Simple Memory Backend

class cachelib.simple.SimpleCache(threshold=500, default_timeout=300)

Bases: BaseCache

Simple memory cache for single process environments. This class exists mainly for the development server and is not 100% thread safe. It tries to use as many atomic operations as possible and no locks for simplicity but it could happen under heavy load that keys are added multiple times.

Parameters

  • threshold (int) – the maximum number of items the cache stores before it starts deleting some.

  • 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.

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 (Optional[int]) – 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

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

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

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

serializer = <cachelib.serializers.SimpleSerializer 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 (Optional[int]) – 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