Redis Backend

class cachelib.redis.RedisCache(host='localhost', port=6379, password=None, db=0, default_timeout=300, key_prefix=None, **kwargs)

Bases: BaseCache

Uses the Redis key-value store as a cache backend.

The first argument can be either a string denoting address of the Redis server or an object resembling an instance of a redis.Redis class.

Note: Python Redis API already takes care of encoding unicode strings on the fly.

Parameters:

  • host (Any) – address of the Redis server or an object which API is compatible with the official Python Redis client (redis-py).

  • port (int) – port number on which Redis server listens for connections.

  • password (str | None) – password authentication for the Redis server.

  • db (int) – db (zero-based numeric index) on Redis Server to connect.

  • default_timeout (int) – the default timeout that is used if no timeout is specified on set(). A timeout of 0 indicates that the cache never expires.

  • key_prefix (str | Callable[[], str] | None) – A prefix that should be added to all keys.

  • kwargs (Any) –

Any additional keyword arguments will be passed to redis.Redis.

add(key, value, timeout=None)

Works like set() but does not overwrite the values of already existing keys.

Parameters:

  • key (str) – the key to set

  • value (Any) – the value for the key

  • timeout (int | None) – the cache timeout for the key in seconds (if not specified, it uses the default timeout). A timeout of 0 indicates that the cache never expires.

Returns:

Same as set(), but also False for already existing keys.

Return type:

boolean

clear()

Clears the cache. Keep in mind that not all caches support completely clearing the cache.

Returns:

Whether the cache has been cleared.

Return type:

boolean

dec(key, delta=1)

Decrements the value of a key by delta. If the key does not yet exist it is initialized with -delta.

For supporting caches this is an atomic operation.

Parameters:

  • key (str) – the key to increment.

  • delta (int) – the delta to subtract.

Returns:

The new value or None for backend errors.

Return type:

Any

delete(key)

Delete key from the cache.

Parameters:

key (str) – the key to delete.

Returns:

Whether the key existed and has been deleted.

Return type:

boolean

delete_many(*keys)

Deletes multiple keys at once.

Parameters:

keys (str) – The function accepts multiple keys as positional arguments.

Returns:

A list containing all successfully deleted keys

Return type:

boolean

get(key)

Look up key in the cache and return the value for it.

Parameters:

key (str) – the key to be looked up.

Returns:

The value if it exists and is readable, else None.

Return type:

Any

get_many(*keys)

Returns a list of values for the given keys. For each key an item in the list is created:

foo, bar = cache.get_many("foo", "bar")

Has the same error handling as get().

Parameters:

keys (str) – The function accepts multiple keys as positional arguments.

Return type:

List[Any]

has(key)

Checks if a key exists in the cache without returning it. This is a cheap operation that bypasses loading the actual data on the backend.

Parameters:

key (str) – the key to check

Return type:

bool

inc(key, delta=1)

Increments the value of a key by delta. If the key does not yet exist it is initialized with delta.

For supporting caches this is an atomic operation.

Parameters:

  • key (str) – the key to increment.

  • delta (int) – the delta to add.

Returns:

The new value or None for backend errors.

Return type:

Any

serializer = <cachelib.serializers.RedisSerializer object>
set(key, value, timeout=None)

Add a new key/value to the cache (overwrites value, if key already exists in the cache).

Parameters:

  • key (str) – the key to set

  • value (Any) – the value for the key

  • timeout (int | None) – the cache timeout for the key in seconds (if not specified, it uses the default timeout). A timeout of 0 indicates that the cache never expires.

Returns:

True if key has been updated, False for backend errors. Pickling errors, however, will raise a subclass of pickle.PickleError.

Return type:

boolean

set_many(mapping, timeout=None)

Sets multiple keys and values from a mapping.

Parameters:

  • mapping (Dict[str, Any]) – a mapping with the keys/values to set.

  • timeout (int | None) – the cache timeout for the key in seconds (if not specified, it uses the default timeout). A timeout of 0 indicates that the cache never expires.

Returns:

A list containing all keys successfully set

Return type:

boolean