以下是一个基于Python实现的缓存淘汰替换策略算法,该算法将缓存分区,并根据不同分区的优先级进行淘汰,同时会自适应地调整缓存汰换的时机和力度,还会与GPTCache自带的LRU和FIFO策略进行对比。
import time
from gptcache.manager import CacheBase, VectorBase, get_data_manager
from gptcache.processor.pre import get_prompt
from gptcache.adapter.api import init_similar_cache
from gptcache.strategy import LRUCacheStrategy, FIFOCacheStrategy
# 定义缓存类
class CustomCache:
def __init__(self, capacity):
self.capacity = capacity
self.high_priority = {}
self.hot_window = {}
self.medium_priority = {}
self.other_cache = {}
self.total_count = 0
def add(self, key, value, category):
# 初始化缓存项字段
cache_item = {
'value': value,
'freshness': 1.0,
'activity': 1,
'timestamp': time.time(),
'eviction_rate': 0.0,
'category': category
}
self.total_count += 1
# 根据类别分配到不同分区
if category == 'high':
self.high_priority[key] = cache_item
elif category == 'hot':
self.hot_window[key] = cache_item
elif category == 'medium':
self.medium_priority[key] = cache_item
else:
self.other_cache[key] = cache_item
# 检查是否需要淘汰
if self.total_count > self.capacity:
self.evict()
def get(self, key):
for cache in [self.high_priority, self.hot_window, self.medium_priority, self.other_cache]:
if key in cache:
cache[key]['activity'] += 1
cache[key]['timestamp'] = time.time()
cache[key]['freshness'] = 1.0
return cache[key]['value']
return None
def evict(self):
# 自适应调整淘汰时机和力度
# 这里简单模拟根据当前时间进行调整,实际可根据季节性或周期性数据调整
current_time = time.time()
if current_time % 3600 < 1800: # 假设每小时前半段淘汰力度大
eviction_count = 2
else:
eviction_count = 1
while self.total_count > self.capacity and eviction_count > 0:
if self.other_cache:
key = next(iter(self.other_cache))
del self.other_cache[key]
elif self.medium_priority:
key = next(iter(self.medium_priority))
del self.medium_priority[key]
elif self.hot_window:
# 淘汰热点窗口中活跃度最低的项
min_activity_key = min(self.hot_window, key=lambda k: self.hot_window[k]['activity'])
del self.hot_window[min_activity_key]
elif self.high_priority:
# 淘汰高优先级中最旧的项
oldest_key = min(self.high_priority, key=lambda k: self.high_priority[k]['timestamp'])
del self.high_priority[oldest_key]
self.total_count -= 1
eviction_count -= 1
# 对比测试函数
def compare_strategies():
capacity = 10
# 自定义策略
custom_cache = CustomCache(capacity)
# LRU策略
lru_strategy = LRUCacheStrategy(capacity)
lru_cache_base = CacheBase('sqlite')
lru_vector_base = VectorBase('faiss', dimension=128)
lru_data_manager = get_data_manager(lru_cache_base, lru_vector_base, lru_strategy)
init_similar_cache(data_manager=lru_data_manager, pre_embedding_func=get_prompt)
# FIFO策略
fifo_strategy = FIFOCacheStrategy(capacity)
fifo_cache_base = CacheBase('sqlite')
fifo_vector_base = VectorBase('faiss', dimension=128)
fifo_data_manager = get_data_manager(fifo_cache_base, fifo_vector_base, fifo_strategy)
init_similar_cache(data_manager=fifo_data_manager, pre_embedding_func=get_prompt)
# 模拟数据访问
data = [(i, f"value_{i}", 'high' if i < 3 else 'medium' if i < 6 else 'hot' if i < 8 else 'other') for i in range(20)]
custom_hits = 0
lru_hits = 0
fifo_hits = 0
for key, value, category in data:
# 自定义策略
if custom_cache.get(key) is None:
custom_cache.add(key, value, category)
else:
custom_hits += 1
# LRU策略
if lru_data_manager.get_data(key, None) is None:
lru_data_manager.save(key, value, None, None)
else:
lru_hits += 1
# FIFO策略
if fifo_data_manager.get_data(key, None) is None:
fifo_data_manager.save(key, value, None, None)
else:
fifo_hits += 1
print(f"Custom Cache Hits: {custom_hits}")
print(f"LRU Cache Hits: {lru_hits}")
print(f"FIFO Cache Hits: {fifo_hits}")
if __name__ == "__main__":
compare_strategies()
代码说明:
-
CustomCache类:
__init__
:初始化缓存分区和容量。add
:将缓存项添加到相应的分区,并在需要时调用evict
方法进行淘汰。get
:根据键查找缓存项,并更新其活跃度、时间戳和新鲜度。evict
:根据分区优先级进行淘汰,同时自适应地调整淘汰的时机和力度。
-
compare_strategies函数:
- 初始化自定义缓存、LRU缓存和FIFO缓存。
- 模拟数据访问,记录每个缓存的命中次数。
- 输出每个缓存的命中次数。
注意事项:
- 代码中使用了GPTCache库,需要确保已经安装了该库。
- 自适应调整淘汰时机和力度的逻辑可以根据实际需求进行修改,这里只是简单模拟了每小时前半段淘汰力度大的情况。