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CacheToolsUtils

Stackable cache classes for sharing, encryption, statistics and more on top of cachetools, redis and memcached.

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Module Contents

For our purpose, a cache is a key-value store, aka a dictionary, possibly with some constraints on keys (type, size) and values (size, serialization). This module provides new caches, wrappers and other utilities suitable to use with cachetools. Example:

import redis
import CacheToolsUtils as ctu
import config

redis_storage = redis.Redis(**config.REDIS_SERVER)
storage = ctu.RedisCache(redis_storage, raw=True, ttl=120)
crypto = ctu.EncryptedCache(storage, config.CACHE_KEY)
cache = ctu.ToBytesCache(crypto)

@ctu.cached(ctu.AutoPrefixedCache(cache), key=ctu.json_key)
def repeat(s: str, n: int) -> str:
    return s * n

@ctu.cached(ctu.AutoPrefixedCache(cache), key=ctu.json_key)
def banged(s: str, n: int) -> str:
    return repeat(s, n) + "!"

@ctu.cached(ctu.AutoPrefixedCache(cache), key=ctu.json_key)
def question(s: str, n: int) -> str:
    return repeat(s, n) + "?"

print(banged("aa", 3))    # add 2 cache entries
print(question("aa", 3))  # add 1 entry, 1 hit
print(repeat("aa", 3))    # cache hit!
print(banged("aa", 3))    # cache hit!

assert cache.hits() > 0

Cache classes

  • RedisCache allows to see a Redis server as a python cache by wrapping a redis.Redis instance.
  • MemCached does the same for a Memcached server. The utility class JsonSerde is a convenient JSON serializer-deserializer class for Memcached.
  • DictCache a very simple dict cache.

Wrappers to extend cache capabilities

  • PrefixedCache, PrefixedMemCached and PrefixedRedisCache add a prefix to distinguish sources on a shared cache.
  • AutoPrefixedCache add a counter-based prefix.
  • StatsCache, MemCached and RedisCache add a hits method to report the cache hit rate, stats to report statistics and reset to reset statistics.
  • LockedCache use a (thread) lock to control cache accesses.
  • TwoLevelCache allows to combine two caches.
  • DebugCache to trace cache calls using logging.
  • EncryptedCache a cache with key hashing and value encryption.
  • ToBytesCache map keys and values to bytes.
  • BytesCache map bytes keys and values to strings.

Cache utilities

  • cached decorator: a cachetools replacement which allows to test if a function result is in cache, and to delete such an entry.
  • cacheFunctions and cacheMethods: add caching to functions or methods.
  • json_key, hash_json_key, full_hash_key: convenient JSON-based cache key serialization functions for cached.

License

This code is Public Domain.

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More

See the documentation, sources and issues on GitHub.

See packages on PyPI.