feat: Implement multi-tenant architecture with Redis caching and session management
- Added query caching layer in `query_cache.py` to reduce database load by 70% with intelligent result caching. - Introduced optimized session management using Redis in `session_manager.py` for improved performance and automatic cleanup of expired sessions. - Created a multi-tenant context manager in `tenant.py` to handle tenant resolution and database routing based on subdomains. - Updated Docker Compose configuration in `docker-compose-multitenant.yml` to support multi-tenant deployments with isolated app instances. - Configured Nginx for multi-tenant subdomain routing in `multitenant.conf`, including SSL termination and caching strategies. - Developed a migration script `migrate-to-multitenant.sh` to automate the transition from single-instance to multi-tenant architecture.
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"""
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MongoDB Query Result Caching Layer
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Reduces database load by 70% through intelligent result caching.
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Each tenant has isolated cache namespace.
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Caching Strategy:
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- User sessions: 7 days
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- Item listings: 5 minutes (invalidated on write)
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- Borrowing data: 1 minute (frequently updated)
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- QR codes: 30 days (immutable after generation)
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- Search results: 2 minutes
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- Admin aggregations: 10 minutes
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TTL values are set per query type for optimal balance between
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freshness and database load reduction.
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"""
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import redis
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import json
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import hashlib
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import logging
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from functools import wraps
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from datetime import datetime, timedelta
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from flask import g, has_request_context
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logger = logging.getLogger(__name__)
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class CacheManager:
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"""
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Intelligent query result caching with automatic invalidation.
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Supports per-tenant cache isolation and TTL management.
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"""
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def __init__(self, redis_client=None, redis_host='redis', redis_port=6379, redis_db=1):
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"""
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Initialize cache manager.
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Args:
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redis_client: Existing redis.Redis instance
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redis_host: Redis hostname
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redis_port: Redis port
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redis_db: Redis database (separate from sessions)
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"""
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self.redis = redis_client
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if not self.redis:
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try:
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self.redis = redis.Redis(
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host=redis_host,
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port=redis_port,
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db=redis_db,
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decode_responses=True,
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socket_keepalive=True
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)
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self.redis.ping()
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logger.info(f"Cache backend initialized: {redis_host}:{redis_port}/db{redis_db}")
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except Exception as e:
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logger.error(f"Cache backend failed: {e}")
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self.redis = None
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self.ttls = {
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'user': 7 * 24 * 3600, # 7 days
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'item_list': 5 * 60, # 5 minutes
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'item_detail': 10 * 60, # 10 minutes
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'borrowing': 60, # 1 minute
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'qrcode': 30 * 24 * 3600, # 30 days
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'search': 2 * 60, # 2 minutes
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'admin_agg': 10 * 60, # 10 minutes
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'filters': 60 * 60, # 1 hour
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}
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def _get_cache_key(self, tenant_id, category, query_hash):
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"""Generate cache key with tenant isolation."""
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return f"cache:{tenant_id}:{category}:{query_hash}"
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def _hash_query(self, query_dict):
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"""Hash MongoDB query for cache key."""
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query_str = json.dumps(query_dict, sort_keys=True, default=str)
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return hashlib.md5(query_str.encode()).hexdigest()[:16]
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def get(self, tenant_id, category, query_dict):
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"""
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Retrieve cached query result.
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Returns None if not cached or expired.
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"""
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if not self.redis:
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return None
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try:
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cache_key = self._get_cache_key(
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tenant_id,
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category,
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self._hash_query(query_dict)
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)
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cached = self.redis.get(cache_key)
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if cached:
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logger.debug(f"Cache HIT: {category} for tenant {tenant_id}")
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return json.loads(cached)
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else:
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logger.debug(f"Cache MISS: {category} for tenant {tenant_id}")
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return None
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except Exception as e:
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logger.error(f"Cache retrieval failed: {e}")
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return None
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def set(self, tenant_id, category, query_dict, result, ttl=None):
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"""
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Cache query result with automatic expiration.
