You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
99 lines
2.7 KiB
99 lines
2.7 KiB
import time
|
|
from collections.abc import MutableMapping
|
|
from functools import lru_cache
|
|
|
|
|
|
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
|
|
"""
|
|
|
|
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 or float (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):
|
|
entries = list(self._cache)
|
|
|
|
return (k for k in entries if k in self)
|
|
|
|
def __reduce__(self):
|
|
return (
|
|
DirCache,
|
|
(self.use_listings_cache, self.listings_expiry_time, self.max_paths),
|
|
)
|