Todd
224
web/backend/cache_manager.py
Normal file
224
web/backend/cache_manager.py
Normal file
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"""
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Redis-based cache manager for Media Downloader API
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Provides caching for expensive queries with configurable TTL
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"""
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import json
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import sys
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from pathlib import Path
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from typing import Any, Optional, Callable
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from functools import wraps
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import redis
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from redis.exceptions import RedisError
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# Add parent path to allow imports from modules
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sys.path.insert(0, str(Path(__file__).parent.parent.parent))
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from modules.universal_logger import get_logger
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from web.backend.core.config import settings
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logger = get_logger('CacheManager')
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class CacheManager:
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"""Redis cache manager with automatic connection handling"""
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def __init__(self, host: str = '127.0.0.1', port: int = 6379, db: int = 0, ttl: int = 300):
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"""
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Initialize cache manager
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Args:
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host: Redis host (default: 127.0.0.1)
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port: Redis port (default: 6379)
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db: Redis database number (default: 0)
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ttl: Default TTL in seconds (default: 300 = 5 minutes)
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"""
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self.host = host
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self.port = port
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self.db = db
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self.default_ttl = ttl
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self._redis = None
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self._connect()
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def _connect(self):
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"""Connect to Redis with error handling"""
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try:
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self._redis = redis.Redis(
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host=self.host,
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port=self.port,
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db=self.db,
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decode_responses=True,
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socket_connect_timeout=2,
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socket_timeout=2
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)
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# Test connection
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self._redis.ping()
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logger.info(f"Connected to Redis at {self.host}:{self.port}", module="Redis")
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except RedisError as e:
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logger.warning(f"Redis connection failed: {e}. Caching disabled.", module="Redis")
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self._redis = None
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@property
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def is_available(self) -> bool:
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"""Check if Redis is available"""
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if self._redis is None:
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return False
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try:
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self._redis.ping()
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return True
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except RedisError:
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return False
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def get(self, key: str) -> Optional[Any]:
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"""
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Get value from cache
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Args:
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key: Cache key
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Returns:
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Cached value (deserialized from JSON) or None if not found/error
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"""
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if not self.is_available:
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return None
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try:
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value = self._redis.get(key)
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if value is None:
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return None
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return json.loads(value)
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except (RedisError, json.JSONDecodeError) as e:
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logger.warning(f"Cache get error for key '{key}': {e}", module="Cache")
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return None
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def set(self, key: str, value: Any, ttl: Optional[int] = None):
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"""
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Set value in cache
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Args:
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key: Cache key
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value: Value to cache (will be JSON serialized)
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ttl: TTL in seconds (default: use default_ttl)
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"""
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if not self.is_available:
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return
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ttl = ttl if ttl is not None else self.default_ttl
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try:
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serialized = json.dumps(value)
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self._redis.setex(key, ttl, serialized)
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except (RedisError, TypeError) as e:
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logger.warning(f"Cache set error for key '{key}': {e}", module="Cache")
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def delete(self, key: str):
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"""
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Delete key from cache
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Args:
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key: Cache key to delete
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"""
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if not self.is_available:
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return
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try:
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self._redis.delete(key)
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except RedisError as e:
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logger.warning(f"Cache delete error for key '{key}': {e}", module="Cache")
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def clear(self, pattern: str = "*"):
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"""
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Clear cache keys matching pattern
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Args:
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pattern: Redis key pattern (default: "*" clears all)
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"""
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if not self.is_available:
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return
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try:
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keys = self._redis.keys(pattern)
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if keys:
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self._redis.delete(*keys)
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logger.info(f"Cleared {len(keys)} cache keys matching '{pattern}'", module="Cache")
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except RedisError as e:
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logger.warning(f"Cache clear error for pattern '{pattern}': {e}", module="Cache")
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def cached(self, key_prefix: str, ttl: Optional[int] = None):
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"""
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Decorator for caching function results
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Args:
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key_prefix: Prefix for cache key (full key includes function args)
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ttl: TTL in seconds (default: use default_ttl)
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Example:
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@cache_manager.cached('stats', ttl=300)
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def get_download_stats(platform: str, days: int):
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# Expensive query
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return stats
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"""
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def decorator(func: Callable) -> Callable:
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@wraps(func)
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async def async_wrapper(*args, **kwargs):
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# Build cache key from function args
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cache_key = f"{key_prefix}:{func.__name__}:{hash((args, tuple(sorted(kwargs.items()))))}"
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# Try to get from cache
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cached_result = self.get(cache_key)
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if cached_result is not None:
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logger.debug(f"Cache HIT: {cache_key}", module="Cache")
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return cached_result
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# Cache miss - execute function
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logger.debug(f"Cache MISS: {cache_key}", module="Cache")
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result = await func(*args, **kwargs)
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# Store in cache
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self.set(cache_key, result, ttl)
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return result
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@wraps(func)
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def sync_wrapper(*args, **kwargs):
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# Build cache key from function args
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cache_key = f"{key_prefix}:{func.__name__}:{hash((args, tuple(sorted(kwargs.items()))))}"
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# Try to get from cache
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cached_result = self.get(cache_key)
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if cached_result is not None:
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logger.debug(f"Cache HIT: {cache_key}", module="Cache")
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return cached_result
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# Cache miss - execute function
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||||
logger.debug(f"Cache MISS: {cache_key}", module="Cache")
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result = func(*args, **kwargs)
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# Store in cache
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self.set(cache_key, result, ttl)
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return result
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# Return appropriate wrapper based on function type
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import asyncio
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if asyncio.iscoroutinefunction(func):
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return async_wrapper
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else:
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return sync_wrapper
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return decorator
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||||
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||||
# Global cache manager instance (use centralized config)
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||||
cache_manager = CacheManager(
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||||
host=settings.REDIS_HOST,
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||||
port=settings.REDIS_PORT,
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||||
db=settings.REDIS_DB,
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||||
ttl=settings.REDIS_TTL
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||||
)
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||||
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||||
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def invalidate_download_cache():
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"""Invalidate all download-related caches"""
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||||
cache_manager.clear("downloads:*")
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cache_manager.clear("stats:*")
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cache_manager.clear("filters:*")
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logger.info("Invalidated download-related caches", module="Cache")
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