pyzim.cache.HybridCache

class documentation

class HybridCache(BaseCache):

Constructor: HybridCache(on_leave, last_cache_size, top_cache_size)

A pyzim.cache.BaseCache that internally utilizes both a pyzim.cache.LastAccessCache and a pyzim.cache.TopAccessCache.

Method	`__init__`	The default constructor.
Method	`clear`	Empty this cache.
Method	`get`	Return the element that has been cached for this key.
Method	`has`	Return True if an element is cached for the specific key.
Method	`push`	Push an element for this key into this cache.
Method	`remove`	If an element is cached for key, remove it from the cache.
Instance Variable	`last_cache`	the last-access cache
Instance Variable	`top_cache`	the top-access cache
Method	`_on_leave`	A helper method that will be called whenever any element leaves one of the wrapped chaches.

Inherited from BaseCache:

Instance Variable on_leave a callable expecting two arguments (key, value) that will be called when an element leaves the cache

def __init__(self, on_leave=None, last_cache_size=8, top_cache_size=8): ¶

overrides pyzim.cache.BaseCache.__init__

The default constructor.

Parameters
on_leave:callable or `None`	See `BaseCache.__init__`
last_cache_size:`int`	size of the last-access cache
top_cache_size:`int`	size of the top-access cache

def clear(self, call_on_leave=True): ¶

overrides pyzim.cache.BaseCache.clear

Empty this cache.

Parameters
call_on_leave:`bool`	if nonzero (default), call `BaseCache.on_leave` for each element cleared

def get(self, key): ¶

overrides pyzim.cache.BaseCache.get

Return the element that has been cached for this key.

Parameters
key:hashable	key for the element that should be returned

Returns
same as passed to `BaseCache.push`	the element

Raises
`KeyError`	if no element was cached for this key

def has(self, key): ¶

overrides pyzim.cache.BaseCache.has

Return True if an element is cached for the specific key.

Parameters
key:hashable	key of element that should be checked

Returns
`bool`	True if an element has been cached for this key

def push(self, key, element, allow_replacement=True): ¶

overrides pyzim.cache.BaseCache.push

Push an element for this key into this cache.

It is up for the cache to decide whether the element will actually be cached or not. If allow_replacement=False is set, no other element should be kicked from the cache.

Re-pushing an already cached element will not update the cached element.

Parameters
key:hashable	key which will be used to identify the element
element:any	element to cache
allow_replacement:`bool`	if this value is false, do not cache if this would kick another element from the cache

Returns
`bool`	True if the element is now cached, False otherwise

def remove(self, key, call_on_leave=True): ¶

overrides pyzim.cache.BaseCache.remove

If an element is cached for key, remove it from the cache.

Parameters
key:hashable	key of element to remove
call_on_leave:`bool`	if nonzero (default), call `BaseCache.on_leave` on the removed element

last_cache: pyzim.cache.LastAccessCache = ¶

the last-access cache

top_cache: pyzim.cache.TopAccessCache = ¶

the top-access cache

def _on_leave(self, key, value): ¶

A helper method that will be called whenever any element leaves one of the wrapped chaches.

It is used to ensure that even if HybridCache.on_leave is changed after init, the wrapped caches will call the new new function.

Parameters
key:any	the key of the element leaving the cache
value:any	value of the element leaving the cache