286 lines
9.8 KiB
Python
286 lines
9.8 KiB
Python
"""缓存管理器：支持过期时间、内存保护、持久化"""
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import os
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import json
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import hashlib
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import logging
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import threading
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import tempfile
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from pathlib import Path
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from datetime import datetime, timedelta
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from typing import Any, Optional, Dict
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from functools import wraps
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logger = logging.getLogger(__name__)
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# 缓存配置 - 使用 tempfile 获取安全的临时目录
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try:
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CACHE_DIR = Path(tempfile.gettempdir()) / "homework_cache"
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except Exception:
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CACHE_DIR = Path("/tmp/homework_cache")
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CACHE_EXPIRE_DAYS = 30 # 缓存过期天数
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MAX_MEMORY_CACHE_SIZE = 1000 # 内存缓存最大数量
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class CacheManager:
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"""
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缓存管理器：内存缓存 + 文件缓存
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- 内存缓存：快速访问，有大小限制
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- 文件缓存：持久化存储，支持过期时间
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- 异常安全：文件操作失败不影响主流程
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"""
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def __init__(self, cache_name: str, maxsize: int = MAX_MEMORY_CACHE_SIZE, expire_days: int = CACHE_EXPIRE_DAYS):
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"""
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初始化缓存管理器
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Args:
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cache_name: 缓存名称（用于区分不同类型的缓存）
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maxsize: 内存缓存最大数量
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expire_days: 缓存过期天数
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"""
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self.cache_name = cache_name
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self.maxsize = maxsize
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self.expire_days = expire_days
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# 内存缓存（使用字典 + 简单的LRU淘汰）
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self._memory_cache: Dict[str, Any] = {}
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self._cache_keys: list = [] # 记录访问顺序，用于LRU淘汰
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self._lock = threading.Lock() # 线程安全锁
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self._file_cache_enabled = True # 文件缓存是否可用
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# 文件缓存目录 - 带异常处理
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try:
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self.cache_dir = CACHE_DIR / cache_name
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self.cache_dir.mkdir(parents=True, exist_ok=True)
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# 测试写入权限
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test_file = self.cache_dir / ".test_write"
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test_file.write_text("test")
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test_file.unlink()
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logger.info(f"CacheManager initialized: {cache_name}, dir={self.cache_dir}")
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except Exception as e:
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logger.warning(f"File cache disabled due to permission error: {e}")
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self._file_cache_enabled = False
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logger.info(f"CacheManager initialized (memory only): {cache_name}")
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def _get_cache_key(self, key: str) -> str:
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"""生成缓存键（使用MD5哈希）"""
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return hashlib.md5(key.encode()).hexdigest()
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def _get_cache_file(self, cache_key: str) -> Path:
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"""获取缓存文件路径"""
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return self.cache_dir / f"{cache_key}.json"
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def _is_expired(self, cache_time: str) -> bool:
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"""检查缓存是否过期"""
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try:
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cached_dt = datetime.fromisoformat(cache_time)
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expire_dt = cached_dt + timedelta(days=self.expire_days)
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return datetime.now() > expire_dt
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except Exception:
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return True # 解析失败视为过期
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def _evict_lru(self):
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"""LRU淘汰：移除最久未使用的缓存项"""
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while len(self._memory_cache) >= self.maxsize and self._cache_keys:
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oldest_key = self._cache_keys.pop(0)
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if oldest_key in self._memory_cache:
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del self._memory_cache[oldest_key]
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logger.debug(f"LRU evicted: {oldest_key[:8]}...")
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def get(self, key: str) -> Optional[Any]:
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"""
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获取缓存
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优先级：内存缓存 > 文件缓存 > None
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Args:
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key: 缓存键
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Returns:
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缓存值，不存在或过期返回None
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"""
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cache_key = self._get_cache_key(key)
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# 1. 检查内存缓存（线程安全）
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with self._lock:
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if cache_key in self._memory_cache:
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# 更新访问顺序（移动到末尾）
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if cache_key in self._cache_keys:
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self._cache_keys.remove(cache_key)
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self._cache_keys.append(cache_key)
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logger.debug(f"Memory cache hit: {cache_key[:8]}...")
