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Proxy_Cache_DS.py
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Proxy_Cache_DS.py
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import collections
import os
class Node(object):
def __init__(self, name, freq):
self.name = name
self.freq = freq
self.next = None
self.prev = None
def getValue(self):
return self.name
class LinkedList(object):
def __init__(self):
self.head = None
self.tail = None
def append(self, node):
if self.head is None:
self.head = node
else:
self.tail.next = node
node.prev = self.tail
self.tail = node
def delete(self, node):
if node.prev:
node.prev.next = node.next
else:
self.head = node.next
if node.next:
node.next.prev = node.prev
else:
self.tail = node.prev
del node
def print_list(self):
curr = self.head
while curr is not None:
print(curr.name)
curr = curr.next
class LFUCache(object):
def __init__(self, capacity):
self.capa = capacity
self.size = 0
self.min_freq = 0
self.freqList = collections.defaultdict(LinkedList)
self.nameHash = {}
def getItem(self, name):
if name not in self.nameHash:
return -1
old_node = self.nameHash[name]
self.nameHash[name] = Node(name, old_node.freq)
self.freqList[old_node.freq].delete(old_node)
if not self.freqList[self.nameHash[name].freq].head:
del self.freqList[self.nameHash[name].freq]
if self.min_freq == self.nameHash[name].freq:
self.min_freq += 1
self.nameHash[name].freq += 1
self.freqList[self.nameHash[name].freq].append(self.nameHash[name])
return self.nameHash[name].freq
def insertItem(self, name):
if self.capa <= 0:
return
if self.getItem(name) != -1:
return
if self.size == self.capa:
# print("deleting")
n = self.freqList[self.min_freq].head
os.remove(n.name)
del self.nameHash[self.freqList[self.min_freq].head.name]
self.freqList[self.min_freq].delete(self.freqList[self.min_freq].head)
if not self.freqList[self.min_freq].head:
del self.freqList[self.min_freq]
self.size -= 1
self.min_freq = 1
self.nameHash[name] = Node(name, self.min_freq)
self.freqList[self.nameHash[name].freq].append(self.nameHash[name])
self.size += 1
def print_cache(cache):
for list_i in cache.freqList:
print("\nCache Item with frequency ",list_i)
print("-----------------------------------------------")
cache.freqList[list_i].print_list()