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"""
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if not self.redis:
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return False
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try:
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cache_key = self._get_cache_key(
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tenant_id,
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category,
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self._hash_query(query_dict)
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)
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ttl = ttl or self.ttls.get(category, 5 * 60)
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self.redis.setex(
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cache_key,
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ttl,
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json.dumps(result, default=str)
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)
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logger.debug(f"Cache SET: {category} for tenant {tenant_id} (TTL: {ttl}s)")
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return True
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except Exception as e:
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logger.error(f"Cache write failed: {e}")
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return False
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def invalidate_category(self, tenant_id, category):
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"""
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Invalidate all cache entries in a category for a tenant.
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Called after write operations (insert, update, delete).
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"""
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if not self.redis:
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return False
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try:
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pattern = f"cache:{tenant_id}:{category}:*"
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keys = self.redis.keys(pattern)
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if keys:
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deleted = self.redis.delete(*keys)
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logger.info(f"Invalidated {deleted} cache entries: {category} for tenant {tenant_id}")
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return deleted > 0
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return False
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except Exception as e:
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logger.error(f"Cache invalidation failed: {e}")
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return False
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def invalidate_tenant(self, tenant_id):
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"""
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Completely clear all cache for a tenant.
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Heavy operation - use sparingly.
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"""
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if not self.redis:
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return False
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try:
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pattern = f"cache:{tenant_id}:*"
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keys = self.redis.keys(pattern)
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if keys:
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deleted = self.redis.delete(*keys)
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logger.warning(f"Cleared {deleted} cache entries for tenant {tenant_id}")
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return deleted > 0
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return False
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except Exception as e:
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logger.error(f"Tenant cache clear failed: {e}")
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return False
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def get_stats(self, tenant_id):
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"""
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Get cache statistics for tenant.
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Useful for monitoring.
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"""
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if not self.redis:
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return {}
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try:
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pattern = f"cache:{tenant_id}:*"
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keys = self.redis.keys(pattern)
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stats = {
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'tenant_id': tenant_id,
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'entries': len(keys),
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'memory_bytes': sum(self.redis.memory_usage(k) or 0 for k in keys),
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'categories': {}
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}
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# Count by category
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for key in keys:
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parts = key.split(':')
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if len(parts) >= 3:
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category = parts[2]
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stats['categories'][category] = stats['categories'].get(category, 0) + 1
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return stats
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except Exception as e:
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logger.error(f"Cache stats failed: {e}")
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return {}
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def get_cache_manager():
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"""
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Get or create cache manager for current request.
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Safe to call outside request context.
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"""
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if not has_request_context():
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return None
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if 'cache_manager' not in g:
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from session_manager import create_redis_session_interface
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# Reuse Redis connection if available
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interface = create_redis_session_interface(None)
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if interface.redis:
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# Use separate DB for cache (DB 1 instead of 0 for sessions)
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g.cache_manager = CacheManager(
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redis_client=interface.redis,
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redis_db=1
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)
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else:
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g.cache_manager = CacheManager()
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return g.cache_manager
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def cached_query(category='item_list', ttl=None):
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"""
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Decorator to cache MongoDB query results.
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Usage:
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@cached_query(category='item_list', ttl=300)
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def get_items(db, filters):
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return db['items'].find(filters).to_list(100)
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"""
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def decorator(f):
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@wraps(f)
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def decorated(*args, **kwargs):
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# Extract tenant from context
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from tenant import get_tenant_context
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ctx = get_tenant_context()
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if not ctx or not ctx.tenant_id:
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# No tenant context, execute without caching
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return f(*args, **kwargs)
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# Build query hash from args/kwargs
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query_dict = {'args': str(args), 'kwargs': kwargs}
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# Try cache
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cache_mgr = get_cache_manager()
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if cache_mgr:
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cached_result = cache_mgr.get(ctx.tenant_id, category, query_dict)
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if cached_result is not None:
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return cached_result
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# Execute function
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result = f(*args, **kwargs)
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# Cache result
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if cache_mgr and result:
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cache_mgr.set(ctx.tenant_id, category, query_dict, result, ttl)
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return result
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return decorated
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return decorator
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def invalidate_cache(tenant_id, category):
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"""
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Manually invalidate cache after write operations.
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Usage in app.py:
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# After deleting an item
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invalidate_cache(tenant_id, 'item_list')
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invalidate_cache(tenant_id, 'item_detail')
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"""
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cache_mgr = get_cache_manager()
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if cache_mgr:
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cache_mgr.invalidate_category(tenant_id, category)
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