What is LRU caching and how can I implement it in Python?

What is LRU caching and how can I implement it in Python?

LRU stands for Least Recently Used. It's a caching algorithm that removes the least recently used items first. In Python, you can implement it using a dictionary and a doubly linked list or by using the built-in functools.lru_cache decorator.

Can you show me a simple example of LRU caching in Python?

Sure! Here's a simple example using functools.lru_cache:

from functools import lru_cache

@lru_cache(maxsize=3)
def get_data(x):
    print(f'Fetching data for {x}')
    return x * 2

print(get_data(1))  # Fetching data for 1
print(get_data(2))  # Fetching data for 2
print(get_data(3))  # Fetching data for 3
print(get_data(1))  # Cached result
print(get_data(4))  # Fetching data for 4, evicts 2

What happens when the cache reaches its maximum size?

When the cache reaches its maximum size, the least recently used item is removed to make space for the new item. This ensures that the cache retains the most relevant data.