blob: 2a3b7f2ef41a6b7117e04545f1c5733e2e0e221c [file] [log] [blame]
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Authors:
# Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
import hashlib
import ujson
# Internal record of the size of a cache key
_CACHEKEY_SIZE = len(hashlib.sha256().hexdigest())
# Hex digits
_HEX_DIGITS = "0123456789abcdef"
# is_key()
#
# Check if the passed in string *could be* a cache key. This basically checks
# that the length matches a sha256 hex digest, and that the string does not
# contain any non-hex characters and is fully lower case.
#
# Args:
# key (str): The string to check
#
# Returns:
# (bool): Whether or not `key` could be a cache key
#
def is_key(key):
if len(key) != _CACHEKEY_SIZE:
return False
return not any(ch not in _HEX_DIGITS for ch in key)
# generate_key()
#
# Generate an sha256 hex digest from the given value. The value
# can be a simple value or recursive dictionary with lists etc,
# anything simple enough to serialize.
#
# Args:
# value: A value to get a key for
#
# Returns:
# (str): An sha256 hex digest of the given value
#
def generate_key(value):
ustring = ujson.dumps(value, sort_keys=True, escape_forward_slashes=False).encode("utf-8")
return hashlib.sha256(ustring).hexdigest()