scistag.common.disk_cache.DiskCache¶

class DiskCache(version=1, cache_dir=None)[source]¶

Bases: object

Helper class to persist data such as computation results on disk.

This class is usually not used directly, see Cache which makes use of the DiskCache. All elements you store with a beginning “./” using the Cache class will automatically be stored on disk, all entries without in memory.

Parameters

version (int) –
The cache version. 1 by default.

When ever you change this version all old cache values will be removed and/or ignored from the cache.
cache_dir (str | None) – The directory in which the data shall be cached

Methods

`delete`	Deletes a single cache entry
`encode_name`	Encodes the name of the object to be cached to a unique hash
`get`	Tries to read an element from the disk cache.
`get_cache_name`	Encodes the name of the object to be cached to a unique hash
`set`	Persists a single value in the cache

Attributes

`__dict__`
`__doc__`
`__module__`
`__weakref__`	list of weak references to the object (if defined)
`version`	Returns the cache version
`_version`	The cache version.
`valid`	Defines if the cache is valid

_ensure_cache_dir()[source]¶: Verifies the caching directory is present

delete(key)[source]¶

Deletes a single cache entry

Parameters: key – The cache’s key
Return type: bool
Returns: True if the element was found and deleted

static encode_name(name)[source]¶

Encodes the name of the object to be cached to a unique hash

Parameters: name – The name of the data
Returns: The encoded name

get(key, params=None, version=1, hash_params=False, default=None)[source]¶

Tries to read an element from the disk cache.

Parameters

key – The name of the object to load from cache or a combination of key and version separated by an @ sign, e.g. “database@1”
params (dict) – The creation parameters which were passed into the loading function and still should match.
version (int | str) – The assumed version of this element we are searching for. If the version does not match the old entry is ignored.
hash_params (bool) – Defines the parameters shall be hashed to detect modifications.
default – The default value to return if no cache entry could be found

Return type

Any | None

Returns

Either the cache data or the default value as fallback

get_cache_name(name)[source]¶

Encodes the name of the object to be cached to a unique hash

Parameters: name – The name of the data
Returns: The encoded name

set(key, value, params, version=1, hash_params=False)[source]¶

Persists a single value in the cache

Parameters

key (str) – The name of the object to cache or a combination of key and version separated by an @ sign, e.g. “database@1”
value (Any) – The element’s value
version (int | str) – The cache version for this entry.
params (dict) – The creation parameters which were passed into the loading function and should match upon a cache fetch try.
hash_params (bool) – Defines the parameters shall be hashed to detect modifications.

_version¶

The cache version.

It is stored along all cache values stored on disk and only elements sharing the same version will be accepted.

valid¶: Defines if the cache is valid

property version: int¶

Returns the cache version

Return type: int