove_tempdir(tempdir):
try:
rmtree(tempdir)
except Exception:
pass
def _mkcache(self):
os.makedirs(self.storage[-1], exist_ok=True)
def cache_size(self):
"""Return size of cache in bytes.
If more than one cache directory is in use, only the size of the last
one (the writable cache directory) is returned.
"""
if self._cache_size is None:
cache_dir = self.storage[-1]
self._cache_size = filesystem("file").du(cache_dir, withdirs=True)
return self._cache_size
def load_cache(self):
"""Read set of stored blocks from file"""
self._metadata.load()
self._mkcache()
self.last_cache = time.time()
def save_cache(self):
"""Save set of stored blocks from file"""
self._mkcache()
self._metadata.save()
self.last_cache = time.time()
self._cache_size = None
def _check_cache(self):
"""Reload caches if time elapsed or any disappeared"""
self._mkcache()
if not self.cache_check:
# explicitly told not to bother checking
return
timecond = time.time() - self.last_cache > self.cache_check
existcond = all(os.path.exists(storage) for storage in self.storage)
if timecond or not existcond:
self.load_cache()
def _check_file(self, path):
"""Is path in cache and still valid"""
path = self._strip_protocol(path)
self._check_cache()
return self._metadata.check_file(path, self)
def clear_cache(self):
"""Remove all files and metadata from the cache
In the case of multiple cache locations, this clears only the last one,
which is assumed to be the read/write one.
"""
rmtree(self.storage[-1])
self.load_cache()
self._cache_size = None
def clear_expired_cache(self, expiry_time=None):
"""Remove all expired files and metadata from the cache
In the case of multiple cache locations, this clears only the last one,
which is assumed to be the read/write one.
Parameters
----------
expiry_time: int
The time in seconds after which a local copy is considered useless.
If not defined the default is equivalent to the attribute from the
file caching instantiation.
"""
if not expiry_time:
expiry_time = self.expiry
self._check_cache()
expired_files, writable_cache_empty = self._metadata.clear_expired(expiry_time)
for fn in expired_files:
if os.path.exists(fn):
os.remove(fn)
if writable_cache_empty:
rmtree(self.storage[-1])
self.load_cache()
self._cache_size = None
def pop_from_cache(self, path):
"""Remove cached version of given file
Deletes local copy of the given (remote) path. If it is found in a cache
location which is not the last, it is assumed to be read-only, and
raises PermissionError
"""
path = self._strip_protocol(path)
fn = self._metadata.pop_file(path)
if fn is not None:
os.remove(fn)
self._cache_size = None
def _open(
self,
path,
mode="rb",
block_size=None,
autocommit=True,
cache_options=None,
**kwargs,
):
"""Wrap the target _open
If the whole file exists in the cache, just open it locally and
return that.
Otherwise, open the file on the target FS, and make it have a mmap
cache pointing to the location which we determine, in our cache.
The ``blocks`` instance is shared, so as the mmap cache instance
updates, so does the entry in our ``cached_files`` attribute.
We monkey-patch this file, so that when it closes, we call
``close_and_update`` to save the state of the blocks.
"""
path = self._strip_protocol(path)
path = self.fs._strip_protocol(path)
if "r" not in mode:
return self.fs._open(
path,
mode=mode,
block_size=block_size,
autocommit=autocommit,
cache_options=cache_options,
**kwargs,
)
detail = self._check_file(path)
if detail:
# file is in cache
detail, fn = detail
hash, blocks = detail["fn"], detail["blocks"]
if blocks is True:
# stored file is complete
logger.debug("Opening local copy of %s", path)
return open(fn, mode)
# TODO: action where partial file exists in read-only cache
logger.debug("Opening partially cached copy of %s", path)
else:
hash = self._mapper(path)
fn = os.path.join(self.storage[-1], hash)
blocks = set()
detail = {
"original": path,
"fn": hash,
"blocks": blocks,
"time": time.time(),
"uid": self.fs.ukey(path),
}
self._metadata.update_file(path, detail)
logger.debug("Creating local sparse file for %s", path)
# call target filesystems open
self._mkcache()
f = self.fs._open(
path,
mode=mode,
block_size=block_size,
autocommit=autocommit,
cache_options=cache_options,
cache_type="none",
**kwargs,
)
if self.compression:
comp = (
infer_compression(path)
if self.compression == "infer"
else self.compression
)
f = compr[comp](f, mode="rb")
if "blocksize" in detail:
if detail["blocksize"] != f.blocksize:
raise BlocksizeMismatchError(
f"Cached file must be reopened with same block"
f" size as original (old: {detail['blocksize']},"
f" new {f.blocksize})"
)
else:
detail["blocksize"] = f.blocksize
f.cache = MMapCache(f.blocksize, f._fetch_range, f.size, fn, blocks)
close = f.close
f.close = lambda: self.close_and_update(f, close)
self.save_cache()
return f
def _parent(self, path):
return self.fs._parent(path)
def hash_name(self, path: str, *args: Any) -> str:
