Issue : Incorrect type hint in LinkedList class of query_cache_snippets.py #1094
Description
The Cache class' get and set methods refer to a member named lookup that is defined as a dictionary: self.lookup = {}. Therefore, the line node = self.lookup[query] will throw an exception if query is not present in the cache. The code should use self.lookup.get(query) instead which will return None instead of throwing an exception. Additionally, the Cache class refers to a member called map which is never defined. It is likely a typo and it should be lookup.
class Cache(object):
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.
Accessing 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, results, query):
"""Set the result 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, removes the oldest entry
before the new entry is added.
"""
node = self.lookup.get(query)
if node is not None:
# Key exists in cache, update the value
node.results = results
self.linked_list.move_to_front(node)
else:
# Key does not exist in cache
if self.size == self.MAX_SIZE:
# Remove the oldest entry from the linked list and lookup
self.lookup.pop(self.linked_list.tail.query, None)
self.linked_list.remove_from_tail()
else:
self.size += 1
# Add the new key and value
new_node = Node(query, results)
self.linked_list.append_to_front(new_node)
self.lookup[query] = new_node