fsl.utils.cache

This module provides the Cache class., a simple in-memory cache.

exception fsl.utils.cache.Expired

Bases: Exception

Exception raised by the Cache.get() metho when an attempt is made to access a cache item that has expired.

__module__ = 'fsl.utils.cache'

__weakref__

list of weak references to the object (if defined)

class fsl.utils.cache.CacheItem(key, value, expiry=0)

Bases: object

Internal container class used to store Cache items.

__init__(key, value, expiry=0)

__dict__ = mappingproxy({'__module__': 'fsl.utils.cache', '__doc__': 'Internal container class used to store :class:`Cache` items. ', '__init__': <function CacheItem.__init__>, '__dict__': <attribute '__dict__' of 'CacheItem' objects>, '__weakref__': <attribute '__weakref__' of 'CacheItem' objects>, '__annotations__': {}})

__module__ = 'fsl.utils.cache'

__weakref__

list of weak references to the object (if defined)

class fsl.utils.cache.Cache(maxsize=100, lru=False)

Bases: object

The Cache is a simple in-memory cache built on a collections.OrderedDict. The Cache class has the following features:

• When an item is added to a full cache, the oldest entry is automatically dropped.

• Expiration times can be specified for individual items. If a request is made to access an expired item, an Expired exception is raised.

__init__(maxsize=100, lru=False)

Create a Cache.

Parameters:

• maxsize – Maximum number of items allowed in the Cache before it starts dropping old items

• lru – (least recently used) If False (the default), items are dropped according to their insertion time. Otherwise, items are dropped according to their most recent access time.

put(key, value, expiry=0)

Put an item in the cache.

Parameters:

• key – Item identifier (must be hashable).

• value – The item to store.

• expiry – Expiry time in seconds. An item with an expiry time of 0 will not expire.

get(key, *args, **kwargs)

Get an item from the cache.

Parameters:

• key – Item identifier.

• default – Default value to return if the item is not in the cache, or has expired.

clear()

Remove all items from the cache.

__len__()

Returns the number of items in the cache.

__getitem__(key)

Get an item from the cache.

__setitem__(key, value)

Add an item to the cache.

__contains__(key)

Check whether an item is in the cache. Note that the item may be in the cache, but it may be expired.

keys()

Return all keys in the cache.

values()

Return all values in the cache.

items()

Return all (key, value) pairs in the cache.

__parseDefault(*args, **kwargs)

Used by the get() method. Parses the default argument, which may be specified as either a positional or keyword argumnet.

Returns:

A tuple containing two values:

• True if a default argument was specified, False otherwise.

• The specified default value, or None if it wasn’t specified.

__dict__ = mappingproxy({'__module__': 'fsl.utils.cache', '__doc__': 'The ``Cache`` is a simple in-memory cache built on a\n    ``collections.OrderedDict``. The ``Cache`` class has the following\n    features:\n\n       - When an item is added to a full cache, the oldest entry is\n         automatically dropped.\n\n       - Expiration times can be specified for individual items. If a request\n         is made to access an expired item, an :class:`Expired` exception is\n         raised.\n    ', '__init__': <function Cache.__init__>, 'put': <function Cache.put>, 'get': <function Cache.get>, 'clear': <function Cache.clear>, '__len__': <function Cache.__len__>, '__getitem__': <function Cache.__getitem__>, '__setitem__': <function Cache.__setitem__>, '__contains__': <function Cache.__contains__>, 'keys': <function Cache.keys>, 'values': <function Cache.values>, 'items': <function Cache.items>, '_Cache__parseDefault': <function Cache.__parseDefault>, '__dict__': <attribute '__dict__' of 'Cache' objects>, '__weakref__': <attribute '__weakref__' of 'Cache' objects>, '__annotations__': {}})

__module__ = 'fsl.utils.cache'

__weakref__

list of weak references to the object (if defined)