# Kept for backward compatibility with downstream libraries.
# Ignores extra arguments, previously same_name boolean.
return self._mapper(path)
def close_and_update(self, f, close):
"""Called when a file is closing, so store the set of blocks"""
if f.closed:
return
path = self._strip_protocol(f.path)
self._metadata.on_close_cached_file(f, path)
try:
logger.debug("going to save")
self.save_cache()
logger.debug("saved")
except OSError:
logger.debug("Cache saving failed while closing file")
except NameError:
logger.debug("Cache save failed due to interpreter shutdown")
close()
f.closed = True
def __getattribute__(self, item):
if item in [
"load_cache",
"_open",
"save_cache",
"close_and_update",
"__init__",
"__getattribute__",
"__reduce__",
"_make_local_details",
"open",
"cat",
"cat_file",
"cat_ranges",
"get",
"read_block",
"tail",
"head",
"_check_file",
"_check_cache",
"_mkcache",
"clear_cache",
"clear_expired_cache",
"pop_from_cache",
"_mkcache",
"local_file",
"_paths_from_path",
"get_mapper",
"open_many",
"commit_many",
"hash_name",
"__hash__",
"__eq__",
"to_json",
"cache_size",
"pipe_file",
"pipe",
"start_transaction",
"end_transaction",
]:
# all the methods defined in this class. Note `open` here, since
# it calls `_open`, but is actually in superclass
return lambda *args, **kw: getattr(type(self), item).__get__(self)(
*args, **kw
)
if item in ["__reduce_ex__"]:
raise AttributeError
if item in ["transaction"]:
# property
return type(self).transaction.__get__(self)
if item in ["_cache", "transaction_type"]:
# class attributes
return getattr(type(self), item)
if item == "__class__":
return type(self)
d = object.__getattribute__(self, "__dict__")
fs = d.get("fs", None) # fs is not immediately defined
if item in d:
return d[item]
elif fs is not None:
if item in fs.__dict__:
# attribute of instance
return fs.__dict__[item]
# attributed belonging to the target filesystem
cls = type(fs)
m = getattr(cls, item)
if (inspect.isfunction(m) or inspect.isdatadescriptor(m)) and (
not hasattr(m, "__self__") or m.__self__ is None
):
# instance method
return m.__get__(fs, cls)
return m # class method or attribute
else:
# attributes of the superclass, while target is being set up
return super().__getattribute__(item)
def __eq__(self, other):
"""Test for equality."""
if self is other:
return True
if not isinstance(other, type(self)):
return False
return (
self.storage == other.storage
and self.kwargs == other.kwargs
and self.cache_check == other.cache_check
and self.check_files == other.check_files
and self.expiry == other.expiry
and self.compression == other.compression
and self._mapper == other._mapper
and self.target_protocol == other.target_protocol
)
def __hash__(self):
"""Calculate hash."""
return (
hash(tuple(self.storage))
^ hash(str(self.kwargs))
^ hash(self.cache_check)
^ hash(self.check_files)
^ hash(self.expiry)
^ hash(self.compression)
^ hash(self._mapper)
^ hash(self.target_protocol)
)
def to_json(self):
"""Calculate JSON representation.
Not implemented yet for CachingFileSystem.
"""
raise NotImplementedError(
"CachingFileSystem JSON representation not implemented"
)
[docs]class WholeFileCacheFileSystem(CachingFileSystem):
"""Caches whole remote files on first access
This class is intended as a layer over any other file system, and
will make a local copy of each file accessed, so that all subsequent
reads are local. This is similar to ``CachingFileSystem``, but without
the block-wise functionality and so can work even when sparse files
are not allowed. See its docstring for definition of the init
arguments.
The class still needs access to the remote store for listing files,
and may refresh cached files.
