class Node(object):
def __init__(self, results):
self.results = results
self.prev = None
self.next = None
class LinkedList(object):
del __init__(self):
self.head = None
self.tail = None
def move_to_front(self, node): # ...
def append_to_front(self, node): # ...
def remove_from_tail(self): # ...
class Cache(obejct):
def __init__(self, MAX_SIZE):
self.MAX_SIZE = MAX_SIZE
self.size = 0
self.lookup = {}
self.linked_list = LinkedList()
def get(self, query)
'''
Get the stored query result from the cache
Accsssing a node updates its position to the front of the LRU list
'''
node = self.lookup.get(query)
if node is None:
return None
self.linked_list.move_to_front(node)
return node.results
def set(self, resuts, query):
'''Set the results for the given query key in the cache.
When updating an entry, updates its position to the front of the LRU list
If the entry is new and the cache is at capacity, remove the oldest entry before the new entry is added '''
node = self.lookup.get(query)
if node is not None:
node.results = results
self.linked_list.move_to_front(node)
else:
if self.size == self.MAX_SIZE
self.lookup.pop(self.linked_list.tail.query, None)
self.linked_list.remove_from_tail()
else:
self.size += 1
new_node = Node(results)
self.linked_list.append_to_front(new_node)
self.lookup[query] = new_node