Source code for fsspec.dircache

import time
from collections.abc import MutableMapping
from functools import lru_cache


[docs]class DirCache(MutableMapping): """ Caching of directory listings, in a structure like:: {"path0": [ {"name": "path0/file0", "size": 123, "type": "file", ... }, {"name": "path0/file1", }, ... ], "path1": [...] } Parameters to this class control listing expiry or indeed turn caching off """
[docs] def __init__( self, use_listings_cache=True, listings_expiry_time=None, max_paths=None, **kwargs, ): """ Parameters ---------- use_listings_cache: bool If False, this cache never returns items, but always reports KeyError, and setting items has no effect listings_expiry_time: int (optional) Time in seconds that a listing is considered valid. If None, listings do not expire. max_paths: int (optional) The number of most recent listings that are considered valid; 'recent' refers to when the entry was set. """ self._cache = {} self._times = {} if max_paths: self._q = lru_cache(max_paths + 1)(lambda key: self._cache.pop(key, None)) self.use_listings_cache = use_listings_cache self.listings_expiry_time = listings_expiry_time self.max_paths = max_paths
def __getitem__(self, item): if self.listings_expiry_time is not None: if self._times.get(item, 0) - time.time() < -self.listings_expiry_time: del self._cache[item] if self.max_paths: self._q(item) return self._cache[item] # maybe raises KeyError def clear(self): self._cache.clear() def __len__(self): return len(self._cache) def __contains__(self, item): try: self[item] return True except KeyError: return False def __setitem__(self, key, value): if not self.use_listings_cache: return if self.max_paths: self._q(key) self._cache[key] = value if self.listings_expiry_time is not None: self._times[key] = time.time() def __delitem__(self, key): del self._cache[key] def __iter__(self): return (k for k in self._cache if k in self) def __reduce__(self): return ( DirCache, (self.use_listings_cache, self.listings_expiry_time, self.max_paths), )