"""
protocol = "filecache"
local_file = True
def open_many(self, open_files, **kwargs):
paths = [of.path for of in open_files]
if "r" in open_files.mode:
self._mkcache()
else:
return [
LocalTempFile(
self.fs,
path,
mode=open_files.mode,
fn=os.path.join(self.storage[-1], self._mapper(path)),
**kwargs,
)
for path in paths
]
if self.compression:
raise NotImplementedError
details = [self._check_file(sp) for sp in paths]
downpath = [p for p, d in zip(paths, details) if not d]
downfn0 = [
os.path.join(self.storage[-1], self._mapper(p))
for p, d in zip(paths, details)
] # keep these path names for opening later
downfn = [fn for fn, d in zip(downfn0, details) if not d]
if downpath:
# skip if all files are already cached and up to date
self.fs.get(downpath, downfn)
# update metadata - only happens when downloads are successful
newdetail = [
{
"original": path,
"fn": self._mapper(path),
"blocks": True,
"time": time.time(),
"uid": self.fs.ukey(path),
}
for path in downpath
]
for path, detail in zip(downpath, newdetail):
self._metadata.update_file(path, detail)
self.save_cache()
def firstpart(fn):
# helper to adapt both whole-file and simple-cache
return fn[1] if isinstance(fn, tuple) else fn
return [
open(firstpart(fn0) if fn0 else fn1, mode=open_files.mode)
for fn0, fn1 in zip(details, downfn0)
]
def commit_many(self, open_files):
self.fs.put([f.fn for f in open_files], [f.path for f in open_files])
[f.close() for f in open_files]
for f in open_files:
# in case autocommit is off, and so close did not already delete
try:
os.remove(f.name)
except FileNotFoundError:
pass
self._cache_size = None
def _make_local_details(self, path):
hash = self._mapper(path)
fn = os.path.join(self.storage[-1], hash)
detail = {
"original": path,
"fn": hash,
"blocks": True,
"time": time.time(),
"uid": self.fs.ukey(path),
}
self._metadata.update_file(path, detail)
logger.debug("Copying %s to local cache", path)
return fn
def cat(
self,
path,
recursive=False,
on_error="raise",
callback=DEFAULT_CALLBACK,
**kwargs,
):
paths = self.expand_path(
path, recursive=recursive, maxdepth=kwargs.get("maxdepth", None)
)
getpaths = []
storepaths = []
fns = []
out = {}
for p in paths.copy():
try:
detail = self._check_file(p)
if not detail:
fn = self._make_local_details(p)
getpaths.append(p)
storepaths.append(fn)
else:
detail, fn = detail if isinstance(detail, tuple) else (None, detail)
fns.append(fn)
except Exception as e:
if on_error == "raise":
raise
if on_error == "return":
out[p] = e
paths.remove(p)
if getpaths:
self.fs.get(getpaths, storepaths)
self.save_cache()
callback.set_size(len(paths))
for p, fn in zip(paths, fns):
with open(fn, "rb") as f:
out[p] = f.read()
callback.relative_update(1)
if isinstance(path, str) and len(paths) == 1 and recursive is False:
out = out[paths[0]]
return out
def _open(self, path, mode="rb", **kwargs):
path = self._strip_protocol(path)
if "r" not in mode:
fn = self._make_local_details(path)
user_specified_kwargs = {
k: v
for k, v in kwargs.items()
# those kwargs were added by open(), we don't want them
if k not in ["autocommit", "block_size", "cache_options"]
}
return LocalTempFile(self, path, mode=mode, fn=fn, **user_specified_kwargs)
detail = self._check_file(path)
if detail:
detail, fn = detail
_, blocks = detail["fn"], detail["blocks"]
if blocks is True:
logger.debug("Opening local copy of %s", path)
# In order to support downstream filesystems to be able to
# infer the compression from the original filename, like
# the `TarFileSystem`, let's extend the `io.BufferedReader`
# fileobject protocol by adding a dedicated attribute
# `original`.
f = open(fn, mode)
f.original = detail.get("original")
return f
else:
raise ValueError(
f"Attempt to open partially cached file {path}"
f" as a wholly cached file"
)
else:
fn = self._make_local_details(path)
kwargs["mode"] = mode
# call target filesystems open
self._mkcache()
if self.compression:
with self.fs._open(path, **kwargs) as f, open(fn, "wb") as f2:
if isinstance(f, AbstractBufferedFile):
# want no type of caching if just downloading whole thing
f.cache = BaseCache(0, f.cache.fetcher, f.size)
comp = (
infer_compression(path)
if self.compression == "infer"
else self.compression
)
f = compr[comp](f, mode="rb")
data = True
while data:
block = getattr(f, "blocksize", 5 * 2**20)
data = f.read(block)
f2.write(data)
else:
self.fs.get_file(path, fn)
self.save_cache()
return self._open(path, mode)
[docs]class SimpleCacheFileSystem(WholeFileCacheFileSystem):
"""Caches whole remote files on first access
This class is intended as a layer over any other file system, and
will make a local copy of each file accessed, so that all subsequent
reads are local. This implementation only copies whole files, and
does not keep any metadata about the download time or file details.
