284 lines
11 KiB
Python
284 lines
11 KiB
Python
"""
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Persistent Research Cache Service
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Provides database-backed caching for research results to survive server restarts
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and provide better cache management across multiple instances.
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"""
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import hashlib
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import json
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import sqlite3
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from typing import Dict, Any, Optional, List
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from datetime import datetime, timedelta
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from pathlib import Path
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from loguru import logger
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class PersistentResearchCache:
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"""Database-backed cache for research results with exact keyword matching."""
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def __init__(self, db_path: str = "research_cache.db", max_cache_size: int = 1000, cache_ttl_hours: int = 24):
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"""
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Initialize the persistent research cache.
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Args:
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db_path: Path to SQLite database file
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max_cache_size: Maximum number of cached entries
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cache_ttl_hours: Time-to-live for cache entries in hours
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"""
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self.db_path = db_path
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self.max_cache_size = max_cache_size
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self.cache_ttl = timedelta(hours=cache_ttl_hours)
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# Ensure database directory exists
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Path(db_path).parent.mkdir(parents=True, exist_ok=True)
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# Initialize database
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self._init_database()
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def _init_database(self):
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"""Initialize the SQLite database with required tables."""
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with sqlite3.connect(self.db_path) as conn:
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conn.execute("""
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CREATE TABLE IF NOT EXISTS research_cache (
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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cache_key TEXT UNIQUE NOT NULL,
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keywords TEXT NOT NULL,
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industry TEXT NOT NULL,
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target_audience TEXT NOT NULL,
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result_data TEXT NOT NULL,
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
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expires_at TIMESTAMP NOT NULL,
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access_count INTEGER DEFAULT 0,
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last_accessed TIMESTAMP DEFAULT CURRENT_TIMESTAMP
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)
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""")
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# Create indexes for better performance
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conn.execute("CREATE INDEX IF NOT EXISTS idx_cache_key ON research_cache(cache_key)")
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conn.execute("CREATE INDEX IF NOT EXISTS idx_expires_at ON research_cache(expires_at)")
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conn.execute("CREATE INDEX IF NOT EXISTS idx_created_at ON research_cache(created_at)")
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conn.commit()
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def _generate_cache_key(self, keywords: List[str], industry: str, target_audience: str) -> str:
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"""
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Generate a cache key based on exact keyword match.
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Args:
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keywords: List of research keywords
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industry: Industry context
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target_audience: Target audience context
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Returns:
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MD5 hash of the normalized parameters
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"""
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# Normalize and sort keywords for consistent hashing
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normalized_keywords = sorted([kw.lower().strip() for kw in keywords])
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normalized_industry = industry.lower().strip() if industry else "general"
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normalized_audience = target_audience.lower().strip() if target_audience else "general"
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# Create a consistent string representation
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cache_string = f"{normalized_keywords}|{normalized_industry}|{normalized_audience}"
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# Generate MD5 hash
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return hashlib.md5(cache_string.encode('utf-8')).hexdigest()
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def _cleanup_expired_entries(self):
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"""Remove expired cache entries from database."""
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with sqlite3.connect(self.db_path) as conn:
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cursor = conn.execute(
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"DELETE FROM research_cache WHERE expires_at < ?",
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(datetime.now().isoformat(),)
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)
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deleted_count = cursor.rowcount
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if deleted_count > 0:
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logger.debug(f"Removed {deleted_count} expired cache entries")
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conn.commit()
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def _evict_oldest_entries(self, num_to_evict: int):
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"""Evict the oldest cache entries when cache is full."""
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with sqlite3.connect(self.db_path) as conn:
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# Get oldest entries by creation time
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cursor = conn.execute("""
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SELECT id FROM research_cache
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ORDER BY created_at ASC
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LIMIT ?
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""", (num_to_evict,))
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old_ids = [row[0] for row in cursor.fetchall()]
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if old_ids:
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placeholders = ','.join(['?' for _ in old_ids])
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conn.execute(f"DELETE FROM research_cache WHERE id IN ({placeholders})", old_ids)
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logger.debug(f"Evicted {len(old_ids)} oldest cache entries")
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conn.commit()
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def get_cached_result(self, keywords: List[str], industry: str, target_audience: str) -> Optional[Dict[str, Any]]:
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"""
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Get cached research result for exact keyword match.
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Args:
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keywords: List of research keywords
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industry: Industry context
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target_audience: Target audience context
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Returns:
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Cached research result if found and valid, None otherwise
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"""
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cache_key = self._generate_cache_key(keywords, industry, target_audience)
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with sqlite3.connect(self.db_path) as conn:
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cursor = conn.execute("""
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SELECT result_data, expires_at FROM research_cache
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WHERE cache_key = ? AND expires_at > ?
