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)

Initialize self. See help(type(self)) for accurate signature.

__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>})

__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.

__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__>, '_Cache__parseDefault': <function Cache.__parseDefault>, '__dict__': <attribute '__dict__' of 'Cache' objects>, '__weakref__': <attribute '__weakref__' of 'Cache' objects>})

__module__ = 'fsl.utils.cache'

__weakref__

list of weak references to the object (if defined)