def get(self, url):
f = LockedFile(self._file, 'r+', 'r')
try:
f.open_and_lock()
if f.is_locked():
cache = _read_or_initialize_cache(f)
if url in cache:
content, t = cache.get(url, (None, 0))
if _to_timestamp(datetime.datetime.now()) < t + self._max_age:
return content
return None
else:
logger.debug('Could not obtain a lock for the cache file.')
return None
except Exception as e:
logger.warning(e, exc_info=True)
finally:
f.unlock_and_close()
def __init__(self, max_age):
"""Constructor.
Args:
max_age: Cache expiration in seconds.
"""
self._max_age = max_age
self._file = os.path.join(tempfile.gettempdir(), FILENAME)
f = LockedFile(self._file, 'a+', 'r')
try:
f.open_and_lock()
if f.is_locked():
_read_or_initialize_cache(f)
# If we can not obtain the lock, other process or thread must
# have initialized the file.
except Exception as e:
logging.warning(e, exc_info=True)
finally:
f.unlock_and_close()
def __init__(self, filename, warn_on_readonly=True):
"""Initialize the class.
This will create the file if necessary.
"""
self._file = LockedFile(filename, 'r+', 'r')
self._thread_lock = threading.Lock()
self._read_only = False
self._warn_on_readonly = warn_on_readonly
self._create_file_if_needed()
# Cache of deserialized store. This is only valid after the
# _MultiStore is locked or _refresh_data_cache is called. This is
# of the form of:
#
# ((key, value), (key, value)...) -> OAuth2Credential
#
# If this is None, then the store hasn't been read yet.
self._data = None
def set(self, url, content):
f = LockedFile(self._file, 'r+', 'r')
try:
f.open_and_lock()
if f.is_locked():
cache = _read_or_initialize_cache(f)
cache[url] = (content, _to_timestamp(datetime.datetime.now()))
# Remove stale cache.
for k, (_, timestamp) in list(cache.items()):
if _to_timestamp(datetime.datetime.now()) >= timestamp + self._max_age:
del cache[k]
f.file_handle().truncate(0)
f.file_handle().seek(0)
json.dump(cache, f.file_handle())
else:
logger.debug('Could not obtain a lock for the cache file.')
except Exception as e:
logger.warning(e, exc_info=True)
finally:
f.unlock_and_close()