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""", (cache_key, datetime.now().isoformat()))
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row = cursor.fetchone()
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if row is None:
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logger.debug(f"Cache miss for keywords: {keywords}")
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return None
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# Update access statistics
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conn.execute("""
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UPDATE research_cache
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SET access_count = access_count + 1, last_accessed = CURRENT_TIMESTAMP
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WHERE cache_key = ?
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""", (cache_key,))
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conn.commit()
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try:
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result_data = json.loads(row[0])
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logger.info(f"Cache hit for keywords: {keywords} (saved API call)")
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return result_data
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except json.JSONDecodeError:
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logger.error(f"Invalid JSON in cache for keywords: {keywords}")
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# Remove invalid entry
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conn.execute("DELETE FROM research_cache WHERE cache_key = ?", (cache_key,))
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conn.commit()
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return None
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def cache_result(self, keywords: List[str], industry: str, target_audience: str, result: Dict[str, Any]):
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"""
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Cache a research result.
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Args:
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keywords: List of research keywords
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industry: Industry context
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target_audience: Target audience context
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result: Research result to cache
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"""
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cache_key = self._generate_cache_key(keywords, industry, target_audience)
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# Cleanup expired entries first
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self._cleanup_expired_entries()
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# Check if cache is full and evict if necessary
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with sqlite3.connect(self.db_path) as conn:
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cursor = conn.execute("SELECT COUNT(*) FROM research_cache")
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current_count = cursor.fetchone()[0]
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if current_count >= self.max_cache_size:
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num_to_evict = current_count - self.max_cache_size + 1
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self._evict_oldest_entries(num_to_evict)
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# Store the result
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expires_at = datetime.now() + self.cache_ttl
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with sqlite3.connect(self.db_path) as conn:
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conn.execute("""
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INSERT OR REPLACE INTO research_cache
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(cache_key, keywords, industry, target_audience, result_data, expires_at)
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VALUES (?, ?, ?, ?, ?, ?)
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""", (
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cache_key,
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json.dumps(keywords),
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industry,
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target_audience,
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json.dumps(result),
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expires_at.isoformat()
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))
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conn.commit()
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logger.info(f"Cached research result for keywords: {keywords}")
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def get_cache_stats(self) -> Dict[str, Any]:
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"""Get cache statistics."""
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self._cleanup_expired_entries()
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with sqlite3.connect(self.db_path) as conn:
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# Get basic stats
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cursor = conn.execute("SELECT COUNT(*) FROM research_cache")
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total_entries = cursor.fetchone()[0]
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cursor = conn.execute("SELECT COUNT(*) FROM research_cache WHERE expires_at > ?", (datetime.now().isoformat(),))
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valid_entries = cursor.fetchone()[0]
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# Get most accessed entries
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cursor = conn.execute("""
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SELECT keywords, industry, target_audience, access_count, created_at
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FROM research_cache
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ORDER BY access_count DESC
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LIMIT 10
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""")
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top_entries = [
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{
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'keywords': json.loads(row[0]),
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'industry': row[1],
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'target_audience': row[2],
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'access_count': row[3],
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'created_at': row[4]
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}
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for row in cursor.fetchall()
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]
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# Get database size
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cursor = conn.execute("SELECT page_count * page_size as size FROM pragma_page_count(), pragma_page_size()")
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db_size_bytes = cursor.fetchone()[0]
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db_size_mb = db_size_bytes / (1024 * 1024)
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return {
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'total_entries': total_entries,
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'valid_entries': valid_entries,
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'expired_entries': total_entries - valid_entries,
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'max_size': self.max_cache_size,
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'ttl_hours': self.cache_ttl.total_seconds() / 3600,
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'database_size_mb': round(db_size_mb, 2),
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'top_accessed_entries': top_entries
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}
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def clear_cache(self):
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"""Clear all cached entries."""
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with sqlite3.connect(self.db_path) as conn:
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conn.execute("DELETE FROM research_cache")
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conn.commit()
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logger.info("Research cache cleared")
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def get_cache_entries(self, limit: int = 50) -> List[Dict[str, Any]]:
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"""Get recent cache entries for debugging."""
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with sqlite3.connect(self.db_path) as conn:
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cursor = conn.execute("""
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SELECT keywords, industry, target_audience, created_at, expires_at, access_count
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FROM research_cache
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ORDER BY created_at DESC
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LIMIT ?
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""", (limit,))
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return [
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{
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'keywords': json.loads(row[0]),
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'industry': row[1],
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'target_audience': row[2],
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'created_at': row[3],
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'expires_at': row[4],
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'access_count': row[5]
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}
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for row in cursor.fetchall()
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]
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# Global persistent cache instance
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persistent_research_cache = PersistentResearchCache()
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