/usr/share/pyshared/flickrapi/cache.py is in python-flickrapi 1.2-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 | # -*- encoding: utf-8 -*-
'''Call result cache.
Designed to have the same interface as the `Django low-level cache API`_.
Heavily inspired (read: mostly copied-and-pasted) from the Django framework -
thanks to those guys for designing a simple and effective cache!
.. _`Django low-level cache API`: http://www.djangoproject.com/documentation/cache/#the-low-level-cache-api
'''
import threading
import time
class SimpleCache(object):
'''Simple response cache for FlickrAPI calls.
This stores max 50 entries, timing them out after 120 seconds:
>>> cache = SimpleCache(timeout=120, max_entries=50)
'''
def __init__(self, timeout=300, max_entries=200):
self.storage = {}
self.expire_info = {}
self.lock = threading.RLock()
self.default_timeout = timeout
self.max_entries = max_entries
self.cull_frequency = 3
def locking(method):
'''Method decorator, ensures the method call is locked'''
def locked(self, *args, **kwargs):
self.lock.acquire()
try:
return method(self, *args, **kwargs)
finally:
self.lock.release()
return locked
@locking
def get(self, key, default=None):
'''Fetch a given key from the cache. If the key does not exist, return
default, which itself defaults to None.
'''
now = time.time()
exp = self.expire_info.get(key)
if exp is None:
return default
elif exp < now:
self.delete(key)
return default
return self.storage[key]
@locking
def set(self, key, value, timeout=None):
'''Set a value in the cache. If timeout is given, that timeout will be
used for the key; otherwise the default cache timeout will be used.
'''
if len(self.storage) >= self.max_entries:
self.cull()
if timeout is None:
timeout = self.default_timeout
self.storage[key] = value
self.expire_info[key] = time.time() + timeout
@locking
def delete(self, key):
'''Deletes a key from the cache, failing silently if it doesn't exist.'''
if key in self.storage:
del self.storage[key]
if key in self.expire_info:
del self.expire_info[key]
@locking
def has_key(self, key):
'''Returns True if the key is in the cache and has not expired.'''
return self.get(key) is not None
@locking
def __contains__(self, key):
'''Returns True if the key is in the cache and has not expired.'''
return self.has_key(key)
@locking
def cull(self):
'''Reduces the number of cached items'''
doomed = [k for (i, k) in enumerate(self.storage)
if i % self.cull_frequency == 0]
for k in doomed:
self.delete(k)
@locking
def __len__(self):
'''Returns the number of cached items -- they might be expired
though.
'''
return len(self.storage)
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