lisa.utils.DirCache

class lisa.utils.DirCache(category, populate=None, fmt_version=None)

Bases: Loggable

Provide a folder-based cache.

Parameters:

• category (str) – Unique name for the cache category. This allows an arbitrary number of categories to be used under lisa.utils.LISA_CACHE_HOME.

• populate (collections.abc.Callable) –

  Callback to populate a new cache entry if none is found. It will be passed the following parameters:

  • The key that is being looked up

  • The path to populate

  It must return a subfolder of the passed path to populate, or None, which is the same as returning the passed path.

• fmt_version (str or None) – Version of the format of this cache category. This allows re-using the cache across multiple versions of lisa, at the expense of having to manually bump the format version in source code when the format of the cache changes. This format version is logically added to each key lookup so that multiple versions of lisa do not interfere with each other.

The cache is managed in a process-safe way, so that there can be no race between concurrent processes or threads.

Properties

logger inherited

Convenience short-hand for self.get_logger().

Methods

get_entry()	Return the folder of a cache entry.
get_key_token()	Return the token associated with the given key.
has_key()	Check if the given key is already present in the cache. If the key is present, return the path, otherwise returns None.
get_logger() inherited	Provides a logging.Logger named after cls.
log_locals() inherited	Debugging aid: log the local variables of the calling function.

Properties

property DirCache.logger

Inherited property, see lisa.utils.Loggable.logger

Convenience short-hand for self.get_logger().

Methods

DirCache.get_entry(key)

Return the folder of a cache entry.

If no entry is found, a new one is created using the populate() callback.

Parameters:

key (object) –

Key of the cache entry. All the components of the key must be isomorphic to their repr(), otherwise the cache will be hit in cases where it should not. For convenience, some types are normalized:

• Mapping is only considered for its keys and values and type name. Keys are sorted are sorted. If the passed object contains other relevant metadata, it should be rendered to a string first by the caller.

• Iterable keys are normalized and the object is only considered as an iterable. If other relevant metadata is contained in the object, it should be rendered to a string by the caller.

Note

The return folder must never be modified, as it would lead to races.

DirCache.get_key_token(key)

Return the token associated with the given key.

DirCache.has_key(key)

Check if the given key is already present in the cache. If the key is present, return the path, otherwise returns None.

Parameters:

key – Same as for get_entry().

classmethod DirCache.get_logger(suffix=None)

Inherited method, see lisa.utils.Loggable.get_logger()

Provides a logging.Logger named after cls.

classmethod DirCache.log_locals(var_names=None, level='debug')

Inherited method, see lisa.utils.Loggable.log_locals()

Debugging aid: log the local variables of the calling function.