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return self._memory_cache[cache_key]
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# 2. 检查文件缓存（仅在文件缓存可用时）
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if self._file_cache_enabled:
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cache_file = self._get_cache_file(cache_key)
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if cache_file.exists():
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try:
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with open(cache_file, 'r', encoding='utf-8') as f:
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cached_data = json.load(f)
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# 检查是否过期
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if self._is_expired(cached_data.get("cache_time", "")):
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# 过期，删除文件
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try:
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cache_file.unlink()
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except Exception:
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pass
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logger.debug(f"File cache expired: {cache_key[:8]}...")
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return None
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# 未过期，加载到内存缓存
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with self._lock:
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self._evict_lru() # 淘汰旧的
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self._memory_cache[cache_key] = cached_data["data"]
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self._cache_keys.append(cache_key)
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logger.debug(f"File cache hit: {cache_key[:8]}...")
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return cached_data["data"]
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except Exception as e:
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logger.warning(f"Failed to read cache file: {e}")
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# 删除损坏的缓存文件
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try:
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cache_file.unlink()
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except Exception:
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pass
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return None
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return None
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def set(self, key: str, value: Any):
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"""
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设置缓存
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同时存入内存缓存和文件缓存
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Args:
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key: 缓存键
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value: 缓存值
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"""
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cache_key = self._get_cache_key(key)
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# 1. 存入内存缓存
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with self._lock:
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self._evict_lru() # 淘汰旧的
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self._memory_cache[cache_key] = value
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if cache_key in self._cache_keys:
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self._cache_keys.remove(cache_key)
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self._cache_keys.append(cache_key)
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# 2. 存入文件缓存（仅在文件缓存可用时）
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if self._file_cache_enabled:
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cache_file = self._get_cache_file(cache_key)
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try:
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cached_data = {
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"cache_time": datetime.now().isoformat(),
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"data": value
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}
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with open(cache_file, 'w', encoding='utf-8') as f:
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json.dump(cached_data, f, ensure_ascii=False, indent=2)
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logger.debug(f"Cache saved: {cache_key[:8]}...")
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except Exception as e:
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logger.warning(f"Failed to save cache file: {e}")
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def clear_expired(self):
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"""清理所有过期的文件缓存"""
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if not self._file_cache_enabled:
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return 0
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cleaned = 0
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try:
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for cache_file in self.cache_dir.glob("*.json"):
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try:
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with open(cache_file, 'r', encoding='utf-8') as f:
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cached_data = json.load(f)
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if self._is_expired(cached_data.get("cache_time", "")):
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cache_file.unlink()
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cleaned += 1
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except Exception:
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# 损坏的文件也删除
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try:
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cache_file.unlink()
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except Exception:
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pass
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cleaned += 1
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if cleaned > 0:
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logger.info(f"Cleaned {cleaned} expired cache files")
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except Exception as e:
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logger.error(f"Failed to clear expired cache: {e}")
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return cleaned
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def get_stats(self) -> dict:
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"""获取缓存统计信息"""
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memory_size = len(self._memory_cache)
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# 统计文件缓存数量
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file_size = 0
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if self._file_cache_enabled:
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try:
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file_size = len(list(self.cache_dir.glob("*.json")))
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except Exception:
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pass
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return {
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"cache_name": self.cache_name,
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"memory_cache_size": memory_size,
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"memory_cache_maxsize": self.maxsize,
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"file_cache_size": file_size,
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"file_cache_enabled": self._file_cache_enabled,
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"expire_days": self.expire_days
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}
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def cached(cache_manager: CacheManager):
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"""
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缓存装饰器
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用法：
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@cached(answer_doc_cache)
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def parse_answer_doc(url: str):
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# 解析逻辑
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return result
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"""
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def decorator(func):
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@wraps(func)
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def wrapper(*args, **kwargs):
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# 生成缓存键（使用函数名和参数）
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cache_key = f"{func.__name__}:{str(args)}:{str(kwargs)}"
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# 尝试从缓存获取
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cached_result = cache_manager.get(cache_key)
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if cached_result is not None:
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return cached_result
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# 缓存未命中，执行函数
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result = func(*args, **kwargs)
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# 存入缓存
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if result is not None:
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cache_manager.set(cache_key, result)
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return result
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return wrapper
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return decorator
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# 创建全局缓存实例
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answer_doc_cache = CacheManager(
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cache_name="answer_doc",
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maxsize=MAX_MEMORY_CACHE_SIZE,
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expire_days=CACHE_EXPIRE_DAYS
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)
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grade_standards_cache = CacheManager(
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cache_name="grade_standards",
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maxsize=100, # 评分标准缓存数量较少
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expire_days=CACHE_EXPIRE_DAYS
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)
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