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55 lines
1.7 KiB
Python
55 lines
1.7 KiB
Python
"""
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In-memory TTL cache for RAG responses.
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Keyed on (collection_name, normalised query).
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Only used for stateless queries (no conversation history).
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"""
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import hashlib
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import time
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from typing import Any, Optional
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_store: dict[str, tuple[Any, float]] = {}
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_index: dict[str, set[str]] = {} # collection_name → set of cache keys
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_MAX_ENTRIES = 500
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TTL = 6 * 3600 # 6 hours
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_set_ctor = set # save builtin before it's shadowed by our module-level `set` function
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def _make_key(collection_name: str, query: str) -> str:
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raw = f"{collection_name}::{query.lower().strip()}"
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return hashlib.sha256(raw.encode()).hexdigest()
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def get(collection_name: str, query: str) -> Optional[Any]:
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k = _make_key(collection_name, query)
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entry = _store.get(k)
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if entry is None:
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return None
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value, expires_at = entry
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if time.monotonic() > expires_at:
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_store.pop(k, None)
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_index.get(collection_name, _set_ctor()).discard(k)
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return None
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return value
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def set(collection_name: str, query: str, value: Any) -> None:
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if len(_store) >= _MAX_ENTRIES:
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now = time.monotonic()
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expired = [k for k, (_, exp) in _store.items() if exp < now]
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for k in expired:
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_store.pop(k, None)
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if len(_store) >= _MAX_ENTRIES:
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oldest = min(_store, key=lambda k: _store[k][1])
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_store.pop(oldest, None)
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k = _make_key(collection_name, query)
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_store[k] = (value, time.monotonic() + TTL)
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_index.setdefault(collection_name, _set_ctor()).add(k)
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def invalidate(collection_name: str) -> int:
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"""Drop all cached entries for a collection — call after any KB update."""
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keys = _index.pop(collection_name, _set_ctor())
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for k in keys:
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_store.pop(k, None)
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return len(keys)
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