It is therefore safer to use in multi-threaded/concurrent situations.
This is the only of the caching filesystems that supports write: you will
be given a real local open file, and upon close and commit, it will be
uploaded to the target filesystem; the writability or the target URL is
not checked until that time.
"""
protocol = "simplecache"
local_file = True
transaction_type = WriteCachedTransaction
[docs] def __init__(self, **kwargs):
kw = kwargs.copy()
for key in ["cache_check", "expiry_time", "check_files"]:
kw[key] = False
super().__init__(**kw)
for storage in self.storage:
if not os.path.exists(storage):
os.makedirs(storage, exist_ok=True)
def _check_file(self, path):
self._check_cache()
sha = self._mapper(path)
for storage in self.storage:
fn = os.path.join(storage, sha)
if os.path.exists(fn):
return fn
def save_cache(self):
pass
def load_cache(self):
pass
def pipe_file(self, path, value=None, **kwargs):
if self._intrans:
with self.open(path, "wb") as f:
f.write(value)
else:
super().pipe_file(path, value)
def pipe(self, path, value=None, **kwargs):
if isinstance(path, str):
self.pipe_file(self._strip_protocol(path), value, **kwargs)
elif isinstance(path, dict):
for k, v in path.items():
self.pipe_file(self._strip_protocol(k), v, **kwargs)
else:
raise ValueError("path must be str or dict")
def cat_ranges(
self, paths, starts, ends, max_gap=None, on_error="return", **kwargs
):
lpaths = [self._check_file(p) for p in paths]
rpaths = [p for l, p in zip(lpaths, paths) if l is False]
lpaths = [l for l, p in zip(lpaths, paths) if l is False]
self.fs.get(rpaths, lpaths)
return super().cat_ranges(
paths, starts, ends, max_gap=max_gap, on_error=on_error, **kwargs
)
def _open(self, path, mode="rb", **kwargs):
path = self._strip_protocol(path)
sha = self._mapper(path)
if "r" not in mode:
fn = os.path.join(self.storage[-1], sha)
user_specified_kwargs = {
k: v
for k, v in kwargs.items()
if k not in ["autocommit", "block_size", "cache_options"]
} # those were added by open()
return LocalTempFile(
self,
path,
mode=mode,
autocommit=not self._intrans,
fn=fn,
**user_specified_kwargs,
)
fn = self._check_file(path)
if fn:
return open(fn, mode)
fn = os.path.join(self.storage[-1], sha)
logger.debug("Copying %s to local cache", path)
kwargs["mode"] = mode
self._mkcache()
self._cache_size = None
if self.compression:
with self.fs._open(path, **kwargs) as f, open(fn, "wb") as f2:
if isinstance(f, AbstractBufferedFile):
# want no type of caching if just downloading whole thing
f.cache = BaseCache(0, f.cache.fetcher, f.size)
comp = (
infer_compression(path)
if self.compression == "infer"
else self.compression
)
f = compr[comp](f, mode="rb")
data = True
while data:
block = getattr(f, "blocksize", 5 * 2**20)
data = f.read(block)
f2.write(data)
else:
self.fs.get_file(path, fn)
return self._open(path, mode)
class LocalTempFile:
"""A temporary local file, which will be uploaded on commit"""
def __init__(self, fs, path, fn, mode="wb", autocommit=True, seek=0, **kwargs):
self.fn = fn
self.fh = open(fn, mode)
self.mode = mode
if seek:
self.fh.seek(seek)
self.path = path
self.fs = fs
self.closed = False
self.autocommit = autocommit
self.kwargs = kwargs
def __reduce__(self):
# always open in r+b to allow continuing writing at a location
return (
LocalTempFile,
(self.fs, self.path, self.fn, "r+b", self.autocommit, self.tell()),
)
def __enter__(self):
return self.fh
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
def close(self):
if self.closed:
return
self.fh.close()
self.closed = True
if self.autocommit:
self.commit()
def discard(self):
self.fh.close()
os.remove(self.fn)
def commit(self):
self.fs.put(self.fn, self.path, **self.kwargs)
try:
os.remove(self.fn)
except (PermissionError, FileNotFoundError):
# file path may be held by new version of the file on windows
pass
@property
def name(self):
return self.fn
def __getattr__(self, item):
return getattr(self.fh, item)