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simple_cache.py
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simple_cache.py
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#!/usr/bin/env python3
"""
Problem:
Implement a simple in memory cache with the following interface.
public interface Cache {
public string get(key);
public void set(key, value);
public int getMaxSize();
public void setMaxSize(size);
public int getCurrentCacheSize();
}
"""
import random
class SimpleCache(object):
keys = None
values = None
maxSize = 50
def __init__(self):
self.keys = []
self.values = {}
def get(self, key):
""" get a key """
return self.values[key]
def set(self, key, value):
""" set a key """
# if the cache is full, drop the oldest entry
if len(self.keys) >= self.maxSize:
self.values.pop(self.keys.pop(0))
if key not in self.keys:
self.keys.append(key)
self.values[key] = value
def getMaxSize(self):
""" return max size of cache in items """
return self.maxSize
def setMaxSize(self, size):
""" set max size of cache in items """
self.maxSize = size
# if the new maxSize is less than the current size of the cache, purge all the oldest entries
while len(self.keys) > self.maxSize:
self.values.pop(self.keys.pop(0))
def getCurrentCacheSize(self):
""" get current amount of items in cache """
return len(self.keys)
if __name__ == "__main__":
cache = SimpleCache()
# fill up the cache (default is 50)
for x in range(200):
cache.set("key_{}".format(x), 'lhslksdhflksdhfkldh!!!{}'.format(random.randint(0,500)))
print("I have {} items in cache".format(cache.getCurrentCacheSize()))
# old entries got bumped off
try:
value = cache.get("key_1")
except KeyError:
print("key_1 was expired")
pass
print("key_160 value is : {}".format(cache.get("key_160")))
cache.setMaxSize(10)
print("I have {} items in cache".format(cache.getCurrentCacheSize()))
# old entries got bumped off
try:
value = cache.get("key_160")
except KeyError:
print("key_160 was expired")
pass