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import json |
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import os |
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import time |
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from typing import Optional, Dict, Any |
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class AnswersCache: |
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def __init__(self, filename: str = "cache.json", max_size: int = 1000): |
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self.filename = filename |
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self.max_size = max_size |
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self.cache: Dict[str, Dict[str, Any]] = {} |
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self._load_cache() |
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def _load_cache(self): |
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"""Load cache from file if it exists""" |
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if os.path.exists(self.filename): |
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try: |
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with open(self.filename, 'r') as f: |
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self.cache = json.load(f) |
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except (json.JSONDecodeError, FileNotFoundError): |
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self.cache = {} |
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def _save_cache(self): |
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"""Save cache to file""" |
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with open(self.filename, 'w') as f: |
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json.dump(self.cache, f, indent=2) |
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def set(self, key: str, value: str, ttl: Optional[int] = None): |
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"""Set a key-value pair with optional TTL (time to live in seconds)""" |
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if len(self.cache) >= self.max_size: |
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self._evict_oldest() |
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cache_entry = { |
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'value': value, |
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'created_at': time.time(), |
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'ttl': ttl |
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} |
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self.cache[key] = cache_entry |
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self._save_cache() |
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def get(self, key: str) -> Optional[str]: |
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"""Get value for key, returns None if not found or expired""" |
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if key not in self.cache: |
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return None |
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entry = self.cache[key] |
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if entry['ttl'] is not None: |
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if time.time() - entry['created_at'] > entry['ttl']: |
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self.delete(key) |
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return None |
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return entry['value'] |
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def delete(self, key: str): |
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"""Delete a key from cache""" |
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if key in self.cache: |
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del self.cache[key] |
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self._save_cache() |
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def clear(self): |
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"""Clear all cache entries""" |
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self.cache = {} |
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self._save_cache() |
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def _evict_oldest(self): |
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"""Remove the oldest entry when cache is full""" |
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if not self.cache: |
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return |
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oldest_key = min(self.cache.keys(), |
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key=lambda k: self.cache[k]['created_at']) |
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del self.cache[oldest_key] |
